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 http://www.slideshare.net/drpsdeb/presentations Middle ear transmission of the signal from the tympanic membrane to the oval window and perilymph http://www.slideshare.net/drpsdeb/presentations • 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 Inner ear transmission of mechanical undulations of the perilymph to the neural (electric) signal http://www.slideshare.net/drpsdeb/presentations Tonotopic arrangement Organ of Corti  Inner hair cells  Outer hair cells Inner hair cells • sensory cells http://www.slideshare.net/drpsdeb/presentations 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 • their number increases in the direction to the apex (low frequencies) • 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 Innervation of the organ of Corti • 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 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 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 http://www.slideshare.net/CsillaEgri/presentations • Ampullae • Semicircular canals – upper – horizontal – posterior http://www.slideshare.net/CsillaEgri/presentations Information about angular acceleration Mechanism • Flexion towards stereocilia – opening of mechanically activated K+ channels –depolarization • Flexion away from stereocilia – closing of the channels - hyperpolarization http://www.slideshare.net/CsillaEgri/presentations • 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