Coherence between cerebellar thalamus, cortex and muscle in man: Cerebellar thalamus interactions

Abstract

Local field potentials (LFPs) were recorded in seven unanaesthetized patients between the four adjacent contacts of a macroelectrode stereotactically implanted for the treatment of tremor. The LFPs were presumed to arise predominantly from the nucleus ventralis intermedius (Vim) of the thalamus, the implantation target. They were recorded simultaneously with the ipsilateral EEG and contralateral EMG during an isometric contraction or at rest. The patients had a history of either isolated tremor (essential tremor, n = 2; benign tremulous Parkinson's disease, n = 1) or tremor with signs of a cerebellar syndrome (multiple sclerosis, n = 3; essential tremor and ataxia, n = 1), although clinical tremor was absent at the time of recording because of a temporary microthalamotomy effect in four patients. In patients with isolated tremor, oscillatory activity picked up by contacts in Vim (cerebellar thalamus) was invariably coherent with that in the sensorimotor cortex or contracting muscle in the 8-27 Hz range. Such coherence was absent in two of the four subjects with tremor associated with a cerebellar syndrome. Coherence between LFPs recorded from more caudally placed contacts and the sensorimotor cortex or contracting muscle was negligible in all patients. These caudally placed contacts demonstrated the highest sensory evoked potential in response to median nerve stimulation. Oscillatory activity in the cerebellar thalamus (Vim) lagged behind that in both cortex and muscle. Coherent activity between the cerebellar thalamus (Vim) and the cortex persisted at rest. It is suggested that rhythmicities in the 8-27 Hz range could provide the basis for a temporal framework that is widely distributed within the motor system.

High Thalamocortical Theta Coherence in Patients with Parkinson's Disease

“…The magnitude of ␤ coherence, however, was below 16% and thereby much lower than in the theta band. Values of similar magnitude were reported for ␤ coherence between scalp EEG and recording sites in the cerebellar thalamus (Marsden et al, 2000;Paradiso et al, 2004) and basal ganglia (Marsden et al, 2001;Williams et al, 2002;Fogelson et al, 2006), indicating that activity at these sites also interacts with cortical activity. Anatomically and functionally, the main output of the basal ganglia occurs via the pallidothalamic and nigrothalamic tract to the thalamus.…”

“…LFP recordings come mainly from sites in the cerebellar thalamus (Marsden et al, 2000;Paradiso et al, 2004) or in the basal ganglia (Marsden et al, 2001;Williams et al, 2002;Fogelson et al, 2006) and reflect the sites of surgical intervention.…”

Neuronal activity and outcomes from thalamic surgery for spinocerebellar ataxia

“…However, the present results showed that the discharge rates, bursting, and oscillatory activity in Vim in SCA were not different from those in ET, suggesting that ataxia may occur independent of changes in rate, burst, or oscillatory activity in Vim. The present results are in contrast to the disrupting patterns of background neural activity underlying akinesia/bradykinesia of Parkinson's disease 45, 46. Coherent oscillation underlies movement‐related activities within the motor system including the basal ganglia and cerebellar systems in the normal condition 47.…”

Changes in Cortically Related Intermuscular Coherence Accompanying Improvements in Locomotor Skills in Incomplete Spinal Cord Injury

“…Complete identification of the source of the coherence would require simultaneous recordings from the cortex, brain stem, spinal cord, and muscle during the movement. Direct recordings from motor cortex and muscle have been analyzed in the monkey (Jackson et al 2002) and in patients (Marsden et al 2000) and have provided further evidence for the cortical origin of the higher-frequency coherence at least to hand and upper limb muscles.…”