Abstract
The cerebellum receives signals directly from peripheral sensory systems and indirectly from the neocortex. Even a single tactile stimulus can activate both of these pathways. Here we report how these different types of signals are integrated in the cerebellar cortex. We used in vivo whole-cell recordings from granule cells and unit recordings from Purkinje cells in mice in which primary somatosensory cortex (S1) could be optogenetically inhibited. Tactile stimulation of the upper lip produced two-phase granule cell responses (with latencies of ~8 ms and 29 ms), for which only the late phase was S1 dependent. In Purkinje cells, complex spikes and the late phase of simple spikes were S1 dependent. These results indicate that individual granule cells combine convergent inputs from the periphery and neocortex and send their outputs to Purkinje cells, which then integrate those signals with climbing fiber signals from the neocortex.
Highlights
The cerebellum receives signals directly from peripheral sensory systems and indirectly from the neocortex
In mice anesthetized with ketamine/xylazine (K/X), a brief (50 ms) air puff applied to the upper lip evoked large responses both in the upper lip area of S1 (3.8–4.5 mm lateral and 0–1.0 mm rostral to bregma) and in the granule cell layer (GCL) of the crus II area
When S1 activity was suppressed by focal illumination with blue light in alternating trials, the response of S1 and the late component of the GCL response were eliminated (Fig. 2a, b), indicating that the late component of the GCL response depends on the activity of S1
Summary
The cerebellum receives signals directly from peripheral sensory systems and indirectly from the neocortex. In Purkinje cells, complex spikes and the late phase of simple spikes were S1 dependent These results indicate that individual granule cells combine convergent inputs from the periphery and neocortex and send their outputs to Purkinje cells, which integrate those signals with climbing fiber signals from the neocortex. At the single-cell level, it is still not clear whether these inputs project to different groups of granule cells[9,12] or converge on the same individual granule cells This issue is important in order to understand the basis of cerebellar computation. Marr and Albus independently proposed similar ideas that the mossy fiber-granule cell system expands the neural representation of information[14,15] This idea, called the expansion recoding hypothesis, assumes that each granule cell receives inputs from a near-random combination of mossy fibers that convey different types of signals, thereby creating numerous combination patterns. The inferior olivary nuclei receive indirect inputs from the neocortex[9,11,19,20,21], it is not known whether the neocortex mediates sensory-evoked climbing fiber responses
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
