Psych119F Midterm Study Guide
Psych119F Midterm Study Guide Psychology 119F
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This 137 page Study Guide was uploaded by Marissa Mayeda on Saturday January 31, 2015. The Study Guide belongs to Psychology 119F at University of California - Los Angeles taught by Blair in Winter2015. Since its upload, it has received 212 views. For similar materials see Neural Basis of Behavior in Psychlogy at University of California - Los Angeles.
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Mapping ITD onto spatial locations 126 4 o 42 126 s 3 Q Left 4 AZIMUTH gt Right Down ELEVATION Up 30 r center 39 3 W a o 0 on o 0 Co 0 0 httpwwwowpagescompicturesspeciesTytoaba1jpg 11quot II 30 0 30 Right 4 AZIMUTH Left 90 60 Owl Auditory Localization Pathways External nucleus Inferior colliculus T Lateral shell of central nucleus 4 little F Inferior COHICUIUS Intensin Core of central nucleus Inferior colliculus e l Anterior lateral lemniscal nucleus Posterior lateral 4 lemniscal nucleus Nucleus laminaris 4N Nucleus magnocellularis Audifory Iwae Inner ear Nucleus angularis Delay lines can convert a time code to a place code Jeffress Model Right Rightinput time code gt Right NM NL 39gt Iqgtc II pqp q r Output place code I I I I I abcde Leftinput time code llll Left NM Assume neurons AE are NL neurons and each receives input from NM neurons in the left amp right hemisphere The delay from each L or R input is different for each NL neuron so that each cell prefers a different ITD The sound s location determines when NM neurons will fire time code The sound s location determines which NL neurons will fire place code k ITD l lll R a xi x ttK J Does the mammalian brain work the same way Mammals can localize sounds too but not as well as owls Do they also have Jeffress delay lines in their brains Predator hears where prey is ocatedand prey hears where the predator is coming from httpwwwnaturecomnaturejournalv417n6886images417322af12jpg Mammalian ITD detector circuitry In mammals ITD detection occurs in a brainstem nucleus called the medial superior olive MSO which receives bilateral excitatory input from the ventral cochlear nucleus VCN Therefore MSO may be regarded as homologous with NL and VCN may be regarded as homologous with NM Left Ear Right Ear 1 is t x l W VCN contains two types of frequency tuned G phaselocking neurons spherical bushy cells GBC I SBCs and globular bushy cells SBCs But only I I Left VCN the SBCs project to the MSOso where do the 39 Right VCN GBCs project to I f Mammalian ITD detector circuitry GBC neurons send bilateral excitatory projections to the nucleus of the trapezoid My NTB The ipsilateral projection targets the lateral NTB and the contralateral projection targets the medial NTB The GBC synapse onto medial NTB neurons is a highly specialized synapse called the Calyx of Held Left Ear Right Ear quot1 Left MS Right J GBC Right VCN lJ I I I Left VCN 39 IJ LngL LNIE 39 quotLeft NTB Calyx of Held Largest synapse in mammalian brain Fastest and most reliable When GBC cell fires potential MTB will almost alwa a 0 e fire after Get sound inf fro otiier side of ralraacross midline to the othier ear before con rjalateral neuroris e e receive sound from itplslilateral ear T e a yx of e IS the argest astest an most re Ia e synapse In e entire mammalian brain Many synapses in the central nervous system are quite unreliable for example cortical glutamate boutons often have only 10 chance of releasing glutamate on each presynaptic action potential The Calyx of Held is 100 reliable and always fires the postsynaptic MNTB neurons with every action potential MNTB eriirteipal cell V y Ggmv mii nall eynaetie batith aw of Held Galyeiferdua eaten Mature Hemiewe ll Heureee ienee Feedforward inhibition from NTB LNTB neurons convey feedforward inhibitory inputs from the ipsilateral ear to MSO MNTB neurons convey feedforward inhbitory inputs from the contralateral ear to M50 The inhibitory neurotransmitter used at these synapses is glycine Left Ear Feed Forvyarol Ilnhibition I Ear nght ear InhlbIIS and excutes same area Excitator is de olarization and inhibitor means h er olarization I I I I I I I I I I I GBC Right VCN LJ Inhibitory gt Excitatory Left VCN LJ quotLeft NTB h ContralateraI inhibitory input Zfro ITD Summed EPSP amp IPSP is a precedes excitatory input awn biphasic PSP inh then exc IpsilateraI excitatory input Ax PSI Summed EPSP amp IPSP is a Vrest precedes eaeeltater y Input V monophasnc PSP exc only inhibitory V TOTAL Summed ipsi and contra solid line is sum of dotted lineEest inputs form a biphasic PS EPSP at zero ITD M50 1 ms IVISO essentially receives four inputs an ipsilateral excitatory and inhibitory input and a contralateral excitatory and Ear inhibitory input The Calyx of held is so fast that the contralateral inhibition is the FIRST input to arrive in M50 even though it travels the farthest At zero ITI the two excitatory inputs are about simultaneous Ipsi Contra Ear lpsiearlags V CONTRA rest TOTAL V rest big itd best Ipsi Ear Contra Ear Zero ITD l CONTRA l TOTAL 1ms Contra ear lags l CONTRA l E a g TOTAL sounds from ipsilateral cell do little way out of alignment no itd from ipsi is best When the sound in one ear is delayed both the EPSP and IPSP from that ear are shifted in time together Hence the effect is to shift the summed ipsilateral and summed contralateral PSPs against each other in time This causes the M50 neuron to produce a graded response that is maximal when the ipsi ear lags medium at zero ITD and minimal when the contra ear lags diff neurons prefer diff time delays whole range of lTDs owl experiencaBarrl diff neuron encode each poss ITD just say which neuron fired the mostwhat place of the brain fired the most and know where sound came from place code or sparse code EXPER ENCED RA GE 5iquot Hi HHF if 39Ji39i39li39 EggL 5 Elm rm l diff neurons prefer sounds from diff sources 0000000000 perfered itd curves ti39titi E39EIEI ght arl a lng ITDE E3 g Mammal all this happens at certain frequency lGE both use time code but in owl it is turned into a place code and in 93 EB mammal it is turned into a be ITD it rate code differs by it frequency I preference l1lll m3 l mgrL lg ITD l l EMH 200 us prefer neg itds on this side 0000000000 Sparse 0000000000 Code place code 0000000000 which firing most 0000000000 100 us know Where Sound 0 don39t know contraatera H Come from What neurons fire most fires most if 100 5 firing comparativelg9999 099 200 us EXPER ENCED it for mouse all the neurons prefer the same ITD ie some prefer 200 some prefer 200 but no one for Ops Vsome ITD preference greater 39 e head never hear itd of Zootig flecause head is so small if sound come from middle neurons that prefer 200 and neurons that prefer 200 fire exactly the same rate code or distributed code Kim I I I m Eli L 39 EH liming all neurons in mso prefer same itd long itd on contralateral side Distributed rate code Code if all fire equally sound is in the middle rate code how MUCH more some neurons firing than others Auditory Localization III Insects Crickets The common field cricket gryllus assimilis is a member of the insect order Orthoptera which also includes grasshoppers amp katydids All members of Orthoptera members have large hindlegs for jumping female crickets must be able to localize sound Female crickets have a long ovipositor used for laying their eggs after mating ovip os itor Male crickets have specialized Wings used for singing to attract females Phonotaxis by female crickets Phonotaxis is defined as movement taxis that is directed by sound phone Speaker 1 Speaker 2 different species same species able to go to the speaker of her own species V v 39 n39f39h r r 39 k 39039 399 g H An t 5 y 92quot a r f v a 39 quot quotquot 39 quot 9 U 39 r quot39o lt l h I Experimental Demonstration by Manfred Hartbauer Cricket Song Male crickets produce their song by rubbing their wings together a behavior called