Physiology 7-Auditory-vestibular-analyser
Transcript of Physiology 7-Auditory-vestibular-analyser
Physiology of acoustic Physiology of acoustic and vestibular analyzerand vestibular analyzer
Sound conducting apparatusSound conducting apparatus1. directs the sound1. directs the sound2. increases sound intensity2. increases sound intensity3. protects the ear from 3. protects the ear from
intensive soundintensive sound
Functions of receptors in acoustic Functions of receptors in acoustic analyzeranalyzer
Detection of sound pitchDetection of sound pitch Detection of sound intensityDetection of sound intensity Detection of sound directionDetection of sound direction Coding of information into a special Coding of information into a special
pattern of action potentials pattern of action potentials
Functions of ascending pathways in Functions of ascending pathways in acoustic analyzeracoustic analyzer
Transmission of information to cerebral Transmission of information to cerebral cortexcortex
Detection of sound direction, produced by Detection of sound direction, produced by superior olivary nucleussuperior olivary nucleus
Organization of primary reflexes by Organization of primary reflexes by midbrainmidbrain
Functions of the cortex in hearingFunctions of the cortex in hearing The main function- formation of acoustic sensationsThe main function- formation of acoustic sensations Location-Heshle gyrus (superior temporal gyrus) Location-Heshle gyrus (superior temporal gyrus) Functions: 1. discrimination of sound frequencesFunctions: 1. discrimination of sound frequences Psychic sensations of sound pitchesPsychic sensations of sound pitches Detection of the direction of the sounds Detection of the direction of the sounds Detection of special modulation of sounds, such as noise Detection of special modulation of sounds, such as noise
versus pure frequency soundsversus pure frequency sounds Function of association cortex: Recognition of soundsFunction of association cortex: Recognition of sounds Associate sound information with information from other Associate sound information with information from other
sensory areas of the cortexsensory areas of the cortex recognition of words (Wernike’s area)recognition of words (Wernike’s area)
Determination of sound frequencyDetermination of sound frequency
Place principle for determination of sound frequency:Place principle for determination of sound frequency: Low frequency sounds cause maximal activation of the Low frequency sounds cause maximal activation of the
basilar membrane near the apex of the cochleabasilar membrane near the apex of the cochlea High frequency sounds cause maximal activation of the High frequency sounds cause maximal activation of the
basilar membrane near the basis of the cochlea (oval & basilar membrane near the basis of the cochlea (oval & round windows)round windows)
Intermediate distances activate the basilar membrane Intermediate distances activate the basilar membrane between these two extremesbetween these two extremes
Thus, there is spatial organization of the nerve fibers Thus, there is spatial organization of the nerve fibers from the cochlea to the cerebral cortex. Specific brain from the cochlea to the cerebral cortex. Specific brain neurons are activated by specific sound frequencies.neurons are activated by specific sound frequencies.
Determination of sound frequencyDetermination of sound frequency
Sounds up to 1000 Hz are coded by Sounds up to 1000 Hz are coded by frequency principle, i.e. by the number of frequency principle, i.e. by the number of action potentials caused in n.cochlearisaction potentials caused in n.cochlearis
700 Hz = 700 AP, 900 Hz = 900 AP700 Hz = 700 AP, 900 Hz = 900 AP This coding is restricted by 1000 Hz This coding is restricted by 1000 Hz
because of nerve labilitybecause of nerve lability
Sensory cells of cochlear
Spiral ganglion
Cochlear nuclei
Olives nuclei
Inf. col.
MGB
Temporallobe
Cochlear nuclei
Olives nuclei
Inf.col.
MGB
Temporallobe
ADEQUATE STIMULIADEQUATE STIMULI For otolit apparatusFor otolit apparatus – – gravitational gravitational
accelerationacceleration ( (disposition of the center of disposition of the center of gravitygravity))
For semicircular channels receptorsFor semicircular channels receptors – – angular accelerationangular acceleration ( (turning of the headturning of the head))
Vestibuloreceptors
Vestibular nucleiR, B, Sh. D
γ & α motoneurons
extensors
Neck muscles
cerebellum
hypothalamus
MidbrainIII,IV, VI
thalamusVPL
Somato-sensory cortex
Life important centers
Eye nystagmus
Movement disorders
Vegetative disorders
Sensor disorders