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333 Final

Terms in this set (118)

What is the relationship between receptive field size, sensitivity, and acuity? As you increase the size of a receptive field how does it affect those two properties (2 points)? What is the advantage of having receptive fields of different sizes and how are these different size receptive fields accomplished physiologically (2 points)?
Smaller receptive fields will have greater acuity but lower sensitivity. As you increase the size of a receptive field the acuity decreases and the sensitivity increases. The advantage of this is you can have high sensitivity receptive fields to detect low intensity stimuli and you can have high acuity receptive fields to make out fine details. Physiologically the receptive field size is accomplished through private lines (small receptive fields) or convergence (large receptive fields).
Draw a Signal Detection Theory (SDT) graph with number of trials on the y axis and spikes per trial on the x axis, featuring two distributions: one distribution representing noise and another distribution representing a signal (stimulus) plus noise (2 points). Give the observer a liberal response criterion (β)with no responses to the left and yes responses on the right (1 point). Show d' clearly using a labeled line between the two distributions. (1 point)
Look at key
Explain how the retina accomplishes lateral inhibition, including relevant cell types (2 points), give an example of an illusion that is explained by lateral inhibition (1 point), and why lateral inhibition is useful in helping us detect objects in the real world. (1 point)
The visual system achieves lateral inhibition through the amacrine (horizontal is also acceptable) cells inhibiting neighboring ganglion cells, creating a center-surround receptive field. It can explain Mach bands, the Hermann Grid and simultaneous contrast. It is useful for edge detection in real life.
What are the inputs to simple cells in V1 (cell type) (1 point), what kind of stimuli do they prefer (1 point), and what is their purpose (1 point)? Draw a receptive field for a simple cell showing the ON and OFF regions. (1 point).
The inputs to simple cells are LGN cells with center surround receptive fields. They like oriented bars of light and are the building blocks for feature detectors at later stages. Their receptive field looks like this (look at key)
What are the inputs to complex cells in V1 (cell type), what kind of stimuli do they prefer, and what is their purpose? Do complex cells have a fixed ON and OFF region? (Up to 4 points Extra Credit)
Complex cells get their input from simple cells in V1. Complex cells like oriented bars of light that are moving in a certain direction at a certain speed. They are used to detect motion and do not have fixed ON and OFF regions.
___________________ is the process of interpreting electro-chemical (neural) signals for conscious awareness.
Perception
The ________________________________________ (2 words) is the minimum amount of stimulus intensity that is needed to detect a stimulus 50% of the time.
Absolute threshold
Different types of electromagnetic radiation, including visible light, are distinguished from each other by their differences in ___________________ (one word).
Wavelength
___________________________ occurs when the ciliary muscles are tightened or loosened which causes the lens of the eye to thicken or thin allowing for focus on nearby or distant objects.
Accommodation
During phototransduction, isomerization of ______________________ causes a conformational change in the protein.
Retinal
_________________ adapt to the dark more quickly due to faster photopigment regeneration.
Cones
The first true neurons (cells that have action potentials) in the visual pathways are the _______________________ cells.
Ganglion
The ____________________________________ (2 words) layer of the retina is the first layer that incoming light passes through.
Ganglion cells
The concentration of cones is highest in the _______________________.
Fovea
Highly convergent neural circuits are found in the _____________________ region of the retina.
Periphery
The koniocellularlayers of the LGN receive input primarily from _____________________ ganglion cells.
Small bistratisfied
An _____________________________________ (2 words) column consists of neurons that predominantly receive input from only one eye.
ocular dominance
The LGN receives top-down input from _______________________.
Cortex
Layers ___, ___, and ___ of the LGN receive ipsilateral input with the rest receiving contralateral input. (3 numbers, 1 point total)
2, 3, 5
The disproportionate representation of the fovea on the retinotopic map in V1 is an example of _______________________________________. (2 words)
Cortical magnification
The ventral pathway of the visual system is primarily involved in recognizing _____________ objects are.
What
The parvocellular layers of LGN synapse onto layer ___________ of V1.
4C Beta
Cells from layer 4Cα synapse onto the ___________ stripes/bands of V2.
Thick
Give a definition of sensation.
