Area-specific processing of cerebellar-thalamo-cortical information in primates

Abstract

The cerebellar-thalamo-cortical (CTC) system plays a major role in controlling timing and coordination of voluntary movements. However, the functional impact of this system on motor cortical sites has not been documented in a systematic manner. We addressed this question by implanting a chronic stimulating electrode in the superior cerebellar peduncle (SCP) and recording evoked multiunit activity (MUA) and the local field potential (LFP) in the primary motor cortex ([Formula: see text]), the premotor cortex ([Formula: see text]) and the somatosensory cortex ([Formula: see text]). The area-dependent response properties were estimated using the MUA response shape (quantified by decomposing into principal components) and the time-dependent frequency content of the evoked LFP. Each of these signals alone enabled good classification between the somatosensory and motor sites. Good classification between the primary motor and premotor areas could only be achieved when combining features from both signal types. Topographical single-site representation of the predicted class showed good recovery of functional organization. Finally, the probability for misclassification had a broad topographical organization. Despite the area-specific response features to SCP stimulation, there was considerable site-to-site variation in responses, specifically within the motor cortical areas. This indicates a substantial SCP impact on both the primary motor and premotor cortex. Given the documented involvement of these cortical areas in preparation and execution of movement, this result may suggest a CTC contribution to both motor execution and motor preparation. The stimulation responses in the somatosensory cortex were sparser and weaker. However, a functional role of the CTC system in somatosensory computation must be taken into consideration.

Area-specific thalamocortical synchronization underlies the transition from motor planning to execution

“…Pinpointing thalamic cells that are part of nonsensory nuclei is challenging given the complex anatomy of the thalamic nuclei. To overcome this difficulty, we used single-pulse stimulation delivered to the superior cerebellar peduncle (SCP), which efficiently activates the CTC system (12,13) and serves to tag motor thalamic and motor cortical neurons that integrate cerebellar signals (Fig. 1C).…”

“…To insert a chronic stimulating electrode into the ipsilateral SCP, we implanted a small chamber above the estimated insertion point (based on a primate neuro atlas) and used a postsurgery MRI to plan the electrode trajectory. A bipolar concentric electrode (NSEX100; David Kopf Instruments; impedance range of 30 to 60 kΩ) and the evoked intracortical responses to stimulation through the electrode were used to verify its location (3,12,13,25).…”

Reversible Block of Cerebellar Outflow Reveals Cortical Circuitry for Motor Coordination

“…To insert a chronic stimulating electrode into the ipsilateral SCP, we implanted a small chamber above the estimated insertion point and used a post-surgery MRI to plan the electrode trajectory. A bi-polar concentric electrode (NSEX100, David Kopf Instruments, impedance range of 30-60 kU) and the evoked intra-cortical responses to stimulation through the electrode were used to verify its location (Nashef et al, 2018a;Ruach et al, 2015;Nashef et al, 2018b).…”

Multiparametric mapping of white matter microstructure in catatonia

“…Our findings suggest that reduced myelination of CC and CST might lead to less efficient neural signal transmission causing difficulties in movement execution and coordination [69,74], as we can observe them in catatonia. Third, the T_PREM cortical fiber tract is part of the cerebellar-thalamo-cortical system, which is the major bundle through which the cerebellum affects voluntary movements in higher mammals [75,76]. Interestingly, CST and T_PREM showed higher FA in catatonic compared to non-catatonic patients.…”