Lecture 4 visual system Flashcards
What do sensory systems not process
Random information
What does the right hemifield activate
LEFT BRAIN
Where does the ventral pathway terminate
inferior temporal
Where does the dorsal pathway terminate
posterior parietal
Where is the outer plexiform layer
between PR BP H
Where is the inner plexiform layer
between G A
Amacrine are between
ganglion and bipolar
Horizontal between
bipolar and PR
Pathway from front to back of eye
optic nerve gang BP Rod/cone nuclei Rod/cone outer segment Pigmented epithelium Choroid Sclera
Where is phototransduction
Outer segment PR
Humans PR response to light
hyperpolarise
Describe pathway in dark
cGMP non-selective channels open
na+ influx dark current
depolarise PR
Describe pathway in light
Rhodopsin activated Conf change Activate transducin Tranducin GTP alpha activates phosphodiesterase decrease cGMP Closes Na+/cGMP channels hyperpolarised
describe what happens to bipolar ON cells when ligh shone
Less glutamate from PRs Metabotropic R's = inhibitory Not stimulated so channels open na= influx depolarised
describe what happens to bipolar OFF cells when ligh shone
Less glutamate from PRs ionotropic glutamate = excitatory Channels not stimulated so closed no influx Na+ hyperpolarised
Bipolar ON centre vs surround
centre dep
surround hyper
Bipolar OFF centre vs surround
centre hyper
surround dep
explain centre OFF cells BP with light
Direct activation
PR hyperpolarises BP
Glutamate release stopped
BP hyperpolarises
explain surround OFF cells BP with light
PR hyperpolarises
Horizontal hyperpolarises
Horizontl inhibitory so stops hyperpol of PR
Bp depolarised
