Effect of Feedback Signals on Tuning Shifts of Subcortical Neurons in Echolocation of Bat
Most species of bats making echolocation use Doppler-shifted frequency of ultrasonic echo pulse to measure the velocity of target. The neural circuits for detecting the target velocity are specialized for fine-frequency analysis of the second harmonic constant frequency (CF2) component of Doppler-shifted echoes. To perform the fine-frequency analysis, the feedback signals from cortex to subcortical and peripheral areas are needed. The feedback signals are known to modulate the tuning property of subcortical neurons. However, it is not yet clear the neural mechanism for the modulation of the tuning property. We present here a neural model for detecting Doppler-shifted frequency of echo sound reflecting from a target. We show that the model reproduce qualitatively the experimental results on the modulation of tuning shifts of subcortical neurons. We also clarify the neural mechanism by which the tuning property is changed depending on the feedback connections between cortical and subcortical neurons.
KeywordsAuditory Cortex Inferior Colliculus Feedback Signal Electric Stimulation Neural Model
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