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Gaucher, Q.

Publications and source records attributed to Gaucher, Q..

3 recordsLinked to original sources

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↗

Neurons in auditory cortex integrate information within constrained temporal windows that are invariant to the stimulus context and information rate

Much remains unknown about the computations that allow animals to flexibly integrate across multiple timescales in natural sounds. One key question is whether multiscale integration is accomplished by diverse populations of neurons, each of which integrates information within a constrained temporal window, or whether individual units effectively integrate across many different temporal scales depending on the information rate. Here, we show that responses from neurons throughout the ferret auditory cortex are nearly completely unaffected by sounds falling beyond a time-limited "integration window". This window varies substantially across cells within the auditory cortex ([~]15 to [~]150 ms), increasing substantially from primary to non-primary auditory cortex across all cortical layers, but is unaffected by the information rate of sound. These results indicate that multiscale computation is predominantly accomplished by diverse and hierarchically organized neural populations, each of which integrates information within a highly constrained temporal window.

neuroscience↗

Complexity of frequency receptive fields predicts tonotopic variability across species

Primary cortical areas contain maps of sensory features, including sound frequency in primary auditory cortex (A1). Two-photon calcium imaging in mice has confirmed the presence of these large-scale maps, while uncovering an unexpected local variability in the stimulus preferences of individual neurons in A1 and other primary regions. Here we show that fractured tonotopy is not unique to rodents. Using two-photon imaging, we found that local variance in frequency preferences is equivalent in ferrets and mice. Much of this heterogeneity was due to neurons with complex frequency tuning, which are less spatially organized than those tuned to a single frequency. Finally, we show that microelectrode recordings may describe a smoother tonotopic arrangement due to a bias towards neurons with simple frequency tuning. These results show that local variability in the tonotopic map is not restricted to rodents and help explain inconsistencies in cortical topography across species and recording techniques.

neuroscience↗