Unit 9: The Visual System: The Brain

what is the work done by torsten wiesel and david hubel?

• grad students who received a nobel prize for their work on the anatomy and physiology of the visual cortex

• discovered that areas of the visual brain, thalamus and occipital cortex (specifically sensitive to certain kinds of stimuli)

• sensitivity can be mapped into predictable patterns

• cat experiment, dot reflecting

what structures are along the visual pathway?

optic nerve, optic chiasm, optic tract, LGN, optic radiation, visual cortex

what is the optic nerve?

makes our blind spot, and goes throughout the brain to the LGN

• axons lead our eyeball and make the first synapse in the LGN

what is the optic chiasm?

when you see in your eye you have the nasal retina, sends information to optic nerve into brain

what is the optic tract?

optic chiasm connects to the LGN

what is the LGN?

has 6 layers:

• layers 1-2- receive information from magnocellular cells (beginning of magnocellular pathway)

• layers 3-6- receive information from p ganglion cells (beginning of parvocellular pathway)

• purple layers (m & l cones bring information)

• white dotted layers (s, knoiocellular layer)

what are the 8 properties of the LGN?

1. cross projection, left visual field projects in the nasal retina, right visual field project on the temporal retina

2. temporal retina has ipsilateral projections (stays on same side of body), nasal retina has contralateral projections (opposite side)

3. each LGN receives information from the left and right eye

4. the right LGN process the left visual field

5. left LGN processes the right visual field

6. information from both eyes is maintained in seperate layers

7. layers 1-2 (magnocellular pathway) & layers 3-6 (parvocellular pathway)

8. topographic mapping, locations are next to each other in the real world (and retina) are processed by neurons next to each other in the brain

what is the optic radiation?

highway that brings information upwards into visual cortex

what is the superior colliculus?

• structure at the top of the brainstem

function: control of rapid eye movements

what is the saccades?

sudden eye movements used to look from one object to another

what is smooth-pursuit eye movements?

voluntary tracking eye movements (like objects)

what is the primary visual cortex?

• location where visual information reaches the cortex first, located in the occipital lobe

layers:

retinotopic map

cortical magnification

visual crowding

what is bar detector?

what is simple cells: orientation tuning curve?

what is complex cells and end-stopped cells?

what is organization of V1: hypercolumn?

what are the organizations of V2?

what are the functional pathways?

what is the ventral pathway?

“what”, parvo

what is the dorsal pathway?

“where”, mango

what is the experiment on monkeys?

what does vision come together?

what is the development of the visual system?

• the kitten carousel experiment

what is the critical period?

cataract

strabism

what is the visual acuity and spatial frequency?

what development of spatial frequency in children?

what is selective adaptation?

what is the tilt after effect?

what is the color after effect?

what is spatial frequency after effect?

what is blindsight?