Single unit correlates of auditory oddball responses in the sensory, prefrontal, and amygdala regions of the macaque

Authors

• KC Scarim
• CR Camalier
• M Mishkin
• BB Averbeck

Abstract

Change detection is key to survival; a suspected neural correlate to change detection, mismatch negativity (MMN), is commonly investigated due to its possible utility as an effective biomarker for schizophrenia. To probe the neural underpinnings of MMN, we utilized a variant of the auditory oddball paradigm in which a series of “standard” tone-pips are interwoven with infrequent “deviant” tones, which differ in frequency by a predetermined amount. Due to this link with psychosis, it is critical to establish neural underpinnings of the MMN- especially in a nonhuman primate model which shares key anatomical homologies with humans. In this study, two macaques (Macaca mulatta) were presented with an auditory frequency oddball paradigm while neurons were recorded in the auditory cortex (A1, n=690 neurons), dorsolateral prefrontal cortex (dlPFC, n=597) and amygdala (n=626). Consistent with previous animal studies, a substantial fraction of sensory neurons showed a stronger response to the deviant than standard (A1 33%). The number of units that showed deviance sensitivity in prefrontal cortex and amygdala was much lower (dlPFC 5%, Amy 6%). At a population level, A1 showed stronger responses to the deviant than the standard, while the amygdala displayed no difference, and dlPFC showed only a very slight increase in response to the deviant. The A1 results further confirm the hypothesized sensory generator of the MMN. However, these results do not lend support to the involvement of other areas that have been implicated in novelty (e.g. amygdala) or memory (e.g. dlPFC) to the generation of the MMN.

Scientific Focus Area: Neuroscience

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