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90 Cards in this Set
- Front
- Back
Frequency (pitch)
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the rate at which waves vibrate, measured as cycles per second, or hertz.
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Amplitude (loudness)
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the intesity of sound, usually measured in decibels. Amplitude roughtly corresponds to our perception of loudness
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Complexity (timbre)
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most sounds are a mixture detemines the sound's timbre or perceived uniqueness. timbre provides info about the nature of a sound
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Sound perception
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Auditory system converts the physical properties of sound-wave energy into electrochemical neural activity that travels to the brain
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Auditory Receptors: Hair Cells
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Transduction of sound waves into neural activity takes place primarily in the 3500 inner hair cells.
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Frequency Coding on Basilar Membrane
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a narrow thick base is tuned for high frequencies. A wide thin apex is tuned for low frequency
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Sensory Transduction Occurs in the Hair Cells
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Movement of cilia ____towards____ the tallest one depolarizes the cell, causing K+ influx (depolarization), which opens Ca2+ channels and release of transmitter, which stimulates cells that form the auditory nerve.
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Sensory Transduction Occurs in the Hair Cells
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Movement of cilia towards the shortest one hyperpolarizes the cell, resulting in less neurotransmitter release.
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Sensory Transduction - 2
first part |
At Rest: ~15% of cilia K+ channels are open. This influx slightly depolarizes hair cell, opening of Ca2+ channels and release of sml amt of glutamate onto spiral ganglion cells. Moderate firing rate of ganglion cells.
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Sensory Transduction - 2
Second part |
Displacement toward tallest cilia: Stretches tip links many more K+ channels open. K+ influx depolarizes hair cell further greater Ca2+ influx and release of larger amt of glutamate onto spiral ganglion cells. High firing rate of ganglion cells.
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Sensory Transduction - 2
third part |
Displacement toward shortest cilia: Relaxes tip links 100% K+ channels closed. Hair cell hyperpolarizes. Much less Ca2+ influx and much less release of glutamate onto spiral ganglion cells. Low firing rate of ganglion cells.
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Two Distinct Bilateral Auditory Pathways
first part |
Ventral Cochlear N. Superior Olive N. (Where)
Millisecond differences in arrival times of auditory signals at L & R ears is preserved in Ventral Cochlear Nucleus. Differences in timing and amplitude detected in superior olive, permit localization of sound or the direction of sound origin. |
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Two Distinct Bilateral Auditory Pathways
Second part |
2. Dorsal Cochlear N. Inferior Colliculus N. (What)
Dorsal Cochlear Nucleus detects differences in the frequencies within sound signals. Permits detection of sound qualities and may be first step in phonetic discrimination of words Auditory “What” Pathway has Tonotopic Maps |
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Two Distinct Bilateral Auditory Pathways
first part (WHERE) |
Differences in time that sound arrives at each ear & detected by cochlear ganglion cells of each inner ear permit the localization of sounds.
This process works fine except for sounds originating from directly ahead or behind us. |
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Auditory Cortex – Detection of Patterns in Sound
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Music and language are perhaps the primary sound-wave patterns that humans recognize:
– Music = right hemisphere – Language = left hemisphere Most research on audition comes from nonhuman primates – e.g., Winter & Funkenstein (1971): neurons in A1 of the squirrel monkey are responsive to vocalizations made by other squirrel monkeys. |
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For Musicians – Size Does Matter
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Neurophysiological recording and functional imaging studies indicate strong correlation between activity & size of primary auditory cortex (A1) and musical ability.
Color-coded depiction of the temporal lobe area comprising A1 in 3 groups of human subjects. 130% increase in size of A1 in musicians vs. nonmusicians |
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Monosynaptic Spinal Reflexes
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• Hammer tap stretches quadriceps muscle, the la sensory fibers in muscle spindles sense increased stretch, the la sensory fibers stimulate alpha motor neurons in the spinal cord, and alpha motor neurons cause quadriceps muscle to contract, foot kicks
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Primary Motor Cortex (M1)
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M1 neurons project long axons to excite spinal motor neurons.
