week of 11/16
week of 11/16 NSCI 3310
Popular in Cellular Neuroscience
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This 21 page Class Notes was uploaded by Emma Notetaker on Thursday November 19, 2015. The Class Notes belongs to NSCI 3310 at Tulane University taught by Jeffrey Tasker in Summer 2015. Since its upload, it has received 37 views. For similar materials see Cellular Neuroscience in Nutrition and Food Sciences at Tulane University.
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Date Created: 11/19/15
Central Visual System 111915 558 PM Ganglion cells 4 types 0 M cells parasol cells large dendritic arbor O 0 00000 large ganglion cells 510 of total ganglion cells in retina project to magnocellular large receptive field mediate lower spatial discrimination faster AP conduction fairly insensitive to color respond to low contrast light detects movement transient adaptive response to center light adapt rapidly P cells 0 0 small cells 8090 of total ganglion cells in retina midget cells small receptive field higher spatial discrimination more discrete signals slower AP conduction sustained response to center light adapt slowly detect form edge formation and color vision redgreen color vision project to parvocellular neurons in lateral geniculate nucleus 0 bistratified cells nonMnonP cells O 0000 O neither small ganglion cells 510 intermediate sized receptive field conduction velocity contrast detection detect color mainly blueyellow 0 light sensitive ganglion cells small O 0 have photopigment in membranes can directly respond to light don t really work for visual field but regulate circadian rhythm 0 each of these ganglion cells project to different pathways to the lateral geniculate nucleus all axons unmyelinated in retina until reach optic nerve retinofugal projection retina covers 34 of the inside of the eye 0 optic nerve myelination begins 0 optic chiasm crossover o axons enter brain here 0 optic tract 0 fiber tract IN brain ganglion cell target projections 4 o 1 lateral geniculate nucleus of thalamus perception 2 hypothalamic suprachiasmatic nucleus circadian rhythms 3 pretectum pupil lens reflexes 4 superior colliculus eye head movement pathways to visual cortex ganglion cells 9 optic nerves 9 optic chiasm 9 optic tracts 9 lateral geniculate nucleus 9 optic radiation 9 primary visual cortex color opponency centersurround color opponent receptive field 0 redgreen P cell receptive field due to red and green cones o blueyellow nonMnonP cell receptive field blue and yellow redgreen cones 0 designed for detection of color contrast visual field projections 0 objects inverted on retina 0 light crosses in lens 0 similar to camera lens visua field divided into quadrants retina divided into quadrants o fovea at center 0 temporal and nasal hemiretinas superior and inferior visual field binocular both eyes monocular one eye o nose in the way 0 temporal crescent retina divided into halves o hemiretinas temporal and nasal hemiretinas receive light from opposite half of the visual field 0 left visual field 9 right hemiretina axons from nasal hemiretinas cross contralateral in optic chiasm axons from temporal DON T cross ipsilateral defecits optic nerves carry info from single eye about both sides of field 0 optic tracts carry info from both eyes about apposite visual field projections to the LGN LGN gets info from o ipsilateral temporal retina o contralateral nasal retina 0 about opposite visual field 0 LGN 6 layered structure 0 3 layer ipsilateral retina o 3 layers contralateral retina outputs from LGN o parvocellular neurons what form and color info inputs from P ganglion cells 0 magnocellular neurons where location movement inputs from M cells parallel visual streams 0 form color and motion info carried by segregated retinotopically organized pathways in brain 0 parvocellular magnocellular and konicellular layers in LGN retinotopic organization of visual cortex 0 projections to primary 0 occipital lobe 0 info from only half of visual field to each hemisphere o superior and inferior quadrants segregated retinotopic organization 0 about 50 of primary devoted to fovea 0 different quadrants project to different regions of primary visual cortex visual field mapped on cortex projections to primary visual cortex 0 neocortex o 6 layers VI deepest o LGN projection to layer IV 0 layer IV projections to other layers local circuit projections n spiny stellate neurons nt glutamate columnar organization 0 ocular dominance columns alternating columns receive projections from each eye 0 blobsinterblobs blob color info interblob form 0 orientation columns line orientation of 180 degree scale inputs and outputs pyramidal cells are output cells 0 projections to other areas cortical and non