6.2 How The Brain Processes Visual Information

Question 0

Horizontal cells make inhibitory contact onto bipolar cells, which in turn makes synapses onto amacrine cells and ganglion cells. All these cells are within the ____.

Answer 0

eyeball

Question 1

The rods and cones of the retina make synapses with ____ cells and ____ cells.

Answer 1

horizontal : bipolar

Question 2

The axons of the ganglion cells form the ____ ____, which leaves the retina and travels along the lower surface of the brain.

Answer 2

optic nerve

Question 3

The optic nerves from the two eyes meet at the ____ ____, where, in humans, half of the axons from each eye cross to the opposite side of the brain.

Answer 3

optic chiasm

Question 4

Information from the ____ half of each eye (the side closer to the nose) crosses to the ____ hemisphere. Information from the ____ half (the side towards the temple cortex) go to the ____ hemisphere.

Answer 4

nasal-contralateral : temporal-ipsilateral

Question 5

Most ganglion cell axons go to the ____ ____ ____, part of the thalamus.

Answer 5

lateral geniculate nucleus

Question 6

A smaller number of axons go to the ____ ____ and other areas, including part of the hypothalamus the controls the waking-sleeping schedule.

Answer 6

superior colliculus

Question 7

The lateral geniculate, in turn, sends axons to other parts of the thalamus and the ____ ____.

Answer 7

occipital cortex

Question 8

The cortex returns many axons to the ____, so the thalamus and cortex constantly feed information back and forth.

Answer 8

thalamus

Question 9

At any instant, the rods and cones of your two retinas combined send a quarter of a ____ messages.

Answer 9

billion

Question 10

____ ____ is the retinas way of sharpening contrasts to emphasise the borders of objects.

Answer 10

Lateral inhibition

Question 11

In lateral inhibition, the receptors send messages to excite the closest bipolar cells and also send messages to slightly inhibit them and the ____ to their sides.

Answer 11

neighbours

Question 12

Actually, light striking the rods and cones decreases their spontaneous output. However, they have inhibitory synapses to the bipolar cells, and therefore, light on the rods or cones decreases the inhibitory output. A decrease in the ____ means net excitation.

Answer 12

inhibition

Question 13

Lateral inhibition is the ____ of activity in one neuron by activity in neighbouring neurons.

Answer 13

reduction

Question 14

Lateral inhibition heightens ____. When light falls on the surface, the bipolar cells just inside the border are most excited, and those outside the border respond the least.

Answer 14

contrast

Question 15

Each cell in the visual system of the brain has a ____ ____, which is the area in visual space that excites or inhibits it.

Answer 15

receptive field

Question 16

The receptive field of the receptor is simply the point in space from which ____ strikes the cell. Other visual cells derive their receptor fields from the connections they receive.

Answer 16

light

Question 17

A rod or cone has a tiny receptive field in space to which it is ____.

Answer 17

sensitive

Question 18

A small group of rods or cones connect to a bipolar cell. With a receptive field that is the sum of those cells ____ to it.

Answer 18

connected

Question 19

Several bipolar cells report to ____ cell, which therefore has a still larger receptive field. The receptive fields of several ganglion cells converge to form the receptive field at the next level, and so on.

Answer 19

ganglion