The process of transforming physical stimuli to electrical signals
What is the difference between proximal and distal stimuli?
Proximal: is what your receptors actually detect
Distal: what is actually present that you are trying to infer from the information from the proximal stimulus.
The JND for a 100 gram weight is 2 grams. Based on Weber's law, what should the JND be for 1 kilogram (1000 grams)? (2 points) Show your work!
100/2 = 50 --> 1000/x = 50
So, JND = 20
Steven's Power law shows three different types of curves relating physical stimuli to their perceived magnitude. Explain the difference between response compression and response expansion in terms of these curves.
Response compression: logarithmic increase in perceived magnitude relative to stimulus intensity increase.
Response expansion: exponential increase in perceived magnitude relative to stimulus intensity increase
What happens to the amount of neurotransmitter being released when light is transduced by a photoreceptor, why?
The amount of glutamate release decreases following phototransduction since the cascade of events that starts with conformational change in retinal leads to hyperpolarization of the cell membrane.
What part of the eye is responsible for the "blind spot"? Give one reason why we don't perceive a blind spot when using binocular (both eyes) vision?
The optic disk causes the blind spot, but we fill it in using information obtained from the opposite eye during binocular vision.
The right LGN receives input from which parts of each eye (specify nasal/temporal and left/right). What part of the visual field do those areas represent?
L-nasal R-temporal, left visual field
Draw a picture of a stimulus that would maximize the firing rate for an OFF-Center, ON-Surround retinal ganglion cell. Label the light portion and dark portion of the circular receptive field.
look at key
Name one of the two structures that receives input from the retina, but is not involved in conscious vision. Give a function for it. (Up to 2 points Extra Credit)
The superior colliculus is a center for reflex movements of the eyes, head, and neck and direction of gaze
The Gestalt Psychology central principle of ________________________ says that we tend to order our experience in a manner that is regular, orderly, symmetrical, and simple.
Pragnanz
_______________________ features are an example of bottom-up processing that can guide global-interpretation of a visual scene, as shown in the various M.C. Escher paintings.
Local
Regions with ______________________ curvature are more likely to be perceived as objects.
Convex
An example of pareidolia is the phenomenon of seeing _______________ in objects such as clouds or rocks.
Faces
The three most commonly used colors for additive color mixing (the kind used in monitors and televsions), due to providing the largest variety of perceptible colors, are ______________, ______________ and ______________. (1 point total)
Red, blue, green
The color axes in the layers of the ________________________ are different than the unique hue axes, but the responses in the globs of ________________________ look similar to the unique hue axes.
LGN, V4
______________________________ Theory can explain why we see color after-images when we adapt to a colored object and then look away (such as the Spanish castle illusion from class).
Opponent Process
Differences in apparent speed of objects passing by a car window give rise to the depth cue known as ______________________________ (2 words).
Motion parallax
Binocular disparity produces ______________________, the "3D" perception of depth.
Stereopsis
After adapting to a red or green room for a long period of time, people will show a change in their unique ________________________ red-green color balance.
yellow
_______________________ is the first place in the nervous system that cells tuned to binocular disparity can be found.
V1
Light from an object on the horopter will fall on _______________________ points of the two retinas.
Corresponding
________________________________ (two words) theory is an explanation of the moon illusion that says the moon looks larger on the horizon because it appears farther away.
Apparent distance
Reichardt detectors are a plausible neural circuit to explain the perception of _____________________ motion.
Apparent
_______________________ motion is processed separately from other types of motion in the superior temporal sulcus.
Biological
_______________________ is a color that only appears in the presence of a sufficiently bright surround. Without a bright surround it looks yellow-orange.
Brown
A study on facial attractiveness discussed briefly in class and linked on the course website found that people's ratings of facial attractiveness were based on ________________________ to the faces they are exposed to. (1 point extra credit)
Familiarity
When viewing a masculine face for a long time, a neutral face will look more feminine by comparison when viewed right afterward. Why does this happen? What does it suggest about face perception?
You adapt to the masculine face, causing rebound excitation in the direction of a more feminine face. It suggests there are specialized mechanisms for face detection.
What do color double-opponent cells in cortex respond best to? What might this be useful for?
