NATURALISTIC STIMULI INCREASE THE RATE AND EFFICIENCY OF INFORMATION-TRANSMISSION BY PRIMARY AUDITORY AFFERENTS

Natural sounds, especially communication sounds, have highly structure d amplitude and phase spectra. We have quantified how structure in the amplitude spectrum of natural sounds affects coding in primary audito ry afferents. Auditory afferents encode stimuli with naturalistic ampl itude spectra dramatically better than broad-band stimuli (approximati ng white noise); the rate at which the spike train carries information about the stimulus is 2-6 times higher for naturalistic sounds. Furth ermore, the information rates can reach 90 % of the fundamental limit to information transmission set by the statistics of the spike respons e. These results indicate that the coding strategy of the auditory ner ve is matched to the structure of natural sounds; this 'tuning' allows afferent spike trains to provide higher processing centres with a mor e complete description of the sensory world.