o ntgutamate simple cells 0 higher order neurons 0 receive inputs from spiny stellate cells pyramidal cells 0 receptive fields 0 large rectilinear 0 lines and bars 0 perceive outline 0 formed by integration of multiple concentric fields 0 orientation and position selective simple cells tuned to different orientations cortical receptive fields organization 0 orientation selectivity simple cells o binocular o orientation selective o elongated onoff region with antagonistic flanks responds to optimally oriented bar of light 0 possibly composed of 3 LGN cell axons with centersurround receptive fields orientation columns cells in same column respond to same orientation cells in adjacent columns repond to orientations shifted by around 10 degrees hypercolumns set of orientation ocular dominance columns and blobs full analysis of single point on 2 retinas all 180 degree colors and both eyes around 1 mm2 111915 558 PM 111915 558 PM Central Visual System 111715 843 PM Ganglion cells 4 types M cells parasol cells large dendritic arbor 0 large ganglion cells 5 10 of total ganglion cells in retina 0 project to magnocellular 0 large receptive field mediate lower spatial discrimination faster AP conduction fairly insensitive to color respond to low contrast light detects movementmotion transient adaptive response to center light adapt rapidly OOOOO P cells 0 small cells 80 90 of total ganglion cells in retina midget cells 0 small receptive field higher spatial discrimination more discrete signals 0 slower AP conduction o sustained response to center light adapt slowly o detect form edge formation and color vision red green color vision 0 project to parvocellular neurons in lateral geniculate nucleus bistratified cells nonM nonP cells 0 neither small ganglion cells 510 intermediate sized receptive field conduction velocity contrast detection 0 detect color mainly blue yellow light sensitive ganglion cells small 0 have photopigment in membranes can directly respond to light 0 don t really work for visual field but regulate circadian rhythm each of these ganglion cells project to different pathways to the lateral geniculate nucleus all axons unmyelinated in retina until reach optic nerve retinofugal projection retina covers 34 of the inside of the eye optic nerve myelination begins optic chiasm crossover o axons enter brain here optic tract 0 fiber tract IN brain ganglion cell target projections 4 1 lateral geniculate nucleus of thalamus o perception 2 hypothalamic suprachiasmatic nucleus 0 circadian rhythms daily night and day rhythms sends projectsionf rot drive daily rhythms 395 LL I I CI 0 O O O daily night and day rhythms sends projectsionf rot drive daily rhythms 3 pretectum pupil lens reflexes 4 superior colliculus o in midbrain o eyehead movement pathways to visual cortex ganglion cells a optic nerves a optic chiasm a optic tracts a lateral geniculate nucleus 31 optic radiation axonal projections that fan out from LGN a primary visual cortex outputs of retinal ganglion cells 3 types of info transmitted by retinal ganglion cells 0 form p cells 0 color p cells 0 motion m ganglion cells transmitted by different galgnion cells 0 mcells o p cells 0 nonM nonP bistratified ganglion cells project to konicellular regions between magno and parvocellular mainly color information a blue yellow color opponency center surround color opponent receptive field 0 red green P cell receptive field clue to red and green cones red light in the center green in the surround o blue yellow nonM nonP cell receptive field blue and yellow redgreen cones make yellow with red and green surround has both red and green cones 0 designed for detection of color contrast visual field projections objects inverted on retina 0 light crosses in lens 0 similar to camera lens both eyes get info from both sides but not as much for opposite side clue to nose visual field divided into quadrants retina divided into quadrants o fovea at center 0 temporal and nasal hemiretinas halves left and right 0 superior and inferior projections inverted AND reversed on retina visual field binocular both eyes monocular one eye 0 nose in the way 0 temporal crescent retina divided into halves o hemiretinas temporal and nasal hemiretinas receive light from opposite half of the visual field 0 left visual field a right hemiretina axons from nasal hemiretinas cross contralateral in optic chiasm 0 left visual field a right hemiretina axons from nasal hemiretinas cross contralateral in optic chiasm axons from temporal DON T cross ipsilateral right optic tract only gets info from opposite visual field 0 each optic nerve only carrying opposite info deficits optic nerves carry info from single eye about both sides of field optic tracts carry info from both eyes