Sensory inputs reach cortical and subcortical areas in parallel, but how they coordinate to guide decisions remains unknown. We examined the roles of the primary somatosensory cortex (S1) and the superior colliculus (SC) in mice performing whisker-mediated tactile detection. While inactivating S1 contralateral to the stimulus increased detection threshold, inactivating ipsilateral S1 decreased it.
These opposing effects reflected shifts in choice bias rather than sensitivity. Unilateral SC inactivation produced similar directional effects, whereas bilateral inactivation of either S1 or SC neutralized bias. Furthermore, SC lesions impaired detection performance, and combined S1 inactivation caused no further impairment, indicating that S1-mediated shifts in bias were SC-dependent.
S1 inactivation also decreased sensory-evoked neural activity in SC, and choice decoding revealed that behavioral impairment was more closely associated with changes in SC population activity than with loss of sensory encoding in S1. Thus, S1 shapes perceptual bias by modulating SC-dependent circuits that transform sensory evidence into perceptual decisions. Sachidhanandam for suggestions on implementing the electromagnetic whisker stimulus, C.
Rodgers for the two lick-port design, J. Huang for Rosa–H2B–GFP mice, J. Kurpios for Pitx2-Cre mice, and M.
Shushruth for advice on psychometric data analysis. Caldas Martinez for helpful feedback on the manuscript. This work was supported by the Shurl and Kay Curci Foundation (#1031409 YKH), Simons Foundation Autism Research Initiative (#965159 YKH), Research Corporation for Science Advancement (RCSA # 29062 YKH), NIH 1T32NS126122-01 (AYN), and the Simons Foundation (AN-SURFiN-00007311, NC-SURFiN-00003473).
Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA Alice Y. Nam, Jiwook Shin, Morgan Tenney, Baihe Zhang & Y. Kate Hong Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA, USA Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA The authors declare no competing interests.
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