Sensitivity of rat inferior colliculus neurons to frequency distributions

Abstract

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.

Aging Affects Adaptation to Sound-Level Statistics in Human Auditory Cortex

“…Little is known about the extent to which adaptation to stimulus statistics may be affected by aging. Sensitivity to sound-frequency statistics appears to be unaffected in older people (Herrmann et al, 2013a). However, auditory cortex neurons of older adults seem to recover faster from neural adaptation compared with younger people (consistent with observations in older animals; de Villers-Sidani et al, 2010;Herrmann et al, 2016a).…”

“…However, neurons supporting perceptual inferences are inherently limited in the range with which they respond to sensory inputs (Laughlin, 1981). One way to overcome this limitation is to adjust dynamically a neuron's response range (input-output function) to statistical distributions of acoustic features in the environment in a process called adaptation to stimulus statistics, dynamic range adaptation, or gain control (Salinas and Thier, 2000;Nagel and Doupe, 2006;Wark et al, 2007;Robinson and McAlpine, 2009;Wen et al, 2009Wen et al, , 2012Dahmen et al, 2010;Hildebrandt et al, 2011;Rabinowitz et al, 2011;Herrmann et al, 2014). Neural adaptation to stimulus statistics has been studied almost exclusively in nonhuman mammals and whether the results generalize to humans, particularly to older humans, is unknown.…”

“…In humans, neural responses (measured using EEG or MEG) adapt to different sound-frequency distributions (Garrido et al, 2013;Herrmann et al, 2013aHerrmann et al, , 2014). Adaptation to sound-level (as opposed to sound-frequency) statistics has not been investigated despite this being crucial for avoiding neural response saturation in loud sound environments.…”

Ageing affects dual encoding of periodicity and envelope shape in rat inferior colliculus neurons

“…The ABR responses showed clear age‐related changes in hearing thresholds (all values dB SPL and standard deviation: nine older animals: click 53.3 ± 6.6, 8 kHz tone 36.7 ± 2.5; nine younger animals: click 36.4 ± 3.8, 8 kHz tone 30.0 ± 7.5), with a larger threshold discrepancy for clicks vs. 8 kHz tones as reported previously (Parthasarathy & Bartlett, ). Methods for surgery, sound stimulation and recording are similar to those described in (Rabang et al ., ; Herrmann et al ., ). Surgeries and recordings were performed in a 9′ × 9′ double walled acoustic chamber (Industrial Acoustics Corporation).…”

Hierarchical winner-take-all particle swarm optimization social network for neural model fitting

“…Responses were recorded from Fischer-344 rats, similar to Rabang et al 30 and Herrmann et al 13 Briefly, all surgical procedures used were approved by the Purdue University animal care and use committee (PACUC 06-106). Auditory brainstem responses were recorded from these animals a few days preceding surgery to ensure all animals had hearing thresholds typical for their age and to ensure there were no abnormal auditory pathologies.…”