THE AUDITORY SYSTEM AND THE CHEMICAL SENSES

D. C. MIKULECKYPROFESSOR OF PHYSIOLOGY

ANDFACULTY MENTORING PROGRAM

THE NATURE OF SOUND

COMPRESSION AND RARIFICATION OF AIR

WAVES OF HIGH AND LOW PRESSURE

TRANSMIT MECHANICAL FORCES

CHARACTERISTICS OF A PRESSURE WAVE

A

T = WAVELENGTH

A = AMPLITUDE

f = 1/T FREQUENCY

ANATOMY OF THE EAR

OUTER EAR

MIDDLE EAR

INNER EAR

OUTER EAR

ACTS TO FOCUS SOUND WAVES ON THE TYMPANIC MEMBRANE

SHAPED LIKE A SOUND CONE

OUTER EAR

PINNA

CANAL

MIDDLE EAR

THREE BONES LINK TYMPANIC MEMBRANE TO OVAL WINDOW

VIBRATIONS TRANSMITTED MECHANICALLY

MIDDLE EAR

TYMPANICMEMBRANE

OVALWINDOW

BONES OFMIDDLE EAR COCHLEAR

FLUIDSOUNDWAVE IN EAR CANAL

INNER EAR

SITE OF TRANSDUCTIONVIBRATION OF COCHLEAR FLUID

CAUSES BASILAR MEMBRANE TO VIBRATE

HAIR CELLS ARE DEFORMEDAUDITORY NERVE BECOMES EXCITED

AS HAIR CELLS DEPOLARIZE

INNER EAR

OVALWINDOW

COCHLEA

STRUCTURE OF THE COCHLEA

SCALA VESTIBULI

COCHLEAR DUCT

SCALATYPANI

OVALWINDOW

ROUND WINDOW

STRUCTURE OF COCHLEAR DUCT

BASILAR MEMBRANE

TECTORIAL MEMBRANEORGAN OF CORTI

TRANSDUCTION MECHANISM

BASILAR MEMBRANE…..VIBRATES

TECTORIAL MEMBRANE STATIONARY

STEROCILIA

AUDITORY NERVE

HAIRCELLS

TRANSDUCTION MECHANISM

TECTORIAL MEMBRANE STATIONARY

BASILAR MEMBRANE…..VIBRATES

STEROCILIABEND

AUDITORY NERVE HAIR

CELLS

FREQUENCY DISCRIMINATION: LOCALIZATION OF DISPLACEMENT OF BASILAR MEMBRANE

BASE APEX

HIGH

LOW

MID

AUDITORY PATHWAYS

COCHLEA

VENTRALCOCHLEARNUCLEUS MIDLINE

VENTRALCOCHLEARNUCLEUS

SUPERIOROLIVE

INFERIOR

COLLICULUS

AUDITORY PATHWAYS (CONT.)

MIDLINE

SUPERIOROLIVE

INFERIOR COLLICULUS

INFERIOR COLLICULUS

MEDIAL GENICULATE

MEDIAL GENICULATE

TEMPORALCORTEX

TEMPORALCORTEX

CHARACTERISTICS OF A PRESSURE WAVE

A

T = WAVELENGTH

A = AMPLITUDE

f = 1/T FREQUENCY

PROPERTIES OF AUDITORY NERVE CELLS

EACH AUDITORY NERVE FIBER HAS AN OPTIMUM FREQUENCY

THIS TONOTOPIC ORGANIZATION ARISES FROM POSITION IN THE COCHLEA

TONIC AND PHASIC NEURONS IN EACH AREASOME RESPOND TO CHANGE IN FREQUENCYSOME RESPOND TO CHANGE IN AMPLITUDE

SOUND LOCALIZATION

INTERAURAL TIME DIFFERENCE

TIME DELAY BETWEEN TWO EARS

ALSO INTENSITY DIFFERENCES

DISORDERS OF AUDITION

LOSS OF HAIR CELLS: FREQUENCY SPECIFIC

TINNITUS: RINGINGCONDUCTIVE:l DAMAGE TO MIDDLE

EARCENTRAL: BRAIN TUMORS AND

LESIONS

TASTE SENSATION

GUSTATORY RECEPTORS

GUSTATORY PATHWAYS

GUSTATORY RECEPTORS

TASTE BUDS ON TONGUE LOCALIZEDSWEET: TIPBITTER:BACKSOUR SIDESSALT: FRONT

GUSTATORY PATHWAYS

VII, IX, X CRANIAL NERVESTO GUSTATORY NUCLEUS IN BRAIN

STEMVPM NUCLEUS OF THALAMUSGUSTATORY AREA OF NEOCORTEXVIA LIMBIC SYSTEM TO

HYPOTHALAMUS

THE OLIFACTORY SYSTEM

RECEPTOR CELLS IN OLIFACTORY MUCOSAL MEMBRANE

AXONS CROSS CRIBIFORM PLATE AND TERMINATE ON MITRAL CELLS IN OLIFACTORY BULB-FORM OLIFACTORY TRACT

OLIFACTORY TRACT GOES TO LIMBIC SYSTEM AND TO ORBITOFRONTAL CORTEX

CLOSELY ASSOCIATED WITH EATING AND MATING BEHAVIOR