Ch. 4 Coursera Flashcards
You discover a snake, which lives in an environment that seems completely dark, pitch black, to you. This snake has two globular structures that look like eyes . Which of the following is the most likely explanation for these eye-like structures in this newly discovered snake?
the eye like structures are sensitive to wavelength of light that humans can not detect and which are present in the eels environment.
Different living beings have developed particular adaptations to help them live effectively in their specific environment. We know that snakes are sensitive to infrared wavelengths which essentially allows them to “see” heat. Think of bionic versions of high-tech night vision glasses. To offer another example, shrimp are sensitive to both shorter and longer wavelength light than we are, presumably matching the range of wavelengths present in their environment.
Which of the following stimulus features most influences perceived pitch (pitch is a perception related to how high or low a note sounds)?
fundamental frequency
If you watch the auditory illusion video, you will see that we assign the pitch perception to the fundamental frequency rather than to the harmonics, even when that fundamental frequency is not present in the stimulus.
A movie-maker is interested in using neurobiology to aid her in setting the right atmosphere. She wants the words spoken by the character on screen to be clearly understood but spoken softly while also making it clear that the character is in a noisy bar. How could she best accomplish this?
have the character speak normally on top of bar sounds that are electronically decreased in volume
This is all about Weber’s law. The difference between a stimulus and the background is the determining factor in whether you will detect the stimulus. Absolute magnitude is not important.
As light travels from the outside world to the photoreceptors, which of the following does it pass through? Check all that apply.
lens, ganglion cell layer of the retina, pupil
Light first enters the eye through the cornea, then the pupil, then passes through the lens, vitreous humour and then hits the retina. In the retina, the light passes through the ganglion cell layer and then other cell layers before hitting the photoreceptor outer segments. Still behind the photoreceptor outer segments are the pigment epithelium, choroid and then the sclera/dura.
Which of the following are the TWO greatest influences on distance vision (acuity when viewing far objects)? Check all that apply.
cornea, eye length
The cornea bends light and provides the bulk of the focus - almost all of it for far-away objects. The refraction caused by the cornea has to match the length of the eye in order for light to be focused exactly correctly.
Which of the following occur when switching from viewing clouds to looking at a hand-held map? Check all that apply.
eye convergence, pupil constriction, change in lense shape
When going from far vision to near vision, the eyes will converge to fixate on a very close object, the pupil will constrict (this reduces the cone of blur that is possible), and the lens will change shape (rounds up) to fine-tune the refractive power of the eye. These three actions make up the Near Triad, a group of three actions that allow for near vision.
Which of the following are true of the retinal pigment epithelium? Check all that apply.
it is necessary for photoreceptor cell function
it is un pigmented in individuals with albinism
it is part of the central nervous system
When light reaches the retina, the first cell type it reaches is the ganglion cells in the inner (closer to the center, farther from the edge) retina. The retinal pigment epithelium is critical for photoreceptor function. WIthout the retinal pigment epithelium, the photoreceptors will stop transducing light and die. The retina (both the neural retina and the retinal pigment epithelium) derive from an outpouching of the diencephalon and are therefore part of the central nervous system. It is the pigment in the retinal pigment epithelium and in skin that individuals with ocular albinism lack.
You decide to go out bird-watching before dawn. Initially, before the sun is up, the conditions are scotopic. At this point, you can identify birds by their songs and which of the following additional features? Check all that apply.
general size and shape
Additionally, birds have structural color rather than pigmented color. This means that if you took a feather and ground it up, it would appear black or gray. There is no pigment in the feather. We perceive color when we look at a feather only under certain lighting conditions, conditions where light of only certain wavelengths bounces back. This is akin to an oil slick where we perceive a rainbow of colors that is simply dependent on the distance between water and oil. For more see http://www.the-scientist.com/?articles.view/articleNo/34200/title/Color-from-Structure/
An elderly friend tells you that over the past 2-3 years, she has had increasing difficulty reading. You ask her to try to read from a book with her left eye closed. She cannot. Then you ask her to try to read from a book with her right eye closed. She cannot do this either. She can read a large sign if she looks to the left or right of the sign. Which of the following could possibly explain her symptoms?
she has macular degeneration in both eyes
Since the problems remains in each eye when the other eye is closed, this cannot be a problem of misalignment. It also cannot be a problem of her left visual cortex because her right visual field is working as evidenced that she can read a large sign is she looks to the left of the sign, putting the sign in her right visual field. Hysteria, no comment. And macular degeneration is increasingly common in people as they age and it involves a loss of acuity in the central visual field. And it also involves both eyes very frequently. With macular degeneration, it may be difficult to read or recognize faces when the affected person is looking directly at the words or faces.
A baby is born with cataracts over both eyes. The cataracts are detected early but no surgery is possible until the baby is a teenager. Therefore, the cataracts are removed when the child is 17 years old. Which of the following is likely to be an immediate result from surgery at this age?
0 / 1 point
*not normal color vision
A person falls and hits the back of his head. An image of the brain shows a hemorrhage in the primary visual cortex on the right. Although this person recovers, his right visual cortex is permanently damaged and not functioning. Which of the following are possible for this individual? Check all that apply.
reading a sign in the right visual field
reading with both eyes
Each eye projects to both the opposite side primary visual cortex (via the thalamus), meaning that even if the right primary visual cortex doesn’t work, information from both eyes is still being processed in the left primary visual cortex. Therefore, reading with each eye should still be possible. Furthermore objects in the right visual field will still be processed in the healthy left primary visual cortex.
