Sensation & Perception (part 2) Flashcards
The course from week 6 and on! So after exam 1.
MAE (abbreviation)
Motion aftereffect
Motion aftereffect
Illusion of motion of a stationary object that occurs after prolonged exposure to a moving object.
How do MAEs arise?
Neurons tuned to the direction of motion of the adaption stimulus become adapted. When gaze switches to stationary object, neurons sensitive to the opposite direction fire at spontaneous rate which is faster than the adapted neurons, so we perceive stationary as going in opposite direction.
Interocular transfer
The transfer of an effect (such as adaptation) from one eye to the other.
MT (abbreviation)
Middle temporal area
Middle temporal area (MT)
An area of the brain thought to be important in the perception of motion. Also called V5 in humans.
How do we know that the motion aftereffect (MAE) is due to activity in V1 or beyond?
We still find a strong MAE when one eye is adapted and the other eye tested, so effect happens where info from two eyes is combined already.
Where does the motion aftereffect (MAE) arise?
In area MT.
Apparent motion
The illusory impression of smooth motion resulting from the rapid alternation of objects that appear in different locations in rapid succession.
(Ex: two separate sparks close together soon after each other are perceived as motion)
Correspondence problem (in motion detection)
The problem faced by the motion detection system of knowing which feature in frame 2 corresponds to a particular feature in frame 1.
Aperture problem
The fact that when a moving object is viewed through an aperture (or RF), the direction of motion of a local feature of part of the object may be ambiguous.
Aperture
An opening that allows only a partial view of an object.
MST (abbreviation)
Medial superior temporal area
TO (abbreviation)
Temporal - occipital
First-order motion
The motion of an object that is defined by changes in luminance.
Second-order motion
The motion of an object that is defined by changes in contrast or texture, but not by luminance.
Luminance-defined object
An object that is delineated by differences in reflected light.
Texture-defined / contrast-defined object
An object that is defined by differences in contrast, or texture, but not by luminance.
Akinetopsia
A rare neuropsychological disorder in which the affected individual has no perception of motion. Appears to be caused by disruptions to V5 / MT area.
Double dissociation
The phenomenon in which one of two functions, such as first- and second-order motion, can be damaged without harm to the other and vice versa.
MIB (abbreviation)
Motion induced blindness
Motion induced blindness (MIB)
If you fixate a central target, stationary targets in the periphery will simply dissapear when a global moving pattern is superimposed.
Troxler effect
When an unchanging target in peripheral vision will fade and dissapear if you steadily fixate a central target.
Optic array
The collection of light rays that interact with object in the world that are in front of a viewer.
Optic flow
The changing angular positions of points in a perspective image that we experience as we move through the world.
Focus of expansion
The point in the center of the horizon from which, when we’re in motion, all points in the perspective image seem to emanate. It is one aspect of optic flow.
Outflow
Optic flow toward the periphery, indicates that you are approaching a particular destination.
Inflow
Optic flow that indicates retreat.
Focus of constriction
The focus of expansion if you’re looking forward while driving in reverse.
TTC (abbreviation)
Time to collision
time to collision (TTC)
The time required for a moving object to hit a stationary object, measured in distance/rate.
How do humans accurately estimate TTC even though they are quite bad at judging absolute time and distance?
There is an alternative source of information in the optic flow: tau.
tau
Information in the optic flow that could signal TTC without the necessity of estimating absolute distances or rates. The ratio of the retinal image size at any moment to the rate at which the image is expanding.
Biological motion
The pattern of movement of living beings (humans and animals).
Smooth pursuit
A type of voluntary eye movement in which the eyes move smoothly to follow a moving object.
Superior colliculus
A structure in the midbrain that is important in initiating and guiding eye movements.
How many muscles do we have attached to each eye?
Six.
Microsaccade
An involuntary, small, jerk-like eye movement.
Vergence
A type of eye movement in which the two eyes move in opposite directions, converging or diverging.
Convergence
When both eyes turn toward the nose.
Divergence
When both eyes turn away from the nose.
Saccade
A type of eye movement made both voluntarily and involuntarily, in which the eyes rapidly change fixation from one object or location to another.
Reflexive eye movement
A movement of the eye that is automatic and involuntary.
Vestibular eye movement
When the eyes move to compensate for head and body ovement while maintaining fixation on a particular target.
VOR (abbreviation)
Vestibulo-ocular reflex
Optokinetic nystagmus (OKN)
A reflexive eye movement in which the eyes will involuntarily track a continually moving object.
OKN (abbreviation)
Optokinetic nystagmus
Saccadic suppression
The reduction of visual sensitivity that occurs when we make saccadic eye movements. Eliminates the smear from retinal image motion during an eye movement.
Corrollary discharge signal
The outgoing signal from the motor cortex that is copied in efference copy.
Efference copy
The phenomenon in which outgoing signals from the motor cortex are copied as they exit the brain and are rerouted to other areas in the sensory cortices
Comparator
An area of the visual system that receives one copy of the command issued by the motor system when the eyes move. It compares the image motion signal with the eye motion signal and can compensate for the image changes caused by the eye movement.
When is OKN present in development?
From birth.
When is motion direction present in development?
From birth
When is global motion sensitivity present in development?
Around 3-4 years of age.
Why do we say that motion processing is robust?
There are many areas involved, so it’s not easily impaired.
What two models of motion detection are discussed?
- the Bilocal correlator
- the Reichart detector
Bilocal correlator
A model for understanding motion detection, based on fly eyes.
How does motion processing work in the bilocal correlator?
You have two receptive fields: RF A and RF B. There is a cell D that delays the signal of RF A, and a cell X that receives from D and RF B.
How does motion processing work in the Reichart detector?
You have two receptive fields, RF A and RF B. Cell D delays the signal of RF A and cell E delays the signal of RF B. Then there are two X cells: one receives from D and B and one from A and E.
What is the difference between the bilocal correlator and the Reichart detector in terms of direction selectivity?
The bilocal correlator detects motion in only one direction, the Reichart detector can detect in two directions.
How do you adjust speed selectivity in the bilocal correlator?
By changing the delay.
Prosopagnosia
The inability to recognize faces.
What is the difference in response between the bilocal correlator and the Reichart detector?
The bilocal correlator responds to motion with specific direction and speed, as well as to flickering and static stimuli. The Reichart detector gives inhibition if there is no movement or if there’s flickering.
Where does local motion processing happen?
In V1.
What RF size does local motion processing require?
Small receptive fields.
What is V1 known for?
Orientation selectivity.
What does V1 receive input from?
The LGN, V2 and MT.
Where does global motion processing happen?
In MT.
What RF size does global motion processing use?
Large receptive fields.
What does low convergence do in motion processing?
It gives information on the exact location and is less sensitive when detecting stimulus.
What does high convergence do in motion processing?
it gives loose info on specific spatial location of the input and is more sensitive when detecting a stimulus.