Colored edges/borders. Color Constancy is assisted by this due to not responding to changes in brightness.
What is the difference between an anomalous trichromat and a dichromat?
Anomalous trichromats have three functional cone classes but one has a shifted peak sensitivity that affects color discrimination. Dichromats have two functional cone classes.
Why are males more likely to be colorblind than females? For what type of colorblindness is this not the case?
Red-Green color blindness involves a gene on the X-Chromosome, so males who only have one X-Chromosome are more likely to inherit it. Blue-Yellow colorblindness involves an autosomal chromosome and affects both sexes equally.
What are two factors the Ames room uses to cause viewers to perceive people as changing size when they move through the room?
The viewer is limited to single viewpoint with a single eye and the room's shape is distorted to mask the different distances of the sides of the room.
Name and define two pictorial depth cues.
Relative height: objects that are higher in the field of vision are more distant
Familiar size: distance information based on our knowledge of object size
Describe the relationship between perceived size and perceived distance (include the equation).
As perceived distance increases, perceived size increases.
P ~ R x D
What is the aperture problem in motion detection and how can we solve it?
An individual cell cannot detect which direction an object is moving, as many directions can produce the same pattern on the cell's receptive field. By comparing activity across many cells tuned to different types of motion we can estimate the actual direction of movement.
Different languages have different amounts of color categories. Does this affect their color discrimination ability? Why or why not? (up to 2 points extra credit)
No, discrimination is based on our physiological system (cone types), not our labels for different percepts. Dichromats use the same color labels, but have worse discrimination than trichromats.
Draw examples of any 2 Gestalt Psychology principles (1 point each) and explain how the drawing illustrates that principle (1 point each).
Orientation: objects of similar orientation tend to be grouped together
Similarity: similar objects are grouped together
Draw a diagram of the 3 cone photoreceptors (1 point) and show how they are combined to create the two chromatic opponent-process systems (1 point each).
Look at key
What are metamers? (1 point) Why would someone who is a dichromat have different metamers than a trichromat? (1 point) Why are metamers psychophysical evidence for thrichromatic theory? (1 point) How do metamers relate to the concept of univariance? (1 point)
-Metamers: lights that are physically different but perceived as identical
- Dichromats only need two different monochromatic lights of varying intensity to match a comparison monochromatic light, rather than the three that trichromats need.
- Trichromatic metamers indicate that there must be 3 color receptor types in order for three monochromatic lights to match the pattern of a monochromatic light.
- An individual cone photoreceptor is blind to the wavelength it absorbs, so different combinations of wavelengths can produce similar responses.
Draw a diagram showing two eyes, the fixation point (1 point), the horopter (1 point), and an object at crossed disparity (1 point) whose information falls on the left side of each retina's fovea (1 point).
Look at key
The sound frequencies most likely to be affected by noise induced hearing loss are the _______ frequencies that are coded on the base of the cochlea.
high
The ossicles amplify vibrations for the purpose of ________________ matching.
Impedence
The ________________________ (two words) is the membrane through which the middle ear passes on sound vibration to the inner ear.
oval window
If you increase the physical pressure of a sound source by ten times it is equivalent to a _____dB increase in amplitude.
20
If you hit the middle C note on a piano and then hit a C note one octave higher, the second C note will be approximately _____________ the frequency (Hz) of the first C note and produce a consonant sound.
double
If we delete the fundamental frequency from a sound it will take on the perceptual pitch of the _______________ harmonic.
first
We can still understand the speech of someone who inhaled helium, because the _____________ (1 word) changes but the _______________________________ (2 words) does not.
formants, fundamental frequency
A _______________ is the smallest unit of speech that changes the meaning in a word.
phoneme
The high sensitivity to temporal response of the Pacinian corpuscles of the ________________ mechanoreceptors in the lower dermis facilitates the perception of fine textures.