about opposite visual field 0 becomes optic tract after the optic chiasm projections to the LGN LGN gets info from o ipsilateral temporal retina o contralateral nasal retina 0 about opposite visual field LGN 6 layered structure 0 3 layer ipsilateral retina o 3 layers contralateral retina 0 layers divided into ones cl 2 devoted to magnocellular layers 1 and 2 4 devoted to parvocellular layers 3 6 0 intermediate zones in between layers outputs from LGN o parvocellular neurons what form and color info inputs from P ganglion cells 0 magnocellular neurons where location movement inputs from M cells parallel visual streams form color and motion info carried by segregated retinotopically organized pathways in brain parvocellular magnocellular and konicellular layers in LGN retinotopic organization of visual cortex projections to primary 0 occipital lobe 0 info from only half of visual field to each hemisphere o superior and inferior quadrants segregated retinotopic organization 0 about 50 of primary devoted to fovea 0 different quadrants project to different regions of primary visual cortex visual field mapped on cortex projections to primary visual cortex neocortex o 6 layers VI deepest o LGN projection to layer IV 0 layer IV projections to other layers local circuit projections n spiny stellate neurons nt glutamate columnar organization 0 ocular dominance columns alternating columns receive projections from each eye 0 blobsinterblobs blob color info interblob form blob color info interblob form 0 orientation columns line orientation of 180 degree scale inputs and outputs pyramidal cells are output cells 0 projections to other areas cortical and non o ntglutamate simple cells higher order neurons receive inputs from spiny stellate cells pyramidal cells receptive fields 0 large rectilinear 0 lines and bars 0 perceive outline 0 formed by integration of multiple concentric fields orientation and position selective simple cells tuned to different orientations cortical receptive fields organization orientation selectivity simple cells 0 binocular o orientation selective o elongated on off region with antagonistic flanks responds to optimally oriented bar of light 0 possibly composed of 3 LGN cell axons with center surround receptive fields orientation columns cells in same column respond to same orientation cells in adjacent columns repond to orientations shifted by around 10 degrees hypercolumns set of orientation ocular dominance columns and blobs full analysis of single point on 2 retinas all 180 degree colors and both eyes around 1 mm2 cortical hypercolumn cortical module 0 each module capable of analyzing every aspect of a portion of the visual field cortical receptive fields monocular receptive fields 0 laver IVC similar to LGN cells 0 layer IVCa insensitive to wavelength 0 layer IVCB center surround color opponency binocular receptive fields 0 layers superficial to IVC first binocular receptive fields in the visual pathway direction selectivity o neuron fires action potentials in response to moving bar of light 0 magnocellular inputs from LGN complex cells 0 cortical receptive fields rnmnlov rolle 39 LUIIIpICX LCllb o cortical receptive fields complex cells a binocular n orientation selective n ON and OFF responses to the bar of light but unlike simple cells NO distinct on and off regions pyramidal cells input from simple cells receptive fields rectilinear n orientation selective a position unselective a movement selective n respond to oriented edges integration of inputs from simple cells with adjacent receptive fields simple and complex cells perception of form color 0 blob receptive fields circular monocular no orientation of direction selectivity majority of color sensitive neurons outside layer IVC specialized for analysis of object color parallel pathways within V1 magnocellular koniocellular parvocellular higher visual cortices dorsal stream 0 analysis of visual motion and the visual control of action ventral stream 0 perception of the visual world and the recognition of objects visual cortex beyond the striate cortex dorsal stream V1 V2 V3 MT MST other dorsal areas 0 area MT temporal lobe most cells direction selective respond more to motion than shape 0 beyond area MT 3 roles of cells in area MST parietal lobe navigation directing eye movements motion perception ventral stream V1 V2 V3 IT other ventral areas 0 area V4 achromatopsia partial or complete loss of color vision a caused by damage to area V4 0 area IT major output of V4 higher order selectivity objectsfaces from single neurons to perception visual perception 0 identifying and assigning meaning to objects hierarchy of complex receptive fields 0 retinal ganglion cells center surround structure sensitive to contrast and