stridulation The chirping frequency varies with temperature You can use a cricket as a thermometer by counting the number of chirps in 15 seconds and adding 37 to estimate the temperature in degrees Farenheit The singing response can be triggered by a variety of different stimuli Aggressive song may be elicited by a male competitor Alarm song may be elicited by a predator to warn other crickets Courtship song is triggered by an internal stimulus the desire to mate ll Closing Opening Song Production The cricket s forewing is called the tegmen It is a transducer that converts mechanical energy into sound energy One wing is called the m and it is lined with a series of teeth The other wing is called the scraper or plectrum and it runs across the teeth to generate the cricket s song Syllables of the Cricket s Song A syllable is a single sound pulse produced by a single takes 30ms forwings to close once The carrier frequency is the rate in Hz at which the scraper strikes each successive tooth of the file spikes per second I39U l t s Chirps trills and sequences hirp lllill t39l w pulses antlnrp A a syllables in rapid succession separated from other chirps by a pause 39 gw39hm 39 The syllable repetition rate MW is the rate of syllable WNW Willa ma um generation In Hz during the chirp A triH is a very long chirp uninterrupted by a pause mtllaim39pulw 39liir39pnr rillul pain Tlpulsw A a IL 39239 j a a pattern of chirps and trills quot quot quotquotquotquotquot occurring in a particular order Carrier Frequency has pauses to allow crickets to open and close wings Simulated Cricket Song LIIP kHz able to localize sound at certain Hz frequency Syllable Repetition Rate 0 Hz 33 Hz 33 Hz 22 Hz quotll iE l l Tone Trilling Chlrpmg At 25 Hz Auditory localization She obeys a very simple rule Turn toward the sound and walk But how does she know which direction the sound is coming from y F W s f x 5 FEMALE I I I I I I I I I I I A Controller Ormia Fly Infra red camera Umdspea ker 9 Computer The Insect Treadmill The direction and speed of an insect s walking behavior can be measured using a clever device called an insect treadmill The insect is placed on top of a very lightweight ball which rotates beneath the animal s feet whenever it walks so that the insect remains centered on top of the ball The rotation of the ball is measured as the animal walks to record the speed and direction of walking Why 0 why dear fly Fly walks Mason AC Oshinsky ML Hoy RR2001 Nature 41068690 f0 rwa rd when speaker is in front of the treadmill Fly walks right when speaker is to the right Fly walks left when speaker is to the left When the ormia fly is on the treadmill the cricket song doesn t just stimulate the fly to walkthe fly walks TOWARD the sound of the cricket Left Fight OVERHEAD VIEW OF TREADIVIILL circle AND RECONSTRUCTED WALKING PATHS lines httph5ggphtcomX6JnoLOU4BY58686jszAAAAAAAAYDEy0108iV1u stmp918thumbthumbjpgimgmax800 httpevolutionberkeleyeduevolibraryimagesnewscricketparasitizedjpg When the female ormia fly reaches the male cricket she mounts him and inserts a needlelike ovipositor into his abdomen then injects her fertilized eggs into his body A few days later the male cricket is dead and he becomes food for the ormia fly larvae to feed on as they grow into adults Ormia fly s hearing organ phonotaxis walk toward or away from sound SIDE VIEW The ormia fly s hearing organ is located on the front of its thorax just behind its chin localize sound source and perform Heaan organ phonotaxi The hearing organ consists of a tympanum eardrum on each side numbered 1 amp 2 joined together at the midline by a flexible hinge called the intertympanal bridge numbered 3 The left and right tympani are only about 05 mm apart How long would it take for a sound to travel this distance ITD 90 z 15 us can39t measure this difference The intertympanal bridge physical couples the left and right tympani together so that oscillations of one tympanum can affect oscillations of the other strength of coupling affect how much second eardrum vibrates Interaural latency difference in neural responses Neural recordings of field potentials can be made from the fly s auditory nerve on one side either left or right Y39LDasbigasifitsheadwereas big as a mouse39s head When the speaker is positioned at 39atency difference Very 39arge 09 i90 azimuth the response in the nerve contralateral to the speaker is delayed by 100 us with respect to the response in the nerve ipsilateral to the speaker This interaural response difference is over 60X larger than g 220 the ITD of 15 us 8 5 SU J 39pSllale al F 391 r quot39l 39139quot f D U 5 50 39 I quotVquotquotquot g Cf 7 l 3 1531 a l latenc diff re e 50 m3 how muo ear Ier an th 3 H30 1 U 0 13 1 DO contralateral response IS the Ipsnateral respons p8 aker azimuth degrees B F Flexible hinge F2 The intertympanal bridge constrains the left t th f coupmgsreng IS and right tympani to almost always oscnllate In the mode is affected either bending or rocking mode and only very when ITD less than 15 us A Fulcrum rarely in intermediate mode When 39TD 0 g39d mOde bend at same time C Bending mode is an phase oscillation 0 phase offset without rigid connection weak copuling BendmgAm0de 1 Rocking mode is anti phase oscillation 180 Rocking mode 2 phase OffSEt rigid connection strong coupling two waves out of phase Intermediate mode is midphase oscillation u Intermediate other phase offsets mode 1 2 httpnelsonbeckmanillinoiseducoursesneuroe nOt purely OUt Of phase or In phase tholmodelsflyhearingpresternumearjpg ITD too small in fly measure IPD ears built so that it changes dep on where location of sound is 1396 13 i439r0Cking A The intertympanal bridge I 3 G 3 U co C 396 2 GE 9 bending 42 g 39 5quot c D G 8 8 pm Flexnble hinge Fun 25 t rocking a W F at iv 39Etr length of cycle is 200 us A FU Crum period Of 5 Khz tone iS ZOOHS comparable to ITD of owl what time arrive at one place or another O f a e P atSHZ at what pornt does one ear Response of the two tympanl d 3 Sslfh c vibrate m cricket carrier freq depends upon how stiffly they are coupled by the Bending them to nme 1 intertympanal bridge Stiff coupling A permits only the rocking mode Soft Rocking couping permits only the bending timing when one upor A down is ov 100us time interval different bridges different freq39s mode Medium coupling yields a phase offset that varies linearly with the Intermediate azimuth angle of the sound source A quot1000 12 httpnelsonbeckmanilinoiseducoursesneuroe iftimin of oscillations erfect then don39t measure time of arrival of sou 39 9 Prigidity of bridge is set wo deQ lyHQathgg rgs P anmearJpg mode 2 red is cricket ganglionic nervous syste similar from brainsterrfjglgy C C to spinal cord Spiracle massive ganglia in flea Iikeourbrain f 3 l The cricket s ears are in it s legs front knees The tympanum eardrum is located just below the I I quot quotQquot5f H Em knee on the rear surface of x i J l the foreleg III e X M tmacheal kg Tympanum The tympanum connects to r J Tube an airfilled channel called the tracheal tube which Sound waves that Vibrate the tympanum runs through the leg and can reach it by two different routes mm the bOdV 1 They can strike the outer tympanic The tracheal tube connects SUI fEICC diI39GCtly ffOIIl thC OUtSidC air to a hole in the side of the 2 They can strike the inner tympanic body called the spiracle surfaCC tl aVCIiIlg into tha SpiIaCIBS outer and inner circles of the tympanum on either side and through the tracheal tube PressureGradient Ears Movement of the tympanum is determined by a pressure gradient difference in air density between the inner and outer surface Movement of the tympanum triggers action potentials in auditory nerve fibers that convey the signal to the prothoracic ganglion tie Iramite quot To prothoracic I Jr i i r i ll l i i F L 7 L i y l r y or l l L L Lh lL i L I r Ll I ll L11 L F J 7 Til l7ng 7 7r 7 l7 7 LjL 77 77 TL 7D 7 7 7 J 17 L 7L 1 l 7 7 74 lg lil7 7L