Where does the MT area get input from?
The superior colliculus, pulvinar and V1-4.
What kinds of cells does MT consist of?
90% direction selective cells, mainly motion processing cells with large receptive fields.
Where does complex motion processing happen?
In the MST area.
What kind of RFs does complex motion processing use?
Large receptive fields.
What processes are considered complex motion processes?
- Contraction
- Expansion
- Rotation
What three models explaining the motion after effect are discussed?
- the Ratio model
- the Disinhibition model
- the Distribution-shift model
Ratio model
A model explaining the motion after-effect. Cells responding to the adaptation direction decrease in response, so the ratio changes in favor of the opposite response when viewing a stationary pattern.
Disinhibition model
A model explaining the motion after-effect. Motion-tuned cells for opposite directions inhibit each other. After adaptation, the anti-preferred stimulus response is enhanced.
DS (abbreviation)
direction selective
Distribution-shift model
A model explaining the motion after-effect. Uses the ratio between multiple direction channels.
What motion after-effect model is based on relative activity?
The ratio model.
What motion after-effect model is based on absolute activity?
The disinhibition model.
Amplitude
The magnitude of displacement of a pressure wave, the difference between the highest pressure and the lowest pressure of the wave.
Frequency
The number of times per second that a pattern of pressure change repeats.
Hz (abbrevation)
Hertz
Hertz (Hz)
A unit of measure for frequency; 1 hertz equals 1 cycle per second.
Loudness
The psychological aspect of sound related to perceived intensity (amplitude).
Pitch
The psychological aspect of sound related mainly to the fundamental frequency.
dB (abbreviation)
decibel
decibel (dB)
A unit of measure for the physical intensity of sound. Define the difference between two sounds as the ratio between two sound pressures.
How many dB does 10:1 sound pressure equal?
20 dB
How many dB does a 100:1 sound pressure ratio equal?
40 dB
What is the usual value of p0 in the decibel equation?
0.0002 dyne / cm^2
If the pressure of the sound that you’re measuring is 0.0002 dyne/cm2, then dB =
20 log (1).
Sine wave
The waveform for which variation as a function of time is a sine function.
Spectrum
A representation of the relative energy (intensity) present at each frequency.
Harmonic spectrum
The spectrum of a complex sound in which energy is at integer multiples of the fundamental frequency.
Fundamental frequency
The lowest-frequency component of a complex periodic sound.
Timbre
The psychological sensation by which a listener can judge that two sounds with the same loudness and pitch are dissimilar.
What is the shape of the frequency spectrum called?
Spectral shape
Pinna
The outer, funnel-like part of the ear that collects sound from the environment.
Ear canal
The canal that conducts sound vibrations from the pinna to the tympanic membrane and prevents damage to the tympanic membrane.
Tympanic membrane
The eardrum; a thin sheet of skin at the end of the outer ear canal. Vibrates in response to sound.
Outer ear
The external sound-gathering portion of the ear, consisting of the pinna and the ear canal.
Middle ear
An air-filled chamber containing the middle bones, or ossicles. Conveys and amplifies vibration from the tympanic membrane to the oval window.
Ossicle
Any of the three tiny bones of the middle ear: malleus, incus and stapes.
Malleus
The most exterior of the three ossicles. Receives vibration from the tympanic membrane and is attached to the incus.
Incus
The middle of the three ossicles, connecting the malleus and the stapes.
Stapes
The most interior of the three ossicles. Connected to the incus on one end and presses against the oval window of the cochlea on the other end.
Oval window
The flexible opening to the cochlea through which the stapes transmits vibration to the fluid inside. Border between middle and inner ear.
In what two ways do the ossicles amplify sound vibrations?
- Lever action makes the energy on the other side more than on this side.
- Energy is concentrated from larger to smaller surface area
Inner ear
A hollow cavity in the temporal bone of the skull, and the structures within this cavity: the cochlea and the semicircular canals of the vestibular system.
What two muscles does the middle ear have?
- Tensor tympani
- Stapedius
Tensor tympani
The muscle attached to the malleus. Tensing the tensor tympani decreases vibration.
Stapedius
The muscle attached to the stapes. Tensing the stapedius decreases vibration.
Acoustic reflex
A reflex that protects the ear from intense sounds, via contraction of the stapedius and tensor tympani muscles.
Cochlea
A spiral structure of the inner ear containing the organ of Corti.
What are the two smallest muscles in the body?
- Tensor tympani
- Stapedius
What three canals does the cochlea have?
- Tympanic canal
- Vestibular canal
- Middle canal
Tympanic canal
One of three fluid-filled passages in the cochlea. Extends from the round window at the base of the cochlea to the helicotrema at the apex.
What is another name for the tympanic canal?
Scala tympani.
Vestibular canal
One of three fluid-filled passages in the cochlea. Extends from oval window at the base of the cochlea to the helicotrema at the apex.
What is another name for the vestibular canal?
Scala vestibuli
Middle canal
One of three fluid-filled passages in the cochlea. Sandwiched between the tympanic and vestibular canals and contains the cochlear partition.
What is another name for the middle canal?
Scala media
Helicotrema
The opening that connects the tympanic and vestibular canals at the apex of the cochlea.
Reissner’s membrane
A thin sheath of tissue separating the vestibular and middle canals in the cochlea.
Basilar membrane
A plate of fibers that forms the base of the cochlear partition and separates the middle and tympanic canals in the cochlea.
Cochlear partition
The combined basilar membrane, tectorial membrane and organ of Corti, which are together responsible for the transduction of sound waves into neural signals
Round window
A soft area of tissue at the base of the tympanic canal that releases excess pressure remaining from extremely intense sounds.
Organ of Corti
A structure on the basilar membrane of the cochlea that is composed of hair cells and dendrites of auditory nerve fibers.
Hair cell
Any cell that has stereocilia for transducing mechanical movement in the inner ear into neural activity sent to the brain.
Auditory nerve
A collection of neurons that convey information from hair cells in the cochlea to the brain stem and vice versa.
Stereocilium
Any of the hairlike extensions on the tips of hair cells in the cochlea that, when flexed, initiate the release of neurotransmitters.
Tectorial membrane
A gelatinous structure, attached on one end, that extends into the middle canal of the cochlea, floating above inner hair cells and touching outer hair cells.
Tip link
A tiny filament that stretches from the tip of a stereocilium to the side of its neighbor.
What are the two fundamental characteristics of sound?
- Amplitude
- Frequency
The larger the amplitude, the … the firing rate of neurons.
Higher
Where do high frequencies cause the largest displacements in the ear?
Close to the oval window near the base of the cochlea.
Where do lower frequencies cause the largest displacements?
Further away from the oval window, near the apex.
Place code
Tuning of different parts of the cochlea to different frequencies, in which information about the particular frequency of an incoming sound wave is coded by the place along the cochlear partition that has the greatest mechanical displacement.
