Figure 1: Echo delay sensitive areas in bat auditory cortex.
From: Auditory cortex of newborn bats is prewired for echolocation
(a) Cortex organization in adult P. parnellii (adapted from refs 4,38,39, based on physiological and anatomical data) and in adult C. perspicillata (adapted from refs 10,37, based on physiological data). Auditory cortex in PP (left) with three delay-sensitive areas FM–FM, DF (dorsal fringe), VF (ventral fringe). Arrows give direction of decreasing characteristic echo delay. DM (dorsomedial area), AIp (posterior AI), AIa (anterior AI), DSCF (Doppler shift constant frequency area), VA (ventroanterior area), DP (dorsoposterior area). Inset: representative spectrogram of echolocation calls with constant-frequency (CF) and frequency-modulated (FM) components. In adult CP (right) delay-sensitive neurons are located in the high-frequency (HF) area and in the border region between the anterior auditory field (AAF), primary auditory cortex (AI) and AII (secondary auditory cortex). (b) Example of neuronal responses to FM call–echo pairs in a 7-day-old CP. Upper row: scheme of presented stimuli with increasing delay between a FM2 call and FM2 echo component. Middle, lower row: post stimulus time histograms of spike activity of a single neuron during presentation of a FM2 call component (level: 90 dB SPL) followed by a FM2 echo component. The neuron is tuned to echo delays of 6–8 ms. SPL: sound pressure level, expressed in dB re 20 μPascal.
