Activity in monkey substantia nigra neurons related to a simple learned movement

Abstract

Single cell activity was recorded in the pars compacta (SNc) and pars reticulata (SNr) of the substantia nigra (SN) in 4 unanesthetized Macaca fascicularis to determine the motor role of the nucleus. Animals were trained to perform a simple task that involved moving a lever by elbow flexion-extensions, in the horizontal plane using the hand contralateral to the recording site. Two monkeys learnt to execute the task on both sides. Electromyograms (EMG) of limb muscles were recorded simultaneously with SN neurons. Discharge rate modulation related to specific movement phases was present in 35% of the neurons. A significant positive correlation of the discharge rate with movement velocity and amplitude was found in SNc and SNr neurons. Some SNr cells discharged in anticipation of the EMG, suggesting a participation of the nucleus in the preparation of movement. The activity of SNr neurons was also related to movement of the left and right upper limb. In conclusion, the SN seems to play an important role in the control of specific motor mechanisms, probably modulating movement velocity, amplitude and direction, with little participation of somatosensory feedback. The involvement of the SNr in the coordination of bilateral arm activity is discussed.

Ensemble neural activity of the frontal cortical basal ganglia system predicts reaction time task performance in rats

“…Behavioral studies indicate that infusion of NMDA receptor antagonist into SNr induced a dramatic increase in the number of premature lever releases and decreased mean reaction time (Baunez and Amalric, 1996); injections of GABA A antagonist into SNr produced a dose-related suppression of operant responding (Correa et al, 2003). Electrophysiological studies displayed that a large proportion of SNr neurons showed responses which were related to memory, attention, or movement preparation (Wichmann and Kliem, 2004): and a significant positive correlation was found between the discharge rate in primate SNr neurons and elbow movement velocity as well as amplitude, some SNr cells discharged in anticipation of the EMG (Magarinos-Ascone et al, 1992), which are consistent with our findings. Morphological studies demonstrate that SNr neurons usually extended the dendritic arborizations within the adjacent striatal projection fields (Mailly et al, 2001), which may be one of the structure substrates for SNr integration function.…”

Neuronal Activity in the Primate Substantia Nigra Pars Reticulata During the Performance of Simple and Memory-Guided Elbow Movements

“…In our experiments as well as previously published studies (DeLong et al 1983;Schultz 1986;Schwarz et al 1984), some SNr neurons indeed responded preferentially during the execution of proximal forelimb movements. In this respect, our findings are closest to those of DeLong et al (1983), whereas a somewhat larger proportion of movementrelated neurons was identified in some of the other studies that either used a less constrained task than ours (Schultz 1986) or a task that required self-initiated sinusoidal ballistic arm movements (Magarinos-Ascone et al 1992). The differences between our data and the results of the latter study suggest that the SNr may be more directly engaged in self-initiated rather than externally triggered movements.…”

Gamma-aminobutyric acidB receptor activation suppresses stimulus-evoked burst firing in rat substantia nigra reticulata neurons

“…Increased SNR neuronal activity has been associated with normal limb movement [17] and cessation of saccadic eye movements [18]. Thus, the bursting firing pattern likely plays a role in normal physiology.…”