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PSY280 JULY 12.docx

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PSY280 JULY 12, 2012 The brain and its role in vision Images in - On retina - Not exact view pint - Inverted top bot - And split left to right and vice versa - Topocgrapichal org - Spatial relationships perseerrved in retina, consistent even when in cortex it is stable or maps Patway - How exit optic nerve tract of axons - Axon right eye and left and cross brain and same side and project optic chasm - Half crossed to contralateral and other half satys on same side - Nasal retina closest to nose - And temperal closest to temple - Nasal retina crosses to crontralateral hemisphere - Processing visual field, right and left one, field of right and left eyes - Roght visual right of right and lest of left - Left right and left of left - Right visual to left and blue to right - So lesion is riht optic nerve their right eye - Lesion left nerve brsain - Closer to back, past optic chasm right lesion then left vis fiked - Infront or behind optic chasm Two - Tect – perceptual of motion and control of eye movement primitive and overall, only 10 percent, predom in brids and primtitve species, motions of eye mov and percept - Geni – our predom – form and colour 90 percent, more criticlkal for our vison Tect - From optic chasm - Cross over - Over – the tect – to brainstem – eye to suerpior coliculu brainstem and then up toi midbrain then to nuclui of thalamus from lateral nucl to v2 higher visual area then to v5 process visual motion and back to eye and thalamus – know how much accomadate infor from brain stem project info to eye bc to much blur one of tect path - Most input from bigger gagnglion cells rod – very sens and rapid bc lots of convergaence Gen - Pred pathway - From optic chasm to lgn nucleus in thalamus – thalamus is rely station and proiject to cortex – uses optic radiation tract thamlums to cortex then coprtex at back at back of brain primary viusual cortex and further up high cortical processing Lgn - Why import - Maintains org of rentinal ganglio cells - 6 layers - Top 4 parvo cells to parvo ganglio inputs mostly from cones - Bottom two magno the rods - Lgn – similar to ganglia cells off center on center and oppp surround - Keeping same infor as the ganglion cells coded for Contdf - Each layer - Left hem from right visual field from either cont or is eye - 235 signals from ipsilitalter eye, 146 contr organized as oppp - Same top map as in eye, everythiong sent from ganglia to lgnb Pvc - First area process visual info, first place info proceses - Also visual area 1 - Stain it strioes – all different names for same area Cell in pvs - Simple complex and end stop Simple - Receptive fierld linera bars - Overlap middle exc and around would be inhibitory, codes for just lines - Best light orientated certain angles - Specific - Code by prientation specifity Contd - Had three ganglia cells overalp - Main area middle is exc other is inhin - Respnisvce to veticle lines best at zero degrees and less as tiltr - For test lateral inhibition – had point or stop area which is inh and pointed area is eciticatio, if shown then which one excitory and which inh Complex - More complicared - Bars lines - But moving part direction simple not respond to movement - Left or right - Position insensitive not where moving but specific orientation End stop - More com - More specific and more complicated Selective adaptation - How coding, - Slectiv adapt – neurons to specific stimulu fatigue, after exposure weaken in repsinding - Top coding zero degrees – most at zero - Now mostly at -10 called tilt effect, neurons adapt cetain orientation, perceive oppp direction bc nerions het fatigured Example - Left side titleted 20 degree left and right focus per minute adapt and see vertical lines as tilt - Get fatigued still firing same manner closest to that neuron and reduce and get shift Contrast sen - Sine wave, diff in contrast - Diff prop Cont - What is spatial frequ - Rep width of bars bigger width smaller - Small more freq then big low spatial fequ Orientation Contrast - Diff of peak in valley, greater differ light to dark then contast - Low reduced peaks Phase - Dark vs light bar - Chane different rading Cont sen function - Focus on a fatigued then - Low to high need - Middle least amount of contros - Low and high need more contrast - Adapted to a shifts not bell shape but dip where become adapeted – contrast sent function – how Sp freq and cont channels - Differntes in spatial freq allow more infor to be picked up by neuron - Low freq the just of info which is c broad outlines – like how many people - High sp freq b – more detail know actual person, different info depend what is needed Pvc - Map to it - Cortex organ same as ganglia cells organized in retina – - Fovea – 1 percnt input takes up 10 percent of cortex bc acuity more nureol processing in pvs Columsn - Pvc in columsn – one is location - Location sim then same column in pvc Contd - With column sim orientation - All cells respond to 20 degree angle - Move away neurons for diff angles Contd - Occ dom – wheter form contra to ips eye, when merge all 3 columsn hyper column, single location area in retina and both right and left contr and ips and complete set of prentations, coding spec amount of info orga regylry Beyond v1 - Simple complex and hyero complex in ovc - Out diff process - V2 same v1 - V3 differences codes for form and local movement – edges of patricul and motion but no colour – brain folded under v1 v2, in fron v2 v2 – smushed area back of brain - V4 – mapl of colour – not colour info but location as well binds it colour location in space – damage colourblind achro – dame to cones or cerbreal defecit - V5 – not just spec edges or moving but how whole obect moving, binds common elements of pbject and how moves more complex – akin see world in still images dif moving through space – talking not get mouth moving bad convo – and pouring coffee not see how full Beyond - What and where - Where is dorsal up from pvc - And what is down - What hippo and temperal what objects and faces and up somatosensory where things are - Deficits in where is ataxia – rec object but not reach approp – diff defincit in dif damage pathways - What agnosia not rec objects but grab them Perceptopn of objects - Have all info of simp0le perceptual feature how use perceive objects - How compese larger rec of objects - Problem inverse pr problem – numerpus info on retina orga 1000 of ways and how group them to perceive as objects - Complex porblme – info from retina is ambig lines and bars ot how combine Obe - Gestalt - Coomon rules how group them - And rbc – breakdown comp and build – non acc – stable properties in diff orientations - Rbc bases on human varients – same thing no matter what view, Ges - Strcutilaims – al
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