Afferent fiber
A neuron that carries sensory information to the central nervous system.
Efferent fiber
A neuron that carries information from the central nervous system to the periphery.
Threshold tuning curve
A graph plotting the thresholds of a neuron in response to sine waves with varying frequencies at the lowest intensity that will give rise to a response.
Cf (abbreviation)
Characteristic frequency
Characteristic frequency (CF)
The frequency to which a particular auditory nerve fiber is most sensitive.
In what fibers do inner hair cells mostly cause synapse?
Afferent fibers
In what fibers do outer hair cells mostly cause synapse?
Efferent fibers.
AN
auditory nerve
Two-tone suppression
A decrease in the firing rate of one auditory nerve fiber due to one tone, when a second tone is presented at the same time.
AN fibers fire in response to…
the displacement of stereocilia on hair cells.
Isointensity curve
A map plotting the firing rate of an auditory nerve fiber against varying frequencies at varying intensities.
Rate saturation
The point at which a nerve fiber is firing as rapidly as possible and further stimulation is incapable of indreasing the firing rate.
Rate-intensity function
A graph plotting the firing rate of an auditory nerve fiber in response to a sound of constant frequency at indreasing intensities.
Low-spontaneous fiber
An auditory nerve fiber that has a low rate (less than 10 spikes per second) of spontanoues firing. Requires relatively intense sound before they will fire at higher rates.
High-spontaneous fiber
An auditory nerve fiber that has a high rate (30+ spikes per second) of spontaneous firing. Increases its firing rate in response to relatively low levels of sound.
Mid-spontaneous fiber
An auditory nerve fiber that has a medium rate (10-30 spikes per sec) of spontaneous firing. Intermediate between low- and high-spontanoues fibers as for firing rate increasing.
Phase locking
Firing of a single neuron at one distinct point in the period (cycle) of a sound wave at a given frequency.
Why does phase locking happen?
AN fibers fire when stereocilia of hair cells move in one direction but not the other direction.
Temporal code
Tuning of different parts of the cochlea to different frequencies, in which info about the particular frequency of an incoming sound wave is coded by the timing of neural firing as it relates to the period of the sound
Volley principle
The idea that multiple neurons can provide a temporal code for frequency if each neuron fires at a distinct point in the period of a sound wave but does not fire on every period.
Cochlear nucleus
The first brain stem nucleus at which afferent auditory nerve fibers synapse. Contains many types of specialized neurons.
Medial superior olive
A relay station in the brain stem where inputs from both ears contribute to detection of the interaural time difference.
Inferior colliculus
A midbrain nucleus in the auditory pathway. Neurons from cochlear nucleus & superior olive go up the brain stem to the inferior colliculus
Medial geniculate nucleus
The part of the thalamus that relays auditory signals to the temporal cortex and receives input from the auditory cortex
Tonotopic organization
An arrangement in which neurons that respond to different frequencies are organized anatomically in order of frequency
A1
Primary auditory cortex
Primary auditory cortex (A1)
The first area within the temporal lobes of the brain responsible for processing acoustic information.
Belt area
A region of cortex, directly adjacent to A1 with inputs from A1, where neurons respond to more complex characteristics of sound.
Parabelt area
A region of cortex, lateral and adjacent to the belt area, where neurons respond to more complex characteristics of sounds as well to input from other senses.
Psychoacoustics
The branch of psychophysics that studies the psychological correlates of the physical dimensions of acoustics in order to understand how the auditory system operates.
Audibility threshold
The lowest sound pressure level that can be reliably detected at a given frequency.
Equal-loudness curve
A graph plotting sound pressure level (dB SPL) against the frequency for which a listener perceives constant loudness.
Temporal integration
The process by which a sound at a constant level is perceived as being louder when it is of greater duration.
What is the limit on temporal integration?
100-200ms. So if the difference in length is more than this, the effect doesn’t hold.
Masking
Using a second sound, frequently noise, to make the detection of another sound more difficult.
White noise
Noise consisting of all audible frequencies in equal amounts.
Critical bandwidth
The range of frequencies conveyed within a channel in the auditory system.
Conductive hearing loss
Hearing loss caused by problems with the bones of the middle ear.
Otis media
Inflammation of the middle ear, commonly in children as a result of infection.
Otosclerosis
Abnormal growth of the middle-ear bones that causes hearing loss.
Sensorineural hearing loss
Hearing loss due to defects in the cochlea or auditory nerve.
In what two ways can sensorineural hearing loss be caused?
- Metabolic
- Sensory
Metabolic sensorineural hearing loss
Caused by changes in the fluid environment of the cochlea, so decreased activity of hair cells.
Sensory sensorineural hearing loss
Hearing loss by injury to hair cells.
PLD
personal listening device
Describe the road from sound wave to sound perception in broad terms:
Sound is moved into the ear by the outer ear, made more intense by the middle ear, and transformed into neural signals by the inner ear.
Vestibular organs
The set of five sense organs—three semicircular canals and two otolith organs—in each inner ear that sense head motion and head orientation with respect to gravity.
Spatial orientation
A sense consisting of three interacting modalities: perception of linear motion, angular motion, and tilt.
Vestibular system
The vestibular organs as well as the vestibular neurons in cranial nerve VIII and the central neurons that contribute to the functional roles that the vestibular system participates in.
Vertigo
A sensation of rotation or spinning. Often used more generally to mean any form of dizziness.
VOR (abbreviation)
vestibulo-ocular reflex
Vestibulo-ocular reflex (VOR)
A reflex that helps stabilize vision by counterrotating the eyes when the vestibular system senses head movement.
Balance
The neural processes of postural control by which weight is evenly distributed, enabling us to remain upright and stable.
Kinesthesia
Perception of the position and movement of our limbs in space.
Active sensing
Sensing that includes
self-generated probing of the environment.
Efferent commands
Information flowing outward from the central nervous system to the periphery.
Efferent copy
The copy of efferent motor commands.
Afferent signals
Information flowing inward to the central nervous system
from sensors in the periphery.
Graviception
The physiological structures and processes that sense the relative orientation of gravity with respect to the organism.
Angular motion
Rotational motion.
Linear motion
Translational motion: motion along the same line or direction.
Tilt
To attain a sloped position.
Transduce
To convert from one form
of energy to another.
Semicircular canal
Any of three toroidal tubes in the vestibular system that sense angular motion.
Angular acceleration
The rate of change of angular velocity.
What is the integral of angular acceleration?
Angular velocity
What is the integral of angular velocity?
Angular displacement
Otolith organ
Either of two mechanical structures (utricle and saccule) in the vestibular system that sense both linear acceleration and gravity.
Linear acceleration
The rate of change of linear velocity.
What is the integral of linear acceleration?
Linear velocity
What is the integral of linear velocity?
