Textbook Notes (363,452)
Canada (158,372)
Psychology (1,390)
PSYC 211 (154)
Chapter 7

Chapter 7 Notes.pdf

10 Pages
Unlock Document

McGill University
PSYC 211
Yogita Chudasama

PSYC211 Chapter 7 Notes Definitions: Pitch: A perceptual dimension of sound; corresponds to the fundamental frequency Hertz (Hz): Cycles per second Loudness: A perceptual dimension of sound; corresponds to intensity Timbre:A perceptual dimension of sound; corresponds to complexity Tympanic Membrane: The eardrum Ossicle: One of the three bones of the middle ear Malleus: The “hammer”; the first of the three ossicles Incus: The “anvil”; the second of the three ossicles Stapes: The “stirrup”; the last of the three ossicles Cochlea: The snail-shaped structure of the inner ear that contains the auditory transducing mechanisms Oval Window: An opening in the bone surrounding the cochlea that reveals a membrane, against which the baseplate of the stapes presses, transmitting sound vibrations into the fluid within the cochlea Organ of Corti: The sensory organ on the basilar membrane that contains the auditory hair cells Hair Cell: The receptive cell of the auditory apparatus Deiter’s Cell: A supporting cell found in the organ of Corti; contains the organ of Corti Basiliar Membrane: A membrane in the cochlea of the inner ear; contains the organ of Corti Tectorial Membrane: A membrane located above the basilar membrane; serves as a shelf against which the cilia of the auditory hair cells move Round Window: An opening in the bone surrounding the cochlea of the inner ear that permits vibrations to be transmitted, via the oval window, into the fluid in the cochlea Cilium: A hairlike appendages of a cell involved in movement or in transfusing sensory information; found on the receptors in the auditory and vestibular system Tip Link: An elastic filament that attaches the tip of one cilium to the side of the adjacent cilium Insertional Plaque: The point of attachment of a tip link to a cilium Cochlear Nerve: the branch of the auditory nerve that transmits auditory information from the cochlea to the brain Olivocochlear Bundle: A bundle of efferent axons that travel from the olivary complex of the medulla to the auditory hair cells on the cochlea Cochlear Nucleus: One of a group of nuclei in the medulla that receives auditory information from the cochlea Superior Olivary Complex: A group of nuclei in the medulla; involved with auditory functions, including localization of the source of sounds Lateral Lemniscus: A band of fibers running rostrally through the medulla dn. Pons; carries fibers of the auditory system Tonotopic Representation: A topographically organized mapping of different frequencies of sound that are represented in a particular region of the brain Core Region: The primary auditory cortex, located on a gyrus on the dorsal surface of the temporal lobe Belt Region: The first level of auditory association cortex; surrounds the primary auditory cortex Parabelt Region: The second level of auditory association cortex; surrounds the belt region Place Code: The system by which information about different frequencies is coded by different locations on the basilar membrane Cochlear Implant: An electronic device surgically implanted in the inner ear that can enable a deaf person to hear Rate Coding: The system by which information about different frequencies is coded by the rate of firing of neurons in the auditory system Fundamental Frequency: The lowest, and usually most intense, frequency of a complex sound; most often perceived as the sound’s basic pitch Overtone: The frequency of complex tones that occurs at multiples of the fundamental frequency Amusia: Loss or impairment of musical abilities, produced by hereditary factors or brain damage Cutaneous Sense: One of the somatosenses; includes sensitivity to stimuli that involve the skin Proprioception: Perception of the body’s position and posture Kinesthesia: Perception of the body’s won movements Organic Sense: A sense modality that arises from receptors located within the inner organs of the body Glabrous Skin: Skin that does not contain hair; found on the palms and the soles of the feet Ruffini Corpuscle: A vibration-sensitive organ located in hairy skin Pacinian Corpuscle: A specialized, encapsulated somatosensory nerve ending that detects mechanical stimuli, especially vibration Messiness’ Corpuscle: The touch-sensitive end organs located in the papillae, small elevations of the dermis that project up into the epidermis Merkel’s Disk: The touch-sensitive end organs found at the base of the epidermis adjacent to sweat ducts Phantom Limb: Sensations that appear to originate in a limb that has been amputated Nucleus Raphe Magnus: A nucleus of the raphe that contains serotonin-secreting neurons that project to the dorsal gray matter of the spinal cord and is involved in analgesia produced by opiates The Stimulus: Sounds are produced by objects that vibrate and set molecules of air into motion; the movements of • molecules cause air surrounding it alternately to condense and rarefy (pull apart), producing waves that travel away from the object at approximately 700 miles per hour • Waves with vibration ranges between 30 - 20,000 times per second will stimulate as a sound in human ear • Pitch is determined by frequency of vibration, measured in Hz or cycles per second • Loudness is a function of intensity - the degree to which the condensations and rarefactions of air differ from each other. More vigorous vibrations = more intense sound waves • Timbre provides information about the nature of the particular sound. The mixture of frequencies determine the timbre you hear • An ear is an analytical organ (“to undo”). When two different frequencies are mixed, we do not perceive an intermediate tone; instead, we hear both original tones Anatomy of the Ear: • Sound is funneled via the pinna (external ear) through the ear canal to the tympanic membrane (eardrum), which vibrates with the sound • Middle ear consists of 2mL in volume and contains 3 ossicles (bones): malleus (hammer), incus (anvil) and stapes (stirrup) in that order to the cochlea which contains the receptors • The baseplate of the stapes presses against the membrane behind the oval window, the opening in the bony process surrounding the cochlea • Cochlea is filled with fluid and is part of the inner ear • The chain of ossicles serves as an extremely efficient means of energy transmissions with the stapes making smaller but more forceful excursions against the oval window than the tympanic