Effect of dorsal rhizotomy on postural tremor in the monkey

Connections from the Basal Ganglia to the Thalamus

“…First, many pathological observaFeger/D eniau/H ammond-Le G uyader/O hye 273 tions give a more or less close relationship between a clinical syndrome such as athetosis, rigidity, chorea, ballism, parkinsonism and lesions in volving one or more of these structures. Such observations have been confirmed by experimental lesions in the monkey [3,4,5,8,51,52,56,58,59,60,77]. These experiments could sometimes establish a clear rela tionship between the basal ganglia and movement but did not elucidate its organization.…”

Physiopathology of Experimental Parkinsonism in the Monkey

“…The evidence that tremor is not abolished by deafferentation of the limbs in Parkinsonian patients (Pollock and Davis, 1930) and in lesioned monkeys (Ohye et al, 1970) supports the idea that the abnormal rhythmic bursts are centrally built up. In this respect the motor and premotor cortices together with the ventrolateral thalamus and the corresponding pallidum apparently play an important role in the elaboration of the abnormal rhythmic activity associated with postural tremor (Figure 2).…”

“…The interruption of the direct corticospinal fibers at peduncular or spinal cord level (Ohye et al, 1970) however, does not prevent the appearance of postural tremor in monkeys (as also reported in hemiplegic patients). These facts coupled with the observation that the destruction of the motor cortex (associated with a partial degeneration of the pyramid) abolishes tremor, suggest that the indirect cortico-subcortico-spinal system (from the motor cortex) is more directly involved than the direct corticospinal system in the transmission of the nervous impulses related to the production of postural tremor.…”

Role of the Thalamus in Parkinsonian Tremor: Evidence from Studies in Patients and Primate Models

“…In the monkey model of rest tremor pro duced by a lesion of the ventromedial midbrain tegmentum, tremor persists following dorsal root section [51]. Furthermore, dorsal root section in a parkinsonian patient did not abolish the tremor although it did alter the '... amplitude, rhythm and rate' of tremor.…”

“…Additionally, the phase of cortical tremor related activity is altered by perturbations of the trem ulous joint [50]. However, the fact that motor cortical bursting activity persists following curarization may suggest that this activity is not sole ly generated by peripheral inputs [4,51].…”