Linear displacement
What is linear displacement also referred to?
translation
Gravity
A force that attracts a body toward the center of the Earth.
Sensory conflict
Sensory discrepancies that arise when sensory systems
provide conflicting information.
Sense of angular motion
The perceptual modality that senses rotation
Sense of linear motion
The perceptual modality that senses translation.
Sense of tilt
The perceptual modality that sense head inclination with respect to gravity.
Velocity
The speed and direction in which something moves. The integral of acceleration.
Acceleration
A change in velocity. The derivative of velocity.
Hair cell
Any cell that has stereocilia for transducing mechanical movement in the inner ear to neural activity sent to the brain.
Mechanoreceptor
A sensory receptor that responds to mechanical stimulation (pressure, vibration, movement).
Receptor potential
A change in voltage across the membrane of a sensory receptor cell (in vestibular system = haircell) in response to stimulation.
Ampulla
An expansion of each semicircular-canal duct that includes that canal’s cupula, crista, and hair cells, where transduction occurs.
Crista
Any of the specialized detectors of angular motion located in each semicircular canal in a swelling called the ampulla.
Oscillatory
Referring to back-and-forth movement that has a constant rhythm.
Sinusoidal
Referring to any oscillation, such as a sound wave or rotational motion, whose waveform is that of a sine curve.
Fourier analysis
A mathematical procedure by which any signal can be separated into component sine waves at different frequencies. Combining these sine waves
will reproduce the original motion trajectory.
Utricle
One of the two otolith organs.
A saclike structure that contains the utricular macula. Also called utriculus.
Saccule
One of the two otolith organs. A saclike structure that contains the saccular macula. Also called sacculus.
Macula
Any of the specialized detectors of linear acceleration and gravity found in each otolith organ.
Otoconia
Tiny calcium carbonate stones in the ear that provide inertial mass for the otolith organs, enabling them to sense gravity and linear acceleration.
Velocity storage
Prolongation of a rotational response by the brain beyond the duration of the rotational signal provided to the brain by the semicircular canals; typically yielding responses that are nearer the actual rotational motion than the signal provided by the canals.
Dizziness
A commonly used lay term
that nonspecifically indicates any form
of perceived spatial disorientation, with
or without instability.
Imbalance
Lack of balance, unsteadiness, nearly falling over.
Sensory integration
The process of combining different sensory signals.
Vection
An illusory sense of self-motion caused by moving visual cues when one is not, in fact, actually moving.
Sensory reafference
Change in afference caused by self-generated activity. For the vestibular system, vestibular afference evoked by an active self-generated head motion would yield sensory reafference.
Sensory exafference
Change in afference caused by external stimuli.
For the vestibular system, vestibular afference evoked by passive head motion would yield sensory exafference.
Balance system
The sensory systems, neural processes, and muscles
that contribute to postural control.
Autonomic nervous system
The part of the nervous system that is responsible for regulating many involuntary actions and that innervates glands, heart, digestive system, etc.
Spatial disorientation
Any impairment of spatial orientation.
What 3 sensory modalities does perception of spatial orientation include?
- Angular motion
- Linear motion
- Tilt
What 3 stimuli do the 3 different sensory modalities require?
- Angular acceleration
- Linear acceleration
- Gravity
What two types of vestibular sense organs sense the 3 stimulation energies?
- Semi-circular canals
- Otolith organs
What do the semi-circular canals sense?
Angular acceleration
What do the otolith organs sense?
Linear acceleration and gravity.
What are the two qualities of each spatial orientation modality?
- Amplitude
- Direction
In what 3 independent ways can the head rotate?
- Roll angular velocity
- Pitch angular velocity
- Yaw angular velocity
Where are motion signals transduced?
In the vestibular organs, next to the cochlea in the inner ear.
What does a vestibular labyrinth consist of?
5 sensory organs: 3 semi-circular canals for rotational motion and 2 otolith organs for gravity and linear acceleration.
Describe the state of vestibular hair cells in absence of stimulation:
They have negative voltage and release neurotransmitter at a constant rate.
Name the semi-circular canals
- Horizontal
- Anterior
- Posterior
What is each semi-circular canal sensitive to?
Rotations about the axis perpendicular to it.
Name the 3 push-pull pairs of semi-circular canals:
- Horizontal canals
- Right anterior and left posterior canal
- Left anterior and right posterior canal.
On what two structures does sensing of gravity and linear acceleration depend?
- Utricle
- Saccule
What 3 techniques are used to investigate spatial orientation perception?
- Thresholds
- Magnitude estimation
- Matching
What is the first place in the brain that vestibular informaiton reaches?
The vestibular nucleus.
Mal de debarquement syndrome
Disembarking sickness: when people are unable to adapt and symptoms of spatial disorientation last a month or longer after they disembark.
Olfaction
The sense of smell
Gustation
The sense of taste.
What are our two main chemical detection systems?
- Olfaction
- Gustation
Trigeminal system
The chemical-sensing system that does both olfaction and gustation
Orthonasal olfaction
Sniffing in and perceiving odors through our nostrils, which occurs when we are smelling something that is in the air.
Retronasal olfaction
Perceiving odors through the mouth while breathing and chewing. This is what gives us the experience of flavor.
Odor
The translation of a chemical stimulus into the sensation of an odor percept.
Odorant
A molecule that is defined by its physicochemical characteristics and that can be translated by the nervous system into the perception of a smell.
What properties do odorant molecules need to have in order to be smelled?
- Volatile
- Hydrophobic
Volatile
Able to float through theair
Hydrophobic
Repellant to water
What is the primary function of the nose?
To filter, warm and humidify the air that we breathe.
Olfactory cleft
A narrow space at the back of the nose into which air flows and where the olfactory epithelium is located.
Olfactory epithelium
A secretory mucous membrane in the nose that detexts odorants in inhaled air.
What 3 types of cells does the olfactory epithelium contain?
- Olfactory sensory neurons
- Basal cells
- Supporting cells
Nasal dominance
The assymetry characterizing the intake of air by the two nostrils, which leads to differing sensitivity to odorants between the two nostrils.
Supporting cell
One of the 3 types of cells in the olfactory epithelium. Provides metabolic and physical support for the olfactory sensory neurons.
Basal cell
One of the 3 types of cells in the olfactory epithelium. Is the precursor cell to olfactory sensory neurons
OSN (abbreviation)
Olfactory sensory neurons
Olfactory sensory neuron (OSN)
The main one of 3 cell types in the olfactory epithelium. A small neuron located within a mucous layer. Cilia on the OSN dendrites contain the receptor sites for odorant molecules.
Cilium
Any of the hairlike protrusions on the dendrites of olfactory sensory neurons. Contains receptor sites for odorant molecules.
OR (abbreviation)
Odorant receptor
Odorant receptor (OR)
The region on the cilia of olfactory sensory neurons where odorant molecules bind.
