Final: Lectures Flashcards
equation for spatial frequency
1/ ___ cpd (cycles per degree).
Equation for contrast of sinusoidal grating
(Imax-Imin)/(Imax + Imin)
Equation for contrast sensitivity
S = 1/T
What are factors that might develop that would underly the improvement in infant contrast sensitivity seen over time?
cones, ability to accommodate
and converge, ability to attend, changes in cortical neurons
a condition that leads to abnormal flow of
information from the eyes to visual cortex - all of the signals from each eye reach the
hemisphere on the same side of the head, and overlapping retinotopic maps for the two sides of the visual field develop in each hemisphere
Achiasma
How is sound transmitted?
Sound is transmitted via an oscillating pressure wave through a medium (air/water).
logarithm decibel scale to specify sound
pressure
dB = 20 * log10 (p/p 0 )
How loud a sound is perceived as goes up with its pressure amplitude.
Perceived loudness
How can a sound waveform be formed?
as a sum of sinusoidal sound waves
of varying frequency, amplitude, and timing.
We call as sinusoidal sound wave a _____________.
pure tone
How are pure tones characterized?
by its frequency and amplitude
The lowest frequency tone is called the ?
fundamental or sometimes the first harmonic.
How is the timbre of a sound determined?
The timbre of a sound of this sort is determined by the relative intensities of the fundamental and the various harmonics
The perceived pitch of a pure tone is determined ?
by its frequency.
the structure of the inner ear that transduces vibration into neural signals. It is filled with fluid, and when the fluid transmits a sound wave it causes vibration in the basilar membrane.
The cochlea
Equation for computing ITD
ITD = rsin(theta) + rtheta
The second term, theta must be in radians
(radians = 2pidegs/360),
What are social cues for distance?
sound level, attenuation of high frequencies, movement parallax, fraction of sound that is reflected (most useful indoors)
the ability to focus on a single stimulus, such as a conversation, while filtering out other sounds in a noisy environment
cocktail party phenomenon
The shortest sound segments that convey
meaning, are distinguished by place of articulation, whether the sound is
voiced or not, and the voice onset time (VOT)
Phonemes
TRUE OR FALSE: Infants can make
the phonemic distinctions used in all languages, but then lose the ability to make those that aren’t relevant as they learn their native language(s)
TRUE
actively amplify signals in the cochlea and
sharpen frequency tuning. One aspect of hearing loss is caused by damage to outer
hair cells, which leads to less frequency tuning of auditory nerves.
Outer hair cells
Deafness can be ameliorated by inserting electrodes into the cochlea to electrically stimulate auditory nerve fibers - an auditory prosthesis
Cochlear implants
Signals from each type of taste cell tend to
produce percepts of the corresponding taste
Fundamental tastes
These mice prefer normally bitter tasting substances more than normal mice. This supports the idea that signals coming out of individual taste cells are driving very specific tastes
Transgenic mice with bitter receptors in sweet taste cells
The miraculin in mBerries binds to sweet receptors without activating them directly, but activates these receptors when a normally sour tastant is ingested. We tried this and found that a sour lemon tasted quite sweet after eating the mBerry. This also supports the idea that signals coming out of individual taste cells are driving very specific tastes
mBerry demonstration
Causes taste dysfunction. It appears to infect cells that support the taste
cells and causes the taste cells to function less well or not at all. However, after
recovery, taste receptors regenerate and in most cases taste is restored.
COVID 19
Humans can follow a scent trail, and get better at it with practice. We do this better when we can use both nostrils, suggesting that our ability to localize scents is mediated in part by comparing signals from the two nostrils.
Odor localization
- Fast adaptation
- Small receptive field
- RA1 = FA I
Meissner corpuscles
- Slow adaptation
- Small receptive field
- SA1 = SA I
Merkel cell complexes
- Slow adaptation
- Large receptive field
- SA2 = SA II
Ruffini endings
- Fast adaptation
- Large receptive field
- RA 2 = FA II
Pacinian Corpuscles
- continuously signal pressure
- responding to presence of pressure
slow adapting
- responding to changes in pressure
- better at sensing vibration
fast adaptation
Known for fine acuity
Merkel disks
- thought to be related to hand control
- slow motion across skin
Meissner corpuscles
known to be about how skin is stretching as we move
Ruffini endings
- sensitive to vibration
- bulb absorbs continuous pressure but transmits rapid vibration
Pacinian Corpuscles
Thought to mediate social touch
Hair cell receptors
TRUE OR FALSE: negative decibels correspond to vibration amplitudes less than the reference amplitude
TRUE
The Merkel receptors appear to mediate detection at __________ frequencies
low
Meissner appear to mediate detection receptors at ___________ frequencies
intermediate
The Pacinian appear to mediate detection at ___________ frequencies
high
Equation for sensitivity
S = 1 / T where T is the threshold amount of force
How can tactile acuity be measured?
by determining two-point threshold, smallest separation where you can tell two points from one
Where is tactile acuity highest? where is it the lowest?
highest on the tips of the fingers and lower on the arms and trunk of the body.
Signals go to spinal cord, then the thalamus, and then cortical area S1. S1 is right next to primary motor cortex. There is a somatotopic organization of sensation in S1 (somatosensory homunculus), meaning that nearby parts of the body are represented in nearby parts of S1. There is also a magnification of the cortical
representation of some parts of the body (e.g., hands, lips), corresponding roughly to
the variation in density of mechanoreceptors
Pathways for touch
Part of the somatosensory system is proprioceptive receptors that
detect tension in muscles and tendons as well as joint positions. These are critical for us to control our body movements. There are proprioceptive spinal reflexes that (e.g.)
cause is to tighten a muscle when a tendon is pulled.
Proprioception
Perception of pain is critical for avoiding bodily harm.
Pain
