PSYC 311 Lecture Notes - Lecture 8: Thalamus, Parietal Lobe, Optic Nerve

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2 Oct 2014
Department
Course
Lecture 8
Thursday, September 26, 2013
Read the Gross Anatomy of the Brain, Cerebral Cortex and Visual Pathways
The visual field depends on where you are fixating
Everything you see goes to the right and left striate cortex through the right and left
visual field
oThings in your right visual field would be seen by the left striate cortex
oThings in your left visual field would be seen by the right striate cortex
Temporal and nasal parts of the eyes
Right visual field receives information from the temporal part of the left eye and nasal
part of the right eye (outer and inner respectively)
Left visual field receives information from nasal part of left eye and temporal part of
right eye
Nasal information crosses over and goes to the other hemisphere
Temporal information goes to the same side and to the thalamus
Information goes to the lateral geniculate body/nucleus from both eyes
oThe right visual field goes to temporal part of left eye and stay in the same
hemisphere and nasal part of the left eye which crosses over to go to the left
LGN
Chiasm – crossing part where axons leave the ganglion cells towards the LGN on the
nasal parts of the eye
Optic tract – after the crossing point (chiasm)
Optic nerve – before the crossing point (chiasm)
Geniculo-calcarine tract – goes from the LGN and thalamus to get computated and is
sent by the geniculo-calcarine tract to go to the striate cortex
oAka optic radiations
Right homonymous hemianopsia – being blind in half the right visual field
oDamage in the left optic tract
Damage in the right optic tract – left homonymous hemianopsia
Damage to the optic chiasm means you cannot see the visual field of the
corresponding eye (i.e. the left eye cannot see the left visual field but the right eye
can)
oBitemporal heteronymous hemianopsia – restricts your field of view
oOnly the extreme parts are not shared
oThe central parts of the visual field will be seen by one part of the eye
Meyers Loop – goes to the lower lip of the calcarine sulcus through the temporal
lobe  the axons are from the ventral area of the LGN
oTemporal damage may destroy some of the Meyers loop axons
Damage to the lower visual field
i.e. damage to the left temporal lobe means you might have visual
problems in the right visual field
Dorsal axons from the LGN go straight to the lower lip of the calcarine sulcus
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