Sensory Processing/Perception Flashcards
What allows us to perceive depth?
Binocular cues: Retinal Disparity and Convergence
What allows us to perceive form?
Monocular cues: Relative size, Interposition, Relative height, Shading and contour
What allows us to perceive motion?
Monocular cues: Motion paralax (relative motion)
What allows us to perceive constancy?
Size constancy
Shape constancy
Color constancy
Perceptual organization
Describes how we see and experience different perceptual phenomena in the world around us
Depth
Form
Motion
Constancy
Describe the process of sensory adaptation regarding hearing
Inner ear muscle contracts when there’s a loud noise, which dampens the noise and protects ear drum from being damaged. This takes a few seconds to kick in –> doesn’t work for immediate loud noises, i.e. gunshot
Describe the process of sensory adaptation regarding touch
Sensory receptors become saturated and stop firing as much –> desensitization
Describe the process of sensory adaptation regarding smell
Sensory receptors in nose become desensitized to particular odors
Describe the process of sensory adaptation with proprioception
Mechanism not stated in video, but if someone puts on goggles that distort image of world, ie flips images upside down, over time the brain adapts and flips the image rightside up
Describe the process of sensory adaptation regarding sight. How does this differ from sensory adaptation in other modalities?
While most other modalities get some kind of down regulation, with sight you can get up or down regulation.
Lots of light: Pupils constrict, rods/cones become desensitized –> down regulation in ability to sense light
Dark: Pupils dilate, rods/cones synthesize more light sensitive molecules –> upregulation in sensitivity
What is Weber’s Law and what kind of relationship does it predict between the JND (incremental threshold) and the background intensity?
dI/I = k
Linear relationship
T/F: The absolute threshold of stimulation is a fixed, unchanging number
False
Can be influenced by: expectations, experiences, motivation, altertness
What are the different types of somatosensation? What determines the intensity for each modality?
- Thermoception (temperature)
- Mechanoception (pressure)
- Nociception (pain)
- Propioception (position)
For each modality, intensity correlates to neuronal firing rate (low intensity = low rate of firing, high intensity = high rate of firing)
How do somatosensory neurons encode information about timing?
Neuron firing may or may not adapt to the stimulus, which provides information regarding stimulus timing.
Non-adapting: The entire time a stimulus is being applied, there is no change in firing rate; each spike is spaced evenly
Slow-adapting: Neurons start off with high firing rate, then slows down over time; slow to adapt to change in stimulus
Fast-adapting: Neurons fires really quickly as soon as stimulus starts, then it will stop firing, then it will start firing again as soon as the stimulus stops
What structures located in the inner ear are particularly important parts of the vestibular system?
Semicircular canals: Anterior, lateral, and posterior
Otolith organs: utricle and saccule
What is the fluid located in the semicircular canals? How does it contribute to our vestibular sense?
Endolymph
When we rotate along a certain plane → causes endolymph to shift within that particular canal → allows us to sense what plane our head is rotating along
We are also sensitive to how much of fluid is moving and how quickly → we can also get information about the strength of rotation
How do the otolith organs contribute to our vestibular system?
They help us detect linear acceleration and head position
Within these structures are calcium carbonate crystals that are attached to hair cells within a viscous gel substance
If we accelerate in a direction or, for example, move from standing up to lying down, this causes the crystals to move because they are heavier than the surrounding gel environment
When they move, they physically pull on the hair cells they’re attached to → triggers an action potential that carries this information to the brain
Describe the physiological process in the semicircular canals that causes dizziness/vertigo
As we spin, the endolymph moves along the direction we’re turning, but this liquid doesn’t always stop spinning when we do (especially true if spinning vigorously or for a long period of time)
Continued movement of endolymph → signals sent to brain indicating you’re still moving even after you have stopped → causes dizziness
When fluid finally stops, dizziness subsides
→ Rotating in the opposite direction of how you were originally spinning encourages the movement of the endolymph in that opposite direction → can help stop the original motion of the endolymph by “canceling it out”
Describe the physiological process in the otolith organs that causes dizziness/vertigo
If you were in a situation without gravity (ie Astronaut), your otolithic organs probably wouldn’t work very well because gravity won’t pull down on them in the same way → concepts of up/down kind of become meaningless → can be really disorienting
Also a danger of scuba diving, because buoyancy can have the same effect as gravity → sometimes results in divers becoming disoriented in water
Especially true when they don’t have visual cues about which way is up and which way is down
Signal Detection Theory
Looks at how we make decisions under conditions of uncertainty.
Tries to figure out, at what point is a signal strong enough that we are able to notice it in the first place; at what point are we able to detect a signal?
