Figure 4. Feedback input enhances and optimizes information transmission via whitening.
Results are shown before and after complete feedback inactivation was achieved via injection of lidocaine into nP. (A) Top: sinusoidal envelope waveform (red). Middle: time dependent firing rate from a typical ELL pyramidal cell before (black) and after (purple) lidocaine application. Bottom: spiking activity from this same neuron in response to stimulation before (black) and after (purple) lidocaine application. (B) Population-averaged tuning curve quantified by the neural gain as a function of envelope frequency before (black) and after (purple) lidocaine application. The dashed lines show the best power law fits to the data. Inset: Population-averaged best-fit power law exponents before (black) and after (purple) lidocaine injection were significantly different from one another (p=0.0156, Wilcoxon Signed-Rank Test). (C) Population-averaged neural response power as a function of envelope frequency before (black) and after (purple) lidocaine application. The dashed lines show the best power law fits to the data. (D) Top: sinusoidal envelope waveform (red). Bottom: time dependent EOD frequency from a typical fish before (black) and after (purple) lidocaine application. (E) Population-averaged behavioral gain as a function of envelope frequency before (black) and after (purple) lidocaine application. The dashed lines show the best power law fits to the data. Inset: Population-averaged best-fit power law exponents before (black) and after (purple) lidocaine injection were significantly different from one another (p=0.0313, Wilcoxon Signed-Rank Test). (F) Left: population-averaged white index values before (black) and after (purple) lidocaine application were significantly different from one another (p=0.0234, Wilcoxon Signed-Rank Test). Right: population-averaged relative changes in neural (left) and behavioral (right) gain following lidocaine application were both significantly different from zero (neuron: p=4.77*10−4, Wilcoxon Signed-Rank Test, behavior: p=0.002, Wilcoxon Signed-Rank Test). ‘*' indicates statistical significance at the p=0.05 level.
Figure 4—figure supplement 1. Complete feedback inactivation does not affect ELL pyramidal cell responses to AMs.
Figure 4—figure supplement 2. Sham complete feedback inactivation achieved by injecting saline bilaterally into nP has no effect on behavior and ELL pyramidal cell tuning properties, as well as optimized coding of natural stimuli.
Figure 4—figure supplement 3. Contralateral feedback inactivation achieved by injecting lidocaine into the contralateral nP gives rise to effects qualitatively similar to those observed when injecting lidocaine bilaterally when recording from pyramidal cells within the ipsilateral ELL.