FA2/RA2
Merkel cells (which mediate light touch sensation) are slow adapting and are located in the _______________ layers of the dermis.
upper
The two-point discrimination threshold of the lower lip is ________________ than that of the back of the hand.
smaller
Much like the visual system, acuity in the somatosensory system is enhanced by ____________________________ (two words) receptive fields which enhance edge detection.
center surround
Referred pain occurs due to _________________ of signals from different areas in the spinothalamic tract or cranial nerves.
convergence
_________________________ is a body sense partially mediated by the semicircular canals.
vestibular
The golgi receptor is one of the cell types involved in the body sense of ________________________.
proprioception
Writing systems can encode phonetic information (as in an alphabet), ________________ information (as in logographic systems), or both with similar literacy rates for all systems.
semantic
What is the difference between place coding and frequency coding?
Place coding: by the cochlear location where the greatest displacement occurs (where farther distances are related to lower pitch)
Frequency coding: rate coding (where faster firing corresponds to higher pitch).
In experiments where subjects had the shape of their outer ear (pinna) changed with foam inserts what happened to their sound localization over time? What localization planes were and were not affected?
It started out bad, but got better over time. Only the vertical plane was affected, the azimuth had no change.
When the stereocilia of a hair cell open mechanically gated ion channels what happens to the internal voltage of the cell and how does this change the amount of neurotransmitter being released?
...
Name one heuristic used to perceptually organize sounds and describe how it is used.
onset/offset cutes. It's used to distinguish between two stimuli as opposed to matching them together
Which frequencies of sound are most informative for localization based on differences in the amplitude of soundwaves arriving at the two ears (1 point)? Explain why this is the case (1 point).
High frequency sounds, because they degrade in amplitude at a faster rate as they move through space
How does experience shape our ability to discriminate phonemes? Use experimental evidence.
We start out able to hear all phonemes, but adapt to specialize only in phonemes from our own language. Japanese children and US children were equally good at discriminating R/L before 6 months, but US children improved and Japanese children lost the ability over time.
In the dual-stream view of speech perception, what are the two streams and what does each do?
The ventral stream is responsible for recognizing what is being said and processing the semantics (meaning). The dorsal stream is responsible for identifying how to produce the sounds necessary to speak (motor control).
Draw the spike rate response of a SA2 and FA1 mechanoreceptor to a hand contracting on an object:
SA2 starts firing after contraction and adapts slowly before stopping after release. FA1 only fire when first contracting and when releasing.
Look at exam 3
What are the two types of fibers involved in nociception? What is the difference in their functional role?
C fibers and Aδ fibers. C fibers: slow dull pain, and Aδ fibers: fast sharp pain.
Sound can be divided into 3 physical properties which correspond to 3 perceptual properties. Explain how each of these 3 physical properties relates to the three perceptual properties of sound (1 point each). Make sure you explain how changing the physical property would change the perceptual property. (1 point)
Amplitude is related to loudness (more amplitude equals more loudness)
Frequency is related to pitch (higher frequencies are higher pitches)
Sound spectrum (distribution of frequencies) relates to timbre (complex tones have many frequencies that change depending on the amount and amplitude of the frequencies).
What physical properties of light can be related to the physical properties of sound? How are they similar and how are they different in terms of the perceptions they create?
Amplitude is similar to intensity, frequency is similar to wavelength, and sound spectrum is similar to spectral purity.
Loudness and brightness both relate to higher amplitude waveforms.
Color and pitch are both formed from frequency of waveforms, though color forms one non-repeating color circle and pitch forms many repeating registers of pitch (octaves).
Saturation and timbre both deal with how many different frequencies are present, but timbre also has temporal components.
What are the ITD and ILD sound localization cues (1 point each) and how does the brain compute them (1 point each)? Describe the types of neuronal signals used in these computations.
ITD has axons of different lengths that synapse onto a single neuron. The greater length disparity = greater time disparities in the sound source. When both signals arrive at the same time, the neuron fires.
ILD gets a negative feedback signal that needs a greater excitatory signal coming from the opposite side. Only when one side has a sufficiently louder stimulus will the excitatory signal overcome the inhibitory signal.
Describe the relationship between two-point discrimination, receptor density, and cortical magnification (2 points) for the cutaneous senses. What is the benefit of having this relationship (1 point)?
Smaller receptive field sizes are more densely packed allowing better two point discrimination and leading to greater cortical magnification. This allows for high-detail (acuity) processing to allow us to discriminate between objects in our environment.
