Bipolar Cell Receptive Fields

The inotropic glutamate receptors of OFF bipolar cells, which are glutamate-gated sodium channels, mediate what kind of action in the cell?

A classical depolarizing excitatory postsynaptic potential

The depolarization of an OFF bipolar cell in the dark is due to the influx of ____

Sodium (Na+)

In the dark, when the photoreceptor of the receptive field center for an OFF-center bipolar cell is depolarized and releasing glutamate, the OFF-center bipolar cell will be depolarized and release more glutamate (the neurotransmitter of bipolar cells is the same as the neurotransmitter for photoreceptors), causing what to occur in the firing pattern of a corresponding OFF-center ganglion cell that the OFF-center bipolar cell synapses with?

The OFF-center ganglion cell that the OFF-center bipolar cell synapses with will have its firing rate increased

In the dark, when the photoreceptor of the receptive field center for an ON-center bipolar cell is depolarized and releasing glutamate, the ON-center bipolar cell will be hyperpolarized and release less glutamate (the neurotransmitter of bipolar cells is the same as the neurotransmitter for photoreceptors), causing what to occur in the firing pattern of a corresponding ON-center ganglion cell that the ON-center bipolar cell synapses with?

The ON-center ganglion cell that the ON-center bipolar cell synapses with will have its firing rate decreased

In addition to direct connections with photoreceptors, bipolar cells also are connected via horizontal cells to a circumscribed ring of photoreceptors that surrounds what?

The central cluster of photoreceptors that directly synapses with the bipolar cell

What makes the ON and OFF bipolar cells physically different?

The glutamate receptors on the membranes of the 2 bipolar cells

Bipolar cells are said to have ________ center-surround receptive fields

Antagonistic

The effect of horizontal cell hyperpolarization is to ______ the effect of light on the photoreceptors it is connected to.

Counteract

Disinhibited means _____

Depolarized

The receptive field center has ________ photoreceptor input

Direct

The opposite of facilitated is ______

Disfacilitated

Another word for facilitated is ______

Disinhibited

The opposite of inhibited is _____

Facilitated

In what layer do bipolar cells synapse with ganglion cells?

Inner plexiform layer

OFF bipolar cells have what kind of glutamate receptors?

Ionotropic glutamate receptors

If you had an OFF bipolar cell, hyperpolarization of the photoreceptor of its receptive field center (which would occur if light were shone onto the photoreceptor of its receptive field center) would result in the typical response---turn the OFF bipolar cell off. But, considering that bipolar cells have antagonistic center-surround receptive fields, hyperpolarization of the photoreceptors of its receptive field surround (which would occur if light were shone onto the photoreceptors of its receptive field surround) would result in the opposite response, turning the OFF bipolar cell on.

Is this right? Ask teachers

The hyperpolarization of an ON bipolar cell in the dark is due to the efflux of ______

Potassium (K+)

Inhibited means _____

Hyperpolarized

Hyperpolarization of the photoreceptor due to light causes less neurotransmitter (glutamate) to be released, resulting in a more ________ OFF bipolar cell

Hyperpolarized bipolar cell

When there is less glutamate being released, like in the light, what happens to ON bipolar cells?

They depolarize

The number of photoreceptors in a cluster that synapses with a bipolar cell ranges from ______ at the center of the fovea to ____ in the peripheral retina

1 at the center of the fovea to thousands in the peripheral retina

ON bipolar cells have what kind of glutamate receptors?

G-protein-coupled (metabotropic) receptors

The receptive field surround gets photoreceptor input via _________

Horizontal cells

When a photoreceptor hyperpolarizes in response to light, output is sent to _____ that also hyperpolarize

Horizontal cells

Another word for disfacilitated is ______

Inhibited

Amacrine cells have ______ connections in the inner plexiform layer

Lateral

The bipolar cells that hyperpolarize when light is shined onto a photoreceptor it is directly connected with are called ______ bipolar cells

OFF bipolar cells

OFF bipolar cells are ______ in the dark because of the present of glutamate and _______ in the light due to the lack of glutamate

OFF bipolar cells: - Facilitated in the dark - Disfacilitated in the light (inhibited, hyperpolarized)

OFF bipolar cells have what kind of receptive field centers and what kind of receptive field surrounds?

OFF receptive field centers and ON receptive field surrounds

The bipolar cells that depolarize when light is shined onto a photoreceptor it is directly connected with are called ______ bipolar cells

ON bipolar cells

ON bipolar cells are ______ in the dark because of the present of glutamate and _______ in the light due to the lack of glutamate

ON bipolar cells: - Inhibited in the dark - Facilitated in the light (disinhibited, depolarized)

ON bipolar cells have what kind of receptive field centers and what kind of receptive field surrounds?

ON receptive field centers and OFF receptive field surrounds

The response of a bipolar cell's membrane potential to light in the receptive field center is ______ to that of light in the receptive field surround

Opposite

Each single bipolar cell receives direct synaptic input from a single or a cluster of photoreceptors?

Receive direct synaptic input from a cluster of photoreceptors

The G-protein-coupled (metabotropic) receptors of ON bipolar cells mediate what kind of action in the cell?

Respond to glutamate by hyperpolarizing

The receptive field of a bipolar cell consists of what 2 parts?

The receptive field center and the receptive field surround

Example and explanation of lateral inhibition: Say we have a ON bipolar cell with a receptive field center, and light falling on this receptive field center will result in the depolarization of the ON bipolar cell (turn the ON bipolar cell on). The ON bipolar cell has a receptive field surround whose activation will result in the OPPOSITE response from the ON bipolar cell (in this case, activation of the receptive field surround would result in hyperpolarization of that ON bipolar cell, turning the ON bipolar cell off, even though normally the ON bipolar cell would be turned on when the photoreceptors are hyperpolarized in the light). The way this works is that the ON bipolar cell is connected to the receptive field surround via horizontal cells, and the job of horizontal cells is always to evoke the exact opposite of the response that a bipolar cell would normally have to light falling on the receptive field center.

We don't really know why this happens

Is the antagonistic center-surround receptive field organization passed on from bipolar cells to ganglion cells when they synapse in the inner plexiform layer?

Yes