Neuronal Mechanisms of Voluntary and Involuntary Movement in the Parafascicular (CM-Pf) Complex of the Thalamus in Patients with Spasmodic Torticollis

Abstract

The responses of 144 neurons in the parafascicular CM-Pf complex of the human thalamus recorded by microelectrodes techniques in 18 stereotaxic neurosurgical operations were studied in patients with spasmodic torticollis. Two previously classified types of neurons with occasional irregular (type A) and volleytype Ca2+-dependent activity (type B) were shown to have high reactivity during performance of verbally controlled voluntary movements. Concordant occurrence of activatory-inhibitory responses of neurons of the two (A and B) types at the stage of presentation of verbal orders were found, with synergistic activatory responses from these neurons at the stage of performing the movement and subsequently. Execution of a voluntary movement could be accompanied by rapid increases in intercellular interactions between closelying neurons in the form of local synchronization with stabilization of rhythmic oscillatory (3–5 Hz) neuron activity. Differences in the responses of neurons were seen during voluntary movements without and with the involvement of the affected axial neck muscles, as well as during involuntary dystonic movements. These data provide evidence of the involvement of the nonspecific CM-Pf complex of the thalamus in the pathological mechanisms of spasmodic torticollis, which may have applied value in relation to the surgical treatment of this disease.