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Biomedical subjects

K M Bennett

Publications and source records attributed to K M Bennett.

32 records · Page 2Linked to original sources
PubMed1995

The drinking action of Parkinson's disease subjects.

Using the ELITE system, a kinematic analysis was performed of the upper limb drinking action of nine Parkinson's disease patients and nine control subjects. The aim was to use a natural task to investigate the reported Parkinson's disease dysfunction in the performance of simultaneous and sequential movements. Subjects were required to reach 28 cm, grasp a half-filled glass and then take a sip of water. Dysfunction for simultaneous movements was supported by the finding that, in both absolute and relative terms, Parkinson's disease subjects often began to open the hand later than control subjects. Dysfunction for sequential movements was supported by the finding that Parkinson's disease subjects often showed a pause between the first ('reach-grasp') and second ('take-to-lips') parts of the drinking action. Despite these delays and pauses, the proportional organization of the action was similar for both groups. This suggested that Parkinson's disease subjects were able to compensate for the problem in activating the different components of the drinking action. The results are discussed in relation to the influence of the abnormal basal ganglia input to cortical motor regions.

Adult↗
PubMed1994

The influence of single monkey cortico-motoneuronal cells at different levels of activity in target muscles.

1. This study assessed the facilitation by cortico-motoneuronal (CM) cells of hand and forearm muscles at different levels of EMG activity. 2. Twenty-three CM cells were recorded in six hemispheres of four trained monkeys. CM cells were identified by the presence of post-spike facilitation (PSF) in spike-triggered averages (STAs) of their target muscles. Cell and muscle activity was recorded during performance of a low force (0.2-1.5 N) precision grip task between the index finger and thumb. The hold periods of this task lasted 1-1.5 s and provided segments of steady EMG activity. 3. The discharge activity of each CM cell, and the amplitude of the PSF produced in one or two target muscles, were compared across two to six different levels of EMG activity during the hold periods. 4. Of the forty-two CM cell-muscle combinations tested, twenty (48%) showed a significant increase in CM cell discharge rate with increased target muscle EMG activity (P < 0.001); three (7%) showed significant negative correlation; and no correlation was found for nineteen combinations (45%). 5. From a low to a high level of EMG activity (0.3-8.65% of the maximum EMG activity recorded), the absolute amount of facilitation produced by each CM cell increased by a factor of 1.2-32 (median value 3.7). This increase in facilitation occurred irrespective of the presence or absence of correlation between CM cell discharge rate and target muscle activity. 6. For thirty cell-muscle combinations in which a significant PSF could be measured at more than one level of EMG activity, the relative degree of facilitation remained constant in nine, increased in thirteen and decreased in seven combinations. In some cases saturation effects were evident. For ten combinations PSF was observed at high but not at low levels of EMG activity. 7. The changes in PSF amplitude with level of EMG activity were also present in STAs compiled from only those spikes with long interspike intervals (20-25 ms or greater). The results suggested that spikes with short interspike intervals did not make a significant contribution to the increase in PSF amplitude observed at the higher levels of EMG activity. 8. The changes in PSF amplitude with target muscle activity are probably explained best by changes at the spinal motoneuronal level, which set the response to the CM input. These changes may also reflect differences in the strength of synaptic connectivity made by a CM cell within the motoneurone pool of the target muscle.

Action Potentials↗
PubMed1994

Parkinson's disease: reorganization of the reach to grasp movement in response to perturbation of the distal motor patterning.

This study assessed the kinematic changes to the reach to grasp movement in response to a perturbation of object size in 15 Parkinson's disease (PD) and 15 control subjects. For non-perturbed trials subjects reached 35 cm to grasp and lift either an illuminated small (0.7 cm) or large (8 cm) diameter cylinder. For perturbed trials (20%), illumination shifted unexpectedly from the small to the large or from the large to the small cylinder at the onset of the reach. For Condition One trials subjects were given no instructions as to which grasp to use. With perturbation, they thus naturally changed grasp from precision grip to whole hand prehension or vice versa. The results for the PD subjects indicated a slowness at the transition from one to another grasp. This contrasted to the smooth transitions when perturbation required only a change of grasp aperture (precision grip--Condition Two; whole hand prehension--Condition Three). PD subjects thus showed dysfunction in the suppression/activation of different grasp programs rather than deficits in the on-line modification of an operating program.

Aged↗
PubMed1994

Reach to grasp: changes with age.

This study provides the first known kinematic assessment of the reach-to-grasp movement in elderly subjects. Twelve subjects (aged 60-71) were compared to gender-matched younger subjects (aged 18-25). Subjects reached 35 cm to grasp either a small (0.7 cm) or a large (8 cm) diameter cylinder. Precision grip was naturally adopted for the small cylinder, and whole hand prehension for the large cylinder. The displacements of active infrared markers (wrist and hand) were recorded with an Optotrak system. Movement initiation time, movement duration, and kinematic parameters of the reach-and-grasp components were computed. Older subjects showed slower, longer movements with a prolonged approach phase. However, the patterning and coordination of this movement, with respect to the utilization of a precision grip or whole hand prehension, were similar for both groups. Subtle changes with age thus appear to reflect a strategy that develops to compensate for deterioration in other systems such as visual or proprioceptive.

Adolescent↗
PubMed1993

The bilateral reach to grasp movement.