wavelength 0 striate cortex Vll vl wullvmllvu U IVIV VII sensitive to contrast and wavelength 0 striate cortex orientation selectivity direction selectivity binocularity o extrastriate cortical areas selective responsive form photoreceptors to grandmother cells 0 grandmother cells face selective neurons in area IT probably not perception NOT based on activity of individual higher order cells parallel processing and perception 0 groups of cortical areas contribute to the perception of color motion and identifying objects vusnon perception combines individually identified properties of visual objects achieved by simultaneous parallel processing of several visual pathways parallel processing like the sound produces by an orchestra of visual areas rather than the end product of an assembly line 111715 843 PM 111715 843 PM Vestibular SystemVisual System 111415 1251 PM importance of vestibular system balance equilibrium posture head body eye movement vestibular labyrinth 2 structures 0 1 otoith organs gravity and tilt o 2 semicircular canals head rotation both use hair cells like auditory system to detect changes otoith organs detect changes in head angle linear acceleration o macular hair cells responding to tilt macula sensory organ in utricle and saccule contains hair cells hair cells transduce movement in gelatinous cap endolymph with defletcions in cilia and influx of potassium via mechanically gated channels otoiths calcium carbonate crystals detect acceleration maculae saccule vertical acceleration utricle horizontal acceleration o mirror images in opposite ears 0 depolarization with tilt in one direction hyperpolarization in the other 0 2 ears have opposite responses vestibular system semicircular canals o angular acceleration o detect rotational movements structure 0 hair cells in ampulla bulge in canal o cupula gelatinous structure hair cell cilia embedded in cupula o canals filled endolymph contralateral canals have opposite responses adaptation to sustained rotation vestibular system otoith organs a lateral vestibular nucleus semicircular canals a medial vestibular nuceus vestibulo ocular reflex VOR 0 eye motor compensation for head movement 0 inputs from vestibular apparatus project to neurons that control muscle in eyes to move eyes appropriate to environment 0 controls eye movements to counteract head movements 0 moves eyes in opposite direction that head is moving in order to keep a stable gaze properties of light light 0 electromagnetic radiation 0 travels in waves A Alaloonnhc anrl amnIiIIlrloc o electromagnetic radiation 0 travels in waves 0 wavelengths and amplitudes electromagnetic spectrum 0 determined by wavelength 0 visible light 400 700 nm 0 UV xrays gamma rays lt400nm smaller wavelengths o infrared radar etc gt700 nm larger wavelengths light refelction 0 light reflects off objects 0 causes light scattering 0 causes loss of visual acuity absorption 0 light absorbed by pigment refraction 0 light is bent to different degrees going through different mediums The Eye Cornea and Lens 0 Refraction of light most occurs at cornea fine tuning at lens 0 Focused at Retina at fovea 34 of eye covered by retina 0 Accommodation Lens shape changes with distance of object Rounder for closer objects a Ciliary muscles Retina o Layered structure that covers 34 of inside of eye 0 Photoreceptors Capture photons Phototransduction outermost layer in retina cells that capture light and trigger sensory response 0 Fovea Center of retina Region of high visual acuity u highest sensory resolution Where layers separate 0 Pigment Epithelium Melanin containing cells n absorb stray light not captured by photoreceptors u prevents light from reflecting around within the eye 0 5 Layers 1 Outer nuclear layer a Photoreceptors 2 Outer pleXiform layer a synapses between photoreceptors and interneurons 3 Inner nuclear Layer DYIIUPDL D LIL LVVLaLaII PIIULUI bbbPLUI D UIIU interneurons 3 Inner nuclear Layer El cell bodies of Interneurons 4 Inner plexiform layer 5 El El El El El Image Formation o Corneal Refraction Bending of light El El Synapses of interneurons and output cells Ganglion Cell Layer inner most layer output layer of retina cells that send signal into brain send axons out over inner surface of retina to optic disk where they collect to form optic nerve and optic nerve exits the retina unmyelinated axons until they get to optic nerve occurs at cornea most refractive power lens can change bend in order to change resolution fine tune focusing Caused by light passing through different media Focal distance cornea to convergence point El El closer the light the more round the lens is more refraction more bending closer the object the greater bending needed to focus same principle as glasses 0 Accommodation