Wiring the Visual System Flashcards
what occurs at the optic chiasm
nasal hemiretina cross (contralateral hemisphere)
temporal RGC axons enter the ipsilateral hemisphere
midbrain projections
RGC - pretectum - pupillary reflex
RGC - superior colliculus - saccadic eye movements
central projections
LGN - primary visual cortex
(ipsilateral)
how are long range and short range cues sent
long range cues - secreted
short range cues - require physical contact
where is the retina made from
neural tissue (diencephalon)
retinal cell types
photoreceptors (1R 3C)
horizontal cells (inhibitory 2)
bipolar cells (around 11)
muller glial cells
amacrine cells
RGCs (>30)
layers of the retina
ONL
OPL
INL
IPL
GCL
optic nerve fibres
how is visual information processed
image
retina
visual input split into different information channels. Information channels defined by different circuits
what is the role of synaptic adhesion molecules
make connections
tenm3 MO
antinucci et al., 2013
cells don’t know where to interact
what are topographic maps
neuronal connections arranged such that neighbouring points in the origin are represented in adjacent locations in the CNS
regeneration experiment
Sperry 1963
remove dorsal retina = axons grow medially
remove ventral retina = axons grow laterally
remove anterior retina = axons grow posterior (bottom pair) tectum
remove posterior retina = axons grow to the anterior tectum
where does the retina project to the SC/tectum
nasal - posterior
temporal - anterior
dorsal - lateral
ventral - medial
frog with rotated eyes
temporal - anterior
nasal - posterior
dorsal - medial
ventral - lateral
if trying to catch fly, go up instead of down
what is the chemoaffinity hypothesis
specificity of wiring is based on chemical tags. Individual neurons express distinct molecular markers during development. Formation of appropriate synaptic connections depends on matching of complementary molecules on pre and post synaptic neurons.
