Movement-related Neuronal Activity Research Articles

Encoding of jaw movements by central trigeminal neurons with cutaneous receptive fields.

Neurons with orofacial cutaneous receptive fields that responded to jaw movements were recorded in the trigeminal subnucleus interpolaris of the cat. Movement-related neuronal activity was identified by imposing passive ramp and hold stretches of the jaw at four different rates. Thirty-nine neurons with hair (26), skin (9), or convergent (4) receptive fields were studied. Thalamic projection neurons were identified by antidromic stimulation of the ventroposteromedial nucleus of the thalamus. The receptive fields of movement-related hair units included multiple hairs located mainly around the angle of the jaw and chin. The receptive fields of movement-related skin units were smaller than those of hair units and they were located primarily around the angle of the mouth. The convergent units had more than one receptive field that usually included hair or skin. All of the hair units were activated both during opening and closing jaw movements. They typically responded with short bursts of action potentials. Four units with skin receptive fields exhibited similar responses. The five skin units that did not show bursting activity included two that were active during both opening and closing of the jaw, two that were active only during opening, and one that was tonically active during maintained open position. All of the convergent units showed biphasic responses, and three responded with bursts. The maximum discharge rate, the mean discharge rate (mean bursting rate for units with bursting responses), and the total number of spikes per movement were measured. Statistical analysis was performed on these variables to assess functional properties of each unit. The results were used to classify units as velocity, speed, direction, or transient motion detectors. Thirty-three percent of the neurons were trigeminothalamic neurons.

Are extent and force independent movement parameters? Preparation- and movement-related neuronal activity in the monkey cortex.

Movement extent and movement force can be independently controlled in motor performance. Therefore, independent representations of extent and force should exist in the central nervous system (CNS). To test this hypothesis, microelectrode recordings were made in sensorimotor cortex of monkeys trained to perform visually cued wrist flexion movements of two extents, against two levels of frictional resistance. An initial preparatory signal (PS) provided complete, partial or no information about extent and/or force of the movement, which had to be performed in response to a second, response signal (RS). The activity of 511 neurons of the primary motor cortex (MI), the premotor cortex (PM), the postcentral cortex (PC), and the posterior parietal cortex (PA) was recorded in two monkeys. Both reaction time (RT) and neuronal data suggest that there exist independent neuronal mechanisms responsible for the programming of either parameter. On the one hand, partial information about either movement parameter shortened RT when compared with the condition of no prior information. On the other hand, there were, among others, two discrete populations of neurons, one related only to extent, the other only to force. Preparatory changes in activity related to either movement parameter were mainly located in the frontal cortex, especially in the PM. After occurrence of the RS, the percentage of selective changes in activity increased and tended to extend to the parietal cortex. In particular during the movement, force-related changes in activity have been encountered in PA. Furthermore, we conducted trial-by-trial correlation analyses between RT and preparatory neuronal activity for all conditions of prior information. The mean correlation coefficient was significantly higher in the condition of information about movement extent than of information about movement force and it was significantly higher in MI/PM than in PC/PA.

Chapter 15 Reward-related activity in the monkey striatum and substantia nigra

The basal ganglia are often considered as parts of the motor system. This concept is derived from the movement disorders arising in Parkinsonism, choreaand hemiballism, from the projections of the primary motor and somatosensory cortex to the putamen and subthalamic nucleus, and from movement-related neuronal activity in several basal ganglia nuclei. The motor role of the basal ganglia can be extended to include preparatory activity preceding the execution of limb and eye movements, which reflects neuronal access to stored information about forthcoming events and thus constitutes a higher function than primary movement processes. However, there are a number of indications suggesting a larger involvement of the basal ganglia in behavioral processes. In particular, the basal ganglia, notably the striatum, receive input from several limbic structures, such as the amygdala and the orbitofrontal and cingulate cortex. In addition, results from lesioning and psychopharmacological experiments indicate that the functions of the nigrostriatal, mesolimbic and mesocortical dopamine systems encompass a larger spectrum of behavioral processes than a primary motor role suggested by the movement disorders. In particular, they appear to participate in motivational processes determining behavioral activity. In order to assess the involvement of the basal ganglia in motivational processes, this chapter discusses the activity of neurons in the dorsal and ventral striatum and of dopamine neurons in the substantia nigra in relation to the delivery of primary rewards. Examples of primary rewards are food objects or fluids that are approached by subjects through innate or instinctive behavior, or are learned very early during ontogenesis. Primary rewards may serve to establish and sustain learned appetitive behavior, in which case they are called positive reinforcers. Thus, primary rewards are key components in the motivational control of behavior.

