Sensitivity of rat inferior colliculus neurons to frequency distributions.
Stimulus-specific adaptation refers to a neural response reduction to a repeated stimulus that does not generalize to other stimuli. However, stimulus-specific adaptation appears to be influenced by additional factors. For example, the statistical distribution of tone frequencies has recently been shown to dynamically alter stimulus-specific adaptation in human auditory cortex. The present study investigated whether statistical stimulus distributions also affect stimulus-specific adaptation at an earlier stage of the auditory hierarchy. Neural spiking activity and local field potentials were recorded from inferior colliculus neurons of rats while tones were presented in oddball sequences that formed two different statistical contexts. Each sequence consisted of a repeatedly presented tone (standard) and three rare deviants of different magnitudes (small, moderate, large spectral change). The critical manipulation was the relative probability with which large spectral changes occurred. In one context the probability was high (relative to all deviants), while it was low in the other context. We observed larger responses for deviants compared with standards, confirming previous reports of increased response adaptation for frequently presented tones. Importantly, the statistical context in which tones were presented strongly modulated stimulus-specific adaptation. Physically and probabilistically identical stimuli (moderate deviants) in the two statistical contexts elicited different response magnitudes consistent with neural gain changes and thus neural sensitivity adjustments induced by the spectral range of a stimulus distribution. The data show that already at the level of the inferior colliculus stimulus-specific adaptation is dynamically altered by the statistical context in which stimuli occur.
Max Planck Research Group "Auditory Cognition," Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; herrmann.b@gmail.com.
Björn
B
Herrmann
Departments of Biological Sciences and Biomedical Engineering, Purdue University, West Lafayette, Indiana; and.
Aravindakshan
A
Parthasarathy
Departments of Biological Sciences and Biomedical Engineering, Purdue University, West Lafayette, Indiana; and.
Emily X
EX
Han
Max Planck Research Group "Auditory Cognition," Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; Department of Psychology, University of Lübeck, Lübeck, Germany.
Jonas
http://orcid.org/0000-0002-7619-0459
J
Obleser
Departments of Biological Sciences and Biomedical Engineering, Purdue University, West Lafayette, Indiana; and.
Edward L
EL
Bartlett
D000161:Acoustic Stimulation; D000222:Adaptation, Physiological; D000818:Animals; D001307:Auditory Perception / Q000502:physiology*; D007245:Inferior Colliculi / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials; D009474:Neurons / Q000502:physiology*; D051381:Rats; D011916:Rats, Inbred F344
inferior colliculus; statistical context; stimulus-specific adaptation