Biology subjects

Dahmen, J. C.

Publications and source records attributed to Dahmen, J. C..

3 recordsLinked to original sources

bioRxiv2023

Midbrain encodes sound detection behavior without auditory cortex

Hearing involves analyzing the physical attributes of sounds and integrating the results of this analysis with other sensory, cognitive and motor variables in order to guide adaptive behavior. The auditory cortex is considered crucial for the integration of acoustic and contextual information and is thought to share the resulting representations with subcortical auditory structures via its vast descending projections. By imaging cellular activity in the corticorecipient shell of the inferior colliculus of mice engaged in a sound detection task, we show that the majority of neurons encode information beyond the physical attributes of the stimulus and that the animals behavior can be decoded from the activity of those neurons with a high degree of accuracy. Surprisingly, this was also the case in mice in which auditory cortical input to the midbrain had been removed by bilateral cortical lesions. This illustrates that subcortical auditory structures have access to a wealth of non-acoustic information and can, independently of the auditory cortex, carry much richer neural representations than previously thought.

neuroscience↗

bioRxiv2020

Neural circuits for somatosensory control of auditory thalamocortical processing

Integration of information across the senses is critical for perception and is a common property of neurons in the cerebral cortex, where it is thought to arise primarily from corticocortical connections. Much less is known about the role of subcortical circuits in shaping the multisensory properties of cortical neurons. We show that stimulation of the whiskers causes widespread suppression of sound-evoked activity in mouse primary auditory cortex (A1). This suppression depends on the primary somatosensory cortex (S1), and is implemented through a descending circuit that links S1, via the auditory midbrain, with thalamic neurons that project to A1. Furthermore, a direct pathway from S1 has a facilitatory effect on auditory responses in higher-order thalamic nuclei that project to other brain areas. Crossmodal corticofugal projections to the auditory midbrain and thalamus therefore play a pivotal role in integrating multisensory signals and in enabling communication between different sensory cortical areas.

neuroscience↗

bioRxiv2019

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↗