Sensory SystemsPrepared and presented by:

Prof. Paola Katherina M. Gonzales, MA

AUDITIONAuditory System, anatomy and transduction

The StimulusPitch

a perceptual dimension of sound;corresponds to the fundamental frequency

Hertz (Hz)

cycles per second

The StimulusLoudness

a perceptual dimension of sound,corresponds to intensity

The StimulusTimbre

a perceptual dimension of sound corresponding tocomplexity

AnatomyTympanic membrane eardrum

Ossicle one of the three bones ofthe middle ear

Malleus the hammer; the first ofthe three ossicles

Incus the anvil; second to thethree ossicles

Stapes the stirrup; the last of thethree ossicles

Cochlea the snail-shaped structureof the inner ear that contains theauditory transducing mechanisms

Oval window an opening in thebone surrounding the cochlea thatreveals a membrane, against whichthe baseplate of the stapes presses,transmitting sound vibrations intothe fluid within the cochlea

Organ of Corti the sensory organ onthe basilar membrane that containsthe auditory hair cells

Hair cell - the receptive cell of theauditory apparatus

Deiterss cell a supporting cell foundin the organ of corti which sustains theauditory hair cells

Basilar membrane a membrane inthe cochlea of the inner ear; containsthe organ of corti.

Tectorial membrane a membranelocated above the basilar membrane;serves as a shelf against which the ciliaof the auditory hair cells move.

Round window an opening in thebone surrounding the cochlea of theinner ear that permits vibrations to betransmitted via the oval window, intothe fluid in the cochlea.

Auditory hair cells and the Transduction of Auditory information

Cilium a hairlikeappendage of a cellinvolved in movement or intransducing sensoryinformation found on thereceptors in the auditoryand vestibular system.

Tip link an elasticfilament that attaches thetip of one cilium to the sideof the adjacent cilium

Insertional plaque thepoint of attachment of atip link to a cilium

Auditory Pathway: Connections with the cochlear nerve

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 olivarycomplex of the medulla to the auditory hair cells on the cochlea.

Central Auditory System Cochlear nucleus

one of a group of nuclei inthe medulla that receive auditoryinformation from the cochlea

Superior Olivary Complex

a group of nuclei in themedulla involved with auditoryfunctions, including localization ofthe source of sounds

Lateral lemniscus

a band of fibers runningrostrally through the medulla andpons which carries fibers of theauditory system.

Tonotopic representation

a topographicallyorganized mapping of differentfrequencies of sound that arerepresented in a particular region ofthe brain

Central Auditory System

Core region the primary auditory cortex, located on a gyrus on the dorsalsurface of the temporal lobe

Belt region the first level of auditory association cortex surrounds theprimary auditory cortex.

Parabelt region the second level of auditory association cortex surrounds thebelt region.

Perception of Pitch

Place coding

the system by whichinformation about differentfrequencies is coded by differentlocations on the basilar membrane.

Perception of Pitch

Cochlear implant

an electronic devicesurgically implanted in the inner earthat can enable a deaf person tohear.

Perception of PitchRate coding

the system by whichinformation about differentfrequencies is coded by the rate offiring of neurons in the auditorysystem.

Perception of Loudness

Most investigators believe that the loudness of low frequencysounds is signaled by the number of axons arising from theseneurons that are active at a given time.

Perception of TimbreFundamental frequency

the lowest, and usually most intense frequency of a complex sound and most often perceived as the sounds basic pitch.

Overtone

the frequency of complex tones that occurs at the multiples of the fundamental frequency.

Localization by means of arrival time and phase difference

Phase difference

the difference in arrival times of sound waves at each of the eardrums

Amusia

loss or impairment of musical abilities, produced by hereditary factors or brain damage.

VESTIBULAR SYSTEM

Vestibular System

Vestibular Sac

one of a set of tworeceptor organs in eachinner ear that detectchanges in the tilt of thehead.

Anatomy of the Vestibular Apparatus

Semicircular canal

one of the three ringlikestructures of the vestibular apparatusthat detect changes in head rotation

Utricle

one of the vestibular sacs

Saccule

one of the vestibular sacs

Ampulla

an enlargement in asemicircular canal that contains thecupula and the crista

Cupula

a gelatinous mass found inthe ampulla of the semicircular canalsthat moves in responses to the flowof the fluid in the canals.

Anatomy of the Vestibular Apparatus

Vestibular ganglion

a nodule on the vestibular nerve thatcontains the cell bodies of the bipolar neuronsthat convey vestibular information to thebrain.

SOMATOSENSES

One of the somatosenses that includes sensitivity to stimuli involving the skin.

ProprioceptionPerception of the bodys position and posture

Perception of the bodys own movement

Organic Sense

A sense modality that arises from receptors located within the inner organs of the body

Anatomy of the SKINGlabrous Skin skin that does not contain hair, found onthe palms and soles of the feet.

Merkels disk - a touch sensitive cutaneous receptor, important for detection of form and roughness, especially by fingertipsRuffini Copuscle a touch sensitive cutaneous receptor, important in detecting stretching or static force against the skin, important in proprioception.

Meissners Corpuscle a touch sensitive cutaneousreceptor important in detecting edge contours or Braille like stimuli, especially by fingertips.

Pacinian Corpuscle a vibration sensitive cutaneousreceptor, important in detecting vibration from an objectbeing held

Perception of Cutaneous Stimulation

Mechanoreceptor

a sensory neuron that responds to mechanical stimuli; forexample, those that produce pressure, stretch, or vibration of theskin or stretch of muscles or tendons.

Temperature Pain

Itch

Somatosensory Pathway

Somatosensory Pathway

Tactile Agnosia

Tactile ApraxiaDifficulty in carrying out purposeful movements in the absence of paralysis or muscular weakness

Phantom Limb

Sensation 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.

(ex. Opiate induced analgesia)

GUSTATION

UmamiThe taste sensation produced by monosodium glutamate (amino acids found in proteins).

The tongue

Anatomy of the taste buds and Gustatory Cells

Papillae

small protuberances of the tongue

Fungiform papillae

located on the anterior two thirds of the tongue, contains up to eighttaste buds, along with the receptors ofpressure, touch and temperature.

Foliate papillae

consists up to eight parallel foldsalong each edge of the back of the tongue(approx. 1,300 taste buds)

Circumvallate papillae

arranged in an inverted V on theposterior third of the tongue (approx.250taste buds)

The structure of taste receptor

Gustatory pathway

Chorda Tympani a branch of facialnerve that passes beneath theeardrum; conveys taste informationfrom the anterior part of thetongue and controls the secretionof some salivary glands.

Nucleus of the solitary tract -nucleus of the medulla thatreceives information from visceralorgans and from the gustatorysystem.

OLFACTION

Stimulus

Anatomy of the olfactory Olfactory epithelium theepithelial tissues of the nasalsinus that covers the cribriformplate; contains the cilia of theolfactory receptors

Olfactory bulb the protrusion atthe end of the olfactory tractwhich receives input from theolfactory receptors.

Mitral cell a neuron located inthe olfactory bulb that receivesinformation from olfactoryreceptors; axons of mitral cellsbring information to the rest ofthe brain.

Olfactory glomerulus a bundleof dendrites of mitral cells and theassociated terminal buttons of theaxons of olfactory receptors

Transduction of Olfactory Information