1. The primary goal of this study was to characterize the information about single-joint forelimb movements supplied to intermediate cerebellar cortex by mossy fibers. Discharge of mossy fibers and Golgi cells was studied while monkeys operated six devices that required movements about specific joints. Additional control experiments in anesthetized cats and monkeys established criteria for identification of mossy fibers and Golgi cells. 2. The control experiments demonstrate that mossy fibers can be distinguished from Purkinje and Golgi cells by the waveshapes of their action potentials. Asynaptic activation from the inferior cerebellar peduncle, in combination with histological localization of recording sites in granular layer or subcortical white matter, verified that mossy fibers produce a variety of waveshapes that are characterized by brief initial phases and relatively small amplitudes. The same waveshapes were observed for the mossy fiber recordings from awake monkeys, and many identified mossy fibers had sensory properties similar to those found in the awake animals. From these combined criteria, we conclude that the recordings in the awake animals were from mossy fibers. Golgi cells, recorded exclusively in the granular layer of cerebellar cortex, were characterized by action potentials of longer duration and larger amplitude as compared with mossy fibers, and none were asynaptically activated from the inferior cerebellar peduncle. 3. Units were isolated while the monkeys made free-form and tracking movements. We studied movement-related discharge of 80 mossy fibers and 12 Golgi cells. Mossy fibers showed high modulations during use of at least one of the six manipulanda and had clear preferences for movement about a specific joint, although they often showed consistent but weaker firing during movement about a neighboring joint. Separation of movements by more than one joint produced a large reduction in discharge: shoulder units never fired well to movements of the finger, and finger units never fired well to movement of the shoulder. 4. The tracking task required maintenance of fixed limb positions (a static phase) as well as movements between these positions (a dynamic phase). Of 80 mossy fibers, 18% had purely tonic discharge patterns, 63% were phasic-tonic, and 20% were purely phasic. Discharge patterns were reciprocal (45%), bidirectional (42%), or unidirectional (13%). 5. Eighty percent of the mossy fibers exhibited tonic discharge that was significantly (P < 0.01) correlated with joint angle (r = 0.65 +/- 0.19, mean +/- SD), and about one third had phasic components that were significantly correlated with movement velocity.(ABSTRACT TRUNCATED AT 400 WORDS)

1. The goal of this study was to investigate the motor organization of monkey nucleus interpositus (NI) and neighboring regions of the lateral nucleus (NL) by correlating discharge of single neurons with active movements. Neurons were surveyed during free-form movements as well as during operation of six devices that required movement about specific forelimb joints. The paradigm allowed us to test the hypothesis that discharge of individual cells relates to movements about individual joints. 2. One hundred sixty-two isolated nuclear neurons from two monkeys were studied. Eighty-three percent showed large increases in discharge (an average of 3 times resting rate for forelimb neurons) during movement of one body part, either forelimb, hindlimb, mouth/face, or eyes. 3. Anterior interpositus contains neurons related to hindlimb movement in anterior regions and neurons related to forelimb movement in posterior regions. A mouth/face-related area exists in the dorsal-posterior regions and is continuous with a mouth/face area in the dorsal regions of NL. Posterior interpositus (NIP) showed no clear separation between forelimb and hindlimb neurons: forelimb neurons were encountered throughout the nucleus, and hindlimb neurons were encountered in the medial-anterior two thirds. A distinct eye movement area exists in lateral, posterior, and ventral regions of NIP. This area borders regions of NL that also contain eye movement-related neurons. 4. Forelimb interpositus neurons discharged strongly during reach and grasp; discharge rates were recorded for 41 neurons during a stereotyped reach and the average depth of modulation was 149 imp/s. Nineteen neurons that modulated during device tracking were also tested during reaching, and the depth of modulation was much greater during reaching. 5. Fifty-nine forelimb neurons were tested with device tracking. Twenty-seven (46%) produced no audible modulation, regardless of the joint being exercised. The remaining 32 neurons modulated during movement on at least one device (mean depth of modulation = 84 imp/s). Comparison of discharge during use of different devices revealed no strong evidence for device-specific discharge. 6. Discharge modulations during device tracking were phasic, preceded movement, and, for a small number of cells, showed consistent parametric relations to duration, amplitude, and velocity of movement. 7. Despite a clear somatotopy within NI and NL, there is no finer mapping based on active movements about individual joints within forelimb regions. Discharge modulation depends on movements involving the whole limb. Progress in understanding the function of intermediate cerebellum depends on determining the variables required to elicit consistent and high modulation of neural discharge.(ABSTRACT TRUNCATED AT 400 WORDS)