Wavelength of Sound physical distance between successive pulses of compressed air emanating from the sound SOUI CB The wavelength of a sound is the ideal size of speaker is the size of the wavelength it is trying to transmit if sound travel 1000 ft per sec wavelength in 1ms iiiFifi I39I39I39II39III slower oscillations Low frequency sounds have longer wavelengths than higher Wavelength of Sound frequency sounds because the time delay and therefore the spatial distance between successive spacings is longer Two Routes to the Tympanum sound hit outer tympanum direct and enters spiracle and strike the inner surface indirect Phase Offset don39t want them to hit at same time to allow tympanum to move Indirect Route Sound enters the spiraole and travels through the tracheal tube to strike the inner surface of the tympanum longer route Direct Route Sound travels through the air and strikes the outer surface of the tympanum OUTER SURFACE cricket has circles of compressed air surrounding its body 6cm apart TYMPANUM INNER SURFACE Indirect route is longer than the direct route The exact difference in the distance between the direct and indirect route is critical for determining the phase relationship between the sound waves hitting the surfaces What would happen if the indirect route was exactly one wavelength longer than the direct route How about half a wavelength 35 cm half a wavelength or half a wavelength plus a wavelength etc C DC 3 Phase Cancellation Summing in phase vs antiphase waves PERFECTLY NPHASE WAVES CONSTRUCTIVE INTERFERENCE fully rarefied on one side so when compressed on one side no resistance PERFECTLY ANTIPHASE WAVES gt DESTRUCTIVE INTERFERENCE doesn39t move at all because both sides compressed at the same time Summing partially phaseshifted waves cricket not quite big enough to fit in 35 in so don39t get a huge oscillation but Close so get pretty good oscillation NEARLY NPHASE WAVES gt CONSTRUCTIVE INTERFERENCE I39 I39 39 I39 I I I I I I I I I PERFECTLY ANTIPHASE WAVES gt DESTRUCTIVE INTERFERENCE Interaural Intensity Differences Song coming from one side of the female constructively interferes With itself at the ipsilateral tympanum same side as sound source and destructively interferes With itself at the contralateral tympanum opposite side The phase cancellation causes an interaural intensity difference IID an asymmetry in the vibration of the left versus right tympanum female cricket hears the song tympani work together on side closer to the ound ore phase on side sound is coming constructive male cricket generates 3 interference less phase on 5 kHz carrler at right opposite side frequency tympanum on right side WW 3 essentially sound louder f f 39 quot Z on side sound is coming I 39 39 39 39 fieStrucuve from Interference gs at left tympanum 4 always hit all four surfaces omega neuron stimulated by auditory nerve neuron on other side m q release inhibitory output on omega p I I n h i b i O n f 39 mi tin J trying to turn each other off theone thatwinds it he one that Q V vI gets the louder sound The cricket s auditory nerve uquot 39 4 p 9 e carries action potentials from the ear into the prothora01c ganglion l CL lCl3939t39 v 39 1 39 ll i m g Two sets of omega neurons Auditui39x tittirupilc L unnucliu 39 age these small diffs can excite one onthe Slde and one W one omega neuron more on the right side are found in than otherto inhibitshut off other one the prothoraac ganglion strengthening itself to fire even more Confnildfuml W 0 2 neurons receive excitatory lI l J I I I input from the ipsilateral ear quotquot quot quot and send inhibitory output to contralateral 2 neurons prfIlcml contrast inhancement small diffs in input result in large diffs in neural activity Thus left and right 2 neurons reciprocally inhibit one another This results in a Winnertake 99 both fly and cricket too small to fix auditory localiza n prob all WthIll fly smaller solutioncouple tympani to make39 era r lt39 in am 1 168 t 6 IntCI aura LBft Ear diffs mimicks that of animal with bigger head 1th Rag p intensity difference cricket also artificially make capitalize on phase for both Owl Auditory Localization Pathways External nucleus Inferior colliculus T Lateral shell of central nucleus 4 little F Inferior COHICUIUS Intensin Core of central nucleus Inferior colliculus e l Anterior lateral lemniscal nucleus Posterior lateral 4 lemniscal nucleus Nucleus laminaris 4N Nucleus magnocellularis Audifory Iwae Inner ear Nucleus angularis Owl Auditory Localization Pathways External nucleus Inferior colliculus I Time F Lateral shell of central nucleus Inferior colliculus Core of central nucleus Inferior colliculus Anterior lateral lemniscol nucleus Convergent input from ITD amp ILD tuned neurons Intensity ITD tuned neurons Posterior lateral lemniscol nucleus Nucleus laminaris I Nucleus magnocellularis Nucleus angularis ILDtuned neurons Auditory I erve Inner ear Spatially Tuned Neurons Neurons in ICC more specifically in its lateral shell respond selectively to sounds in a particular region of space The region of space preferred by the neuron is called the cell s receptive field uopeAala punog 30 R 20 R 10 R 0 10 L Sound azimuth How do they do it 0 Each ICC shell neuron has both an ITD tuning preference and an ILD tuning preference The neuron can only be excited by sounds from sources that match both the preferred ITD and ILD The preferred sound location is derived by combining the preferred ITD xaxis with the preferred Spacespecific neurons are tuned to respond selectively to preferred interaural level differences Spacespecific neurons are tuned to respond selectively to preferred interaural time delays ILD yaxis 100 P 20 o 0 ll 39 3 V c quota E 1 g 2quot u g l quot 1 o l 1 4 39 o 30 so I 39 0 1m 1 L ITD Percent of total spikes 0 w 20 Vector and matrices Of neurons 2D map formed from elevation and azimuth ILD selective cells can be ILD SEIECt39Ve neurOnS In conceptualized as a row vector of posterior lateral lemniscus neurons near eaCh other prefer sounds 8 from similar locations far away prefer sounds come from diff locations in space topographic map due to centel SdrEmdSlnglili neurons that each prefer different lLDs with adjacent neurons in the row preferring similar lLDs ITD selective cells can be conceptualized as a column vector of neurons that each prefer o 150 different ITDs with adjacent 9 lt35 neurons in the column preferring 39 similar ITDs Dorsoventral axis Locationselective cells can be conceptualized as a 2D matrix or sheet of neurons that each prefer different sound locations with adjacent neurons in the sheet preferring similar sound source locations CenterSurround Inhibition inhibit neurons in near surround example of lateral inhibition process contribute to contrast enhancement magnify differences lLD selective neurons in posterior lateral lemnlscus Each ICC Ce reciprocally inhibits its surrounding neighbors whichever one get a little more excitation will quotwin the fightquot and inhibit those Excitatory 65 o O 0 around it 29 center of 9 ICC cell 00 92 Q receDtive 2 0 9 gt quotll 3 field O 15 2 lnthItory Surround 0f ICC Location selective Ce recept39ve neurons in ICC shell field ILD selective neurons ICC neurons are still frequency specific so there are many copies of the spatial map in ICC different neurons copied many times to represent sounds of diff frequencies sheets prefer certain frequencies neurons prefer certain Frequency invariance in ICX Convergent input from spatially tuned neurons Convergent input from ITD amp ILD tuned neurons 7 with differing frequency preferences frequency invariant Time Lateral shell of central nucleus I Intensin not sensmve to changes in I Inferior colllculus frequency Core of central nucleus I I I Inferior colliculus ILD path IS frequency Invariant Anterior lateral lemniscal nucleus Posterior lateral l lemniscal nucleus ITD tuned Nucleus laminarls neurons Nucleus ILD tuned Nucleus angularls magnocellularls Auditory