Week of 11/30
Week of 11/30 NSCI 3310
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This 14 page Class Notes was uploaded by Emma Notetaker on Saturday December 5, 2015. The Class Notes belongs to NSCI 3310 at Tulane University taught by Jeffrey Tasker in Summer 2015. Since its upload, it has received 32 views. For similar materials see Cellular Neuroscience in Nutrition and Food Sciences at Tulane University.
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Date Created: 12/05/15
Central Visual System 12515 1258 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 movementmotion 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 o perception 2 hypothalamic suprachiasmatic nucleus 0 circadian rhythms 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 9 optic nerves 9 optic chiasm 9 optic tracts 9 lateral geniculate nucleus 9 optic radiation axonal projections that fan out from LGN 9 primary visual cortex outputs of retinal ganglion cells 0 3 types of info transmitted by retinal ganglion cells 0 form p cells 0 color p cells 0 motion m ganglion cells 0 transmitted by different galgnion cells 0 mcells o p cells 0 nonMnonP bistratified ganglion cells project to konicellular regions between magno and parvocellular mainly color information n blueyellow color opponency centersurround color opponent receptive field 0 redgreen P cell receptive field due to red and green cones red light in the center green in the surround o blueyellow nonMnonP 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 0 objects inverted on retina 0 light crosses in lens 0 similar to camera lens 0 both eyes get info from both sides but not as much for opposite side due to nose 0 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 9 right hemiretina axons from nasal hemiretinas cross contralateral in optic chiasm axons from temporal DON T cross ipsilateral 0 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 0 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 d 2 devoted to magnocellular layers 1 and 2 4 devoted to parvoceuar layers 36 0 intermediate zones in between layers 0 outputs from LGN o parvoceuar 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 parvoceuar magnocellular and konicellular layers in LGN axons from the ganglion cells make synapses to this relay 4lobes visual cortex in occipital lobe 0 primary visual cortex receives input from LGN retina aka striate cortex V1 secondary visual cortex rceive projection from primary visual cortex retinotopic organization of visual cortex 0 projections to primary o 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 largest representation due to number and density or receptors n more cones n 111 relationship between cones bipolar cells and ganglion cells I SO more of these as well in periphery convergence of multiple photoreceptors on multiple cells lower density so less of the primary visual cortex devoted to these areas outside the 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 parvocellular AND magnocellular LGN projection to layer IVC this layer gets 90 of LGN info 0 layer III gets koniocellular inputs which get info from nonM nonP 0 layer IV projections to other layers divided into sublayers ABC and layer C cubdivided into alpha and beta local circuit projections n spiny stellate neurons nt glutamate 0 first relay neurons receiving inputs from LGN glutamate producing make excitatory projections columnar organization 3 types of columns 0 ocular dominance columns alternating columns receive projections from each eye column from one eye devoted to certain layer in primary visual cortex layers alternate between ipsilateral contralateral within columns in layer IV within each ocular dominance column there is a blob and interblob each eye divided into color and form information o blobsinterblobs columns Figure 1020 blob color info wavelength sensitivity primarily monocular devoted to one eye interblob in between blobs columns within SAME ocular dominance column form a location of ocular dominance columns crossover to interblobs which contain ocular dominance columns a these are binocular ale Three parallel pathways from the retina to striate cortex a Magnocellular pathway b Parvocellular pathway c Konlocellular pathway Striate cortex KA lnterblob Blobs Blobs llandlll 39II and Ill Ilandlll Magnocellular LGN layer 1 C l Contralateral retina Mtype ganglion cell 9 z l Magnocellular Parvocellular Parvocellular Koniocellular Or lVB IVB v IVB I l l B IVC B lVC B IVC V Koniocellular LGN layer 2 LGN layers C LGN layers layers ventral layers ventral 4 and 6 3 and 5 to LGN layers to LGN layers 1 and 4 2 and 3 O lpsilateral Contralateral Ipsrlateral Contralateral lpsllateral retina retina retina retina retina M Iype Ptype Ptype non PnonM nonPnonM ganglion cell ganglion cell ganglion cell ganglion cells ganglion cells b no 2001 apparel V39llidnlb 5 W llkm magnocellular neurons info about motion 0 LGN neurons project to spiny stellate neurons in layer IVCa o M channel terminate in layer IVCa o motion info 0 separated into contralateral and ipsilateral eyes ocular dominance column devoted to each eye only hold up in this layer 0 some cells get monocular inputs come get binocular inputs 0 higher oreder neurons located primarily in layer IVB M cell info to magnocellular layers of LGN to primary visual cortex comes to layer IVCa spiny steate neurons project to higher order neurons in layer IVB n all other neurons pyramidal neurons IVB neurons 0 P channels 0 4 layers of LGN devoted to these 0 synapse onto spiny steate neurons in layer IVCB 80 of info from retina comes here 0 segregated into contralateral and ipsilateral inputs forming ocular dominance columns 0 project to pyramidal neurons in layers II and III glutamatergic neurons some get inputs from one eye some from 