Bilateral cortical ablations attenuate amphetamine-induced excitations of neostriatal motor-related neurons in freely moving rats

Single-unit recordings from neostriatal neurons showing movement-related excitations were obtained in freely moving, cortically ablated rats and sham-lesioned controls. d-Amphetamine (AMPH, 1.0 mg/kg s.c.) increased neuronal activity relative to resting baseline firing rates in both groups of animals, but cortical ablation significantly attenuated this effect. A behavioral clamping analysis, which compared neuronal activity during identically rated pre- and post-AMPH behaviors, revealed that: (a) AMPH enhanced movement-related neuronal activity in sham-lesioned controls, but not in cortically ablated rats; and (b) the drug-induced neuronal activation in control rats was not simply secondary to the behavioral activation produced by AMPH. In contrast to its neuronal effects, cortical ablation did not affect ratings of AMPH-induced locomotion, rearing, or head movements, though sniffing scores showed a postive correlation with lesion size. Thus, corticostriatal projections are critically involved in AMPH-induced excitations of neostriatal motor-related neurons.

Activity of eye movement-related neurons in and near the interstitial nucleus of Cajal during sinusoidal vertical linear acceleration and optokinetic stimuli

1. A total of 43 neurons that showed a close correlation with vertical eye movement with a burst-tonic or tonic type response during spontaneous saccades, were recorded within, and in the close vicinity of, the interstitial nucleus of Cajal (INC) in alert cats. Neuronal responses to sinusoidal vertical linear acceleration (0.2-0.85 Hz, amplitude 10.5 cm) and optokinetic stimuli (0.1-1.0 Hz, amplitude 10.5 cm), were examined. 2. All 43 eye movement-related neurons responded to sinusoidal vertical linear acceleration in the presence of a stationary visual pattern in correlation to robust eye movement responses with compensatory phase. Phase and gain values (re stimulus position) of response of individual cells were independent of the stimulus frequencies tested. Of these, 33 cells were examined during linear acceleration without visual input. Most cells (27/33) did not respond even when a weak linear vestibulo-ocular reflex was present (6/27). The remaining 6 cells (6/33) responded to linear acceleration. Their mean phase values advanced by 80 degrees and gain dropped by 55% compared to the responses with visual inputs. 3. Twenty eight of the 43 cells were examined during vertical optokinetic stimuli. The activity of all 28 cells was modulated in correlation to eye movement responses. Response phase showed more lag, and gain decreased as stimulus frequencies increased, similar to optokinetic eye movement responses. 4. The close correlation between the activity of eye movement-related neurons in the INC region and robust eye movements during linear acceleration with visual inputs and optokinetic stimuli suggest that these neurons are involved in some aspect of vertical eye position generation during such stimuli.

Movement-related neuronal activity in the supplementary motor cortex undergoes plastic changes after long-term training and MI lesion

Movement-related neuronal activity in the supplementary motor cortex undergoes plastic changes after long-term training and MI lesion

Movement-related neuronal activity selectively coding either direction or muscle pattern in three motor areas of the monkey

1. Movement-related neuronal activity in the supplementary motor area (SMA), primary motor cortex (MC), and putamen was studied in monkeys performing a visuomotor tracking task designed to determine 1) the extent to which neuronal activity in each of these areas represented the direction of visually guided arm movements versus the pattern of muscle activity required to achieve those movements and 2) the relative timing of different types of movement-related activity in these three motor areas. 2. A total of 455 movement-related neurons in the three motor areas were tested with a behavioral paradigm, which dissociated the direction of visually guided elbow movements from the accompanying pattern of muscular activity by the application of opposing and assisting torque loads. The movement-related activity described in this report was collected in the same animals performing the same behavioral paradigm used to study preparatory activity described in the preceding paper. Of the total sample, 87 neurons were located within the arm region of the SMA, 150 within the arm region of the MC, and 218 within the arm region of the putamen. 3. Movement-related cells were classified as "directional" if they showed an increase in discharge rate predominantly or exclusively during movements in one direction and did not have significant static or dynamic load effects. A cell was classified as "muscle-like" if its directional movement-related activity was associated with static and/or dynamic load effects whose pattern was similar to that of flexors or extensors of the forearm. Both directional and muscle-like cells were found in all three motor areas. The largest proportion of directional cells was located in the putamen (52%), with significantly smaller proportions in the SMA (38%) and MC (41%). Conversely, a smaller proportion of muscle-like cells was seen in the putamen (24%) than in the SMA (41%) or MC (36%). 4. The time of onset of movement-related discharge relative to the onset of movement ("lead time") was computed for each cell. On average, SMA neurons discharged significantly earlier (SMA lead times 47 +/- 8 ms, mean +/- SE) than those in MC (23 +/- 6 ms), which in turn were earlier than those in putamen (-33 +/- 6 ms). However, the degree of overlap of the distributions of lead times for the three areas was extensive.(ABSTRACT TRUNCATED AT 400 WORDS)

The formulae-relating slopes, correlation coefficients and variance ratios used to determine stimulus- or movement-related neuronal activity

When recording single neuron discharge in an animal during the performance of a conditioned task, the functional interpretation of any change in neuronal activity after the conditioned stimulus but before the conditioned task is difficult. So far, such changes have been described as either stimulus- or movement-related. One way of classifying these two types of response has been use the slope and correlation coefficient between the response latency and the behavioural reaction time. We show that this method is poor and propose a more valid approach.