Mechanical relay for audition tympanic membrane ear drum ossicles oval window fluid in cochlea 3 bones malleus incus stabes vibrate medium that mechanical energy goes through Transduction for audition Organ of Corti basilar membrane tectorial membrane autitory signal transduced to neural signals within cochlea seperates 2 fluid filled tubes that run alongside the cochlea 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 mediates the 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 of the ear it is on Difference in arrival times Differences in intensity if the sound is closer it will be more intense on the side 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 activity o 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 brain o Pitfall of most sleeping aids o If awakened before stage 3 subject may report not having been asleep at all snoring can occur without their attention Stage 4 sleep S4 o Delta Waves very high amplitude low frequency waveforms develop 20 50 of EEG reports delta waves at S3 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 potential o 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 LOW in V1 somnambulance sleepwalking and performing daily activities like cleaning not during REM Other sleep stuff disorders 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 have sleep attacks 2 5 min experience sleep paralysis awaken feeling refreshed pharmacotherapies for insomnia and potential drawbacks with some benzodiapines Halcion for insomnia Ambien for insomnia GABA activity drawbacks patient spends more time in light or REM sleep so many of the restorative functions such as memory consolidation GH release are lost also occurs with ethanols not much slow wave sleep Melatonin