Glomerulus
Any of the spherical conglomerates containing the incoming axons of the olfactory sensory neurons.
What does each OSN converge to?
Onto two glomeruli: one medial and one lateral.
Olfactory bulb
A blueberry-sized extension of the brain just above the nose, where olfactory information is first processed.
Cribriform plate
A bony structure riddled with tiny holes that separates the nose from the brain at the level of the eyebrows. Axons from olfactory sensory neurons pass through the holes of the cribriform plate to enter the brain.
Anosmia
The total inability to smell.
Where are new OSNs formed?
The stem cells in the olfactory epithelium
How frequent do all of our OSNs die and regenerate?
Once every 28 days +_.
Olfactory nerve
The first cranial nerve. Axons of the OSNs bundle together after passing through the cribriform plate. Conducts impulses from the olfactory epithelium in the nose to the olfactory bulb.
Ipsilateral
Referring to the same side of the body or the brain
How many different types of functioning ORs do humans have?
About 350-400.
Juxtaglomerular neurons
The first layer of cells surrounding the glomeruli. They are a mixture of excitatory and inhibitory cells and respond to a wide range of odorants. The selectivity of neurons to specific odorants increases in a gradient fromt he surface of the olfactory bulb.
Tufted cell
The next layer of cells after the juxtaglomerular neurons. Respond to fewer odorants than the j-t neuron, but more than neurons at the deepest layer of cells.
Mitral cells
The deepest layer of neurons in the olfactory bulb. Each mitral cell responds to only a few specific odorants.
Granular cells
Cells at the deepest level of the olfactory bulb, form an extensive network of inhibitory neurons, integrate input from all earlier projections and might be basis of specific odorant identification. Capable of detecting and learning combinatorial patterns of mitral & tufted cell activation.
Olfactory tract
The bundle of axons of the mitral and tufted cells within the olfactory bulb that sends odor information to the primary olfactory cortex.
Piriform cortex
The neural area where olfactory information is first processed. Comprises the amygdala, parahippocampal gyrus and interconnected areas and interacts closely with the entorhinal cortex.
What is another name for the piriform cortex?
Primary olfactory cortex.
Amygdala-hippocampal complex
The conjoined regions of the amygdala and hippocampus, which are key structures in the limbic system. Also critically involved in the unique emotional and associative properties of olfactory cognition.
Entorhinal cortex
A phylogenetically old cortical region that provices the major sensory association input into the hippocampus.
Limbic system
The group of neural structures that includes the olfactory cortex, the amygdala, the hippocampus, the piriform cortex and the entorhinal cortex. Involved in emotion and memory.
Why is olfaction unique among the senses? (2 reasons)
- It has a direct connection to the limbic system, no protective barrier.
- It uses ipsilateral processing.
Pseudogenes
OR genes that are present on the chromosomes, but the proteins coded for by the genes do not get produced.
Trigeminal nerve
The fifth cranial nerve, which transmits information about the “feel” of an odorant as well as pain and irritation sensations.
Shape-pattern theory
The current dominant biochemical theory for how chemicals come to be perceived as specific odors. Says that a specific odor only fits in a specific receptor.
Vibration theory
An alternative to the shape-pattern theory for describing how olfaction works. Says that every odorant has a different vibrational frequency and that molecules that produce the same vibrational frequencies will smell the same.
Specific anosmia
The inability to smell one specific compound amid otherwise normal smell perception. Due to faulty odorant-receptor interactions or lack of specficic ORs.
Isomers
Molecules that can exist in different structural forms.
Stereoismers
Isomers in which the spatial arrangements of the atoms are mirror-image rotations of one another, like a right and left hand. Can contain all the same atoms, but smell completely different.
What does shape-pattern theory say about stereoisomers?
The difference in smell is because rotated molecules do not fit the same receptors.
What 3 things can the perception of different odors be due to?
- Different OR firing patterns.
- Firing of the same receptors at a different rate.
- Firing of the same receptors in a different sequence.
Binaral rivalry
Competition between the two nostrils for odor perception. When a different scent is presented to each nostril simultaneously, we perceive each scent to be alternating back and forth with the other, and not a blend of the two scents.
Olfactory white
The olfactory equivalent of white noise or the color white.
Mix of min. 30 odorants of equal intensity & psychological space creates same perception as any other mix of same span and intensity even without shared odorants.
Psychophysics
The science of defining quantitative relationships between physical and psychological events
Staircase method
A psychophysical method for determining detection threshold, a method of limits.
A stimulus is presented in an ascending concentration sequence until detection is indicated, and then the concentration is shifted to a descending sequence until the response changes to no detection.
Triangle test
A test in which a participant is given 3 odorants to smell, of which 2 are the same and one is different. Participants needs to state which is the odd one out. Repeated.
Tip-of-the-nose phenomenon
The inability to name an odor, even though it is very familiar. One has no leical access to the name of the odor.
AD (abbreviation)
Alzheimer’s disease
PD (abbreviation)
Parkinson’s disease
GPCR (abbreviation)
G protein-coupled receptor
G protein-coupled receptor (GPCR)
Any of the class of receptors that are present on the surface of olfactory sensory neurons. All GPCRs are characterized by a common structural feature of seven membrane-spanning helices
Receptor adaptation (olfaction)
The biochemical phenomenon that occurs after continual exposure to an odorant, whereby receptors are no longer available to respond to the odorant and detection ceases.
Cross-adaptation
The reduction in detection of one odorant following exposure to a prior odorant.
Cognitive habituation
The psychological process by which, after long-term exposure to an odor, one no longer has the ability to detect that odor or has very diminished detection ability.
What 3 mechanisms could be involved in producing olfactory habituation?
- Olfactory receptors internalized during adaptation may be more hindered after continual exposure.
- Odorant molecules absorbed into bloodstream, constantly adapted.
- Cognitive-emotional factors.
Odor hedonics
The liking dimension of odor perception, typically measured by ratings of an odor’s perceived pleasantness, familiarity and intensity.
When is the olfactory system fully functional?
By the third month of gestation (=6 months before birth).
Learned taste aversion
The avoidance of a novel flavor after it has been paired with gastric illness.
WHat is the cause of learned taste aversion?
The smell, not the taste of the substance.
What is the key to olfactory associative learning?
The experience when the odor is first encountered and the emotional connotation of that experience.
OFC (abbreviation)
Orbitofrontal cortex
Orbitofrontal cortex (OFC)
he part of the frontal lobe of the cortex that lies behind the bone (orbit) containing the eyes. The OFC is responsible for the conscious experience of olfaction,as well as the integration of pleasrure and displeasure from food.
MOB (abbreviation)
Main olfactory bulb
Main olfactory bulb (MOB)
The rounded extension of the brain just above the nose that is the first region of the brani where smells are processed.
