Neuronal On- and Off-type heterogeneities improve population coding of envelope signals in the presence of stimulus-induced noise

摘要

Experimental setup and behavioral responses to electrosensory stimulation. ) Recordings were made during stimulation with spatially uniform (‘global’) stimuli mimicking those encountered during interactions with a conspecific. Inset: Stimuli consisted of modulations of the self-generated EOD (not shown). Specifically, stimuli were constructed as non-repetitive low-pass filtered (15 Hz cutoff) Gaussian white noise (i.e., the “noise”; gray) whose amplitude, varied sinusoidally with frequency 1 Hz, (i.e., the “signal”; orange). The gray shading shows each cycle of the signal. ( ) Electrosensory stimuli are sensed by electroreceptor afferents (EAs, left) on the skin that project to pyramidal neurons in the hindbrain electrosensory lateral line lobe (ELL, center) that are either of the On- or Off-type variety: On-type neurons (green) receive direct excitatory EA input while Off-type neurons (magenta) receive EA input indirectly via inhibitory granular interneurons (GR). Both project to higher order brain areas such as the midbrain torus semicircularis. ( ) The signal (orange) elicited behavioral responses (black) that consisted of the animal tracking the stimulus waveform through changes in EOD frequency. ( ) Quantification of behavioral responses to envelopes using linear systems identification techniques from N = 7 fish used in the study. Shown are the gain (D; 0.040 ± 0.017 Hz · mV · cm ) and phase (E; −31 ± 23°).