Exam 22: Transduction and Transmission in the Retina

You train a macaque to respond to the presentation of a red circle by ringing a bell, after which she is presented with a treat. One evening, the power goes out, but you decide to continue your training with the macaque using the waning sunlight. To your surprise, the macaque seems to be unable to respond properly to the red circle after about an hour. What is one explanation for the macaque's regression?

Historical legend suggests that pirates used to wear eye patches over one good eye so that they could quickly switch to using the usually-covered eye when entering the darkened holds of enemy ships. Does this legend have merit from a physiological standpoint? Why or why not?

While watching the sun set in your garden, you notice that at first, the red-colored flowers are very vibrant compared to the blue flowers. However, as the sunlight begins to fade, you notice this reverses: the red flowers start to look dull and dark while the blue flowers look vibrant and bright. What is this phenomenon known as?

What is one reason we cannot clearly read text that we are not focused on?

Within picoseconds of a photon being absorbed by rhodopsin,

In most invertebrates, light _______ photoreceptors; in most vertebrates, light _______ photoreceptors.

What is the primary neurotransmitter released by horizontal cells?

During transduction, the α subunit of the associated G protein binds to which part of the photoreceptor?

Ion channels on photoreceptors that open or close due to cyclic guanosine monophosphate (cGMP) are responsible for maintaining the photoreceptor's resting membrane potential, which is usually about

Describe a possible reason why it is advantageous for humans to be able to adapt quickly to changes in ambient illumination.

Why do some photoreceptors respond to blue light, while others respond to red or green?

Which of the following is true about the center-surround organization of receptive fields?

Pigments in cones are found _______ the cell membrane and pigments in rods are found _______ the cell membrane.

What is the primary neurotransmitter released by photoreceptors?

Receptive fields are an important concept to understand when studying the retina. Define receptive fields and describe their organization.

Which of the following is true about horizontal cells?

While stargazing one night, you notice that a particular star appears to vanish whenever you move your eyes to a specific part of the sky. Why might this occur?

Dark adaptation takes much longer than light adaptation. What is one reason this is the case?

Pigments that are responsive to light are found in the _______ of the photoreceptor.

Photoreceptors synapse with other cell types before their signals reach the optic nerve. Describe how this process differs for the two main types of photoreceptor.