membrane makes against the malleus • Cochlea comes from word meaning “land snail” - looks like it • Cochlea splits into the scala vestibule (“vestibular stairway”), the scala media (“middle stairway”) and the scala tympani (“tympanic stairway”) • Receptive organ is the organ of Corti which consists of the basilar membrane, the hair cells, and the tectorial membrane • Hair cells are anchored via rodlike Dieter’s cells, to the basilar membrane • Sound waves cause the basilar membrane to move relative to the tectorial membrane, which bends the cilia of the hair cells. This bending produces receptor potentials • Vibration energy exerted on the oval window causes the basilar membrane to bend; the portion that bends the most is determined by the frequency of the sound: High-frequency sounds cause the end nearest the oval window to bend • The round window is a membrane covered opening that allows the fluid inside the cochlea to move back and forth. The baseplate of the stapes vibrates against the membrane behind the oval window and introduces sound waves of high or low frequency into the cochlea • Pressure changes in the fluid underneath the basiliar membrane are transmitted to the membrane of the round window, which moves in and out in a manner opposite to the movements of the oval window Fenestration is a (“window making”) surgery to restore hearing due to a middle ear disease • Auditory Hair Cells and the Transduction of Auditory Information: Inner and Outer auditory hair cells are located on the basilar membrane • • The human cochlea contains approximately 3500 inner hair cells and 12000 outer hair cells • The hair cells form synapses with dendrites of bipolar neurons whose axons bring auditory information to the brain • Cilia contain a core of actin filaments surrounded by myosin filaments, and these proteins make the cilia stiff and rigid • Adjacent cilia are linked to each other by elastic filaments known as tip links The points of attachment are known as insertional plaques. Receptor potentials are triggered at • these insertional plaques • Movement of the bundle of cilia in the direction of the tallest of them further stretches these linking fibers, whereas movement in the opposite direction relaxes them. Bending of the bundle of cilia causes receptor potentials • Fluid that surrounds the auditory hair cells is rich in potassium. Each insertion plaque contains a single cation channel • When the bundle of cilia is straight, the probability of an individual ion channel being open is approximately 10%. When the bundle moves towards the tallest one, all the ion channels open up allowing the flow of cations into the cilia and the membrane depolarizes; thus, the release of neurotransmitter by the hair cell increases • When the bundle moves in the opposite direction towards the shortest cilium, the tip links close the opened ion channels resulting in the influx of cations to cease and the membrane hyperpolarizes causing the release of neurotransmitters to decrease The Auditory Pathways: Connections with the Cochlear Nerve • Organ of Corti sends auditory information to the brain via cochlear nerve (auditory nerve) The neurons in the cochlear nerve which are afferent are bipolar type • • The cochlear nerve ganglion is also called the spiral ganglion because it consist of clumps of cell bodies arranged in a spiral caused by the curling of the cochlea. These neurons have axonal processes, capable of sustaining action potential that protrude from both ends of the soma • The end of one process acts like a dendrite, responding EPSP when the NT is released by the auditory hair cells. The EPSP triggers action potentials in the auditory nerve axons, which form synapses with neurons in the medulla • Each cochlear nerve contains 50,000 afferent axons with 95% forming synapses with the inner hair cells (thick and myelinated) • Other 5% of the sensory fibers in the cochlear nerve form synapses with much more numerous outer hair cells (1 fiber: 30 outer hair cells; thin and myelinated) • Inner hair cells connect with auditory nerves suggest they transmit auditory information to the CNS; necessary for normal hearing • Outer hair cells are effector cells, involved in altering the mechanical characteristics of the basilar membrane and thus influencing the effects of sound vibrations on the inner hair cells • Cochlear nerve contains efferent axons in the superior olivary complex, a group of nuclei in the medulla. Efferent bundle constitutes the olivocochlear bundle. They form synapses directly with both the outer hair cells and on the dendrites that serve the inner hair cells • The NT of the afferent synapses is glutamate while efferent synapses is achetylcholine The Central Auditory System: • Axons enter the cochlear nucleus of the medulla and synapse there. The neurons in the cochlear nucleus send axons to the superior olivary complex, also located in the medulla • Axons of neurons in these nuclei pass through a large fiber bundle called the lateral lemniscus to the inferior colliculus, located in the dorsal midbrain. Those neurons then send their axons to the medial geniculate nucleus of the thalamus, which sends its axons to the auditory cortex of the temporal lobe • If we unrolled the basilar membrane into a flat strip following the afferent axons, we would reach successful points in the auditory system and points in the surface of the primary auditory cortex The basal end of the basilar membrane (the end toward the oval window) is represented most • medially in the auditory cortex, and the apical en is represented most laterally there • Different parts of the basiliar membrane respond best to different frequencies of sound, this relationship between cortex and basilar membrane is referred to as tonotopic representation • The primary auditory cortex lies hidden on the upper bank of the lateral fissure. The core region, which contains the primary auditory cortex consists of three regions, each has a separate tonotopic map of auditory information from the ventral division from the medial geniculate nucleus • The belt region surrounds the primary auditory cortex and consists of seven divisions. It receives information both from the primary auditory cortex and from the dorsal and medial divisions of the medial geniculate nucleus • The highest level of auditory association cortex, the parabelt region, receives information from the belt region and from the divisions of the medial genicu
More Less

Related notes for PSYC 211

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.