Sense of Hearing Sense of Balance Auditory system Auditory system • capturing and transmission of mechanical energy to  the receptor organ, transduction into electrical signal (ear) • processing of the transmitted information – interpretation of the sound – interpretation of its importance for the organism • transmission to CNS • processing of the transmitted information – interpretation of the sound – interpretation of its importance for the organism Auditory system • capturing and transmission of mechanical energy to  the receptor organ, transduction into electrical signal (ear) • transmission to CNS Sound • rises by vibration of a solid  object in the air or water http://www.slideshare.net/drpsdeb/presentations • charakteristics: – frequency – pitch of the tone – amplitude – intensity – timbre – given by  representation of harmonic frequencies of the oscillation Sound • simple (clear) • composite – harmonic • periodic – non‐harmonic (noise) • non‐periodic http://www.earmaster.com/music‐theory‐ online/ch03/chapter‐3‐2.html http://physics.bowlerderby.com/soundwaves.html Audible spectrum Intensity of the sound • given by the amplitude of signal  whisper – 20 dB  common speech ‐ 65 dB  jet engine – 100 dB  pain threshold – 120 dB https://www.boundless.com/physics/textbooks/boundless‐physics‐ textbook/sound‐16/sound‐intensity‐and‐level‐129/intensity‐458‐6077/ • volume (loudness) ‐ subjectively perceived intensity of the sound External ear transmission of the acoustic signal from the external environment to the tympanic membrane Middle ear transmission of the signal from the tympanic membrane to the oval  window and perilymph • Reinforcement of the signal – area of the tympanic membrane/ area  of the oval window – leverage mechanism of the middle ear ossicles http://slideplayer.com/slide/3433153/ Middle ear • Protective function – m. stapedius, m. tensor  tympani – Eustachian tube Middle ear Inner ear transmission of mechanical undulations of the perilymph to the neural (electric) signal http://www.slideshare.net/drpsdeb/presentations Inner ear transmission of mechanical undulations of the perilymph to the neural (electric) signal Endocochlear potential endolymph ‐ perilymph = 80mV Tonotopic arrangement  Outer hair cells • modulation of the signal  amplification of the signal of required frequencies http://www.neurophys.wisc.edu/auditory/johc.htmlhttp://www.slideshare.net/drpsdeb/presentations depolarization  shortening • their number increases in the direction to the apex  (low frequencies) Outer hair cells • modulation of the signal  amplification of the signal of required frequencies http://www.neurophys.wisc.edu/auditory/johc.htmlhttp://www.slideshare.net/drpsdeb/presentations depolarization  shortening Otoacoustic emissions ‐ spontaneous Otoacoustic emissions ‐ evoked Innervation of the Corti organ • Nucleus spiralis cochleae • Nucleus cochlearis ventralis – information about the intensity – time delay ‐ the sound direction • Nucleus cochlearis dorsalis  – information about the frequency http://www.slideshare.net/drpsdeb/presentations • Olivary nuclei – analysis of the direction – modulation (increase) of sensitivity of the outer hair cells Sound localization 1. below 3 kHz: based on analysis of the time delay 2. above 3 kHz: based non the analysis of loudness Nucleus olivaris superior medialis localization of the sound based on analysis of the time delay below 1‐3 kHz – time delay from 1‐2 kHz – intensity MNTB – medial nucleus of the trapezoid body Nucleus olivaris superior lateralis localization of the sound based on analysis of the intensity • Nucleus spiralis cochleae • Nucleus cochlearis ventralis – information about the intensity – time delay ‐ the sound direction • Nucleus cochlearis dorsalis  – information about the frequency http://www.slideshare.net/drpsdeb/presentations • Olivary nuclei – analysis of the direction – modulation (increase) of sensitivity of the outer hair cells • Colliculi inferiores – integration of information from the lower structures – centre of the acoustic reflexes Colliculi inferiores in various animal species bat dolphine ibex primate Gerald Schneider. 9.14 Brain Structure and Its Origins, Spring 2014. (Massachusetts Institute of Technology: MIT  OpenCourseWare), http://ocw.mit.edu (Accessed). License:Creative Commons BY‐NC‐SA • Nucleus spiralis cochleae • Nucleus cochlearis ventralis – information about the intensity – time delay ‐ the sound direction • Nucleus cochlearis dorsalis  – information about the frequency http://www.slideshare.net/drpsdeb/presentations • Olivary nuclei – analysis of the direction – modulation (increase) of sensitivity of the outer hair cells • Nucleus corporis geniculati medialis (thalamus) • Auditory cortex • Colliculi inferiores – integration of information from the lower structures – centre of the acoustic reflexes Auditory cortex http://www.slideshare.net/drpsdeb/presentations Auditory cortex Vestibular system Vestibular system • anatomic localization, hair cells http://www.slideshare.net/CsillaEgri/presentations • information about the position • information about the acceleration – Linear – Angular Vestibular system • anatomic localization, hair cells http://www.slideshare.net/CsillaEgri/presentations • information about the position • information about the acceleration – Linear – Angular Information about position and linear acceleration • Macula – Crystals of CaCO3 • Utriculus – Macula horizontally • Sacculus – Macula vertically Information about position and linear acceleration Mechanism • Flexion towards stereocilia – opening of mechanically activated K+ channels – depolarization • Flexion away from stereocilia – closing of the channels ‐ hyperpolarization • Ampullae • Semicircular canals – upper – horizontal – posterior http://www.slideshare.net/CsillaEgri/presentations Information about angular acceleration • projections: http://www.slideshare.net/CsillaEgri/presentations Vestibular nuclei • integration of vestibular, visual and somatosensoric information – cerebellum  – oculomotoric nuclei – nucleus of n. accessorius (neck muscles) – thalamus ‐ cortex