extrageniculate nucleus Flashcards
pupillary light reflex pathways - constriction
Mediated by light
Parasympathetic NS
Pupils constrict for near vision (focusing)
Convergence even happens in blind -> they know where the finger would be
pupillary light reflex pathways - dilation
Mediated by absence of light
Sympathetic NS (driven from hypothalamus)
Innervation to the sphincter is inhibited = muscles relax
Dilation can be emotional e.g. excited
pupillary light reflex - pathway
Neuron 1
Hypothalamus -> THORACIC s.c.
Neuron 2
Thoracic sympathetic trunk -> long ciliary (to eye)
Neuron 3
Pupil dilator
NA (via a1 adrenergic receptors)
horner’s syndrome
Pathway above is disrupted
Pupil loses dilation innervation
Lid droops
Sweating is disrupted
Blood vessel dilation in the region innervated in this area
accessory optic system
Primary visual system in fish and birds
Mammals: concerned with LARGE FIELD MOTION
Of secondary importance in primates
Inputs from: V1, MT/MST
accessory optic system - optokinetic
move then flick back - visual driven
nystagmus
rapid involuntary eye movements
accessory optic system - vestibular
corrections for eye movement
acceleration driven
super colliculus
Sensory layers receive visual, auditory and tactile signals
Arranged in spatiotopic maps
Key area for orienting response
Quickly direct gaze to a stimulus
Ours is quite smaller than in other animals
In birds: projections resemble dorsal and ventral streams
Ours is in cortex
Important for eye movement: depends on attention (can also work to maintain the gaze)
Bi-modal (and tri) Neurons: respond to visual info of seeing something falling AND hearing the sound of it falling
suprachiasmatic nucleus
input from ipRGCs
involved in circadian rhythms
pulvinar nucleus of thalamus
Input from: both layers of SC
Projects: widely to visual cortical areas & parietal cortex
Integrate information from many areas
Lesions = impaired facial expression processing
Pulvinar neuron excited when surprised and anger face