What is the McGurk effect? Describe the visual and auditory stimulus presented (1 point each), and what an observer will perceive (with and without their eyes closed) (1 point). What does this effect suggest about language processing (1 point)?
In the McGurk effect a visual stimulus of someone saying "ga-ga" and an auditory stimulus of "ba-ba" are played simultaneously, causing you to perceive "da-da", that is a combination of the visual and auditory stimulus. It suggests language perception is not strictly auditory, but has visual components as well.
One possible explanation for why "diet" foods have not successfully prevented a rise in obesity is that they do not stimulate receptors responsible for ___________ signaling.
satiety
Piriform cortex is also known as primary ___________ cortex.
olfactory
Synesthesia can be an interaction within one sensory modality, called _________________________ synesthesia, or an interaction between two sensory modalities, called ________________________ synesthesia.
intramodal, intermodal
Umami is primarily signaled by _________________ (an amino acid) molecules.
glutamate
The axons of the olfactory sensory neurons project to the ___________ of the olfactory bulb.
glomeruli
Sweet, umami, and bitter taste receptor cells all have ___________________________________ receptors and release _______________________ molecules into extracellular space.
G-protein coupled, ATP
What are two tastes that are detected solely by ion channels and what ion do they detect?
Salty (Na+) and Sour (H+)
Conditioned preferences for the sensory properties of food containing fat and protein are primarily mediated by receptors located in the ____________________________________.
stomach
There are about __________ different types of active olfactory receptors in humans.
350
___________________ is the only sense that does not pass through the thalamus.
olfaction
Describe an experimental test used to test for synesthesia.
Stroop-like speed tests, where color-grapheme synesthetes can answer math problems more quickly when the correct answer has a colored square next to it
One taste quality for which humans have more than one kind of receptor site is ____________________.
bitter
The nucleus of the _______________ tract is the first place taste signals arrive in the brain.
solitary
Synesthesia could potentially be explained by the ________________________ model which suggests there is increased connectivity and neural volume between the activated areas.
cross-activation
What is the difference between a PTC/PROP taster and a supertaster?
PTC/PROP tasters: extra bitter receptors
Supertaster: increased sensitivity to all tastes b/c they have more taste receptors in general.
How is the perception of "flavor" accomplished? Include the major sensory systems, what aspects of flavor they contribute, and the brain area where these senses combine.
Flavor involves the combination of taste, olfaction, and touch (as well as vision and audition to a less degree) and occurs in the orbital frontal cortex.
Describe the three kinds of olfactory adaptation. What is the time course for each and what are practical examples of how they influence our perception?
Receptor: seconds - why the first scent of something is the strongest.
Cortical: hours - why the smell of a bakery is greatly diminished after an hour.
Cognitive habituation: days - why you don't notice the smell of your own home or yourself.
Childhood memories are most strongly elicited by what sense? Why might this be?
Olfaction, it has direct pathways to the amygdala and entorhinal cortex forming strong memories with high emotional saliency.
What does the chemotopic layout of the olfactory bulb mean in terms of where odors are represented?
Odors are arranged based on their chemical similarity in the olfactory bulb
How are different odors coded? What is the relationship between chemical structure and perception?
Odor is coded by the pattern of activation across receptors. Perception does not directly relate to chemical structure, because similar molecules could activate different patterns and very different molecules could activate the same pattern of receptors.
Odor stimuli from food in the mouth reaches the olfactory mucosa through the ____________.
retronasal route
Where taste and smell signals first meet.
orbitofrontal cortex
Olfaction in the Environment: Top-down and bottom-up influences
Perceptual grouping: We learn to perceive a single odor (e.g., bacon) from familiar combinations of chemicals.
Past experience and expectations have an impact on odor perception and hedonics. -Things that smell bad but you still like to eat
Piriform (primary olfactory) cortex
Represents odor identity.
Anterior (APC) represents features of chemical structure.
Posterior (PPC) represents perceptual quality of odor, independent of physical stimulus
Entorinal cortex
linking odor to memory
to hippocampus
Evolution of olfaction and emotion
Rhinencephalon: the "nose brain"
Includes emotional responses and memories.
The most ancient part of the brain
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