Neural Model of Auditory Cortex for Binding Sound Intensity and Frequency Information in Bat's Echolocation

Most species of bats making echolocation use the sound pressure level (SPL) and Doppler-shifted frequency of ultrasonic echo pulse to measure the size and velocity of target. The neural circuits for detecting these target features are specialized for amplitude and frequency analysis of the second harmonic constant frequency (CF2) component of Doppler-shifted echoes. The neuronal circuits involved in detecting these features have been well established. However, it is not yet clear the neural mechanism by which these neuronal circuits detect the amplitude and frequency of echo signals. We present here neural models for detecting SPL amplitude and Doppler-shifted frequency of echo sound reflecting a target. Using the model, we show that the tuning property of frequency is changed depending on the feedback connections between cortical and subcortical neurons. We also show SPL amplitude is detected by integrating input signals emanating from ipsi and contralatreal subcortical neurons.