AOB (abbreviation)
Accessory olfactory bulb
Accessory olfactory bulb (AOB)
A neural structure found in nonhuman animals that is smaller than the main olfactory bulb and located behind it and that receives input from the vomeronasal organ.
VNO (abbreviation)
Vomeronasal organ
Vomeronasal organ (VNO)
Found in nonhuman animals, a chemical-sensing organ at the base of the nasal cavity with a curved tubular shape. Evolved to detect chemicals that cannot be processed by ORs.
Pheromone
A chemical emitted by one member of a species that triggers a physiological or behavioral response in another member of the same species. May or may not have smell.
What are the two types of pheromone?
- Releaser pheromone
- Primer pheromone
Releaser pheromone
A pheromone that triggers an immediate behvaioarl response among conspecifics.
Primer pheromone
A pheromone that triggers a physiological change among conspecifics. Usually involves prolonged pheromone exposure.
Chemosignal
Any of various chemicals emitted by humans that are deteetd by the olfactory system and that may have some effect on het mood/behaviour of other humans.
Aromatherapy
The manipulation of odors to influence mood, performance, and well-being as well as the physiological correlated of emotion such as heart rate, blood pressure and sleep.
Taste
Sensations evoked by solutions in the mouth that contact receptors on the tongue and the roof of the mouth that then connect to axons in cranial nerves VII, IX, and X.
What perceives food molecules?
Taste and olfactory systems.
Retronasal olfactory sensation
The sensation of an odor that is perceived when chewing and swallowing force an odorant in the mouth up behind the palate into the nose. Perceived as coming from the mouth.
Flavor
The combination of true taste (sweet, salty, sour, bitter) and retronasal olfaction.
Chorda tympani
The branch of cranial nerve VII that carries taste information from the anterior mobile tongue with the trigeminal nerve (cranial nerve V) and then passes through the middle ear on its way to the brain.
Taste bud
A globular cluster of cells that has the function of creating neural signals conveyed to the brain by taste nerves.
Papilla
Any of multiple structures that give the tongue its bumpy appearance.
Name the papilla types from smallest to largest:
- Fungiform
- Foliate
- Circumvallate
- Filiform
Taste receptor cell
A cell within the taste bud that contains sites on its apical projection that can interact with taste stimuli.
What two categories of taste receptor cell sites do we have?
- Ion channels
- G protein-coupled receptors
Filiform papillae
Small structures on the tongue that provide most of the bumpy appearance. Have no taste function.
Fungiform papillae
Mushroom-shaped structures that are distributed most densely on the edges of the tongue, especially the tip. Taste buds are buried in the surface. Max 1mm diameter. About 6 taste buds per papilla.
Foliate papillae
Folds of tissue containing taste buds. Located on the rear of the tongue lateral to the circumvallate papillae, where the tongue attaches to the mouth.
Circumvallate papillae
Circular structures that form an inverted V on the rear of the tongue. Are mound-like structures, each surrounded by a trench. Much larger than the fungiform papillae.
What papilla type does not have a taste function?
The filiform papillae.
Supertaster
An individual whose perception of taste sensations is the most intense.
What contributes highly to the supertaster attribute?
The density of fungiform papillae.
Microvilii
Thin projections of the cell membrane on the tip of some taste bud cells that extend into the taste pore.
Taste bud cell type I
One of 3 taste bud cell types, has mainly housekeeping functions
Taste bud cell type II
One of 3 taste bud cell types. Responds to sweet, bitter or amino acid stimuli. Have GPCRs that wind back & forth 7 times across the microvillus membrane. Do not have synapses but secrete ATP, which activates taste axons.
Taste bud cell type III
One of 3 taste bud cell types, has synapses and mediates sour taste.
Tastant
Any stimulus that can be tasted.
ATP (abbreviation)
Adenosine triphosphate
Adenosine triphosphate (ATP)
A neurotransmitter, produced by type II taste bud cells.
Gastrointestinal tract
gut
Insular cortex
The primary cortical processing area for taste.
Basic taste
Any of the four taste qualities that are generally agreed to describe human taste experience: sweet, salty, sour, bitter.
Salty
One of the four basic tastes, the taste quality produced by the cations of salts.
What produces the purest salty taste?
Sodium chloride (NaCI)
Sour
One of the four basic tastes; the taste quality produced by the hydrogen ion in acids.
Bitter
One of the four basic tastes; the taste quality, generally considered unpleasant, produced by substances like quinine or cafeine
Sweet
One of the four basic tastes; the taste quality produced by some sugars.
What two major groups can taste stimuli be categorized in?
- Salty
- Sour
Ion channels
Small openings in the membranes of the microvilii. Mediate responses to salts and acids.
What two things are salts made up of?
- Cation
- Anion
Cation
Positively charged particle.
Anion
Negatively charged particle
How do hydrogen ions enter the taste receptor cell?
Through ion channels.
UNdissociated acid molecules
Intact molecues that have not split into two charged particles. These cells dissociate inside the taste receptor cell.
Sucrose
The combination of one molecule of glucose and one molecule of fructose
Glucose
A simple suger, source of energy in humans
Heterodimer
A chain of two molecules that are different from each other.
Umami
The taste sensation produced by monosodium glutamate. Also called ‘fifth basic taste’.
MSG (abbreviation)
monosodium glutamate
monosodium glutamate (MSG)
The sodium salt of glutamic acid. A neurotransmitter
Nontaster (of PTC/PROP)
An individual born with two recessive alleles for the TAS2R38 gene and unable to taste the compounds phenylthiocarbamide = PTC and propylthiouracil = PROP.
Prop supertasters
PTC/PROP tasters who also have a high density of fungiform papillae.
Steven’s power law equation
S = I ^b
with S= sensation, I = intensity, b = some constant.
Cross-modality matching
The ability to match the intensities of sensations that come from different sensory modalities.
Specific hungers theory
The idea that deficiency of a given nutrient produces craving (specific hunger) for that nutrient. Right for salty/sweet, but not for other nutrients like vitamins.
Labeled lines
A theory of taste coding in which each taste nerve fiber carries a particular taste quality.
Ethyl mercaptan
The stuff that is added to gas to give it its smell , since gas has no smell originally.
What is the difference between convergence effects in the retina vs in the olfactory bulb?
In the retina, higher convergence gives worse info on spatial location but higher sensitivity when detecting. In the olfactory bulb, the info on the specific scent is the same but there is also higher sensitivity for detecting that scent.
By what evidence is the ratio model supported?
MT cells tuned to the direction of the adaptor show a decrease in activity, but oppositely tuned cells do not show a decrease in activity.
By what evidence is the disinhibition model supported?
V1 cells tuned to an adaptor also show a decrease in response after adaptation and and direction selective cells tuned to anti-preferred stimulus become depolarized. Response enhancement after adaptation to anti-preferred stimulus.
What is a difference between the ratio and the disinhibition model?