Behavior role: executing voluntary movement. Firing the M1 neuron is time locked to movement of a given body part |
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Describe the major role of the premotor (PM) cortex
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• Premotor Cortex, Behavioral role: Planning complex movements by selecting the correct motor program to be executed by M1. Located just rostral to M1 in frontal lobe. Association areas of occipital, temporal, & parietal cortex project to Premotor Cortex
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essential concepts of the Kurata
experiment |
• Kurata and others: Premotor (PM) neurons discharge in response to instructional stimuli that indicate the correct movement to be made
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what “set-related” activity represents
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• This “Set-related activity” is considered to reflect the planning of future movement. PM “instincts” M! about which motor program to execute
• M1 neurons discharge in response to trigger stimulus – “Go!” – movement execution |
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Voluntary movement group
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o corticospinal
o corticobulbar o corticorubral o rubrospinal |
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Involuntary movement group
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o vestibulospinal
o reticulospinal o tectospinal |
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o corticospinal
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M1 -> s.c. = movement of limbs, fingers, hands, trunk
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o corticobulbar
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M1 ->cranial nerve n. = face, jaw, tongue, eyes
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o corticorubral
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M1 -> red nucleus
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o rubrospinal
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Red nucleus ->spinal cord = limbs
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o vestibulospinal
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Vestibular nuclei -> s.c. = balance, posture adjustment
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o reticulospinal
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Pons, medulla reticular form. ->s.c. = posture
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o tectospinal
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Superior colliculus -> s.c. = reflex. eye movements
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"homunculus” in primary motor cortex (M1).
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• Is Penfield(1950, McGill U) Electrical stimulation of M1neuron caused contraction of muscles in the corresponding body part
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Primary Motor Cortex and Corticospinal Tract
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Ex: M1 role in movement
Stimulation of region of left M1 region corresponding to the palm causes contraction of the palm hypothenar muscles in the right hand. |
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Mapping Human M1 with TMS
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Trans-cranial magnetic stimulation (TMS) coil generates magnetic field impulses which stimulate underlying neurons in a focused volume. By measuring responses to the stimulations and tracking the position of the coil relative to the MR scan functional maps of the brain can be generated in a low-cost, non-invasive, and accurate manner
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Premotor Cortex
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Behavioral role: Planning complex movements by selecting the correct motor program to be executed by M1
Located just rostral to M1 in frontal lobe. Association areas of occipital, temporal, & parietal cortex project to Premotor Cortex |
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Premotor Cortex and Motor Planning
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Kurata & Tanji (1986-1993): recorded Premotor (PM) neurons from monkeys performing a delayed response task.
Set-related activity in PM: significant elevation of firing rate during the delay period. Likely reflects motor preparation or the selection of the correct motor program. |
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Supplementary Motor Area (SMA)
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• SMA is involved in Planning movements using internal guides and they execute these plans through their connections with the primary motor cortex( i.e. Memory
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• Roland et al. (1980) measured regional cerebral blood flow (rCBF), in humans performing 2 tasks under 3 conditions:
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o 1. Flexion of finger against spring-loaded device M1 and S1 cortex activated
o 2. Performing a learned sequence of finger movements S1, M1, PMD, SMA o 3. Told to think about performing the same sequence (mental rehearsal), but remain motionless only SMA activated (mental rehearsal) |
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Define the “motor homunculus” in primary motor cortex (M1).
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• Is Penfield(1950, McGill U) Electrical stimulation of M1neuron caused contraction of muscles in the corresponding body part.
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supplementary motor area (SMA)?
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is involved in Planning movements using internal guides and they execute these plans through their connections with the primary motor cortex( i.e. Memory)
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Describe the contribution of the basal ganglia
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• The motor nuclei of the basal ganglia include the caudate nucleus, putamen, and globus pallidus and a strong connections w/ the substantia nigra.(3 forebrain nuclei)
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Direct pathway
basal ganglia |
• Cortex ->Striatum -> Globus pallidus internal (GPi) -> Ventrolateral (VL) + Ventroanterior (VA) thalamus -> SMA, PM, M1
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Indirect pathway
basal ganglia |
• Cortex -> Striatum -> Globus pallidus external (GPe) -> Subthalamic n (STN) -> Globus pallidus internal (GPi) -> VL+VA thalamus ->SMA, PM, M1
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cerebellum contributes to the brain control of voluntary movement
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timing and sequencing of complex movements
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What are the consequences of damage to M1, and to the cerebellum
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Apraxia
Limb Apraxia Constructional Apraxia |
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• Apraxia
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difficulty performing skilled movement
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o Limb Apraxia
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damage to arm region of left M1 results in production of incorrect movements of the right arm. e.g., S given verbal command – “pretend you are unlocking the door of your house with a key” S can hear the command but has difficulty executing the correct motor program to achieve the action.
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• Constructional Apraxia
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damage to right parietal lobe à difficulty making skilled mov’ts with hands. Deficits with an inability to perceive, draw, or imagine geometric and spatial relationships. Understanding pantomiming.
