Lemercier CE, Krieger P. Reducing Merkel cell activity in the whisker follicle disrupts cortical encoding of whisker movement amplitude and velocity.
IBRO Neurosci Rep 2022;
13:356-363. [PMID:
36281438 PMCID:
PMC9586890 DOI:
10.1016/j.ibneur.2022.09.008]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 09/26/2022] [Indexed: 11/26/2022] Open
Abstract
Merkel cells (MCs) and associated primary sensory afferents of the whisker follicle-sinus complex, accurately code whisker self-movement, angle, and whisk phase during whisking. However, little is known about their roles played in cortical encoding of whisker movement. To this end, the spiking activity of primary somatosensory barrel cortex (wS1) neurons was measured in response to varying the whisker deflection amplitude and velocity in transgenic mice with previously established reduced mechanoelectrical coupling at MC-associated afferents. Under reduced MC activity, wS1 neurons exhibited increased sensitivity to whisker deflection. This appeared to arise from a lack of variation in response magnitude to varying the whisker deflection amplitude and velocity. This latter effect was further indicated by weaker variation in the temporal profile of the evoked spiking activity when either whisker deflection amplitude or velocity was varied. Nevertheless, under reduced MC activity, wS1 neurons retained the ability to differentiate stimulus features based on the timing of their first post-stimulus spike. Collectively, results from this study suggest that MCs contribute to cortical encoding of both whisker amplitude and velocity, predominantly by tuning wS1 response magnitude, and by patterning the evoked spiking activity, rather than by tuning wS1 response latency.
The role of Merkel cells (MCs) in cortical encoding of whisker deflection amplitude and velocity was investigated.
Reducing MC synaptic activity increased barrel cortex neurons response sensitivity to whisker deflection.
This effect occurred from a lack of variation in response magnitude to varying whisker deflection amplitude and velocity.
However, stimuli differentiation through changes in cortical response latency was preserved.
MCs are thus suggested to play a predominant role in tuning the cortical response magnitude over the response latency.
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