Auditory cortex Animal echolocation
sketch of regions of auditory cortex in bat s brain
fm-fm area: region of cortex contains fm-fm combination-sensitive neurons. these cells respond combination of 2 fm sweeps: call , echo. neurons in fm-fm region referred delay-tuned, since each responds specific time delay between original call , echo, in order find distance target object (the range). each neuron shows specificity 1 harmonic in original call , different harmonic in echo. neurons within fm-fm area of cortex of pteronotus organized columns, in delay time constant vertically increases across horizontal plane. result range encoded location on cortex, , increases systematically across fm-fm area.
cf-cf area: kind of combination-sensitive neuron cf-cf neuron. these respond best combination of cf call containing 2 given frequencies – call @ 30 khz (cf1) , 1 of additional harmonics around 60 or 90 khz (cf2 or cf3) – , corresponding echoes. thus, within cf-cf region, changes in echo frequency caused doppler shift can compared frequency of original call calculate bat s velocity relative target object. in fm-fm area, information encoded location within map-like organization of region. cf-cf area first split distinct cf1-cf2 , cf1-cf3 areas. within each area, cf1 frequency organized on axis, perpendicular cf2 or cf3 frequency axis. in resulting grid, each neuron codes combination of frequencies indicative of specific velocity
dscf area: large section of cortex map of acoustic fovea, organized frequency , amplitude. neurons in region respond cf signals have been doppler shifted (in other words, echoes only) , within same narrow frequency range acoustic fovea responds. pteronotus, around 61 khz. area organized columns, arranged radially based on frequency. within column, each neuron responds specific combination of frequency , amplitude. suga s studies have indicated brain region necessary frequency discrimination.
^ kanwal, jagmeet s.; rauschecker, josef p. (2007-05-01). auditory cortex of bats , primates: managing species-specific calls social communication . frontiers in bioscience. 12: 4621–4640. doi:10.2741/2413. pmc 4276140 . pmid 17485400.
^ cite error: named reference neuweiler 2003 invoked never defined (see page).
^ cite error: named reference carew 2001 invoked never defined (see page).
^ suga et al. 1975
^ suga et al. 1979
^ suga et al. 1987
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