Refraction by lens Focus on retina By shape of lens Light Path to Photoreceptors o Photoreceptors Located in outer nuclear layer outermost layer Light path to photoreceptors impeded by other layers Fovea El Photoreceptors o Rods and Cones o Morph ology Layers parted to allow direct light access to photoreceptors light doesn t have to go through other 4 layers of retina minimal amount of reflection from other objects Least distortion of light Located in center of retina directly behind cornea andlens Highest concentration of photoreceptors conesa high acuity high density of cones responsible for high visual acuity detection very center foviola least distortion of light a fovia nl ILAquot ni f lml l o Rods and Cones o Morphology Outer segment discs n dendrites n area that captures light Inner segment soma Synaptic Terminal 0 Rods night vision Single visual pigment u Rhodopsin Cannot detect color only light detection more photopigment more sensitive to light than cone high sensitivity but low special resolution High sensitivity Low spatial resolution low acuity n Due to more visual pigment more rhodopisin in rods than opsin in cones a Convergence onto bipolar cells 0 Cones day vision 3 Visual Pigments a Red green blue opsinsa Color detection a low sensitivity because of less photopigment ess membrane to hold photopigment a high visual acuity a primarily in fovea a Each pigment responds to different wavelengths of light a High spatial resolution high acuity low sensitivity a Less visual pigment low convergence often 11 cone to bipolar 11 relationship to interneurons they are talking to Factors contributing to Visual Acuity 0 Convergence of photoreceptor signals 0 Light access to photoreceptors Phototransduction o Occurs at photoreceptor o Rhodopsin Rod photopigment n Opsin 7 transmembrane protein G Protein Coupled u Retinal Light absorbing vitamin A derivative 0 Lighta 11 cis to all trans retinal a activation of opsin Triggers 2nd messenger cascade 2nd Messenger Cascade 0 activation of photoreceptor is a hyperpolarization decreasing neurotransmitter release onto next cell in circuit 0 G protein transducin o cGMP phosphodiesterase a cGMP to 5 GMP decrease cGMP cGMP Phosphodiesterase inactivate cAMP or cGMP 0 Closing of cGMP gated Na channels cGMP Phosphodiesterase inactivate CAMP or cGMP 0 Closing of cGMP gated Na channels 0 Blocks dark current ie current activated in dark n leads to hyperpolarization ie passive signaling Red Green and Blue Cones 0 Color Vision Differential activation of red green and blue cones Retinal Circuits o 5 Cell Types in retina ALL USE GLUTAMATE Photoreceptors rods and cones u in outer nuclear layer a DO NOT GENERATE AP u use glutamate u hyperpolarize in response to light Bipolar Cells u use glutamate inner nuclear layer Interneurons directly linking photoreceptors to ganglions do not produce APs passive response to light in their receptive field is PASSIVE response depolarization or hyperpolarization passive transmission of response a ionotropic Horizontal Cells u inhibitory u use GABA a DO NOT GENERATE AP u interneurons El El El El El El inner nuclear layer link up neighboring photoreceptors Amacrine Cells u interneurons u inhibitory use glycine a multiple subtypes a DO GENERATE AP Ganglion Cells u use glutamate EXCITATORY u will follow whatever bipolar cell is doing a output cell a DO GENERATE AP in order to transmit visual signal to brain a where axons come together to form optic nerve 0 only ones that generate action potentials are ganglion cells to get messages the long distances to the brain and amacrine cells needs to depolarize through electrical cell gap junction channels 0 5 Layers Outer nuclear Outer plexiform n doesn t contain any cells n contains synapses glutamate synapses Inner nuclear n infernal Irnnc u contains synapses glutamate synapses Inner nuclear u interneurons basic retinal circuit 0 processing of visual signals photoreceptors rods and cones a interneurons a ganglion cells 0 interneurons bipolar cells horizontal cells and amacrine cells 0 ganglion cells output cells of retina axons form optic nerve project into brain form optic disk blind spot visual information transmitted to brain by action potentials photoreceptors are ALWAYS hyperpolarized inhibited by light 0 sensory receptor doesn t have a receptive field NOT organized in center surround 0 ALL receptors respond to light in the same way 0 inhibition of dark current hyperpolarization center surround receptive fields antagonistic 0 direct vertical pathways center of receptive field photoreceptor a bipolar cell a ganglion cell indirect lateral pathways surround of receptive field surround by way of lateral projection to horizontal cell interneuron a photoreceptor a ganglion cells