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1 - Intro and Sound, brain , sw , s , l , ll - Coggle Diagram
1 - Intro and Sound
The senses (modalities)
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Traditionally - Aristotle said 5 senses linked to organs (ears, eyes, nose , skin, tongue) (xxx)= number of neurons
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Cognitive neuroscience
single unit recordings
definition = microelectrode inserted in animals and records activity of single sensory cells in response to a stimulus
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Lesions
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Ferrier - removed angular gyrus and the monkeys became blind (later proved that visual guided action was disrupted)
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auditory localisation
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The precedence effect = apparent sound source direction determined by the earliest sound to arrive at the ear
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each time distance doubles, sound intensity decreases by a factor of 4
complex sounds
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Fourier theory
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can be used to show how a transmitting device filters acoustic signals (changing amplitude of certain components)
Filters
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Linearity
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2 - if amplitude is changed, the output must also be changed the same amount
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Auditory processing
what and where pathways
where = localisation of sound, Important function
what = attributes, duration, loudness, frequency
ITDs
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Interaural time differences = sound directly to the side of a person will reach one ear 700 microseconds before the other
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Inner ear (Cochlea)
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point of max displacement = low frequencies and high base (key to cochlea's ability to encode sound frequency)
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organ of corti = cross section of the cochlea where the vibration of the tectorial membrane moves inner hair cells to stimulate cohlea nerve fiber
Inner hair cells
= mechanoreceptors on the basilar membrane that provide signals to the auditory system when the membrane is displaced
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outer and middle ear
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3 interconnected bones - Malleus, incus, stapes
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function of middle ear = match up low acoustic impendence of ear drum with high acoustic impedance of oval window (impendence matching)
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How we hear
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8 - brain decodes it as neruons are synced to the stimulus sine wave and relayed via subcortical structures to primary auditory cortex
Outer hair cells = bridge the gap between basilar membrane and tectorial membrane increasing sensitivity. Lots more than inner but less important
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senses and the brain
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Heirachial processing
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In between transduction and arriving at brain cortex, signals from each sense neuron pass through a series of synapses at different levels of neural processing
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Function - structure
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Cortical homunculi = distorted representation of the human body based on amount of brain dedicated to processing sensory functions for each part of the body
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