SUMMARY1. We recorded from 239 neurons located in the magnocellular division of the red nucleus of four alert macaque monkeys. At the same time, we recorded electromyographic (EMG) signals from as many as twenty electrodes chronically implanted on muscles of the shoulder, arm, forearm and hand. We recorded EMG signals for periods ranging from several months to a year.2. The monkeys were trained to perform three free-form food retrieval tasks, each of which activated all of the recorded muscles and most of the neurons. The 'prehension' task required simply that the monkey grasp a piece of food from a fixed point in space. The 'barrier' task required the monkey to reach around a small barrier to obtain the food, and the 'Kluver' task required that food be removed from small holes. During the prehension task, we found approximately equal numbers of neurons that were strongly active while the hand was being moved toward the target (70% of units), and while the food was being grasped (60%). Relatively few units were active as the hand was returned to the mouth (15%).3. Data files of 1-2 min duration were collected while the monkey performed a single behavioural task. Whenever possible, we recorded files for all three tasks from each neuron. For each file we calculated long time-span analog cross-correlations (± 1X28 s) between instantaneous neuronal firing rate and each of the full-wave rectified, low-pass filtered EMG signals. We used the peak correlation and the time of the peak as two summary measures of the functional relation between modulation of neuronal activity and EMG.4. The magnitude of the strongest correlations was between 0 4 and 0 5 (normalized to a perfect correlation of + 1X0). Distal muscles were the most frequently correlated, and extensors were more frequently correlated than flexors. For all monkeys, the lags for well correlated muscles were distributed broadly about L. E. MILLER AND OTHERS a uni-modal value near 0 ms. Eighty five per cent of the correlations larger than or equal to 0-25 had peaks between -150 and 200 ms.5. The activity of each neuron was represented in a muscle co-ordinate system by an n-dimensional 'functional linkage vector', each element of which was the peak correlation with one of n muscles. The vector for any given neuron points in a particular direction in muscle space, depending on the similarity between the activity of the neuron and the activity of each muscle. Sequential files recorded from a given neuron during a single behaviour yielded very similar linkage vectors, whereas the vectors for different neurons pointed in quite different directions in muscle space. The variation in linkage vectors for any given cell tested repeatedly during different behaviours was intermediate between that of the same cell-same task condition and the different cell-same task condition. Therefore, the correlation between the activity of the magnocellular red nucleus (RNm) neurons and limb muscles is not completely invariant for different tasks, but it varies less than for different RNm ...

Loss of motor function is a common deficit following stroke insult and often manifests as persistent upper extremity (UE) disability which can affect a survivor’s ability to participate in activities of daily living. Recent research suggests the use of brain–computer interface (BCI) devices might improve UE function in stroke survivors at various times since stroke. This randomized crossover-controlled trial examines whether intervention with this BCI device design attenuates the effects of hemiparesis, encourages reorganization of motor related brain signals (EEG measured sensorimotor rhythm desynchronization), and improves movement, as measured by the Action Research Arm Test (ARAT). A sample of 21 stroke survivors, presenting with varied times since stroke and levels of UE impairment, received a maximum of 18–30 h of intervention with a novel electroencephalogram-based BCI-driven functional electrical stimulator (EEG-BCI-FES) device. Driven by spectral power recordings from contralateral EEG electrodes during cued attempted grasping of the hand, the user’s input to the EEG-BCI-FES device modulates horizontal movement of a virtual cursor and also facilitates concurrent stimulation of the impaired UE. Outcome measures of function and capacity were assessed at baseline, mid-therapy, and at completion of therapy while EEG was recorded only during intervention sessions. A significant increase in r-squared values [reflecting Mu rhythm (8–12 Hz) desynchronization as the result of attempted movements of the impaired hand] presented post-therapy compared to baseline. These findings suggest that intervention corresponds with greater desynchronization of Mu rhythm in the ipsilesional hemisphere during attempted movements of the impaired hand and this change is related to changes in behavior as a result of the intervention. BCI intervention may be an effective way of addressing the recovery of a stroke impaired UE and studying neuromechanical coupling with motor outputs.Clinical Trial Registration: ClinicalTrials.gov, identifier NCT02098265.

Pages 74–94: Peter L. E. van Kan, Alan R. Gibson, and James C. Houk, “Movement-related inputs to intermediate cerebellum of the monkey.” Page 86, left column, Fig. 12 legend, the last 3 lines are printed incorrectly; they should read: The modulation in discharge during active finger extension ( E) was considerably larger than the perturbation response ( F). Every 4th spike is plotted in the rasters.