A neural model of medial geniculate body and auditory cortex detecting target distance independently of target velocity in echolocation

摘要

Using frequency-modulated (FM) ultrasonic pulses, echolocating bats detect with a high accuracy the arrival time differences between emitted pulses and their echos generated by targets, even though the targets are moving. We propose a neural mechanism by which the bat may detect the time differences independently of the target velocity using FM ultrasonic pulses. The neural processing model presented consists of the networks in MGB for calculating the temporal correlation between pulse and echo for each frequency and the network of AC for integrating the calculated results over the frequency range used by bat. We found that the key factor generating the detection independent of target velocity is the value of frequency modulation rate of about 6 kHz.