Ratio model does not require output to be above baseline, only relative increase over opposite motion signal.
What do the ratio and the disinhibition model have in common?
They both integrate motion signals from opposite directions.
What motion after effect model does the distribution-shift model fit best and why?
The ratio model, since there is no inhibition effect.
Touch
The sensations caused by stimulation of the skin, muscles, tendons and joints.
Tactile
Referring to the result of mechanical interactions with the skin
Proprioception
Perception mediated by kinesthetic and internal receptors.
Somatosensation
Collectively, sensory signals from the skin, muscles, tendons, joints and internal receptors
Mechanoreceptor
A sensory receptor that responds to mechanical stimulation.
Epidermis
The outer of two major layers of the skin.
Dermis
The inner of two major layers of skin, consisting of nutritive and connective tissues, within which lie the mechanoreceptors.
What does a tactile receptor consist of?
A nerve fiber and an associated expanded ending.
What does a nerve fiber consist of?
An axon and a myelin sheath.
A-beta fiber
A wide-diameter, myelineated sensory nerve fiber that transmits signals from mechanical stimulation.
How many types of tactile receptors do we have?
4
Name the 4 types of tactile receptors:
- Meissner corpuscles
- Merkel cell neurite complexes
- Ruffini endings
- Pacinian corpuscles
What is beneath the epidermis and dermis?
the subcutis.
Glabrous (skin)
Lacking hair.
Meissner corpuscle
A specialized nerve ending associated with fast-adapting (FA I) fibers that have small receptive fields.
FA (fibers)
fast-adapting
SA (fibers)
slowly adapting
Merkel cell neurite complex
A specialized nerve ending associated with slowly adapting (SA I) fibers that have small receptive fields.
Pacinian corpuscle
A specialized nerve ending associated with fast-adapting (FA II) fibers that have large receptive fields
Ruffini ending
A specialized nerve ending associated with slowely adapting (SA II) fibers that have alrge receptive fields.
Which tactile receptor types have endings at the junction of epidermis and dermis?
The Meissner and Merkel receptors.
Which tactile receptor types are embedded in the dermis and subcutaneous tissue?
The Pacinian and Ruffini receptors.
By what characteristics can the tactile receptor types be classified?
By receptive field size and adaptation rate.
Fast adapting tactile receptors
Respond with bursts of action potentials when stimulus is applied and when removed, but not in-between.
Which tactile receptor types are fast adapting?
The Meissner and Pacinian receptors.
Slowly adapting tactile receptors
Remains active throughout contact period.
Which tactile receptor types are slowly adapting?
The Merkel and Ruffini receptors.
Describe the response of a SA I fibers:
Responds best to steady downward ressure and LF vibrations. Important for texture and pattern perception.
Descibe the response of SA II fibers:
Respond best to sustained downward pressure and lateral skin stretch.
Describe the response of FA I fibers:
Respond best to LF vibrations, associated to terminate in the Meissner corpuscles.
Describe the response of FA II fibers:
Responds best to HF vibrations, whenever an object makes contact with the skin, terminates in Pacinian corpuscles.
Kinesthetic
Referring to perception involving sensory mechanoreceptors in muscles, tendons and joints.
Muscle spindles
muscle receptors that convey the rate at which the muscle fibers are changing in length.
Golgi tendon organs
Receptors in the tendons that provide signals about tension in the muscles attached to the tendons.
Thermoreceptor
A sensory receptor that signals information about changes in skin temperature.
Warmth fiber
a sensory nerve fiber that fires when skin temperature increases
Name the two populations of thermoreceptors:
- Warmth fibers
- Cold fibers
What is the cold:warm ratio of thermoreceptors in the body?
30:1
Cold fiber
A sensory nerve fiber that fires when skin temperature decreases.
C-fiber
A narrow-diameter, unmyelinated sensory nerve fiber that transmits pain and temperature signal.
A-delta fiber
An intermediate-sized, myelinated sensory nerve fiber that transmits pain and temperature signals.
Nociceptor
A sensory receptor that responds to painful input, such as extreme heat or pressure.
What temperature is the skin in normal conditions?
Between 30 and 36 degrees.
At what temperature are the warmth fibers activated?
Above 36 degrees Celcius.
At what temperature are cold fibers activated?
Below 30 degrees Celsius.
What two classes can nociceptors be divided in?
- Myelinated A-delta fibers
- Unmyelinated C-fibers
thermoTRP
thermally sensitive transient receptor potential. thermoTRP ion channels regulate flow of charged atoms and molecules across the membrane of a cell.
What are the components of discriminative touch?
- Tactile
- thermal
- pain
- itch
C tactile afferents
A narrow-diameter, unmyelinated sensory nerve fiber that transmits signals from pleasant touch.
What mediates the emotional properties of bodily touch?
Mostly the CT (C tactile) afferent fibers.
Labeled lines
A theory of sensory coding in which each nerve fiber carries a particular stimulus quality.
Dorsal horn
A region at the rear of the spinal cord that receives inputs from receptors in the skin.
Somatotypical
Referring to normal somatosensation.
What two pathways in the spinal cord transport touch information?
- Spinothalamic pathway
- Dorsal column-medial lemniscal pathway
Spinothalamic pathway
The route from the spinal cord to the brain that carries most of the information about skin temperature and pain.
DCML (abbreviation)
Dorsal column-medial lemniscal pathway
Dorsal column-medial lemniscal (DCML) pathway
The route from the spinal cord to the brain that carries signals from skin, muscles, tendons and joints.
Which of the two touch info pathways is the slower one?
The spinothalamic pathway.
S1 (abbreviation)
Somatosensory area 1
Somatosensory area 1 (S1)
The primary receiving area for touch in the cortex, in the parietal lobe behind the postcentral gyrus.
Somatosensory area 2 (S2)
The secondary receiving area for touch in the cortex, located in the upper bank of the lateral sulcus
Where are the motor areas of the cortex located?
In front of the central sulcus.
Somatotopic
Referring to spatial mapping in the somatosensory cortex in correspondence to spatial events on the skin.
Homunculus
A maplike representation of regions of the body in the brain
Where in the brain are touch sensations presented somatotopically?
In S1.
Body image
THe impression of our bodies in space.
Phantom limb
Sensation perceived from a physically amputated limb of the body.
Neural plasticity
the ability of neural circuits to undergo changes in function or organization as a result of previous activity.
Substantia gelatinosa
A region of interconnecting neurons in the dorsal horn of the spinal cord.
Gate control theory
A description of the pain-transmitting system that incorporates modulating signals from the brain
ACC (abbreviation)
Anterior cingulate cortex
Anterior cingulate cortex (ACC)
A region of the brain associated with the perceived unpleasantness of a pain sensation.
Pruciceptors
itch-selective fibers
Analgesia
Decreasing pain sensation during conscious experience.
