Tarka, V. M. | Search bioRxiv

bioRxiv2025

Pitch selectivity in ferret auditory cortex

Our perception of pitch - the tonal quality of a sound at a fundamental frequency (F0) - is essential for musical melody, vocal communication, and attending to a voice in a crowded room. Pitch is distinct from simple frequency tuning. Although pitch perception can arise from either harmonic spectral structure or temporal regularity, it remains unclear how individual neurons represent these distinct cues. We recorded spiking activity in hundreds of ferret auditory cortical neurons while systematically varying harmonic and temporal pitch cues. A subset of neurons represented F0 based on harmonic content, another subset on temporal periodicity, and a third population exhibited invariant pitch tuning across both cue classes. These findings provide the first evidence for specialized pitch neurons in non-primates, and demonstrate that mammalian auditory cortex employs dual spectral-temporal mechanisms for extracting F0. Significance statementPitch allows us to enjoy music, understand speech, and follow voices in noisy settings, yet how the brain represents pitch remains a long-standing question. Pitch selective neurons have been identified previously only in primates, limiting our ability to investigate the neural of pitch. Here, we show that ferret auditory cortex also contains such neurons, which extract pitch from both harmonic structure and temporal periodicity. This discovery reveals that the brain uses dual, complementary strategies for encoding pitch.

neuroscience↗

bioRxiv2024

Psilocybin prevents habituation to familiar stimuli and preserves sensitivity to sound following repeated stimulation in mouse primary auditory cortex.

Psilocybin, a psychoactive substance derived from fungi, has been utilized historically by diverse cultures for both medicinal and non-medicinal purposes, owing to its ability to elicit profound sensory and cognitive alterations and sustain long-term changes in mood and cognition. Promising results from recent clinical studies have generated a wave of interest in employing psilocybin to treat neuropsychiatric and neuro-degenerative conditions. How psychedelics cause acute perceptual effects, and how these relate to long-lasting alterations is still debated. Whereas it is thought that perceptual disturbances may be caused by disrupted flow of information between sensory and higher order areas, in vivo studies have focused mostly on the latter. In particular, there has been little study of how psilocybin affects sensory representations in primary auditory cortex (A1). We used two-photon microscopy and wide field calcium imaging to examine how psilocybin affects A1 neuron response properties in the mouse. Administration of 1 mg/kg psilocybin prevented habituation of sound-evoked responses to repeated stimuli, maintaining overall responsiveness, bandwidth, and sound-level response thresholds after repeated stimulation. This was in contrast to marked habituation of responses and narrowing of tuning in controls. We observed no effect on overall distribution of best frequencies at the cortical level, suggesting psilocybin in A1 disrupts normal sensory gating, rather than tonotopic organization. This supports models of psychedelic action in which perceptual disturbances are driven by disrupted hierarchical sensory gating. With further research, influences of psychedelics on sensory representations could be harnessed to target maladaptive sensory processing in conditions such as tinnitus. Significance StatementDespite its role in altering auditory sensory perception, the impact of psilocybin on modulating neuronal activity in the auditory cortex remains understudied. This study is the first to identify an inhibition of normal auditory habituation to repeated stimuli with single-neuron resolution. We identify a role for psilocybin in the targeted, context-dependent modulation of auditory sensory neural tuning properties, which may help to explain how disruption of hierarchical control of sensory representations leads to perceptual disturbances. With further work, this influence on sensory representations could be used to target conditions where maladaptive sensory processing leads to deleterious health outcomes.

neuroscience↗