neurons Nerv Inner ear send convergent projections to ICX ICX only needs one of the inputs I not all three to fire frequency invariant representation after frequency variant representation throw away frequency variance because just need to tell neck muscles to turn and face the stimulus only require location not frequency of sound 150 15D 150 150 150 ICX neurons are frequency invariant neurons are freq invariant and modality invariant respond to sound or visual Convergent input from stimuli as lon location spatially tuned auditory amp visual neurons 397 Optic Tectum Visual System Convergent input from spatially tuned neurons 7 with differing frequency freq invariant Convergent input from ITD amp lLD tuned neurons preferences fie G Si fiVB Lateral shell of central nucleus qsfime liitensm39 F Inferior colliculus Core of central nucleus Inferior colliculus 6 Anterior lateral lemniscal nucleus Posterior lateral l lemniscal nucleus ITD tuned Nucleus laminaris neurons l Nucleus lLD tuned Nucleus angularis magnocellularis 1 de neu rons I erve Inner ear o The spacespecific neurons in the Visual SyStem ICX nucleus of inferior colliculus Visual map prOJect to the optic tectum 0 Neurons in the optic tectum have a a a a spatial receptive fields for both auditory and visualstimuliand a a a these multimodal receptive fields are normally aligned with one another ICX Optic Tectum Auditory map Audiovisual map Constructing invariant representations 0 Optic tectum Modality visualauditory invariant representation of location 0 CX Frequency but not modality invariant representation of location 0 Amplitude but not frequency invariant representation of location ICC has freq dependent map from azimuth A Normal Visual input from retina and tortbrain Optic tectum ICC U 20 40 azimuth To auditory thalamus a 0 i I t Ascending TD information in freq twncyspwi tic channels udituri39 N hlhln UdJI space map PM map Prism Studies 0 This young owl is wearing a pair of prism lenses These lenses displace the visual world by 23 degrees but sounds are the same introduce misalignment of visual and auditory input 0 How does wearing prism lenses affect the animal s orienting responses to auditory versus visual stimuli ll l attribute simultaneous stimuli to be the same thing look to where stimuli it would be hear it rlll as if it comes from where he is I seeing it through prism l m visual targets ln Before prisms Day 1 R23 prisms auditory response unaffected but visual response is messed up Visual Fe Auditory 1 look at target 390 511011111 l O O llll L111 1 1 3H gt lll Prisms removed oppos1te still confused adaptation doesn39t immediately fix itself will fix itself after long period of time 0 1 i 1 l O nll O 0 Day 42 l ill 11 Rlll Before wearing prisms the owl s gaze accurately locates both auditory and On the first day of wearing prisms orientation to a visual cue is offset by the prisms of course but auditory localization is normal After 42 days of wearing prisms the auditory localization has shifted to match the visual Offset THIS ONLY HAPPENS IN YOUNG OWLS When the prisms are removed the shift persists Prism Experience Shifts Receptive Field Alignment A Normal B Immediate effect C After 8 weeks of of prisms prism experience match cells tha espond to sound and cells that respond to visual stimuli A Before prisms optic tectum neurons have overlapping auditory and visual receptive fields 0 B When prisms are put on the alignment immediately shifts C Over time the auditory receptive field migrates to the new location of the visual receptive fieldlearning quotisa39waysiheauditorythat changes Shift in ITD preference accompanies shift in receptive field g 0 Normal W Prisms non zero itd The prisms cause a shift in the 80 azimuth of the receptive field 60 for ICX and optic tectum neurons but not NL or ICC 3 0 neurons as we shall see 395 715 l lm mfquot 73915 40 0 Since azimuth is encoded by ITD it is expected that the shift should be accompanied by a change the cell s preferred ITD This is exactly what happens over time after wearing prisms as shown in the graphs at right Best TD 5 3O 20 L10 0 R10 20 30 Visual receptive eld azimuth deg Two Types of Glutamate Receptors AM PA amp NMDA must have postsynaptic depolarization to repel Mg2 with positive inner charge releasing NMDA receptor so it can bind to glutamate and open to allow ions to flow throu channel PRE Blocked by Mg2 U Very young owl with immature AV map Optic Tectum Retina don39t respond to visual ICX give auditory input to optic tectum and receive input from ICC convergent info from diff neurons that prefer diff frequencies 4 kHz 6 kHz 8 kHz Q 0 Q Q o o I 0 o 0 O o 0 y 0 o o o o 0 0 0 0 0 0 c 0 0 0 0 0 0000000000 In a very young owl with an immature AV map the ICX neuron that gets input from the 0 optic tectum neuron visual field center is weakly excited by ICC neurons that respond to various ITDs Optic tectum neuron 0 without prisms ICX axon neurOn m responds growth ch dendrite weakly to factors 39 many ITDs AMPA NMDA ICX soma weak A weak Synapse synapse synapse lt gt 639 gt weak To survive pruning ICC axons must ICC ICC receive growth ICC axon axon factors from the axon 3950 S O 5 postsynaptic ICX 50 5 ITD ITD ce ITD flash with no sound When a Silent Visual stimulus is presented at 0 center of visual field azimuth the optic tectum neuron fires and triggers a small subthreshold EPSP in the postsynaptic ICX dendrne Optic tectum neuron 0 without prisms ICX axon Presynaptic action potential triggers glutamate release from terminal ICX neuron responds growth g SEB WeShO39FCX dendrite weakly to fact0rs 39 0 many ITDs 39 39 39 AMPA NMDA ICX soma weak A weak weak Synapse synapse synapse lt gt 639 gt ICC don39t respond to visua ICC stimulus so nothing occurs ICC ICC axon here axon axon 50 us 0 us 50 us ITD ITD ITD Optic tectum neuron 0 ICX axon ICX neuron without prisms nothing occur in opti tectum synapse responds growth sound without flash When an invisible auditory stimulus is presented at 0 us ITD center of azimuth the ICC axon at 0 us fires and triggers a small subthreshold EPSP in the postsynaptic ICX spine weakly to factors many lTDs ICX soma weak synapse 6399 69 ICC axon 50 us ITD weak synapse o A ICC axon 0 us ITD ICX dendrite O O 6 E ESP EPSP is again subthreshold AIVIPA NMDA i i weak A synapse 6399 69 gt Only AM PARs are openedinthe ICC postsynaptic spine axon because NIVIDARs 50 MS remain blocked by ITD Mg ions axon neuron 0 without prisms ICX neuron m responds growth weakly to factors Optic tectum When a visual and auditory stimulus both occur together at the center of azimuth summation of optic tectum and ICC inputs causes a large EPSP to occur in the ICX spine that is postsynaptic to the 0 us ICC axon but not in other many ITDs ICX soma weak synapse 6 9 69 D 69 CC axon 50 us ITD weak synapse only simultaneous excitation of optic teotu and ice neurons can pop off M92 allow glutarn to bind to NMDA re ptor and allow flow of i0 through channel e CC axon 0 us ITD Spines click and a flash ICX dendrite O O 0 weak A synapse The large summed EPSP depolarizes the spine enough to open NIVIDARs by removing the Mg block 6399 gt CC axon 50 us ITD Optic tectum ICX axon neuron 0 ICX neuron without prisms Opening of NMDA receptors allows calcium into the postsynaptic cell which may trigger activation of transcription factors in the nucleus of the ICX neuron in developing nervous system have connections that will be pruned if it is not experiencing growth responds Transcription growth m factors weakly to factors many ITDs ICX soma weak synapse 6399 69 ICC axon 50 us ITD ICX dendrite weak 39 Weak A synapse 39 3 synapse o 0 quot0 69 69 CorL 9 A NMDA calcium also cc triggers release of cc axon growth factors axon 0 MS from the ICX spine 50 us no onto the ICC axon TD terminal Growth factors trigger branching and growth of new axons from the ICC cells at 0 us ITD causing the formation of new quotprobationaryquot Optic tectum neuron 0 without