Neuroscience CA2 - vision

ON bipolar cells

Which type of bipolar cells hyperpolarise in the dark?

OFF bipolar cells

Which type of bipolar cells depolarise in the dark?

Decrease in glutamate release in light

What causes the depolarisation of ON bipolar cells?

Increased glutamate release in dark

What causes depolarisation of OFF bipolar cells?

Blue/yellow or red/green

Bipolar cells are either …

Blue

If a wavelength is short, which bipolar pathway is stimulated

Green

If a medium wavelength is detected, what bipolar pathway is stimulated?

L cones

Which cones are activated to see red light?

S and M equally

What cones do yellow wavelengths stimulate?

Retinal ganglion cell

Where do bipolar cells transfer the graded signal to after being stimulated by a photoreceptor cell ?

iGLUR

What receptor in the RGC causes depolarisation (detects glutamate release)

Increased blind spot

What can abnormal myelination of RGCs cause?

Diameter of axon or thalamic projections

How are RGCs categorised (2)

W (small), X (medium) and Y (large)

Types of RGC based on diameter of axon (3)

M (movement and contrast), P (M+L cones), K (S cones) and ipRGC (pupil diameter, circadian rhythm)

Types of RGCs based on thalamic projections (4)

Lateral geniculate nucleus

Where do M,P and K RGCs project to?

Hypothalamus, superior collicullis and prefecture

Where do ipRGCs project to?

Both pupils contrict

What happens when light is shone in the right eye?

Edinger-Westphal nucleus (generates APs through oculomotor nerve)

Where do the pretectal nuclei stimulate ?

Magnocelullar

What layer of the lateral geniculate nucleus do M RGCs project to?

Parvocellular

What layer of the lateral geniculate nucleus do P RGCs project to?

Koniocellular

What layer of the lateral geniculate nucleus do K RGCs project to?

Chromatic adaptation

Visual cortex is responsible for the stable appearance of object colours despite the wide variation of light reflected and observed by our eyes