Describe the 4 possible outcomes of signal detection theory
Signal Present, Response “Yes” = Hit
Signal Present, Response “No” = Miss
Signal Absent, Reponse “Yes” = False Alarm
Signal Absent, Response “No” = Correct Rejection
How does the strength of the signal (d’) affect the relative amount of hits/misses/false alarms/correct rejections?
If the signal is really strong, you might always get it right (either hit or correct rejection)
Hit>miss
If signal is weak, might get some false alarms and/or misses
Hit
*Note: d’ represents the difference between the means of the noise distribution and signal distribution
What is the difference between top-down and bottom-up processing?
Bottom-up Processing: Stimulus influences our perception; No preconceived cognitive constructs about what it is you’re looking at; Data driven; perception of what you’re looking at directs your cognitive awareness of that object
Top-down Processing: Uses your background knowledge/information/expectation to influence perception; Theory driven; our perception/behavior is influenced by our expectation
If you were looking at a ‘where’s waldo?’ image, what kind of processing (top-down or bottom-up) would you be using?
Top-down
This allows us to be goal-driven and we’re able to look through the picture and find Waldo.
In contrast, if we were using bottom-up processing, we would just be seeing a bunch of little people and we wouldn’t really be goal driven/trying to do anything
What are the laws outlined by the Gestalt Principles?
Similarity: Items that are similar to one another are grouped together by your brain
Pragnanz: Reality os often organized/reduced to the simplest form possible
Proximity: Objects that are close to one another are grouped together
Continuity: Lines are seen as following the smoothest path
Closure: Objects grouped together are seen as a whole
Label the parts of the eye:
Conjunctiva
Helps protect/moisturize the eyeball; protection from dust
If inflamed → pink eye
Cornea
Transparent, thick, fibrous tissue
Anterior ⅙ of the eyeball
Helps bend light; starts to focus the light
Protects front of eyeball
Anterior Chamber
From back of cornea to front of lens
Filled with aqueous humor
Helps provide internal pressure to maintain the shape of the eyeball
Allows nutrients/minerals to flow through this space to supply the cells of the cornea, iris, etc.
Aqueous Humor
Fluid that fills the anterior chamber
Helps provide internal pressure to maintain the shape of the eyeball
Allows nutrients/minerals to flow through this space to supply the cells of the cornea, iris, etc.
Pupil
An opening in the middle of the iris that modulates the amount of light that will be allowed to enter the eyeball
Iris
The colored part of the eye
Surrounds pupil
Muscle that constricts/relaxes to change size of pupil
Levels of pigmentation in the iris determine eye color
Lens
Bends and focuses the light on the retina
Lens adjusts how much it focuses the light by changing its shape
Ciliary Body
Suspensory ligaments + Ciliary Muscles
When ciliary muscle contracts, it’s attached to the suspensory ligaments, which then changes the shape of the lens → changes how much light is bent
Ciliary body secretes the aqueous humor
Posterior Chamber
Space behind the iris/ciliary muscle
Filled with aqueous humor
Vitreous Chamber
Filled with vitreous humor
Jelly-like substance that serves to supply pressure to the inside of the eyeball so that the eyeball maintains its round shape; also provides nutrients to cells inside the eyeball
Retina
Where the ray of light is converted from a physical waveform into an electromagnetic stimulus that the brain can interpret
Packed with cells called photoreceptors
Macula (and fovea)
A special part of the retina that is particularly rich in cones
Cones are involved in discerning high levels of detail in whatever you’re looking at
Fovea: a little dip in the macula
Almost completely covered in cones (compared to the rest of the retina, which is mostly covered in rods)
Cornea/lens bend light to focus on fovea so you can discern/appreciate fine details
Choroid
Layer behind the retina
Pigmented black in humans
→ All the light that hits the choroid is absorbed
Network of blood vessels that helps nourish the retina
Sclera
White, thick, fibrous tissue coat that covers the posterior ⅚ of the eyeball
Attachment point for muscles
Without the sclera, muscles wouldn’t have anything sturdy to attach to and you wouldn’t be able to move your eyes around
Also provides an extra layer of protection and structure to the eyeball
Describe the path light takes from entering the to reaching the brain
light through the eye to the cornea -
aqueous humor - through pupil -
lens - vitreous humor - retina -
optic nerve - brain - the occipital lobe
What are the major differences between rods and cones?