prisms ICX axon synapses ICX neuron m responds growth ch dendrite wea to 0 factors 39 0 many ITDs o c ICX soma New spine weak H weak A Stro synapse synapse synapse C j e 69 C 969 New synapses ICC ICC ICC initiay tend to ICC have a hIgher axon axon axon f axon 50 us 0 us 0 us KEFSthon 0t 50 us ITD ITD ITD recep quot5 ITD than old synapses Optic tectum neuron 0 without prisms With time and repeated use the new synapses get off probation ICX axon ICX neuron responds m EFOWth ICX dendrite weakly to factors many ITDs ICX soma weak Stro synapse synapse synapse C j e 69 C 969 Eventually the weak ICC ICC ICC AM PANMDA ratio ICC axon axon axon reverts to norma axon 50 us 0 us 0 us 50 us ITD ITD ITD ITD strengthened input from ICC Young owl before prisms tolcx dotted lines are weaker synapses bold lines are ICC ICX Optic Visual 2222333 Tectu m System 09 every neuron that prefers certain ITD will get input from neurons that prefer same ITD wire circuits Rf J j messed up circuits two inputs to ICX from Optic Tectum and I m m e d i r p S m SICC were once simultaneously activated but no longer ICC ICX Optic Visual Tectum System l W x Z f changed coincidence relationships With prisms the optic tectum neuron that used to fire for 0 azimuth will now fire for 20 azimuth Hence for an auditoryvisual stimulus this cell will now fire simultaneously with 50 us ICC cells not 0 us cells Optic tectum neuron QI 20 without prisms ICX axon ICX neuron m responds growth ch dendrite factors weakly to many ITDs New spine H ICX soma weak Strong synapse Strong synapse synapse C j G9 69 69 lt69 69 69gt o o o e ICC CC CC CC CC axon axon axon axon axon 50 us 0 us 0 us 50 us 50 us ITD ITD ITD ITD ITD New axons from ICC to ICX Shifted axons from ICC appear in ICX after 8 weeks of prism expenence BEFORE PRISMS AFTER PRISMS now there are a lot of projections from ICC to ICX ROStral in a new shifted location physically see growth of new Learnedaxons Injection Site 4 Normal no longer confused map rewired itself 39 X neuron has changed which ICC 8 e r p S m eurons it gets inputs from preferred ITD changed to match that of Optic ICC ICX Optic TeVisual Tectum System x 77 x 77 7f7 C quot i l l l lkii l l 6 91 lOCa Iion Where changes occur are between ICC and ICX doesn39t occur before ICC Why are old connections weakerOCCUIlS where frequency invariance occurs with prisms grow strong excitatory connection and weak inhibitory connection strengthens to inhibit the excitation of normal ICC result in net 0 excitation cancels out prior to prisms have a little inhibition and high excitation from CC so overall get excitation h Minimal From optic tectum Mmm l From optic tectum lTl e llnretrppe iee mg llrj ucttiiwe l 1 signal 1 Ellglrlll lateral inhibition small inhibition acts as breaks to help system work in safely and GABA 7 Effective39y interneuron in ICX i lLernittl llTlIlre Fiure E theme in ipetnepel eepneetit ity that eeeeptpanyr th eequieitiep Ii we neeIr irnep pi l39lEt in the tee a Nmtlal l1 etter riiern expedient Spheres rpr excitetm jr blue and ilrlhilztiiterpr litleek lliIEtlmiliE in the litilt Benneetine eeiiipeting irrn litre er teturn irlelmeljire and irern lit l t ptretell Tle end leeppetl lllEle are rereeenttl wee eerpieireleee lit SiEE at when iiptlieetee the erep pt lit ennetine 1 qtziitetry eennetin iiphipitryr eennetipn Te pi ipepretrenetpittr receptre that eupppn eerne Ii titre penneeljiepe er indiicettl it temper lily lilllille I3 pee Immediately after prisms removed visual system now working normally again but auditory is altered already has old connections as adult can hunt with or without prim ICC ICX Optic Visual Tectum System I 09 NF w now confused again in opposite direction account for reversal of initial mismatch of visual and auditory responses Several days after prisms removed ICC ICX Optic Visual gt Te ctu m Syste m 0 4 kHz Connectivity changes during prism adaptation A Normal Visualiryptllfrim CC 35in 2 maximum from ICC to ICX are To auditory thalamus topographically organized to form spatial regions encoding similar ITDs Ascending TD in formation in freq uvncyspu i fic channels When juvenile owls wear 433333 tiltTm prisms their developing nervous systems form a new 8 0pm quot t lf39tl39lSEES set of shifted topographic ICC mm 3quot 4 Wmquot connections the old 39 5 connections are weakened but not eliminated Sensitive Period for Prism Adaptation A Juvenile B Adult adjustment adjustment Man best TD relative to normal us 40 L L 50 L l l 1 ll 4 n 20 40 N gt180 Time with prisms days 0 A Juvenile owls show prism adaptation and then recovery after prism removal recovery not shown 0 B Normal adults show no prism adaptation but those that were adapted as juveniles can readapt as adults to the same displacement that they experienced as juveniles When the owl reaches sexual maturity ICC axons that have not received enough growth factor die away pruning Optic tectum neuron 20 without prisms ICX axon ICX neuron responds m weakly to many ITDs ICX dendrite ICX soma A A l AHA A Strong synapse Strong synapse G9 69 69 lt69 69 69gt o o o e ICC CC CC CC CC axon axon axon axon axon 50 us 0 us 0 us 50 us 50 us ITD ITD ITD ITD ITD Optic tectum neuron 20 without prisms At this point plasticity of the AV map is no longer possible ICX axon ICX neuron responds m weakly to many ITDs ICX dendrite ICX soma A l AHA A Strong synapse Strong synapse owl can no longer C j perform this adaptation 69 l l 69 l l 69 l 69 G9 G9 ICC ICC CC CC axon axon axon axon 0 ps 0 ps 50 ps 50 ps ITD ITD ITD ITD Critical periods A critical period is a restricted time window during early life when certain processes of brain development MUST occur if they are to occur at all Critical periods or less restrictive sensitive periods have been shown to exist for development of Language Sensory systems visual auditory vestibular Motor skills Social skills Echolocation in Bats Bats Chiroptera Bats are the only flying mammals Bats are similar to primates their five wing bones are homologous with the five fingers of the primate hand There are almost 1000 different species of bats in two suborders megoptera 150 species and microptera 800 species Microptera bats navigate by echolocation The Behavior Echolocation In the 1700 s Lazarro Spallanzani discovered that bats could navigate in complete darkness but owls could not Spallanzani found that bat navigation was severely impaired when their ears were plugged In 1938 Donald Griffin and GW Pearce discovered that bats emit ultrasonic pulses during flight Griffin found that when the bat was prevented from calling by taping its mouth shut its navigation was impaired as if ears were plugged Griffin correctly concluded that bats navigate by echolocation Hearing Frequency Ranges ANIMAL Human Dog Cat COW Rat Bat Elephant Porpoise Goldfish parakeet Chicken FREQUENCY RANGE Hz 2020000 6745000 45 64000 23 35000 ZOO 76000 2000110000 1612000 75 150000 20 3000 200 8500 1252000 Catching Prey in Flight Griffin found that bats could learn to catch mealworms tossed in the air Bats easily learned to discriminate the mealworms from small plastic disks pursuing only the mealworms and not the disks catch prey in midlflight MWI griffin test if they could I what they were catching could tell difference between mealworm and plastic dummy disk can discriminate between objects with sound Call Rate During Four Stages of Pursuit amp Capture generate calls pulse and it bounces off thing then comes back to its ear the echoes Terminal the echo from prey animal 7 calls 102 10 calls per second 8 9 l I I l l as close in on prey call rate goes way up l I l 39 39 V 39 I the bat cant see until echoes come back to It At 39 7 in f as echoes come back get brief flash of surroundings Ix 0 I I39M faster frame rate means fewer gaps can quotseequot surroundings longed 0 rate increase closer to prey to accurately grab it Echolocation Problems the brain must solve LOCALIZATION PROBLEMS Which direction is the target How far