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Define the motor pathways that are compromised by Huntington’s disease (HD)
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•Neurobiology: Loss of striatal-globus pallidus GABAergic neurons:
Leads to over activity of the indirect pathway à increased expression of unwanted movements. Leads to under activity of the direct pathway à slowness to initiate desired movement. |
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Huntington’s disease (HD), the major
symptoms |
involuntary, jerky movements, slowness to initiate movement, depression, dementia, hallucination and delusions
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Huntington’s disease (HD treatments
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: Antioxidants, caspase inhibitors, neurotrophic factors, fetal tissue transplants and embryonic stem cells may provide treatment in the future.
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Dorsal Cochlear N. ->Inferior Colliculus N. (What)
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o Dorsal Cochlear Nucleus detects differences in the frequencies within sound signals. Permits detection of sound qualities and may be first step in phonetic discrimination of words
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• Ventral Cochlear N. -> Superior Olive N. (Where)
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o Differences in timing and amplitude detected in superior olive, permit localization of sound or the direction of sound origin.
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pinna
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• The outer ear sound is funneled through the ear canal to the tympanic membrane (eardrum) which vibrates the sound.
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tympanic membrane
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(eardrum) which vibrates the sound.
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ossicles,
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middle ear contains the bones of the middle ear which are set into vibration by the tympanic membrane.
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malleus
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(hammer) connects with the tympanic membrane and transmits vibration via the incus (anvil) and stapes (stirrup) to the cochlea, the structure that contains the receptors.
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incus
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(anvil)
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stapes
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(stirrup)
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cochlea
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(snail) is part of the inner ear. It is filled with fluid; therefore, sounds transmitted through the air must be transferred into a liquid medium
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3 sections of the cochlea
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scala vestibule (vestibular stairway), the scala media (middle stairway) and the scala tympani (tympanic stairway)
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Define how different frequencies of sound are represented on the basilar membrane
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• Frequency coding on basilar membrane in an uncoiled cochlea a narrow, thick base is tuned for high frequencies. A wide, thin apex is tuned for low frequencies
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How is amplitude represented?
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• Amplitude is represented as the intensity of the sound and is measured in decibels. Amplitude roughly corresponds to our perception of loudness
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timbre
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a perceptual dimension od sound; corresponds to coplexity
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round window
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an opening in the bone surrounding the cochlea of the inner ear that permits vibrations to be transmitted, via the oval wndow, into the fluid in the cochlea
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lateral lemniscus
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a band of fibers running rostrally through the medulla and pons; carries fibers of the auditory sysstem
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cilium
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hailike structure of a cell involved in movement or in transducing sensory information; found on the reptors in the auditory and vestibular sustemm
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malleus
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the "HAMMER"' the first of 3 ossicles
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kinesthesia
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perception of the body's own movement
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tip link
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an elastic filament that attavhes the tip of one cilium to the side of the adjacent culium
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cochlear nerve
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the branch of the auditory nerve that transmits auditory information from the cochlea to the brain
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cochlear nucleus
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one of a group of nuclei in the medulla that recieve auditory info from the cochlea
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olivocochlear bundle
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bundle of efferent axons that travel from the olivary complex of the medulla to the auditory hair cells on the chochlea
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pitch
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a perceptual dimension of sound; corresponds to the fundamental frequency
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Deiters cell
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a supporting cell found in the organ of the Corti; sustains the auditory hair cells.
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overtone
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the frequency of complex tones that occurs at multiples of the fundamental frequency
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tympanic membrane
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eardrum
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loudness
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a perceptual dimension of sound; corresponds with intensity
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hair cells
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the recptive cell of the auditory system
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tonotopic representation
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a topographically organized mapping of different frequencies of sound that are represented in a particular region of the brain
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Organ of Corti
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the sensory organ on the basilar membrane that contains the auditory hair cells
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superior olivary complex
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a group of nuclei in the medulla; involved with audtory funtions, incl localizatin of the source of sounds.
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ossicle
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one of the three bones of the middle ear
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cochlea
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the snail shaped structure of the inner ear that contains the audtitory transducing mechanisms
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phase difference
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the differnce in arrival times of sound waves at each of the eardrums
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stapes
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the "stirrups" the last of the three ossicles
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tectorial membrane
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a mamenbrane located above the basilar membrane; servers as a shelf against which cilia of the audotry hair cells move.
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incus
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the "anvil" the second of the three ossicles
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oval window
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and opening in the bone surroudning the cochlea that reveals a membrane, against which the baseplate of the stapes presses, transmitting soudn vibrations into the fluid withing the chochlea
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basilar membrane
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a membrane in the cochea of the inner ear; contains the organ of corti
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insertional plaque
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the point of attachment of a tip link to a cilium
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