Layer-specific integration of locomotion and concurrent wall touching in mouse barrel cortex

Abstract

During navigation rodents continually sample the environment with their whiskers. How locomotion modulates neuronal activity in somatosensory cortex and how self-motion is integrated with whisker touch remains unclear. Here, we used calcium imaging in mice running in a tactile virtual reality to investigate modulation of neurons in layer 2/3 (L2/3) and L5 of barrel cortex. About a third of neurons in both layers increased activity during running and concomitant whisking, in the absence of touch. Fewer neurons were modulated by whisking alone (<10%). Whereas L5 neurons responded transiently to wall-touching during running, L2/3 neurons showed sustained activity after touch onset. Consistently, neurons encoding running-with-touch were more abundant in L2/3 compared to L5. Few neurons across layers were also sensitive to abrupt perturbations of tactile flow. We propose that L5 neurons mainly report changes in touch conditions whereas L2/3 neurons continually monitor ongoing tactile stimuli during running.

The Cortical States of Wakefulness

“…A recent study, for example, compared changes in neuronal activity of pyramidal neurons in L2/3 and L5 of wS1 as mice are immobile, during whisker movements and during locomotion (which is always accompanied by whisking). In agreement with previous studies, whisking alone had only minor impact on the mean activity of pyramidal neurons, whereas running was accompanied by an increased activity in the majority of the neurons (Ayaz et al, 2018). Thus, locomotion has an additional impact on cortical activity compared to whisking alone.…”

Virtual reality systems for rodents

“…First examples focus on somatosensory processing. One of the studies developed a tactile VR, to investigate somatosensory processing during active exploration and focuses on integration of sensory signals with motor components (i.e., whisking and locomotion; Ayaz et al 2014 ). While mice are running and whisking along the virtual wall, 2-photon calcium imaging was performed of a population of neurons in superficial and deep layers of vibrissal primary somatosensory cortex (vS1).…”

“…Similarly, Ayaz et al (2014) developed a tactile VR for mice to investigate somatosensory processing during active exploration. They simulate the condition in which mice can run in the dark along a “wall,” on which varying textures (placed on rotating cylinders) are presented ( Figure 2C, D ).…”

“…To reach beyond spatial cognition, fostering attempts to develop VR techniques for other senses and then combine them across sensory modalities to create multimodal VR would strongly advance the scope of rodent VR. For instance, 2 tactile VRs introduced earlier ( Ayaz et al 2014 ; Sofroniew et al 2014 ) could be easily combined with other sensory inputs to create a multisensory VR. Although questions related to spatial navigation would highly benefit from multimodal VR, more general objectives could also be pursued.…”

Wide-field calcium imaging of cortical activation and functional connectivity in externally- and internally-driven locomotion

“…Each of the cortical regions imaged show task-specific activity during walking, such as adjustment of gait in M1 [16][17][18][19] , encoding of obstacles to be avoided in parietal cortex [20][21][22][23] , and modulation of sensory encoding in somatosensory and visual cortices [24][25][26][27] . Therefore, each of these regions engage in unique roles, and the proportion of shared fluorescence activity across them likely decreases.…”