goes indirectly but to same cells via horizontal cell horizontal cell switches polarity o if the center is excitatory the surround is inhibitory and vice versa 0 if ON center receptive field meaning that light hitting the center is excitatory light in the surround causes inhibition or off response because transmits through lateral pathway when light hits the center surround gets synaptic signal from lateral pathway that causes opposite response than would have been if it had been hit directly receptive fields of bipolar cells and ganglion cells ganglion cell receptive fields 0 area of retina that ganglion cell responds to o convergence of interneurons onto ganglion cell 0 job of gangion cells is to relay message to the brain center surround receptive field 0 circular concentric centersurround o antagonistic centersurround o on center and off center ganglion cells on center excited by center light inhibited by surround light off center inhibited by center light excited by surround light tuned for contrast detection 0 diffuse light elicits little response only slight depolarization or hyperpolarization o tuned to detect luminescence differences within field detects edges between darker and lighter objects center pathways rliF39Forinn Inn nr nF39F nonfor oral loo 39IhQI rocnnnrl rliF39ForonIhl 39In O O edges between darker and lighter objects center pathways differing on or off center because they respond differently to glutamate cone aON center bipolar cell synapse o glutamate inhibitory mGluR s o hyperpolarization of cone in response to light less glutamate release onto both on and off center bipolar cells excitation of bipolar cell cone a off center bipolar cell synapse o glutamate excitatory iGIuR s o hyperpolarization of cone less glutamate release inhibition of bipolar cell bipolar cell a ganglion cell synapse o glutamate excitatory iGIuR s o depolarization a more glutamate release onto ganglion cell ganglion cell excitation o hyperpolarization a less glutamate release onto ganglion cell a ganglion cell inhibition surround pathways cone pathways cones hyperpolarize in response to light indirect or lateral pathway to ganglion cells increase spatial resolution mediate surround response on or off light activates cone in surround a glutamate excitatory a hyperpolarizesinhibits with less glutamate release horizontal cell cone in center a bipolar cell in center pathways a ganglion cell horizontal cells are GABA ergic release GABA onto cones photoreceptors causes less GABA release 0 reversal of sign a depolarization of cone 0 opposite from response to light on cone antagonistic response generated in the surround of the receptive field center not responding directly to light but responding to synaptic inputs through lateral pathway through horizontal cell all signals reverse with respect to center response 0 depolarization of center cone increased glutamate release 0 1 hyperpolarization of on center bipolar cell decreased glutamate release hyperpolarization of on center ganglion cell decreased spiking o 2 depolarization of off center bipolar cell increased glutamate release depolarization of off center ganglion cell increased spiking rod pathways rod photoreceptors generate hyperpolarization in response to light indirect pathway 0 via rod bipolar cells 0 A11 amacrine cells rod bipolar cells on center bipolar cells 0 glutamate synapse activating metabotropic receptors to hyperpolarize n rlnnpc NOT nrm39pr l39 rlirpr l39lv l39n nannlinn Fall 51 nnpc l39n nmnr rinp o glutamate synapse acuvating metaDOtropic receptors to hyperpolarize o dooes NOT project directly to ganglion cell 31 goes to amacrine cells amacrine cells action potential generation 0 glycine is nt 0 mediates rod pathway through projecting to both on and off center ganglion cells 0 electrical synapses with on center ganglion cells a excitatory depolarize forms ELECTRICAL synapse with on center cells n channels between which ions flow directly n presynaptic cell generates action potentials accumulation of positive charge in presynaptic cell which flows through channels to depolarize postsynaptic cell 0 chemical synapses with off center ganglion cells a inhibitory hyperpolarized by glycine release 0 excitation of on center and inhibition of off center ganglion cells no center surround antagonism leads to loss of spatial resolution only uses on center bipolar cells 0 loss of lines and borders higher sensitivity lower visual acuity reason you can see stars better when not looking directly at them center of visual field has very few rods and more cones o to use rods you need to use peripheral retina where there are more rods also tap into cone pathway 111415 1251 PM 111415 1251 PM
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