Anatomical Pathways Involved in Generating and Sensing Rhythmic Whisker Movements

Abstract

The rodent whisker system is widely used as a model system for investigating sensorimotor integration, neural mechanisms of complex cognitive tasks, neural development, and robotics. The whisker pathways to the barrel cortex have received considerable attention. However, many subcortical structures are paramount to the whisker system. They contribute to important processes, like filtering out salient features, integration with other senses, and adaptation of the whisker system to the general behavioral state of the animal. We present here an overview of the brain regions and their connections involved in the whisker system. We do not only describe the anatomy and functional roles of the cerebral cortex, but also those of subcortical structures like the striatum, superior colliculus, cerebellum, pontomedullary reticular formation, zona incerta, and anterior pretectal nucleus as well as those of level setting systems like the cholinergic, histaminergic, serotonergic, and noradrenergic pathways. We conclude by discussing how these brain regions may affect each other and how they together may control the precise timing of whisker movements and coordinate whisker perception.

Mapping somatosensory connectivity in adult mice using diffusion MRI tractography and super-resolution track density imaging

“…In TDI, the barrelette connectivity map was seen in the coronal view in the ventro-lateral and interpolar regions as shown in cytochrome oxidase staining to demarcate the barrelettes in these regions (Li et al, 1994). Conversely, our results showed that the stereotypical barrelette connectivity map was not clearly detected using TDI in the oral part, consistent with current and previous histologic findings (Belford and Killackey, 1979;Bosman et al, 2011;Ma, 1991;Ma and Woolsey, 1984).…”

Mechanical responses of rat vibrissae to airflow

“…Whiskers have been the subject of research in both rodents (Bosman et al, 2011) and marine mammals (Dehnhardt et al, 2001;Hanke et al, 2013), but studies in these animals have largely focused on separate aspects of whisker function.…”

A biologically inspired multimodal whisker follicle

“…The mystacial pad concerns the area directly under the nose, and comprises a highly uniform array of whiskers of varying length [2]. Whilst not all whiskers move, the mystacial pad of rodents is musculated, allowing the mammal hosts to 'whisker' -a motion of swaying the whiskers back and forth [3]. In rats, whisking happens at a dominant frequency of 8Hz [4].…”

“…In rats, whisking happens at a dominant frequency of 8Hz [4]. Whilst intrinsic and extrinsic muscles allow 'whisking' to occur, the whole mystacial pad is also changeable in shape [3]. As a tactile sensor array, this means the mystacial pad is highly adaptable with several degrees of freedom.…”