The Central Visual System Flashcards
What are the types of retinal receptive fields?
ON-center/OFF-surround
OFF-center/ON-surround
Hypothalamus role
biological rhythms, including sleep and wakefulness
pretectum role
control size of pupil, certain types of eye movement
superior colliculus role
orients the eyes in response to new stimuli - move fovea to objects of interest
what are nonthalamic targets of the optic tract?
hypothalamus, pretectum, superior colliculus
which layers of the lgn are contralateral
1,4,6
primary visual cortex provides 80% of the synaptic input to _______
the Lateralal geniculate nucleus
receptive fields of LGN neurons
almost identical to the ganglion cells that feed them
magnocellular LGN neurons
large center-surround receptive fields with transient response
properties of parvocellular LGN cells
small center-surround receptive fields with sustained response
which area of the brain contains the striate cortex
area 17
enlarged _______ leads to gigantism and tunnel vision
pituitary gland
what vision would be lost from lesion of the left optic nerve
left peripheral vision
what vision would be lost from lesion of the left optic tract
all right-side vision
what vision would be lost from lesion of the optic chiasm
all peripheral vision
brain stem neurons provide
modulatory influence on neuronal activity
where do the koniocellcular layers (K1-K6) lie
ventral to the principal layers of the same number
Are parvo or magno cells bigger
magno
“top-down” modulation may gate _______ input from LGN back to cortex
“bottom-up”
how are the inputs in the LGN segregated
by eye and ganglion cell type
what is another name for the primary visual cortex
striate cortex
what part of the optic tract does the pituitary sit adjacent to?
the optic chiasm
In a retinotopic map, the _____ is overrepresented
central visual field (fovea)
RM - many cells in the target structure can be activated by
a discrete point of light due to overlapping receptive fields
how many layers are in the striate cortex
6
spiny stellate cells in V1
have spine covered dendrites. found in layer 4C
pyramidal cells in V1
have thick apical dendrites with spines. found in layers 3, 4B, 5, 6
inhibitory neurons in V1
no spines. form local connections in all cortical layers
magnocellular LGN neurons project primarily to which layer of the striate cortex
layer 4C alpha
parvocellcular LGN neurons project to
layer 4C beta of the striate cortex
koniocellular LGN axons make synapses primarily in
layers 1 and 3 of the striate cortex
Which cortical layers project to other cortical areas?
2, 3, and 4B
What cortical layer cells project to the superior colliculus and pons?
layer 5
What cortical layer cells project back to the LGN?
6
studied with transneuronal autoradiography, ________ shows alternating inputs from two eyes
ocular dominance columns
first binocular neurons found in
striate cortex
the striate cortex binocular neurons start at which layer
layer 3
developmental plasticity in ocular dominance occurs at the level of
the cortex
cytochrome oxidase
mitochondrial enzyme used for cell metabolism
what are blobs
CO-stained pillars in the striate cortex representing ocular dominance
orientation selectivity
a bar of light’s orientation can determine the degree of reaction from the cell
direction selectivity
neuron fires AP in the direction-dependent response to moving bar of light
properties of complex cell receptive fields
binocular, orientation-selective, ON and OFF responses to the bar of light WITHOUT distinct regions
properties of simple cell receptive field
binocular, orientation-selective, elongated ON or OFF area flanked with antagonistic surround
properties of cortical module columns
4c concentric fields, 30-150 microMs wide and 2 mm deep
calcium imaging uses
voltage sensitive dyes embedded in membrane
cortical modules are capable of
analyzing every aspect of a portion of the visual field
