Movement sequence-related activity reflecting numerical order of components in supplementary and presupplementary motor areas

The supplementary motor area (SMA) and presupplementary motor areas (pre-SMA) have been implicated in movement sequencing, and neurons in SMA have been shown to encode what might be termed the relational order among sequence components (e.g., movement X followed by movement Y). To determine whether other aspects of movement sequencing might also be encoded by SMA or pre-SMA neurons, we analyzed task-related activity recorded from both areas in conjunction with a sequencing task that dissociated the numerical order of components (e.g., movement X as the 2nd component, irrespective of which movements precede or follow X). Sequences were constructed from eight component movements, each characterized by three spatial variables (origin, direction, and endpoint). Task-related activity recorded from 56 SMA and 63 pre-SMA neurons was categorized according to both the epoch (delay, reaction time, and movement time) and the spatial variable or component movement with which it was associated. All but one instance of task-related activity was selective for one of the spatial variables (SV-selective) rather than for any of the component movements themselves. Of 110 instances of SV-selective activity in SMA, 43 (39%) showed significant effects of numerical order. The corresponding incidence in pre-SMA, 82 (71%) of 116, was substantially higher (P < 0.00001). No effects of numerical order were evident among the hand paths, movement times, or electromyographic activity associated with task performance. We concluded that neurons in SMA and pre-SMA may encode the numerical order of components, at least for sequences that are distinguished mainly by that aspect of component ordering.     

Multiple cortical motor areas and temporal sequencing of movements

This paper analyses the purpose, background, scope, and success to date of designing and implementing a comprehensive electronic patient record system for community care in the UK, in the context of the increasing policy focus upon community care. The project is situated in Plymouth in the UK, a major provider of community care. The paper indicates intended benefits of the system for patients, professionals, and health care organisations. The rationale behind the record content is explained, as is the record structure. Intended uses of the records form a further baseline for study, and the paper assesses the key success factors to achieving the goal of reliability, quality, and effective use of resources.     

Changing directions of forthcoming arm movements: neuronal activity in the presupplementary and supplementary motor area of monkey cerebral cortex

1. To understand roles played by two cortical motor areas, the presupplementary motor area (pre-SMA) and supplementary motor area (SMA), in changing planned movements voluntarily, cellular activity was examined in two monkeys (Macaca fuscata) trained to perform an arm-reaching task in which they were asked to press one of two target buttons (right or left) in three different task modes. 2. In the first mode (visual), monkeys were visually instructed to result and press either a right or left key in response to a forth coming trigger signal. In the second mode (stay), monkeys were required to wait for the trigger signal and press the same target key as pressed in preceding trials. In the third mode (shift), a 50 Hz auditory cue instructed the monkey to shift the target of the future reach from the previous target to the previous nontarget. 3. While the monkeys were performing this task, we recorded 399 task-related cellular activities from the SMA and the pre-SMA. Among them, we found a group of neurons that exhibited activity changes related specifically to shift trials (shift-related cells). The following properties characterized these 112 neurons. First, they exhibited activity changes after the onset of the 50-Hz auditory cue and before the movement execution when the monkeys were required to change the direction of forthcoming movement. Second, they were not active when the monkeys pressed the same key without changing the direction of the movements. Third, they were not active when the monkeys received the 50-Hz auditory cue but failed to change the direction of the movements by mistake. These observations indicate that the activity of shift-related cells is related to the redirection of the forthcoming movements, but not to the auditory instruction itself or to the location of the target key or the direction of the forthcoming movements. 4. Although infrequently, monkeys made errors in the stay trials and changed directions of the reach voluntarily. In that case, a considerably high proportion of shift-related neurons (12 of 19) exhibited significant activity changes long before initiation of the reach movement. These long-lasting activities were not observed during the preparatory period in correct stay trials, but resembled the shift-related activity observed when the target shift was made toward the same direction. Thus these activity changes were considered to be also related to the process of changing the intended movements voluntarily. 5. We found another population of neurons that showed activity modulation when the target shift was induced by the visual instruction in visual trials (visually guided shift-related neurons). These neurons were active when the light-emitting diode (LED) guided the forthcoming reach to the previous nontarget but not to the previous target. Therefore their activity was not a simple visual response to the LED per se. A majority of them also showed shift-related activity in shift trials (19 of 22 in monkey 2). 6. Neurons exhibiting the shift-related activity were distributed differentially among the two areas. In the pre-SMA, 31% of the neurons recorded showed the shift-related activity, whereas in the SMA, only 7% showed such an activity. These results suggest that pre-SMA and SMA play differential roles in updating the motor plans in accordance with current requirements.     

Shared motor error for multiple eye movements

Most natural actions are accomplished with a seamless combination of individual movements. Such coordination poses a problem: How does the motor system orchestrate multiple movements to produce a single goal-directed action? The results from current experiments suggest one possible solution. Oculomotor neurons in the superior colliculus of a primate responded to mismatches between eye and target positions, even when the animal made two different types of eye movements. This neuronal activity therefore does not appear to convey a command for a specific type of eye movement but instead encodes an error signal that could be used by multiple movements. The use of shared inputs is one possible strategy for ensuring that different movements share a common goal.     

Role for cells in the presupplementary motor area in updating motor plans

Two motor areas are known to exist in the medial frontal lobe of the cerebral cortex of primates, the supplementary motor area (SMA) and the presupplementary motor area (pre-SMA). We report here on an aspect of cellular activity that characterizes the pre-SMA. Monkeys were trained to perform three different movements sequentially in a temporal order. The correct order was planned on the basis of visual information before its execution. A group of pre-SMA cells (n = 64, 25%) were active during a process when monkeys were required to discard a current motor plan and develop a plan appropriate for the next orderly movements. Such activity was not common in the SMA and not found in the primary motor cortex. Our data suggest a role of pre-SMA cells in updating motor plans for subsequent temporally ordered movements.     

The role of temporal cortical areas in perceptual organization

The visual areas of the temporal lobe of the primate are thought to be essential for the representation of visual objects. To examine the role of these areas in the visual awareness of a stimulus, we recorded the activity of single neurons in monkeys trained to report their percepts when viewing ambiguous stimuli. Visual ambiguity was induced by presenting incongruent images to the two eyes, a stimulation condition known to instigate binocular rivalry, during which one image is seen at a given time while the other is perceptually suppressed. Previous recordings in areas V1, V2, V4, and MT of monkeys experiencing binocular rivalry showed that only a small proportion of striate and early extrastriate neurons discharge exclusively when the driving stimulus is seen. In contrast, the activity of almost all neurons in the inferior temporal cortex and the visual areas of the cortex of superior temporal sulcus was found to be contingent upon the perceptual dominance of an effective visual stimulus. These areas thus appear to represent a stage of processing beyond the resolution of ambiguities--and thus beyond the processes of perceptual grouping and image segmentation--where neural activity reflects the brain's internal view of objects, rather than the effects of the retinal stimulus on cells encoding simple visual features or shape primitives.     

Both the tool and the carpenter are important

A 67-year-old woman with a history of a skin melanoma that was excised 7 years previously had a 6-month history of decreased vision in her right eye. A choroidal melanoma was diagnosed clinically, and the eye was enucleated. The results of a histopathological examination revealed a primary uveal melanoma. Slides of the skin melanoma were obtained, and the initial diagnosis was confirmed. In an attempt to illustrate a biological difference between the 2 melanomas, immunohistochemical studies were performed on sections of the 2 specimens using S-100 protein, HMB-45, and S-100-beta. Primary cutaneous and choroidal melanomas appearing in a patient with no predisposition are rare; this is believed to be only the fifth such case reported in the literature.     

Sequential hemodynamic activation of motor areas and the draining veins during finger movements revealed by cross-correlation between signals from fMRI

Activity in the human supplementary motor area (SMA), primary motor cortex (M1), and the draining vein of the motor cortex during a visually triggered finger opposition task was measured by functional magnetic resonance imaging with a repetition time of 1 s. Sequential hemodynamic activation in these areas was revealed by cross-correlating a signal sequence in M1 directly with signal sequences from SMA and the draining vein, and applying polynomial fitting with the aid of Akaike's information criterion. We succeeded in detecting a time delay of approximately 0.5 s between the activations of SMA and M1, and a delay of nearly 1.3 s between the activations of M1 and its draining vein. The new combination of fMRI and data analysis techniques has attained a time resolution comparable to those in preceding studies that used shorter fMRI repetition times of 100-200 ms.     

Developmental changes in the organization of prereaching movements.

Examined how the kind and amount of prereaching activity change with age during the period preceding successful grasping of objects. 23 infants were tested at 3-wk intervals from the 1st week of life to 16 wks of age. 12 Ss were also seen at 19 wks of age. At each session, the S was presented with an object moving slowly in different ways in front of him or her. In the middle of each session there was also a 1-min period with no object present. Results show that the amount of prereaching declined at 7 wks and that this decrease was contingent on the presence of the object. Ss did not seem to lose interest in the object at this age, but attending to the object inhibited prereaching activity in some way. The form of prereaching also changed at 7 wks, with the fist clenched during the forward extension of the arm. After this age, the amount of prereaching activity again increased and the hand opened during the forward extension, but only when the S looked at the object. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional demands and the organization of reaching movements in rock climbing

Epiphrenic oesophageal diverticula are of the pulsation type, the underlying cause is a motility disorder. Resection is indicated by severe symptoms like dysphagia, regurgitation or aspiration and should be performed after endoscopic dilatative treatment of the neuromotor disturbance. Thoracoscopic resection under endoluminal endoscopic surveillance is considered to be a reliable procedure with low morbidity for the patient.     

Neuronal activity in the primate supplementary motor area and the primary motor cortex in relation to spatio-temporal bimanual coordination

Single neuronal activity was recorded from the supplementary motor area (SMA-proper and pre-SMA) and primary motor cortex (M1) in two Macaca fascicularis trained to perform a delayed conditional sequence of coordinated bimanual pull and grasp movements. The behavioural paradigm was designed to distinguish neuronal activity associated with bimanual coordination from that related to a comparable motor sequence but executed unimanually (left or right arm only). The bimanual and unimanual trials were instructed in a random order by a visual cue. Following the cue, there was a waiting period until presentation of a "go-signal", signalling the monkey to perform the instructed movement. A total of 143 task-related neurons were recorded from the SMA (SMA-proper, 62; pre-SMA, 81). Most SMA units (87%) were active in both unimanual contralateral and unimanual ipsilateral trials (bilateral neurons), whereas 9% of units were active only in unimanual contralateral trials and 3% were active only in unimanual ipsilateral trials. Forty-eight per cent of SMA task-related units were classified as bimanual, defined as neurons in which the activity observed in bimanual trials could not be predicted from that associated with unimanual trials when comparing the same events related to the same arm. For direct comparison, 527 neurons were recorded from M1 in the same monkeys performing the same tasks. The comparison showed that M1 contains significantly less bilateral neurons (75%) than the SMA, whereas the reverse was observed for contralateral neurons (22% in M1). The proportion of M1 bimanual cells (53%) was not statistically different from that observed in the SMA. The results suggest that both the SMA and M1 may contribute to the control of sequential bimanual coordinated movements. Interlimb coordination may then take place in a distributed network including at least the SMA and M1, but the contribution of other cortical and subcortical areas such as cingulate motor cortex and basal ganglia remains to be investigated.     

The motor organization of the sense of rhythm

Serum inorganic fluoride levels in obese versus control patients were compared during and after sevoflurane anesthesia. Mean serum inorganic fluoride levels in the obese group increased more rapidly and were significantly higher than in the control group at each sampling time (P < 0.01). The area under the curve of fluoride concentration, versus time up to 24 h and 48 h in the obese patients, was significantly greater than that in the nonobese patients (P < 0.001). Peak serum fluoride level in the obese patients was 51.7 +/- 2.5 mumol/L and exceeded 50 mumol/L for nearly 2 h. Our study showed that serum fluoride concentrations between mildly obese and nonobese patients differed during and after sevoflurane anesthesia.     

Evidence for direct connections between the hand region of the supplementary motor area and cervical motoneurons in the macaque monkey

In primates the corticospinal neurons of the hand representation of the primary motor cortex (M1) give rise to direct contacts with the cervical motoneurons that control distal forelimb muscles. We investigated, at the light-microscopy level, whether corticospinal cells present in the hand area of the supplementary motor area (SMA) also establish direct connections with cervical motoneurons, particularly those innervating hand and finger muscles. The hand representation of the M1 (two monkeys) or SMA (two monkeys) was located using intracortical microstimulation and injected with the anterograde tracer biotinylated dextran amine to label corticospinal terminals. Forearm muscles acting on the wrist and hand as well as hand muscles acting on the thumb and index finger, thus including those activated by intracortical stimulation, were injected with the retrograde tracer cholera-toxin B subunit, in order to label the motoneurons. A consistent zone of overlap between the two markers was found in the cervical cord. Close appositions between corticospinal axonal terminals and the somata or dendrites of motoneurons were found after injection in the M1, confirming previous observations. The new finding is the observation of similar close appositions after injection in the SMA, suggesting its control of hand movements in parallel with the M1.     

The mechanism of the organization of the types of goal-directed movements]

A possible organization of motor control during moving from a distant point to a purposive one is considered as a way of reduction of three excessive degrees of freedom at hierarchically coordinated levels of motor control. Computer simulation of such movement organization showed its insensitivity to dynamic noise, fluctuations in driving parameters, deviations, delays, and "clutches" of separate joints.     

Cortical areas and the control of self-determined finger movements: an fMRI study

We investigated cortical areas involved in the control of self-determined finger movements. In a tapping task, subjects tapped with different movement frequencies in two different movement conditions (predetermined vs self-determined). fMRI provided evidence for the involvement of the horizontal and ascending parts of the intraparietal sulcus (IPS), the left superior frontal gyrus and the posterior cingulate gyrus in the control of self-determined finger movements. Higher movement frequency increased the extent of activated area only in the horizontal part of IPS. The results suggest a major role of the IPS in controlling sequences of finger movements. This area probably serves as a region for integration of motor, sensory and sensorimotor feedback information used for movement control.     

Nucleotide-dependent movements of the kinesin motor domain predicted by simulated annealing

A frailty model for multivariate correlated life times is considered. The model both extends, in a rather straight-forward way, ordinary survival analysis with its emphasis on hazard modeling and incorporates well-known variance components models to account for the dependence between events of related individuals. Different approaches to estimation and inference are considered. An example from an ongoing study of genetic and environmental influences on premature death in adults serves to motivate and illustrate the model. Multivariate frailty models offer a conceptually simple and promising framework for analysis of correlated event times data, even if current knowledge is too sparse for such models to be tested critically.