away is the target How is the target moving DISCRIMINATION PROBLEMS How big is the target What is the target Food Echolocation Problems the brain must solve LOCALIZATION PROBLEMS Which direction is the target How far away is the target How is the target moving DISCRIMINATION PROBLEMS How big is the target What is the target Food ITD and ILD tell you about location Elevation amp Azimuth Like the barn owl bats use the ILD of the echo to determine the elevation of a target object and ITD to determine the azimuth Unlike the barn owl bats can cock their ears up and down instead of having permanently cocked ears variable ILD Unlike the barn owl bats generate the sound they are listening to barn owls listen for sounds generated by their prey Azimuthal angle Elevation Echolocation Problems the brain must solve LOCALIZATION PROBLEMS Which direction is the target How far away is the target How is the target moving DISCRIMINATION PROBLEMS How big is the target What is the target Food get loud echo either from small object close up or large object far away Angular Size amp Absolute Size The angular size or subtended angle of an object can be measured by the amplitude loudness of the echo louder echoes correspond to larger angular sizes The object s absolute size actual size can be determined by combining information about the angular size amplitude and distance pulseecho delay of the object l l I I A I Subtcnded f 1 angle plus 1 4 distance Ila14 f 39 1 7 1 7 I I a lute 512 I I Subtended angle structure of bat calls usually combine FM versus CF Calls FM broadband frequency modulated M fllllllllnlllllllllll llll CF constant frequency WWWw T imc ll Ultrasonic Bat Calls Some bats emit very short lt 5 ms frequencymodulated FM pulses referred to as an FM sweep Other bats emit longer 530 ms constant frequency CF pulses Many bats use a combination of FM and CF calls CFFM bats As we shall see FM and CF calls serve different purposes A Eptcsicus gt 100 u 80 5 1 50 Hum 53 5 40 K l quotquotquotquot39 3quot 20 quot39 Illlll f 1 1 1 1 1 1 1 1 L 1 1 1 1 1 1 B Rhinnluplms h 100 3 quot 39 r rm39n39vm J 1313 40 FM component 5 2 f l5 component 1 1 1 1 1 1 1 1 1 1 1 1 1 06 05 04 03 02 01 0 Time to prey capture 5 T Capture Echolocation Problems the brain must solve LOCALIZATION PROBLEMS Which direction is the target How far away is the target How is the target moving DISCRIMINATION PROBLEMS How big is the target What is the target Food Distance Discrimination Sound travels at a constant velocity so distant or proximal objects produce a long or short delay respectively between the emitted pulse and returning echo James Simmons trained bats to retrieve food by flying to the most distant of two platforms with triangular targets In this way he used instrumental conditioning as a tool for investigating sensory discrimination put bats in chamber that absorb echoes bat on one of changing on perch and two platforms in front of it simmons would shift target to make on closer bat would could echo from both the one that was closer would have an echo fas 7quot learn platform that is f her away have food Sound rcflective target k Choice platforms The PulseEcho Delay measures Distance When the triangular targets were replaced with equidistant speakers that played the bat s call back at different time delays in an anechoic chamber trained bats chose the speaker with the longer time delay Bats discriminated pulseecho delays differing by as little as 60 us which corresponds to differences in distance of about 1015 mm 39 HOW DOES THE BAT S BRAIN MEASURE PULSEECHO DELAYS then get rid of reflective mic get its call speakers play it back one speaker plays it later pulse echo delay is the only thing that changes bat still fly to speaker with longer pulse echo delay pulse echo delay is how bats locate object Phantom target 39 Delay circuits Inferior Colliculus Neurons exhibit invariant responses to pulse amp echo Inferior colliculus neurons fire action potentials that are precisely timelocked to the onset of the pulse the echo or both C e 6 each row is p e p p p pulse echo I tria 86 ms 69 ms 54 ms 39 ms g i la 395 3 2 The timing of these actIon g i igneuronsrspnpotentials remains constant e l 39 I 1 5 3 to pulse echoregardless of how loud the pulse a g markt39me of and echo are so these responses zndB s i i 5 3 pulse and p a l r g F gecho are amplitude Invariant e52dB i l 39 l H 3 g a i i 3 ii By marking the exact time of 82 f 1 s 39 each pulse and echo these I e52dB f c 3 y neurons may allow precise measurement of the pulseecho FM 03118 31 6 b61161 than CF 03113 delay for distance calculations for measuring distance Why Firing response percent max IE 5E PulseEcho Tuning Curves measure delay of Fm of pulse and FM of echo tuning curves where neuronsThe area Of the bat L sire moreforspecmc pU39Se nEOCOrtEX COntalnS neurOnS e h d I l t hgfaijYTEJfoif y 0 that do not respond to a call really i cortex have topograpgirone or echo alone map of me to distance to my pr pace code Only respOnd t0 3 pUISE e 1 followed by an echo n I I i I vJ E H Each neuron prefers a neurons tuned for diff Spemfic DUIseEChO dEIayI QU39SeeChOde39ayS corresponding to a specific those closer together 39 in cortex tuned distance the cell s receptive Simi39ar39y Neurons preferring different pulseecho delays are topographicallv arranged on the cortical surface Harmonics 3RD HARMONIC A vibrating object generates oscillations at multiple harmonic frequencies 2ND HARMONIC The fundamental frequency or 1St harmonic is the slowest oscillation 1ST HARMONIC The second harmonic is twice mm the fundamental frequency The third harmonic is three times the fundamental gt frequency etc Time Frequency kHz 120 30 The CFFM call of the mustached bat H 2 CFZ FMZ H h 39 1 CF FMI 0 10 20 30 Time ms The fundamental frequency H1 of the moustached bat s CF call is about 30 kHz but H2 H3 and bat uses harmonics in sound The mustached bat is a CFFIVI bat The bat s call consists of four frequency harmonics H2 is loudest then H3 H4 and H1 The brain uses different components of the call to extract different kinds of informtaation bounces back in echo to tell what the sound bounced off of are emitted as well PE delay is measured between FM components broadband width sound due to many different frequencies due to FM 39 Pullse I 39 120 39 H4 FM4 x 39 39 39 39 It 90 39 I CF3 FM3 395 gt U 60 H quotquotquotquot s g 2 CFZ FMZ h F 30 H 39 quot quot x l CFI FM1 39 b Delay 0 1 l 1 I 0 10 20 30 Time ms The fundamental frequency H1 of the moustached bat s CF call is about 30 kHz but H2 H3 and H4 are emitted as well 5395 all sounds emitted from bat come back The CF component is not good for measuring PE delay because it lasts a long time would you be able to measure an echo by whistling a long note The FM component is not good for measuring PE delay because it lasts a short time would you be able to measure an echo by clapping your hands Since the FM component covers many frequencies it is also good for something else Echolocation Problems the brain must solve LOCALIZATION PROBLEMS Which direction is the target How far away is the target How is the target moving DISCRIMINATION PROBLEMS How big is the target What is the target Food Same note different instruments When an A440 note 440 Hz tone is played on a piano or violin the note is the sameso why do they sound different Because the loudnesses of the harmonics differ re39aiiveampoidi harmomcs cause ability to differentiate Different instruments contain different harmonics 3RD HARMONIC 3RD HARMONIC VVV VWV N generates more 2nd harmonic 2ND HARMONIC 2ND HARMONIC geg a rates more 3rd IST HARM ONIC 15T HARMAQNIQ i W WVVV a i W i i quot i i i i i u 4 i i i r i i i i 4 i ii i M a I 7 tr 1 ii i ii quot 7 77 4 eA 4 J Time Time bats use harmonic content to distinguish between diff animals objects Harmonic reflection All harmonics go out but they don t all come back 120 H4 120 A 90 n3 A 90 3 2 3 2 g 60 H g 60 30 disk reflect 