2 spiny steate neuron gets input from LGN o as you go into spiny steate neurons in layer IVC they retain center surround receptive fields as well 0 higher order neurons are all pyramidal glutamatergic excitatory SEE SLIDES PICTURES inputs and outputs pyramidal cells are output cells 0 projections to other areas cortical and non o ntgutamate spiny steate neurons project to neurons that receive both binocular and monocular inputs monocular in blobs binocular in interblobocular dominance columns inferior layers pyramidal neurons that receive inputs from adjacent areas of visual cortex and project down to brainstem and hypothalamus LGN have similar centersurround receptive field 0 info transmitted directly from center and surround directly to different LGN neurons and maintains the same receptive field BUT there is a loop formed input from retina to superior colliculus that monitors head movements simple cells layers II and III in the visual cortex simple cells pyramidal neurons 0 higher order neurons 0 receive inputs from spiny stellate cells 0 each of which has center surround receptive field center is on surround is off 0 these multiple fields combine to form 0 many spiny stellate cells project to ONE pyramidal cell 0 contain elongated rectangular receptive fields on portion is a vertical line surrounded by inhibitory 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 o certain cells respond to certain orientations 0 simple cells pyramidal 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 0 cells in same column respond to same orientation of light 0 until layer IVC doesn t respond to any orientation 0 inferior layers all respond to same layer within column 0 cells in adjacent columns repond to orientations shifted by around 10 degrees 0 if you go horizontally through multiple columns go through complete 180 degrees of orientation 0 hypercolumns set of orientation ocular dominance columns and blobs 0 full analysis of single point on 2 retinas 0 all 180 degree colors and both eyes 0 around 1 mm2 cortical hypercolumn devoted to one spot on retina cortical module about 1mm 0 each module capable of analyzing every aspect of a portion of the visual field 0 have ocular dominance columns from both eyes in layer IV 0 have orientation columns in interblobs 0 set of orientation ocular dominance columns and blobs 0 full analysis of single point on 2 retinas 0 all 180 degrees of orientation represented has EVERYTHING blobs interblobs columns etc cortical receptive fields monocular receptive fields 0 laver IVC similar to LGN cells centersurround receptive fields 0 layer IVCa insensitive to wavelength 0 layer IVCB centersurround color opponency binocular receptive fields I II III 0 layers superficial to IVC first binocular receptive fields in the visual pathway 0 direction selectivity of motion 0 neuron fires action potentials in response to moving bar of light 0 magnocellular inputs from LGN o more activity in response to moving in a certain direction selective to specific direction of motion 0 complex cells of the visual cortex 0 binocular o orientationselective 0 ON and OFF responses to the bar of light but unlike simple cells NO distinct on and off regions if correct orientation within the receptive field will get same activity ANYWHERE in the receptive field and get the same response 0 several simple cells with rectangular receptive fields project onto a single complex cell keep orientation selectivity but lose surround antagonism o pyramidal cells input from simple cells 0 receptive fields rectilinear orientation selective position unselective movement selective respond to oriented edges 0 integration of inputs from simple cells with adjacent receptive fields simple and complex cells of primary visual cortex responsible for perception of form 0 color sensitivity 0 blob receptive fields circular monocular no orientation of direction selectivity majority of colorsensitive neurons outside layer IVC specialized for analysis of object color physiology of striate cortex 0 parallel pathways within V1 0 magnocellular retinal M type cells project to magnocellular layers in LGN synapse on IVCa then go on to IVB to extrastriate cortical areas OR to blob o koniocellular between 6 layers of LGN nonM non P cells project here koniocellular project on to synapse at layers IIIII go directly to blob o parvocellular retinal P cells project to parvocellular cells in LGN synapse on layer IVCB then go onto interblob OR blob higher visual cortices dorsal stream 0 analysis of visual motion 0 visual control of action ventral stream 0 perception of the visual world recognition of objects 0 shapes and colors from single neurons to perception must piece this information together 0 visual perception 0 identifying and assigning meaning to objects hierarchy of complex receptive fields 0 retinal ganglion cells centersurround structure sensitive to contrast and wavelength colors 0 striate cortex orientation selectivity direction selectivity binocularity o extrastriate cortical areas higher level vsual cortices selective responsive 0 form photoreceptors to grandmother cells 0 grandmother cells faceselective neurons in area IT probably not perception NOT based on activity of individual higher order cells 0 parallel processing and perception 0 groups of cortical areas contribute to the perception of color motion and identifying objects vnsnon perception combines individually identified properties of visual objects 0 achieved by simultaneous parallel processing of several visual pathways parallel processing 0 like the sound produces by an orchestra of visual areas rather than the end product of an assembly line physiology of the striate cortex 0 parallel pathways 12515 1258 PM 12515 1258 PM
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