Rods: ~120 million; Very sensitive to light; Good for night vision; Found all around the periphery of the retina; contains protein rhodopsin; slow recovery time (takes a longer time to fire again than a cone)
Cones: ~6-7 million; Responsible for color vision; 3 types of cones: Red, green, and blue (named for the color they are sensitive to); Centered in the fovea of the retina –> Lets us see really fine details; contains protein photopsin; fast recovery time
When light hits a rod, how does it effect the rod? How does this affect other cells involved in visual processing?
Light causes rod to turn off through the phototransduction cascade
When rod is turned off, on-bipolar cellis turnedon(off-bipolar cellis turnedoff), which then turnsontheretinal ganglion cell, which goes to theoptic nerveand then to thebrain
Describe the main steps in the phototransduction cascade
- When light reaches the rod, retinal, a small molecule round in the proteinrhodopsin, changes conformation from bent (cis-retinal) to straight (trans-retinal), which in turn causesrhodopsin to undergo a conformation change as well
- Transducin (has alpha, beta, and gamma subunits) breaks away from rhodopsin; the alpha subunit binds to cyclic GMP phosphodiesterase (PDE)
- PDE converts cyclic GMP (cGMP) into GMP, which decreases [cGMP] and increases [GMP]
- cGMP binding to sodium channels allows sodium to flow into the cell, so decreased [cGMP] actually hyperpolarizes the cell and turns it off
What are the two types of bipolar cells and how to they respond to hyperpolarization of rods?
On-center bipolar cells normally are being turned off when the rod cell is turned on → when the rod turns off, turns on this bipolar cell
Off-center bipolar cells get turned on when there’s no light → when the rod turns off, turns off this bipolar cell
Why is there a dip where the fovea is in the retina?
These photoreceptors are connected to other neurons that send axons through the optic nerve and to the brain
Benefit of having no axons in the way of the light: When light hits the fovea, you get a higher resolution; more light is able to hit the cones directly rather than get absorbed by these axons
When light hits the periphery of the eye, it has to go through the axons, and as it’s going through, some of the energy is lost → less light hits rods/cones in the periphery
Where do the optics nerves from each eye converge?
Optic chiasm
All light that hits the temporal side of each eye (does/does not) cross the optic chiasm, while all light that hits the nasal side (does/does not) cross the optic chiasm.
This allows information from the _____ visual field to go to the _____ side of the brain, and vice versa.
Does not; does
Right; Left (or left; right)
*Note: light that hits the temporal part of the eyeball does not come from the temporal visual field, but rather comes from the nasal visual field
Feature Detection
When you’re looking at an object, necessary to break it down to its component features in order to make sense of what you’re looking at; there are many components: color, form, motion
Trichromatic Theory
Our ability to see color arises from the presence of cones within our retina; 3 major types
Red (60% of cones in eye), Green (30%) and Blue (10%)
Named for the color of light they are sensitive to
What pathway is responsible for figuring out the shape of an object?
Parvo Pathway
The Parvo Pathway is responsible for the _____ aspect of feature detection, and has a high level of ______ resolution and a low level of _______ resolution
Shape/form
Spatial
Temporal
*Parvo pathway also helps with color detection
Which pathway is responsible for detecting the motion of an object?
Magno Pathway
The Magno Pathway is responsible for the ______ aspect of feature detection, and has a high level of _______ resolution and a low level of _______ resolution
Motion
Temporal
Spatial
Describe the main steps that involve hearing
- Sound is collected by the pinna (the visible part of the ear) and directed through the outer ear canal. 2. The sound makes the eardrum vibrate, which in turn causes a series of three tiny bones (the hammer, the anvil, and the stirrup) in the middle ear to vibrate.
- The vibration is transferred to oval window, and then to the snail-shaped cochlea in the inner ear; the cochlea is lined with sensitive hairs which trigger the generation of nerve signals that are sent to the brain.
Label the parts of the ear
What separates the fluid flowing in/out of the cochlea?
Organ of Corti
How does the organ of corti convert fluid motion into sound?
- Upper and lower membranes of organ of Corti contain hair cells. The fluid flow pushes down on the top membrane and up on the bottom membrane, causing the hair cells to move back and forth
- On the top of the hair cell is the hair bundle, which is composed of a bunch of kinocilium connected to each other by a tip link
- Tip link is directly connected to potassium channels. Movement of hair cells stretches on the tip link; as the kinocilium gets stretched, it opens up this gate
- Potassium flows into the cell, which activate the opening of calcium channels → now also have calcium flowing into the cell
- → cell fires an action potential → stimulates another cell, known as a spiral ganglion cell, which then activates another cell that goes to the brain
What range of frequencies can humans hear?
20 Hz to 20,000 Hz
What method is used in the ear to distinguish different frequencies, and how does it work?
