Mechanical relay for audition ○ tympanic membrane, ■ ear drum○ ossicles, ■ 3 bones: malleus, incus, stabes (vibrate)○ oval window○ fluid in cochlea■ medium that mechanical energy goes throughTransduction for audition ● Organ of Corti, ○ autitory signal transduced to neural signals● basilar membrane○ within cochlea, seperates 2 fluid filled tubes that run alongside the cochlea● tectorial membrane,○ one of two acellular gels located in the basilar membrane within the cochlea● hair cells/stereocilia, CN VIII, cochlear nucleus, SOC and sound localization mechanisms, IC, MGN, AI—Heschl’s Gyrus, belt and parabelt (still need to explain)…ventral and dorsal pathways)○ CN VIII: The vestibulocochlear nerve has a cochlear part (COCHLEAR NERVE) which is concerned with hearing and a vestibular part (VESTIBULAR NERVE) which mediatesthe sense of balance and head position. ● Cochlear Transduction■ Converts mechanical energy into neural energy■ hair cells open ion channels when deflected against the tectorial membrane ■ this causes cations (k+ ions) to rush in and create axons that form the cranial nerve (what??)○ Types of Auditory transduction:■ Basilar Membrane: long membrane that is part of the auditory system. the membrane runs the length of the cochlea (inside the ear) and contains those tiny hairs that act as sound receptors. (takes in the sound and bends hairs according to pitch)■ Tectorial Membrane: membrane of the inner ear that covers the organ of corti. Moves in response to pressure variations in fluid-filled tempanic and vestibular canals.■ Organ of Corti characteristics: sensitive element of the inner ear that can be thought of as the body’s microphone. it is located under the tectorial membrane.- Theory of Audition: Maintains that the location of the hair cells, of the particular stereocilia, stimulated along the basilar membrane determines the pitch that will be experienced.- AKA: Place Coding: perception of sound depends on where each component frequency produces vibrations along the basilar membrane● “Basal” cells respond preferentially to high-frequency stimuli, whereas “apical” cells to low-frequency stimuli.· Localization: how well we can tell where a sound is coming from.- Azimuth (horizontal, or L-R) judgement is much better than is vertical (up-down) judgement ( Azimuth sounds is signaled by the difference in arrival times between the ears, by the relative amplitude of high frequency sounds.)■ Mechanisms:- Difference in arrival times- Differences in intensity: if the sound is closer it will be more intense on the sideof the ear it is on- Differences in phase (of the oscillating sound waves)Know EEG waveforms and stages of sleep● EEG= Electroencephalograph● Gives you accurate info about the electrical activity of the outer cortex● Records the brains fluctuations in voltage activity over a short period of time● During intense concentrations/focus/arousal● Waves are out-of-sync and have short amplitude very frequently● During daydreaming/relaxing waves become more synchronized, increased amplitude, but decreased frequency● Alpha Waves - predominate when the person is awake but relaxed and not thinking too hard about anything, Simply closing your eyes and taking a deep breath will elicit increased alpha activity.● Beta Waves - reflect the most desynchronized state of cortical activity. ● Stage 1 Sleep (S1)=transitional state, not truly asleep○ Brainwaves increase slightly in amp and wavelength, decrease in frequency■ Theta waves = indicate the firing of group neurons in neocortex are becoming increasingly synchronized ■ Eyes sway up and down, 10 min cycle● Stage 2 Sleep (S2)= true sleep■ about 15 min■ Myoclonus -Brief jerking motions of limbs or body, leads to flaccid paralysis■ Flaccid paralysis-deeply relaxed muscles■ Sleep spindles= Spontaneously occur at a rate of about five times per minute during Stages 2 through 4 of sleep● Show as short bursts of waves ● Resemble alpha/beta activityo K complex= occur ONLY during stage 2 and Spontaneously, at a rate of about 1/min● Can be triggered by unexpected noises● May represent a mechanism to prevent ambient noises from awakening the sleeper ● Stage 3 Sleep (S3)= deep sleep is a priority for the braino Pitfall of most sleeping aidso If awakened before stage 3, subject may report not having been asleep at all (snoring can occurwithout their attention)o Delta Waves -very high amplitude, low frequency waveforms develop● 20-50% of EEG reports delta waves at S3Stage 4 sleep (S4)o slow-wave sleep (non-rapid eye mvmt sleep)= occurs in stages 3 and 4, due to the prevalence of delta activity.● up and down states during SWS● important in consolidating memories● The first part of the cycle comprises the down state—a time during which neocortical neurons in that region are completely silent.● The up state involves a period of excitation during which these same neocortical neurons fire at a rapid rate.● Important stage of sleep, NE receptors reset and re-sensitize to Norepinephrine and produce stronger action potentialo REM-paradoxical sleep= Rapid eye movement sleep● 45 min of S4● EEG waves forms look like the person is awake b/c activity of the brain’s neurons during this time is similar to when they are awake (desynchronized)● Cataplexy-profound loss of muscle tone, subject is functionally paralyzed.● SLEEPWALKING DOES NOT OCCUR IN REM SLEEP!● Subject easily aroused (calling name works), wakes alert and attentive● Occurs during the morning when subject wakes up (that’s why you remember dreams)● stage 4 only occurs during first 45 min, as time goes on, you spend more time in REM sleep● LOW Cerebral blood flow in PFC (prefrontal cortex) during REM● Visual Cortex: HIGH Cerebral Blood Flow in visual association cortex, but LOWin V1. ●Other sleep stuff: disorders ● somnambulance = sleepwalking and performing daily activities like cleaning, not during REM sleep, person is not dreaming● REM behavior disorder= failure to activate the cataplexy response, not activated properly. they have powerful night dreams and get up and act on them● insomnia= trouble falling asleep, not sleeping enough○ NOT FEELING REFRESHED○ #1 sleep disorder affecting 25% occasionally● narcolepsy= person is awake, they experience instant onset of cataplexy and fall asleep immediately. they