neuro - Labs on the brain 1. Manually writing down the...

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Labs on the brain 1. Manually writing down the behavioral deficits and waited till they died to see which parts of the brain were damaged 2. Scientists able to find which area of the brain is causing deficits by sticking an electrode into the brains of animals and recording after different stimulus 3. CAT scan (x-ray machine to look at different angles and planes) & MRI (look at structures and areas injured) 4. Use MRI to see which areas of the brain get the most blood flow during specific tasks (fMRI) hemoglobin responds differently when it has oxygen fMRI Turn on magnet H+ go from random to aligned Turn off magnet H+ relax and send radio waves Measure the difference in signals emitted by hemoglobin before and after it drops off the O2 Hearing Sound is produced when something vibrates Speaker compresses air and produces pressure waves that cause ear drum to vibrate Only hear sound when it reaches your cortex Large changes in air compression = large vibration (small=small) High frequency sound = rapid vibration Normal range 20 to 20,000Hz 2000 to 4000Hz most sensitive (spoken words)
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How motion transduced : Hair cells are on basilar membrane and filaments between hairs allow K+ to depolarize hair cell to release neurotransmitter High frequency sounds =oval window Low = other end Loud sounds = larger amplitude more activation in hair cells (small=small) Sound frequency represented on basilar membrane and coded by which neuron is activated Each hair cell encodes the loudness of particular frequency Sound Direction: cue in intensity difference (high frequency sounds cast a shadow) & timing difference between ears (works best for low frequency) Superior olive signal from both ears meet and are compared, cells in lateral superior olive look for sound intensities, medial superior olive look for timing differences Auditory info sent to inferior collicus orient movements of eyes and head toward sounds & via medial geniculate nucleus of thalamus to cortex for conscious perception Primary auditory cortex =all sounds A2 = word like sounds phonemes Wernicke’s area = word comprehension, verbal understanding (if this part has a lesion patient cant understand language but can speak) Broca’s area = language production (lesion then patient cant say right words but can understand language) Three parts of the ear Sound passes down ear canal and strikes ear drum Vibration conveyed in middle ear bone called ossicles (transmit vibrations from large to smaller ear drum called oval window/ round window allows basilar membrane to be compressed, acts as a pressure release outlet) Vibrations reach fluid filled inner ear inside cochlea Functions of the middle ear Impedance matching : fluid in cochlea harder to vibrate, if no middle then waves would bounce off, ear drum picks up weak vibrations over a larger area, ossicles acts like a lever system and concentrates them over a smaller area
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This note was uploaded on 03/30/2012 for the course BISC 230LXG taught by Professor Mcclure,greene during the Spring '08 term at USC.

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neuro - Labs on the brain 1. Manually writing down the...

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