Basilar Tuning
Tonotypical Mapping: Hair cells at the base of the cochlea are activated by high frequencies; hair cells at the apex (tip) of the cochlea are stimulated by low frequencies
As sounds with varying frequencies hit the ear, they will stimulate different parts of the basilar membrane
Hair cell fires an action potential that eventually reaches the brain through the auditory nerve and it will be mapped to a particular part of the brain, the primary auditory cortex
Describe the visual pathway in the brain, starting with the optic nerve
Optic Nerve travels to the Lateral Geniculate Nucleus (LGN) of the thalamus, which preserves the visual map created by the ganglion cells and projects this information to the primary visual cortex, which is located in the occipital lobe
Describe the auditory pathway in the brain starting from the auditory nerve
First, auditory information goes from the auditory nerve to the cochlear nuclei in the medulla. Axons of the cochlear nuclei synapse with neurons in the inferior colliculus (on the way to the inferior colliculus, some crossing occurs such that auditory information from each ear is sent to the opposite hemisphere).
From there, electrical signals are passed on to the medial geniculate nucleus of the thalamus, which sends information to the auditory cortex in the temporal lobe.
What condition results from problems with conduction from the hair cells to the brain? Can it be treated? If so, how?
Sensorineural Hearing Loss, aka “nerve deafness”
Yes, can be surgically treated with a cochlear implant (however, only restores some degree of hearing)
What is the difference between proprioception and kinesthesia?
Proprioception: Our ability to sense exactly where our body is in space; our sense of position and balance; Can be thought of as a cognitive awareness of your body in space; more under the surface/subconscious, you’re not overtly thinking about it
Kinesthesia: Movement of your body; Does not include sense of balance; More behavioral
What specific receptors sense temperature? What else do they also respond to, and where are they located in the body?
TrpV1 receptors are sensitive to both temperature and pain
They are located throughout the whole body
Pain/Temperature send information up to the brain through various nerves - what are the different types of fibers and what are the characteristics of each?
Aβ Fibers: Fast; Large diameter (lowers resistance) and covered in myelin (increased conductance) → fast signal; Sends message that there’s a change in temperature, it’s really hot, or something is really painful
Aδ Fibers: Medium speed; A little bit smaller in diameter, a little bit less myelin → don’t conduct a signal as quickly as the fast fibers
C Fibers: Slow; Small diameter, unmyelinated → sends a very slow signal
Olfactory Epithelium
Specialized epithelial tissue inside the nasal cavity that’s involved in smell; Lies on roof of nasal cavity; directly responsible for detecting odors
Is part of the olfactory mucosa
Olfactory Mucosa
Dime-sized region located high inside the nasal cavity and is the site of olfactory transduction
Contains olfactory receptor neurons
Olfactory receptor neurons have cilia
Describe the main steps of the olfactory pathway
- Olfactory transduction occurs when odorant molecules reach the olfactory mucosa and bind to the olfactory receptor proteins on the cilia (GPCR)
- Receptor protein changes shape –> triggers the flow of ions across the receptor-cell membrane and an electrical response is triggered in the cilium
- Electrical responses in the cilia spread to the rest of the receptor cell, and from there are passed onto the olfactory bulb of the brain in the olfactory nerve
- Inputs from similar receptor neurons go to similar glomeruli (collections of cells within the olfactory bulb)
- From the olfactory bulb, mitral cells and tufted cells carry olfactory information to the olfactory cortex, and to the orbitofrontal cortex
Pheromones
Specialized olfactory cues
A chemical signal that is released by one member of a species and is sense by another member of the species, and it triggers an innate response
Very important in animals, particularly insects: have been linked to mating, fighting, and chemical communications
Sensed in the vomeronasal system, which is within the accessory olfactory epithelium
What are the 5 main tastes?
Bitter, salty, sweet, sour, umami
What are the different types of taste buds?
Fungiform, foliate, and circumvallate
Which taste buds sense which tastes?
All taste buds have receptors for all 5 tastes
Labeled Lines Model
Each cell has an axon projecting from it, and these axons remain separate all the way to the brain and synapse onto different parts of the gustatory cortex in the brain
All cells that are sensitive to a particular taste synapse in the same part of the brain
Individual taste cells are sensitive to how many of the tastes?
Each individual taste cell is sensitive to 1 particular taste
Which types of taste cells have GPCRs?
Sweet, umami, bitter
Cells that are sensitive to __________ rely on ion channels
Sour, salty
What types of receptors are sensitive to:
- Sweet
- Salty
- Sour
- Bitter
- Umami
- GPCR
- Ion channels
- Ion channels
- GPCR
- GPCR
