Class Notes (838,950)
Canada (511,158)
Psychology (5,220)
PSYCH 1XX3 (1,109)
Joe Kim (1,028)
Lecture 10

PSYCH 1XX3 Lecture 10: Module 10: Form Perception II (2017)
Premium

5 Pages
83 Views
Unlock Document

Department
Psychology
Course
PSYCH 1XX3
Professor
Joe Kim
Semester
Winter

Description
Module 10: Form Perception II Feature Detectors Magno and Parvo Cells • Found in retina • Transduce light into neural impulse • Magno mainly in periphery of retina – detect changes in brightness, depth, motion • Parvo found throughout retina – detect colour, pattern, form • From these ganglion cells – their axons exit retina via optic nerve to LGN • LGN to primary cortex in occipital lobe • Feature Detectors – what makes the cells in primary visual cortex fire Hodgkin and Huxley • Pioneered method for recording activity in neurons • Now able to see how individual neurons respond to specific stimuli • Lettvin – neurons in frogs on responding to moving black dots “Bug Detectors” Hubel and Wiesel • Accidently discovered feature detector cells • Used microelectrodes on cats to record neural activity when different visual stimuli presented • Neurons didn’t fire until cracked slide was presented – cats I followed crack, neurons fired intensely • Realized – neurons respond to stimuli more complex than diffuse flashes of light • Each neuron specific about what makes it fire most • Cells fire maximally to certain shape, size, position, and movement Simple Cell • Respond maximally to a bar of a certain orientation in a particular region of the retina • Example o Following simple cell responds most to horizontal bar o Is bar changes orientation/moves out of region – cell is inhibited (fires less than baseline) o Receptive field of simple cell = opponent fashion Complex Cell • Responds maximally to a bar of a certain orientation and direction of movement, regardless of where the bar is located with the receptive field • Example o Some cells don’t care where bar is located a will continue to fire o Some do care, get highest response at certain location, direction, angle Hypercomplex Cells • Responds maximally to a bar of a certain orientation and direction of movement, ending at specific points within receptive field • Have a region of inhibition at the end – making them sensitive to length of bar • Example o Most response when bar of light is in one region o Weak response when touching off Topographical Organization • Preserved in visual cortex Ventral Stream • Visual info must be combined to make sense of a visual scene • Begins in extrastriate cortex (visual association cortex) – surrounds primary visual cortex • Has many sub regions – each receives different type of information from primary cortex (colour, movement, orientation, etc) • Here info separates into dorsal or ventral stream depending on the type of information • Dorsal Stream – “where” – where objects are located and how they’re moving, goes to parietal lobe (processes spatial information) • Ventral Stream – “what” – what object is, form and colour – goes to temporal cortex (feature information comes together) Columns in Temporal Cortex • Temporal cortex arranged in columns oriented perpendicular to surface of cortex • Cells here respond to ver specific and more complex stimuli (hands, faces, chairs, apples, etc) • Each column = 5 layers of neurons responding to complex stimuli from same category • Each layer within column responds to slightly different features o One column of neurons may respond best to apples – layer one responds to red apples, layer 2= green apples, layer 3= yellow apples, layer 4= small apples, layer 5 = big apples • Not every object coded by specific neuron • Rather, objects presented by activity patterns across many cells in different parts of brain Development of Pattern/Object/Face Recognition Infant Pattern Recognition • Infants don’t perceive patterns, objects, and faces like adults • Preferential looking method used to study patterns
More Less

Related notes for PSYCH 1XX3

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit