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PubMedDate not supplied

[The participation of the cholinergic system of the rat sensorimotor cortex in regulating different types of movements].

To study the role of the cholinergic system of the sensorimotor cortex in regulation of different manipulatory movements and locomotion of Wistar rats, the effects of injections of cholinergic drugs (a cholinergic agonist carbachol and an antagonist scopolamine) into the area of forepaw representation in the sensorimotor cortex on motor activity and performance of manipulatory movements (with prolonged and short pushing) were analyzed. The drugs were injected via special cannulae stereotaxically implanted into the cortex during surgery carried out under Nembutal anesthesia. Carbachol injections (0.03-3 micrograms in 1 microliter of physiologic solution) into the cortex resulted in a significant slowing down of both types of movements as well as an increase in locomotion in the open-field test. Injections of scopolamine (0.3-3 micrograms) into the same cortical area were accompanied by an increase in the number of fast manipulatory movements without significant changes in locomotor activity. The obtained evidence suggests that the cholinergic system of the sensorimotor cortex indifferent manners regulates the innate (locomotion) and acquired movements which require different periods of maintaining the muscle tone of the forepaw (short-time periods for the usual movements necessary for food taking from the narrow horizontal tube and prolonged periods for the learned slow movements with additional tactile and tonic components).

Animals↗
PubMed1995

Sensorimotor-correlated discharge recorded from ensembles of cerebellar Purkinje cells varies across the estrous cycle of the rat.

1. In the present study, locomotor-correlated activity of cerebellar Purkinje cells, recorded using arrays of microwires chronically implanted in adult female rats, was examined across estrous-cycle-associated fluctuations in endogenous sex steroids. Ongoing studies from this laboratory have shown that systemic and local administration of the sex steroid 17 beta-estradiol (E2) augments excitatory responses of cerebellar Purkinje cells to iontophoretically applied glutamate, recorded in vivo from anesthetized female rats. In addition, this steroid potentiated discharge correlated with limb movement. For the present study, extracellular single-unit activity was recorded from as many as 5-11 Purkinje cells simultaneously during treadmill locomotion paradigms. Motor modulation of activity was recorded across three to five consecutive estrous cycles from behaviorally identified cohorts of neurons to test the hypothesis that fluctuations in endogenous sex steroids alter motor modulation of Purkinje cell discharge. 2. Locomotor-associated discharge correlated with treadmill locomotion was increased by a mean of 47% on proestrus, when E2 levels are elevated, relative to diestrus 1. These changes in discharge rate during treadmill locomotion were of significantly greater magnitude than corresponding cyclic alterations in discharge during stationary periods. 3. Correlations with the circadian cycle were also significant, because peak levels of locomotor-associated discharge on the night of behavioral estrus, following elevations in circulating E2, were on average 67% greater than corresponding discharge recorded during the light (proestrus). 4. Alterations in the step cycle were also observed across the estrous cycle: significant decreases in the duration of the flexion phase (by 265 ms, P < 0.05) were noted on estrus compared with diestrus. 5. When recorded on estrus, Purkinje cell discharge correlated with the stance or flexion phase of the step cycle was greater in magnitude and preceded the event by an average of 130 ms, compared with values determined on diestrus. 6. On estrus, responses of Purkinje neurons to iontophoretically applied quisqualate were enhanced fourfold after administration of exogenous E2, assessed in urethan-anesthetized female rats. 7. In addition, systemic administration of E2 (30 ng iv) potentiated responses of cerebellar Purkinje cells to electrical stimulation of the forepaw by an average of 150%, recorded in anesthetized female rats. 8. These results are consistent with the hypothesis that elevations in circulating E2 are associated with enhanced discharge of cerebellar Purkinje cells in response to pharmacological or electrical stimuli or associated with locomotor behavior.

Animals↗
PubMed2006

Functional significance of age-related differences in motor activation patterns.

Recent functional MRI (fMRI) studies have revealed an increased task-related activation in older subjects during a variety of cognitive or perceptual tasks, which may signal beneficial compensatory activity to counteract structural and neurochemical changes associated with aging. Under the assumption that incremental movement rates are associated with an increased functional demand on the motor system, we used fMRI and acoustically paced movements of the right index finger at six different frequencies (2.0, 2.5, 3.0, 4.0, 5.0 and 6.0 Hz) to investigate the behavioral significance of additionally recruited brain regions in a group of healthy, older subjects (mean age 66 +/- 8 years) compared with a group of young (mean age 23 +/- 7 years) subjects. The actual tapping frequency (F(1,14) = 0.049, P = 0.829), the tapping interval (F(1,14) = 0.043, P = 0.847), and the error rates (F(1,14) = 0.058, P = 0.743) did not differ significantly between both groups, whereas there was a significant increase in reaction time in the older subjects (F(1,14) = 281.786, P < or = 0.001). At all frequencies, the older subjects demonstrated significant overactivation within the ipsilateral sensorimotor and premotor cortex. However, we did not observe an increased age-related overactivation during higher movements rates in these or other motor regions. Moreover, the magnitude of the hemodynamic response in overactivated regions remained constant across all frequencies. In contrast to cognitive tasks, these findings indicate that an age-related overactivation within the motor system is not related to the functional demand and does not necessarily reflect reorganization to compensate for the neurobiological changes of aging.

Acoustic Stimulation↗
PubMed1997

Ethanol consumption following recovery from unilateral damage to the forelimb area of the sensorimotor cortex: reinstatement of deficits and prevention of dendritic pruning.

Unilateral injury to the forelimb-representation area of the sensorimotor cortex (FL-SMC) in adult rats results in use-dependent proliferation of dendritic processes, followed by partial pruning, of layer V pyramidal neurons of the contralateral homotopic cortex. In development, 'exuberant' growth of neurons is often followed by pruning, a process that has been associated with a glutamatergic-NMDA receptor mechanism. A related mechanism may play a role in injury-related pruning of dendrites in adults. The N-methyl-D-aspartate (NMDA) receptor antagonist MK801, administered throughout the pruning phase to adult animals with FL-SMC lesions, prevents dendritic pruning and disrupts behavioral recovery. Ethanol (ETOH) also acts as an NMDA receptor antagonist. It has been shown to reduce NMDA-active ion currents, inhibit NMDA-evoked electrophysiological responses, and decrease glutamate-binding in the hippocampus and cortex. ETOH also affects neuromorphology in the developing and adult cerebellum, hippocampus, and cortex. Ethanol's involvement with NMDA receptor function and its influence on dendritic morphology led us to examine its effect on dendritic pruning and behavioral recovery following unilateral FL-SMC lesions. Lesioned animals were exposed to moderate doses of ethanol in a liquid diet only during the period of dendritic pruning. As with MK801, ETOH prevented pruning and reinstated chronic behavioral asymmetries.

Animals↗
PubMedDate not supplied

Young children's occupations: explicating the dynamics of developmental processes.

Describing development as sequential sensorimotor, cognitive, and psychosocial milestones does not explain how children learn to do or improve their occupations. In response to changes within occupational therapy and challenges in early intervention, this article focuses on development of occupation and proposes a dynamic system perspective. Contemporary research suggests that processes are in place to ensure that children develop as occupational beings. Social participation and caregiving routines guide the child toward becoming occupational by introducing intentional acts and by endowing experiences with meaning. A self-organizing process enables children to integrate their immature capacities and engage in occupations. Simultaneously, caregiving shapes these emerging behaviors, ensuring that performance is culturally compatible. Finally, using self-organization to maintain occupational engagement enables the child to accommodate to maturing abilities and environmental challenges. This reorganized pattern in turn is the basis for developmental changes, new behaviors, and refinement of current abilities. Application of concepts is made to acquisition of skills for eating a meal.

Child Development↗
PubMed1983

Sensorimotor unit activity related to intention in the pulvinar of behaving Cebus Apella monkeys.

Previous observations made in our laboratory in a waking behaving Cebus Apella monkey revealed that neurons of the Pulvinar nucleus of the thalamus discharged preferentially in relation to intentional movements of the limbs and eyes. We give here a description of further observations made in two waking, behaving Cebus Apella monkeys trained to perform two tasks: in the first to make saccadic eye movements to eccentrically placed visual targets; in the second, to make projection movements of the arm and hand to touch targets within arm's reach. The electrical activity of thalamic neurons was recorded extracellularly and records were made simultaneously of the horizontal eye movements and of tasks events. Four-hundred-sixty-five neurons were studied: of these, the activity of 272 could be correlated with behavioral events, while the remaining 193 could not be correlated or classified in this manner. The cells identified were classed in five groups, as follows: (1) neurons active during attentive fixation of a target, but which did not respond to our ordinary visual test stimuli; (2) neurons active during projection movements of the arm or manipulation with the hand, but which were not active during casual movements of the hand or arm, and which were not activated by passive somatic sensory stimuli; (3) those active before, during or after evoked saccadic movements of the eyes, but which were not activated by our testing visual stimuli; (4) neurons active during tracking movements of the eyes, or during projection movements of the arm, alone, but which discharged maximally when these two events occurred simultaneously; and, (5) neurons active during both saccadic movements of the eyes and during projection movements of the arm. We regularly observed, for each of these classes of neurons of the Pulvinar, that optimal correlated activity depended upon the intentional nature of the associated behavioral events, and the animal's attention to them. We conclude that there exists at the level of the Pulvinar a neural correlate of certain evolving behavioral events, and particularly of intentional activity such as the projection of the arm or the direction of gaze towards targets of interest in the immediately surrounding visual environment. The regions of the Pulvinar containing neurons with these properties are reciprocally related to association areas of the Neocortex known to contain neurons with similar properties. It can then be concluded from both anatomical and electrophysiological observations that the Pulvinar is an essential part of the system controlling these complex behavioral events.

Afferent Pathways↗
PubMed1979

Operant conditioning of EEG rhythms and ritalin in the treatment of hyperkinesis.

Enhanced voluntary motor inhibition regularly accompanies conditioned increases in the sensorimotor rhythm (SMR), a 12--14-Hz Rolandic EEG rhythm in cats.A similar rhythm, presumably SMR, has also been identified in the human EEG. The clinical effectiveness of SMR operant conditioning has been claimed for epilepsy, insomnia, and hyperkinesis concurrent with seizure disorders. The present report attempts to follow up and replicate preliminary findings that suggested the technique's successful application to hyperkinesis uncomplicated by a history of epilepsy. SMR was defined as 12--14-Hz EEG activity in the absence of high-voltage slow-wave activity between 4 and 7 Hz. Anticipated treatment effects were indexed by systematic behavioral assessments of undirected motor activity and short attention span in the classroom. EEG and behavioral indices were monitored in four hyperkinetic children under the following six conditions: (1) No Drug, (2) Drug Only, (3) Drug and SMR Training I, (4) Drug and SMR Reversal Training, (5) Drug and SMR Training II, (6) No Drug and SMR Training. All hyperkinetic subjects were maintained on a constant drug regimen throughout the phases employing chemotherapy. Contingent increases and decreases in SMR occurred in three of four training subjects and were associated with similar changes in classroom assessments of motor inactivity. Combining medication and SMR training resulted in substantial improvements that exceeded the effects of drugs alone and were sustained with SMR training after medication was withdrawn. In contrast, these physiological and behavioral changes were absent in one highly distractible subject who failed to acquire the SMR task. Finally, pretraining levels of SMR accurately reflected both the seve-ity of original motor deficits and the susceptibility of hyperkinetic subjects to both treatments. Although the procedure clearly reduced hyperkinetic behavior, a salient, specific therapeutic factor could not be identified due to the dual EEG contingency imposed combined with associated changes in EMG. Despite these and other qualifying factors, the findings suggested the prognostic and diagnostic value of the SMR in the disorder when overactivity rather than distractibility is the predominant behavioral deficit.

Biofeedback, Psychology↗
PubMed2006

A hierarchical model of operational anticipation windows in driving an automobile.

Driving an automobile is an example of a goal-directed activity with high complexity in which different behavioral elements have to be integrated and brought into a sequential order. On the basis of the reafference principle and experimental results on temporal perception and cognitive control, we propose a hierarchical model of driving behavior, which can also be adapted to other goal-directed activities. Driving is conceived of as being controlled by anticipatory neuronal programs; if these programs are disrupted by unpredictable stimuli, which require an instantaneous reaction, behavioral control returns after completion of the reactive mode to the anticipatory mode of driving. In the model different levels of anticipation windows are distinguished which, however, are interconnected, in a bi-directional way: (a) Strategic level with a representation of the driving activity from the beginning to reaching the final goal; (b) Segmented tactical level with the sequence of necessary milestones to reach the goal; (c) Maneuver level where actions like passing another car or keeping a lane are controlled; (d) Short-term integration level of a few seconds which allows immediate anticipations; and (e) Synchronization level for sensorimotor control and complexity reduction within neuronal assemblies. A flow diagram schematically describes different driving situations stressing the anticipatory mode of control. In a pilot experiment with 20 subjects using a virtual driving situation in a car simulator predictions of the model could be verified, i.e., subjects showed a significant preference for the anticipatory mode of driving.

Automobile Driving↗
PubMedDate not supplied

Three-dimensional plotting of neuronal population response patterns.

A computer technique is described for generating three-dimensional plots of the distribution of spike activity in neuronal populations. Data obtained from single neurons in the sensorimotor cerebral cortex of cats are used to plot spike density with respect to depth in the cortex and time following a cutaneous stimulus. The computer programs include a masking (hidden line) subroutine and produce a cross-hatched plot showing the rise and fall of neuronal activity in both space and time. By manipulation of the data matrix and by axis rotations, the plot can be viewed from any desired perspective. This method constitutes a powerful technique for analyzing the spatio-temporal response patterns of neuronal populations. The significance of neuronal population responses for encoding stimulus information and predicting behavior is discussed. Note: Details concerning the computer programs developed for this plotting technique may be obtained from the Division of Systems and Computer Services, Medical College of Georgia, Augusta, GA 30901.

Action Potentials↗
PubMed2001

Spatial hemineglect in humans.

The paper reviews the main findings of studies of hemispatial neglect after acquired brain lesions in people. The behavioral consequences of experimentally induced lesions in animals and electrophysiological studies, which shed light on the nature of the disorder, are briefly considered. Neglect is behaviorally defined as a deficit in processing or responding to sensory stimuli in the contralateral hemispace, a part of the own body, the part of an imagined scene, or may include the failure to act with the contralesional limbs despite intact motor functions. Neglect in humans is frequently encountered after right parieto-temporal lesions and leads to a multicomponent syndrome of sensory, motor and representational deficits. Relevant findings relating to neglect, extinction and unawareness are reviewed and include the following topics: etiological and anatomical basis, recovery; allocentric, egocentric, object-centered and representational neglect; motor neglect and directional hypokinesia; elementary sensorimotor and associated disorders; subdivisions of space and frames of reference; extinction versus neglect; covert processing of information; unawareness of deficits; human and animal models; effects of sensory stimulation and rehabilitation techniques.

Awareness↗
PubMed1993

Spinal cord transection in adult rats: effects of local infusion of nerve growth factor on the corticospinal tract axons.

The spinal cord of adult female rats was completely transected at the T8 level. Nerve growth factor (NGF) was administered at the lesion site via indwelling, implanted, osmotic minipumps. Purified NGF was supplied at doses of 100, 200, and 500 micrograms during a 30-day period. Control rats were treated with saline. At the end of the treatment, the proximal stump of corticospinal tract axons in the spinal cord was labeled with anterograde transported horseradish peroxidase (HRP) injected into the sensorimotor cortex. In control rats, the corticospinal tract axons ended abruptly, proximal to the zone of maximal damage. Sterile swellings developed at the axon tips, and no labeled axonal sprouts were apparent. On the contrary, in NGF-treated animals, the leading front of the corticospinal tract axons showed a trend of approaching the zone of maximal damage following abnormal paths through the dorsal-injured white matter. Axonal sprouts were seen more proximally, traveling toward the transection site in aberrantly located dorsal paths, completely outside the normal position of the corticospinal tract. NGF seems to partly restore the pattern of the regenerative behavior of the severed corticospinal tract axons after spinal cord transection in newborn rats, i.e., the induction of axonal sprouting in aberrantly located dorsal paths. An automated image analysis of the HRP reaction field close to the transection site demonstrated that the density of HRP-labeled axons in the corticospinal tract was significantly higher in the NGF-treated rats than in the control rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1981

Behavioural recovery following transplantation of substantia nigra in rats subjected to 6-OHDA lesions of the nigrostriatal pathway. I. Unilateral lesions.

The ability of embryonic substantia nigra transplants to compensate for behavioural deficits induced by unilateral destruction of the nigrostriatal dopamine pathway has been investigated in adult rats. Six days following unilateral 6-OHDA lesions of the nigrostriatal pathway, the adequacy of the lesion was assessed by measurement of the intensity of ipsilateral amphetamine-induced rotation. All rats then received surgical cavities in the cortex overlying the head of the caudate-putamen on the lesioned side. In 51 rats, transplants of embryonic substantia nigra were placed on the dorsal surface of the caudate-putamen, and the remaining 19 rats served as unilateral lesioned controls. Behavioural testing was conducted approximately 3 months after transplantation: (a) the transplant animals alone showed a marked reduction in ipsilateral rotation induced by 5 mg/kg amphetamine ('compensation'); (b) although both transplanted and control rats expressed equal contralateral rotation at a dose of 0.25 mg/kg apomorphine, the transplant animals alone showed a marked reduction in rotation at a lower dose of 0.05 mg/kg; (c) the transplanted rats showed less asymmetry in spontaneous rotational behaviour than controls, and the asymmetry was further reduced by mild tailpinch; (d) when tested for spontaneous choice behaviour in a T-maze, control rats showed 97% selection of the arm ipsilateral to the 6-OHDA lesion, whereas the transplanted rats that were well compensated on the amphetamine rotation test turned to the contralateral side on 30-40% of choices; (e) no transplant-induced changes were found in contralateral sensory inattention on a sensorimotor test battery, whether tested spontaneously or under mild tailpinch-induced activation. The results support the conclusion that dopaminergic reinnervation of the dorsal neostriatum is capable of inducing functional recovery in many, but not all, behavioural tests which involve side choice or bias, not only after pharmacological activation but also in the spontaneously behaving animal.

Amphetamine↗
PubMed2005

Postural changes after lesions of the substantia nigra pars reticulata in hemiparkinsonian monkeys.

Current neurosurgical strategies target overactive brain regions including the subthalamic nucleus, globus pallidus and thalamus to control various symptoms of Parkinson's disease. Subthalamotomy improves akinesia and can induce postural deficits in both parkinsonian humans and animals, pallidotomy improves limb dyskinesia and more variably, distal bradykinesia whilst thalamotomy improves tremor. Because the SNr also becomes overactive in PD and there are few surgical studies in parkinsonian primates, we therefore evaluated the effects of lesioning the SNr in hemiparkinsonian marmosets to establish the effects on symptomatology. Nine monkeys received unilateral 6-hydroxydopamine (6-OHDA) lesions. Seven weeks later, four received kainic acid lesions of the SNr. Behavioural tests were performed prior to 6-OHDA surgery and then fortnightly for 14 weeks. Unilateral 6-OHDA lesions induced ipsilateral postural bias, ipsilateral rotation after amphetamine injection and bradykinesia. Whilst, SNr lesions significantly altered the direction of head position and amphetamine-induced rotation relative to 6-OHDA lesions, there was no improvement in 6-OHDA-induced reaching deficits or sensorimotor neglect. Unbiased quantitation of the nigral lesions showed on average 88% loss of dopaminergic neurons after 6-OHDA lesions and 77% loss of non-dopaminergic neurons after SNr lesions. Our results demonstrate that the SNr is important in body orientation changes in parkinsonism.

Adrenergic Agents↗
PubMed2003

Convulsive and postural effects of lesioning the mid-substantia nigra pars reticulata in naïve and 6-hydroxydopamine lesioned rats.

The subthalamic nucleus is targeted for the treatment of Parkinson's disease. Unilateral lesions improve some aspects of parkinsonism but produce postural abnormalities in animal models but the exact pathways producing these effects remain to be defined. Using a battery of tests we evaluated the effects of lesioning one of the two major subthalamic targets, the substantia nigra pars reticulata in naïve and 6-OHDA lesioned rats. Lesions targeting the mid-substantia nigra pars reticulata resulted in acute tonic-clonic seizures and intense contralateral rotational asymmetry. During the first month after substantia nigra pars reticulata lesions there was normalisation of the ipsilateral head position bias induced by unilateral 6-OHDA lesions, significant contralateral body axis bias but no significant alteration of apomorphine induced rotation and sensorimotor neglect in 6-OHDA lesioned rats. Combined with our previous data, this suggests that subthalamic projections via the substantia nigra pars reticulata are important in seizures and postural behaviours. Therefore unilateral subthalamotomy probably induces postural deficits in hemiparkinsonian animals via projections involving the substantia nigra pars reticulata. This has implications for patients undergoing subthalamotomy for treatment of Parkinson's disease.

Animals↗
PubMed2004

Prestimulus oscillations enhance psychophysical performance in humans.

The presence of various ongoing oscillations in the brain is correlated with behavioral states such as restful wakefulness or drowsiness. However, even when subjects aim to maintain a high level of vigilance, ongoing oscillations exhibit large amplitude variability on time scales of hundreds of milliseconds to seconds, suggesting that the functional state of local cortical networks is continuously changing. How this volatility of ongoing oscillations influences the perception of sensory stimuli has remained essentially unknown. We investigated the relationship between prestimulus neuronal oscillations and the subjects' ability to consciously perceive and react to somatosensory stimuli near the threshold of detection. We show that, for prestimulus oscillations at approximately 10, 20, and 40 Hz detected over the sensorimotor cortex, intermediate amplitudes were associated with the highest probability of conscious detection and the shortest reaction times. In contrast, for 10 and 20 Hz prestimulus oscillations detected over the parietal region, the largest amplitudes were associated with the best performance. Our data indicate that the prestimulus oscillatory activity detected over sensorimotor and parietal cortices has a profound effect on the processing of weak stimuli. Furthermore, the results suggest that ongoing oscillations in sensory cortices may optimize the processing of sensory stimuli with the same mechanism as noise sources in intrinsic stochastic resonance.

Adult↗
PubMed1996

Human cortical 40 Hz rhythm is closely related to EMG rhythmicity.

We recorded cortical neuromagnetic rhythms during self-paced index-finger movements from a subject previously reported to show prominent 40 Hz electroencephalographic activity during motor behavior. The 10 and 20 Hz components of the rolandic mu rhythm were bilaterally suppressed, whereas the contralateral 40 Hz (35-41 Hz) activity was slightly enhanced before both fast and slow movements and strongly enhanced during slow movements. The 40 Hz rhythm originated mainly in the hand motor cortex and was clearly correlated with the rhythmicity of the electromyogram from the extensor muscles, with a systematic time lag. In this subject motor preparation, and especially control of finger movements, may thus be associated with enhanced cortical rhythms near 40 Hz. The coherence of these rhythms with muscular firing patterns likely reflects communication between the sensorimotor cortex and the motor units.

Adult↗
PubMed2005

Altered distribution of striatal activity-dependent synaptic plasticity in the 3-nitropropionic acid model of Huntington's disease.

Huntington's disease (HD) is a neurodegenerative disorder characterized by involuntary choreiform movements, neuropsychiatric disturbances and cognitive decline. The hyperkinetic phenomenology has commonly been attributed to a disturbance of the basal ganglia function, mainly the neostriatum, but its pathophysiology mechanisms remain unclear. Activity-dependent long-term changes in synaptic efficacy, such as long-term potentiation (LTP) and long-term depression (LTD), are widely considered to be the cellular models for acquisition and storage of information in neuronal networks. Both LTP and LTD have been described at the corticostriatal pathway and they might be probably involved not only in physiological motor behavior processing but also in disease states affecting that pathway. Systemic injection of 3-nitropropionic acid (3-NP) induces excitotoxic striatal lesions and abnormal movements in rodents, resembling those seen in HD. We examined synaptic plasticity in dorsolateral striatum slices prepared from both control and 3-NP-treated rats by recording extracellular field potentials. Our results reinforce the idea that both forms of activity-dependent synaptic plasticity can be recorded at the dorsolateral region of striatum by the same stimulating protocol in control rats and suggest that 3-NP-induced striatal lesions may be associated with suppression of LTD expression in the sensorimotor striatum.

Animals↗
PubMed1999

The effect of rubrospinal tractotomy on a conditioned limb response in the cat.

Five cats were trained to perform a forelimb conditioned response to a paired tone CS/shock UCS. Rubrospinal tract section ipsilateral to the trained limb was carried out following criterion CR performance. Lesion sites were identified histologically and further confirmed by observation of cellular changes in the red nucleus contralateral to the trained limb. Tractotomy resulted in total or near-total loss of the CR. Prolonged postoperative training resulted in no increase in CR performance levels. The UCR remained unaffected, as did limb placing, accuracy of striking at moving objects, grooming, running and walking. Training of the opposite limb in two subjects resulted in mean scores of 90 and 85% within three sessions. Control lesions in those subjects resulted in no changes in CR performance scores. The red nucleus receives a substantial input from sensorimotor cortex and cerebellum, both of which have been shown to represent essential parts of the brain circuitry involved in associative learning and memory. Since pyramidotomy has no effect on limb CR performance [Vonedia TJ. Exp Neurol 1976;19:483-493], the possible role of the red nucleus/rubrospinal tract is discussed in terms of a critical trigger area for the expression of a learned motor response.

Animals↗