2nd harmonic better worm reflect 3rd better The Griffin experiment Echo from mealworm Echo from plastic dlsk see that echo comes Pullse 5 back at different frequency 120 H4 FM best to measure 120 CF4 FM4 echo pulse delay A 90 H n A 90 g 3 CF3 FM3 g E 39 E 39 60 H quotquotquotquot quotFM 60 2 CF 2 E 2 E 30 bat measure delay 1st harmonic of pulse onics of echo and multiple h l armon respond to one harmonic of pulse followed by diff harmonic of echo ic selectivit in FlVIFIVI Cortex pulse harmoni is always 1st harmonic quiet so can39t hear other bats39 1st harmonic The FMFM area of the cortex contains neurons that do not respond to a call alone or echo alone They only respond to an FMl call followed by an FMZ or FM3 echo Furthermore each neuron prefers a specific pulseecho delay corresponding to a specific distance the cell s receptive field Neurons preferring different pulseecho delays are topographicallv arranged a little radar screen in the brain E Frequency 90 60 30 kHz Frequency kHz 90 F Echo FM3 mealworm FESpOHSIVe Pulse quot FM 1 I I I I disk responsive 0 10 20 30 Time ms Echo Pulse FM PM I I The pulseecho delay axis encodes distance to the target 0 I 210 310 while the harmonic axis encodes identity of the target Time ms Echolocation Problems the brain must solve LOCALIZATION PROBLEMS Which direction is the target How far away is the target How is the target moving DISCRIMINATION PROBLEMS How big is the target What is the target Food harmonicsofechohelpfunormis Velocity Bats hunt on the wing and their prey is usually moving as they pursue it so they need to measure velocity of the target They do this by using the doppler shift the perceived change in frequency of a sound emitted by a moving object Doppler shift quot quot I and flutter Tune delay the way the pitch of object is perceived to change perception 0f pitCh 03999 on hOW air iS compressing or rarefying frequency of sound not actually changing just affected by way object is moving relativeD p p I S h to you 0 e r I Stationary Moving Away Moving Toward Recall that our perception of pitch depends upon the frequency of the sound wave If the speed at which sound waves are traveling is increased then successive compression waves will hit our ears more frequently increasing the perceived pitch If the speed of sound waves it decreased it will lower the perceived pitch A sound source that is moving toward us adds a constant velocity to the speed of sound and a sound source moving away from us subtracts a constant velocity when move closer while still generating sound speed of object moves next cycle of sound way physically closer to previous cycle of B the numbers if moving away cause cycles to be farther part causing frequency to be lower sounds lower Example when a plane approaches you it sounds high because it is moving towards you but when passes you it sounds lower Afis the change in frequency Doppler shift AU Av is the velocity difference between source amp receiver Af f0 positive for approaching negative for receding c is the speed velocity of sound this would be more noticeable at gh frequency easier for bats to measure Doppler effect f0 395 the frequency Of the Source Sound because their frequency is so high even small velocity make big difference a Elppplpr Effiaipt flililiiii Ei in 1 a Elppplspr Effeet F ppel in l i l r39 mm lm pleas I 39l39 t mpquotle sales a 39j 5 Li 1 l j 5 L quot i te iziIrllnu eiv 32 LilI39lllraulflf g l EVIL Efflu httpuploadwikimediaorgwikipediacommonsthumb990DoppIerfrequenzgif250pxDopplerfrequenzgif Doppler Shift Compensation As bats close in on a target they alter the frequency of their call so that the dopplershifted echo maintains a constant frequency This dopplershift compensation is performed only for approaching objects not receding objects Frequency kHz p 4 Forward swing Backward swing Echo Frequency do bats 62 Doppler shift by 9 pendulum swing d0 thlS have bat sit in front of pendulum move I toward and away from bat 61 J when object move towards bat bat 1 es g equ y owers frequency of call to cancel doppler 2 3 effect to keep frequency of echo constant 3 when object move away from bat doesn39t 0 Sounds emitted 1 3 5 H h b k by abat during 3 02 compensate a ow ec o to come ac five swings lower when bat closer on prey that IS when 59 I l I 1 doppler shift is upward can measure 0 1 2 3 velocity of prey with doppler shift Time 5 how much do i have to lower my call frequency to keep echo frequency constant this tells bat velocity of its prey just like we have fovea in eye that is very sensitive acoustic fovea most sensitive to frequencies in middle of 2nd harmonic mostsen1s39 ti eC ar39bnrfn eeinasarge vagvte Wtw nove our e The Acoustic Fovea keeps 2nd harmonic of echo in region that its hearing is most sensitive thats why it doppler shift compensates to keep echo within t k In a nyaesrf offrfregatf f r yy range called the acoustic fovea Bats emit their calls near this frequency and doppler shift compensation keeps echoes within the acoustic fovea for optimal detection here uses CF component of call sound source constant freq Tuning Of primary auditory HBUI OHS iS narrowest within the acoustic fovea just like plane uses it to measure doppler shift 3 10 dB Quality factor Q 400 300 200 100 Horseshoe bat Mustached bat 39 Little brown O 30 61 83 Frequency kHz C Threshold sound level dB 80 l Il lllquot I quotV l 52 55 58 64 Frequency kHz Doppler shift tuning in CFCF Cortex these are the neurons sensitive to doppler shift The CFCF area of the cortex contains neurons that do not respond to a call alone or echo alone They only respond to an CF ca followed by a CF echo Furthermore each neuron prefers a specific Doppler shift compensated call frequency corresponding to a specific relative velocity between the bat an the target the cell s receptive field Neurons preferring different Doppler shifts are topographically arranged Doppler shift tell bat if its moving towards or away from prey CF CF area measure if call frequency can shift usually down dep on which neurons firing tells you if approaching or going away and how fast B l l 90 Echo CE 60 PUISB CF 30 0 i l l l J 0 l O 20 30 Tnmc ms Frequency kHz Echolocation Problems the brain must solve LOCALIZATION PROBLEMS Which direction is the target How far away is the target How is the target moving DISCRIMINATION PROBLEMS How big is the target What is the target Food Doppler Shifted Echoes If a bat s call bounces off of a moving object the frequency of the call will be doppler shifted according to the velocity of the moving object The flutter of insect wings can be perceived as a rapidly alternating doppler shift in the echo signal CF calls are better than FM calls for measuring velocity Why A Frequency modulation B Frequency and amplitude modulation combined Wing moves v A toward bat Pulse W Away Away Away Toward Toward Toward Wing moves away from bat Evasive Maneuvers by IVIoths Some moths have evolved clever anti bat strategies CF calls repel them causing them to y in the other direction FM calls interrupt their ight CPG causing them to fall to the ground wait until danger is gone Some moths can emit ultrasound to jam the bat s sonar can produce fake echoes Midterm will have graphs multiple choice some maybe L 39 h three or four t problems similar to the homework httpWwwbbcCouknaturespeciesDesertLocust Owl Auditory Localization Pathways External nucleus Inferior colliculus T Time F Lateral shell of central nucleus Inferior colliculus Core of central nucleus Inferior colliculus Anterior lateral lemniscal nucleus Convergent input from ITD amp ILD tuned neurons Intensity ITDtuned neurons Posterior lateral lemniscal nucleus Nucleus laminaris l Nucleus magnocellularis Nucleus angularis ILD tuned neurons Auditory Qerve Inner ear Spatially Tuned Neurons Neurons in ICC more specifically in its lateral shell respond selectively to sounds in a particular region of space The region of space preferred by the neuron is