Study Guides (380,000)
CA (150,000)
UTSG (10,000)
PSL (100)
Final

PSL440Y1 Study Guide - Final Guide: Binocular Vision, Tral, Htc


Department
Physiology
Course Code
PSL440Y1
Professor
Doug Hutchinson
Study Guide
Final

This preview shows page 1. to view the full 5 pages of the document.
!
!
Lecture'15:'The'Visual'System'–'Higher'Visual'Processing'
- In!terms!of!primary!visual!pathway,!projections!from!right/left!visual!field!
onto!retina!of!each!eye!
o That!information!is!separated!at!the!optic!chiasm!
o In!the!LGN,!although!you!have!all!the!information!from!left!visual!
field!goes!to!right!LGN,!the!information!is!still!separate!(NOT!
INTEGRATED!YET)!
o Integrated!in!striate!cortex!
§ Termination!of!visual!pathway!
'
Visual'Pathway'Defects!
!
o Injury!to!optic!nerve!of!right!
eye!
§ One!eye!can!see!both!
visual!fields!
§ Lose!bit!of!periphery!on!
one!side,!still!be!able!to!
see!both!visual!fields!
Losing!peripheral!visual!
field,!maps!onto!the!nasal!
fibres!
§ Lose!vision!in!your!right!
eye!
!
!
o Cut!right!at!the!optic!chiasm!
§ No!consensual!pupillary!
reflex!
§ Will!only!have!the!
periphery;!overlap!doesn’t!
exist!
§ Central!visual!field!
information!is!gone!
!
!
o Cut!at!the!right!visual!field!
optic!tract!(after!optic!chiasm)!
§ Will!lose!the!left!visual!
field!(right!part!of!retina,!
sees!left!visual!field)!
!
You're Reading a Preview

Unlock to view full version

Only page 1 are available for preview. Some parts have been intentionally blurred.

!
!
Striate'Cortex!
- Primary!visual!cortex,!
responsible!for!conscious!sight!
- where!the!primary!visual!cortex!
sits!
o Discrete!layers!(for!
various!inputs!and!
outputs)!
§ Subject!to!a!lot!
of!research!for!
functionality!
- Occupies!most!of!the!caudal!
occipital!lobe!!
- Receives!most!input!from!the!
LGN!
- Made!up!of!discrete!layers!(for!various!inputs!and!outputs)!
- !Also!organized!into!functional!columns!
!
Striate'Cortex'Functional'Organization!!
- Layer!4C!generates!a!retinotopic!map!from!projections!
from!the!LGN!
- Magnocellular!(M)!&!Parvocellular!(P)!projections!from!
LGN!terminate!in!sublayers!of!4C!
- Koniocellular!(K)!projections!terminate!in!layers!2!&!3!!
- The!other!layers!are!involved!in!visual!processing!and!are!
a!matter!of!intense!research!
- There!are!four!layers!of!the!striate!cortex!
o Layer!4C!in!particular!responsible!for!retinotopic!
map!
§ Projections!from!LGN!that!terminates!
here!
o What!these!layers!do!and!how!they’re!related!to!
each!other!is!conflicting!
!
Striate'Cortex'Functional'Organization'è!!
- Like!RGCs!and!the!LGN,!cortical!neurons!are!‘tuned’!to!be!responsive!to!particular!
receptive!fields!
- Not!responsive!to!‘spots’!of!light,!but!to!bars!or!edges!in!particular!orientations!
- Each!neuron!has!a!preferred!orientation!
- Other!tuned!responses!are!now!also!recognized,!such!as!direction!of!motion!&!contrast!
changes!
o Cortical!neurons!are!tuned!for!a!particular!receptive!field!
§ E.g.!seem!to!respond!generally!to!bars!or!edges!!
§ Matches!with!particular!orientations!
§ Each!neuron!has!a!particular!preferred!orientation!
o Just!like!with!ganglion!cells,!there!are!other!types!of!receptive!neurons/field!
!
Combining'Input'From'Two'Eyes!
- Signal!from!each!eye!remains!distinct!until!input!in!layer!4C!of!the!striate!
cortex!!
- Eye!specific!signals!are!integrated!in!output!to!other!cortical!layers!
- However!they!are!organized!into!ocular!dominance!columns!in!which!
adjacent!layers!respond!most!to!the!eye!represented!in!the!underlying!layer!
4C!
- The!information!from!both!eyes!is!integrated!in!the!adjacent!layers!through!
mechanisms!that!are!still!not!understood!
- All!signals!distinct!UNTIL!it!reaches!4C!of!striate!cortex!
- Within!a!column!of!striate!cortex!there!is!ocular'dominance'columns!
You're Reading a Preview

Unlock to view full version