Endogenous opiate
A chemical released by the body that blocks the release or uptake of neurotransmitters necessary to transmit pain sensations to the brain.
Placebo effect
Decreasing pain sensation when people think they’re taking an analgesic drug but actually are not.
Hyperalgesia
An increased or heigthened response to a normally painful stimulus. So happens when pain surpasses normal expectations.
Two-point touch threshold
The minimum distance at which two stimuli are just perceptible as separate.
Haptic perception
Knowledge of the world that is derived from sensory receptors in skin, muscles, tendons and joints, usually involving active exploration.
IN what two ways is touch active?
- Action for perception
- Perception for action
Action for perception
using our hands to actively explore the world of surfaces and objects outside our bodies
Perception for action
using sensory input to prepare us to interact with objects and surfaces around us.
Exploratory procedure
A stereotyped hand movement pattern used to touch objects in order to perceive their properties; each procedure is best for determining one (or more) object properties.
Tactile agnosia
The inability to identify objects by touch, mainly caused by lesions in the parietal lobe.
Frame of reference
The coordinate system used to define locations in space,
Egocenter
The center of a reference frame used to represent locations relative to the body.
Endogenous (spatial attention)
A form of top-down control in which attention is voluntarily directed toward the site where the observer anticipates a stimulus will occur.
Exogenous (spatial attention)
A form of bottom-up attention attention reflexvely (involuntarily) directed toward the site at wchih a stimulus has abruptly appeared.
How does convergence differ between the retina and the olfactory epithelium?
The olfactory epithelium doesn’t cause a decrease in discrimination with higher convergence.
Why is V1 not selective for complex motions such as rotation?
V1 has small receptive fields and a lack of spatial integration, reacts to local motion signals only.
Why do so many different compounds taste bitter?
Different bitter receptors converge on the same fiber.
What finding supports the ratio model?
MT cells tuned to the direction of the adaptor show a decrease in activity but oppositely tuned cells do not show an increase in activity.
What finding supports the disinhibition model?
V1 cells tuned to an adaptor also show a decrease in response after adaptation and direction selective cells tuned to the anti-preferred stimulus become depolarised.
ITD (abbreviation)
Interaural time difference
Interaural time difference (ITD)
The difference in time between arrivals of sound at one ear versus the other
Azimuth
The angle of a sound source on the horizontal plane relative to a point in the center of the head between the ears.
Describe the azimuth values & their places:
0 degrees is straight ahead, angle increases to the right and 180 degrees is directly behind.
When are ITD values the largest?
When sound comes from the left or right directly.
When are ITD values the smallest?
When sound is coming from the front or the back directly.
MSO (abbreviation)
Medial superior olive
How does the travelling sound differ between the two ears depending on time?
It reaches a lower frequency further down the cochlea in the ear that is reached first.
ILD (abbreviation)
interaural level difference
Interaural level difference (ILD)
The difference between levels (intensities) of sound at one ear versus the other.
When is ILD the highest?
At 90 and -90 degrees.
When is ILD nonexistent?
At 0 and 180 degrees.
Why is the correlation with the angle of the sound source less precise in ILD than in ITD?
The irregular shape of the head blocks LF more effectively than HF sounds, and the difference between intensity varies because of this shape.
LSO (abbreviation)
Lateral superior olive
Lateral superior olive
relay station in the brain stem where inputs from both ears contribute to detection of the interaural level difference.
Where do we find neurons that are sensitive to sound intensity differences?
In the lateral superior olive (LSO).
What do the neurons in the lateral superior olive (LSO) receive?
Excitatory connections from the ipsilateral ear and inhibitory connections from the contralateral ear.
Cone of confusion
A region of positions in space where all sounds produce the same time and level (intensity) differences (ITDs and ILDs).
DTF (abbreviation)
directional transfer function
Directional transfer function (DTF)
A measure that describes how the pinna, ear canal, head and torso change the intensity of sounds with different frequencies that arrive at each ear from different locations in space (azimuth and elevation).
Inverse-square law
A principle stating that as distance from a source increases, intensity decreases faster such that decrease in intensity is equal to the distance squared.
A cue we can use for judging auditory distance is the fact that the sound arriving at the ear is a combo of…
Direct energy and reverberant energy.
Reverberant energy
Energy which has bounced off surfaces in the environment.
Fundamental frequency
The lowest frequency component of a complex periodic sound.
Attack
The part of a sound during which amplitude increases, the onset.
Decay
The part of a sound during which amplitude decreases, the offset.
Source segregation
Processing an auditory scene consisting of multiple sound sources into separate sound images.
Auditory scene analysis
Processing an auditory scene consisting of multiple sound sources into separate sound images.
Auditory stream segregation
The perceptual organization of a complex acoustic signal into separate auditory events for which each stream is heard as a separate event.
Similarity (sound)
A Gestalt grouping rule stating that the tendency of two sounds to group together will increase as the acoustic similarity between them increases.
Common fate
A Gestalt grouping rule stating that the tendency of sounds to group together will increase if they begin and or end at the same time.
Good continuation (sound)
A Gestalt grouping rule stating that sounds will tend to group together as continuous if they seem to share a common path, similar to a shared contour for vision
Acoustic startle reflex
The very rapid motor response to a sudden sound.
Why is color vision synthetic?
When you combine individual components, you get something new and can’t perceive the individual components anymore.
Why is basic taste basic and not synthetic?
Because you can still perceive the individual components when two flavours are mixed.
What are the three criteria for basic taste?
- Specific receptors
- Specific fibers
- Specific brain areas
Where can you find bitter, sweet, sour and salty receptors?
At the end of taste receptor cells.
What is the division of taste receptor cells based on?
On what the cells look like, not necessarily on what they do.
What classes of taste receptors are second messenger systems?
Bitter and sweet
Salty receptor
Taste receptor that is ion channel based. There is sodium influx, which causes depolarization.
Na+ is…
sodium
What does salt sensitivity depend on?
On salt intake. If you eat a lot of salt, you get a lot of active sodium channels so number of receptors goes down and less sensitive.
Sour receptor
Ion channel based receptors, hydrogen selective.
Sweet receptor
A second messenger system, two proteins form a receptor. Combination of T1R2 and T1R3.
Bitter receptor
A second messenger system, all 25 receptor types converge on the same fiber.
Why is it tricky to say that umami is a basic taste?
The protein molecules are too big for the taste receptors on the tongue.
What are the basic taste if we look at specific taste receptors?
- Sweet
- Sour
- Salty
- Bitter
- Umami
What are the basic tastes if we look at specific fibers?
- Sweet
- Sour
- Salty
- Bitter
What are the basic tastes if we look at specific brain areas?
- Sweet
- Sour
- Salty
- Bitter
- Umami
- CO2/ carbonation
Examples of kinesthetic properties
Toughness, chewiness, tenderness, resistance when chewing and biting.
What basic taste does warmth evoke?
Sweet