called the cell s receptive field uopeAala punog 30 R 20 R 10 R 0 10 L Sound azimuth How do they do it 0 Each ICC shell neuron has both an ITD tuning preference and an ILD tuning preference The neuron can only be excited by sounds from sources that match both the preferred ITD and ILD Spacespecific neurons are tuned to respond selectively to preferred interaural time delays 392 to the right Percent of total spikes ILD dB Spacespecific neurons are tuned to respond selectively to preferred interaural level differences from above 100 Percent of total spikes blevanon deg The preferred sound location is derived by combining the preferred ITD xaxis with the preferred 20 ILD yaxis o o 2 Vector and matrices Of neurons ILD selective cells can be ILD SEIECt39Ve neurons m different latitudes conceptualized as a row vector of posterior lateral lemniscus 8 4 neurons that each prefer different ILDs with adjacent neurons in the row preferring similar ILDs ICC Shell 7 prefer actual 2 locations prefer diff azimuth ITD selective cells can be conceptualized 9 O 0 O A 6 o as a column vector of A x 9 wmmmaem e different ITDs With adjacent 9 A0 neurons in the column preferring 3 similar ITDs Dorsoventral axis Locationselective cells can be conceptualized as a 2D matrix or sheet of neurons that each prefer different sound locations with adjacent neurons in the sheet preferring similar sound source locations CenterSurround Inhibition LECTURE FIVE STOPPED HERE ILD selective neurons In posterior lateral lemnIscus Each ICC Ce reciprocally inhibits its surrounding neighbors Excitatory 65 o O 0 center of ICC cell 0 receptive field O InthItory x d f 9 whatever cell gets most excitation combined inhibit everyone around it surroun O ICC LocatIon selectIve cell FECeptlve neurons in ICC shell field ILD selective neurons ICC neurons are still frequency specific so there are many copies of the spatial map in ICC Frequency invariance in ICX Convergent input from spatially tuned neurons Convergent input from ITD amp ILD tuned neurons 739 with differing frequency preferences Time r Lateral shell of central nucleus 6 Intensity Inferior colliculus Core of central nucleus Inferior colliculus Anterior lateral lemniscal nucleus Posterior lateral l lemniscal nucleus ITD tuned Nucleus laminarls neurons Nucleus ILD tuned Nucleus angularls magnocellularls Auditory neurons Nerv Inner ear ICX neurons are frequency invariant Convergent input from spatially tuned auditory amp visual neurons 397 Convergent input from spatially tuned neurons with differing frequency preferences 739 Time F Core of central nucleus Inferior colliculus Anterior lateral lemniscal nucleus ITDtuned neurons Nucleus laminaris l Nucleus magnocellularis Optic Tectum Lateral shell of central nucleus Inferior colliculus Auditory I erve Intensity Posterior lateral lemniscal nucleus Visual System Convergent input from ITD amp ILD tuned neurons Nucleus angularis ILD tuned neurons Inner ear o The spacespecific neurons in the Visual SyStem ICX nucleus of inferior colliculus Visual map prOJect to the optic tectum 0 Neurons in the optic tectum have a a a 6 spatial receptive fields for both auditory and visualstimuli and a a a these multimodal receptive fields are normally aligned with one another ICX Optic Tectum Auditory map Audiovisual map Constructing invariant representations 0 Optic tectum Modality visualauditory invariant representation of location 0 CX Frequency but not modality invariant representation of location 0 Amplitude but not frequency invariant representation of location A Normal Visual input from retina and tunbrain Ophc tectum ICC l39 20 ill azimuth Tu auditory thalamus a 4 I V Ascending TD in formation in freq uvncyspwi fic channels uditur N hlltln IUdJI SPJCQ ma P SPaCL quot121p Prism Studies 0 This young owl is wearing a pair of prism lenses These lenses displace the visual world by 23 degrees 0 How does wearing prism lenses affect the animal s orienting responses to auditory versus visual stimuli Before prisms Day 1 R23 prisms Anal itnry H1 111 g o 39 111111 13911311011111 11 2H m Llu 70 3n 39 O 411 Day 42 Prisms removed rll 1111 11111 lln Rm ln Before wearing prisms the owl s gaze accurately locates both auditory and visual targets On the first day of wearing prisms orientation to a visual cue is offset by the prisms of course but auditory localization is normal After 42 days of wearing prisms the auditory localization has shifted to match the visual offset THIS ONLY HAPPENS IN YOUNG OWLS When the prisms are removed the shift persists Prism Experience Shifts Receptive Field Alignment A Normal B Immediate effect C After 8 weeks of of prisms prism experience A Before prisms optic tectum neurons have overlapping auditory and visual receptive fields 0 B When prisms are put on the alignment immediately shifts C Over time the auditory receptive field migrates to the new location of the visual receptive fieldearning Shift in ITD preference accompanies shift in receptive field g 0 Nnm Lynda The prisms cause a shift in the 80 azimuth of the receptive field 60 for ICX and optic tectum 2 neurons but not NL or ICC of U neurons as we shall see 5 215 l lm wgquot 73915 1 0 Since azimuth is encoded by ITD it is expected that the shift should be accompanied by a change the cell s preferred ITD This is exactly what happens over time after wearing prisms as shown in the graphs at right Best TD us 30 20 L10 0 R10 20 30 Visual receptive eld azimuth deg Sensitive Period for Prism Adaptation A Juvenile B Adult adjustment adjustment Man best lTD relative to normal us l l 1 ll 4 n 20 40 m gt180 Time with prisms days 0 A Juvenile owls show prism adaptation and then recovery after prism removal recovery not shown B Normal adults show no prism adaptation but those that were adapted as juveniles can readapt as adults to the same displacement that they experienced as juveniles Critical periods A critical period is a restricted time window during early life when certain processes of brain development MUST occur if they are to occur at all Critical periods or less restrictive sensitive periods have been shown to exist for development of Language Sensory systems visual auditory vestibular Motor skills Social skills 4 kHz Before prisms ICC K 7 I k r r ICX t x 3 x H Optic Visual Tectum System gt lt 02 Immediately after prisms ICC ICX Optic Visual Tectum System 8 weeks after prisms ICC ICX Optic Visual System New axons from ICC to ICX Shifted axons from ICC appear in ICX after 8 weeks of prism expenence BEFORE PRISIVIS AFTER PRISIVIS Rostral T 39 Learned Injection sute i quot 4 Normal 500 um 3 lb Hamel Mammal M 1 r lTle llmremlre eme mg llrj ueilw e 7 eeglnll lLenmel llTlElie Fiure E Ehene in leemeeel eeeneetieity met eeeemeeny 1h eequileitiee ell e neeIr l l p ell rm iln the IE e Illmeel l1 elter em eepe eiee Spheres rpr eeeitetmy blue end ilrlhileilterjlr lhleele llliEtlF lll in lime llljli Eenneetine eeiileeting lrm line ele ietum lmmee em lrem 111 IE lemmell ITDe end leemeetl lllEJe ewe rereeentd wee eemieireleei 1h eiee ef wlleielh ilmlieetee the were ef 1h ennetine 1 peiltetryreennetin ilehihitryreennetien Teef leeeretrenemi r neeeptre met eumpe eeme ell Elle eennee eree er indieettl e AMPE ll Heme l3 Gee Immediately after prisms removed ICC ICX Optic Visual Tectum System 09 Several days after prisms removed IC ICX Optic Visual 0 Tectum System c 0 Ms O r C 100 i 4 kHz Connectivity changes during prism adaptation H In normal owls projections W 0pm rziifiii iiii i 113C333 from ICC to ICX are 39CC mm 2quot quot m m topographically organized to form spatial regions encoding similar ITDs Tu auditory thalamus Ascending TD in formation in freq m39ncvspwi fic channels When juvenile owls wear prisms their developing Auditory A ma 1 39i nervous systems form a new a WinWW set of shifted topographic if visual input ICC 253 m m mum connections the old connections are weakened but not eliminated
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