This study investigated the kinematic organization of bilateral reach to grasp movements. In Experiment 1 non-homologous bilateral movements were performed. One limb reached to grasp an object using whole hand prehension; the contralateral limb simultaneously reached to grasp an object using precision grip. Corresponding unilateral movements were assessed. Movement duration for each limb in the bilateral condition was similar. However, with earlier temporal settings for peak wrist acceleration and velocity, the limb performing precision grip showed a longer approach (deceleration) phase to the object. Unilateral precision grip movements showed a longer movement duration and deceleration phase than unilateral whole hand prehension movements. In Experiment 2 homologous bilateral movements were assessed. Both limbs performed either a reach and whole hand prehension or a reach and precision grip. Again the precision grip movements showed longer movement and deceleration times. Experiment 3 consisted of bilateral non-homologous pointing movements and a pointing movement with one limb while reaching to grasp with the contralateral limb. It was found that the earlier temporal settings of peak acceleration and velocity with the precision grip limb of the non-homologous bilateral task (Expt. 1) were largely due to the performance of distal grasping actions. It is concluded that a kinematic parameterization which is independent to each limb is evident for bilateral tasks which require functionally independent actions.

Adolescent↗
PubMed1993

The reach to grasp movement of blind subjects.

The importance of vision for the processing and coordination of the transport and manipulation components of a reach to grasp movement was assessed. Four blind volunteers (two men, two women; aged 25-40) were compared with matched control groups: (1) blindfolded and (2) full vision. Subjects reached 20 or 30 cm for a large or small diameter (6 cm or 0.7 cm, respectively) cylinder. For condition 1 trials they were given no instruction as to the type of grasp to adopt; for condition 2 they were instructed to consistently use a precision grip; while for condition 3 they were required to use whole had prehension. Blind subjects demonstrated a double grip pattern and either a low-velocity phase (20 cm) or a double transport movement (30 cm). However, their pattern of prehension with respect to intrinsic (size) and extrinsic (distance) cylinder properties was similar to that of the control groups. Grip aperture was appropriately scaled and, when greater precision was required, deceleration time was prolonged. Temporal coupling was evident between the two components. It was concluded that experience of vision is not necessary for the coordination or patterning of the basic reach to grasp movement. It does allow, however, for a movement consisting of only one opening and closing of the hand.

Acceleration↗
PubMed1993

Reach to grasp: the natural response to perturbation of object size.

This study assessed the reach to grasp movement and its adaptive response to a perturbation of object size. In blocked trials, subjects (n = 12) were instructed to reach 35 cm to grasp and lift a small- (0.7 cm) or large-diameter (8 cm) cylinder. Under an unconstrained condition (condition 1), no instructions as to the type of grasp to adopt were given. Subjects thus naturally used a precision grip (PG) for the small cylinder and whole hand prehension (WHP) for the large cylinder. Under condition 2, subjects were instructed to utilize a PG for grasps of both the large and small cylinders. For condition 3, the instruction was to use WHP irrespective of object size. Kinematic organization was determined with analysis of the recordings of active markers placed on the wrist, thumb, and three fingers. For condition 1 the results showed a temporal arrangement of both components (transport and manipulation) which differed from that of conditions 2 and 3. In perturbed trials, illumination shifted from the small to large cylinder or vice versa. With condition 1, subjects automatically switched from one grasp to another with no or little increase of movement duration. This was generally achieved by an earlier temporal setting of peak wrist deceleration. For conditions 2 and 3, where a change of aperture was required, movement duration was prolonged without adaptation of earlier transport component parameters. It is concluded that the adaptive responses to a change of distal patterning also affect the organization of the proximal component. Assessment of grasps constrained by instructions may lead to interpretations of central control of the reach to grasp movement which differ from those obtained by assessing more natural prehensile patterns.

Adolescent↗
PubMed1993

A kinematic study of the reach to grasp movement in a subject with hemiParkinson's disease.

The kinematic organization of a reach to grasp movement in a left hemiParkinson subject is compared to that of a control subject. Subjects used the right and left limbs to reach 15, 27 or 40 cm for the grasp of cylinders of 0.7 or 8 cm diameter. In general, the kinematics of the affected limb of the hemiParkinson subject differed from that of the unaffected limb. However, for both arms the hemiParkinson subject showed a delay in the onset of the manipulation component. The subtle dysfunction in the activation of near-simultaneous or sequential movements is thus bilateral, despite unilateral clinical symptomatology.

Aged↗
PubMed1993

Perturbation of the grasp component of a prehension movement in a subject with hemiParkinson's disease.

The response to perturbation of the manipulation component during prehension was assessed for both hands of a hemiParkinson and of a Control subject. With perturbed trials, the hemiParkinson showed the same pattern as the Control: a reorganization of kinematic parameters and no increase of movement time. However, for both limbs of the hemiParkinson subject there was a transition phase from precision grip to whole hand prehension--this was more pronounced for the affected limb. The manipulation component did not show a delay of activation [2]. Thus the global dysfunction in the performance of sequential movement patterns was related to aspects of task predictability.

Aged↗
PubMed1993

Contribution of the monkey corticomotoneuronal system to the control of force in precision grip.

1. The contribution of 33 corticomotoneuronal (CM) cells, recorded in the primary motor cortex, to the production of precision grip force has been investigated in four monkeys (Macaca nemestrina). These CM cells were shown, by spike-triggered averaging, to facilitate electromyographic (EMG) activity of hand and forearm muscles. 2. Single-cell recordings were obtained as the monkey performed a low force precision grip task under either isometric or auxotonic conditions. The monkey had to produce independent control of the forces exerted by the thumb and index finger and maintain them for 1-1.5 s. Steady force segments of data were selected trial-by-trial from these hold periods. For each segment the following mean values were determined: 1) CM cell firing rate, 2) EMG activity of facilitated muscles, and 3) index finger, thumb, and total force. 3. Of the 33 CM cells, 18 had a phasic-tonic pattern of discharge during the task, 7 were tonic, 5 had a ramplike increase, and 3 were deactivated during the hold period. 4. Of the 33 cells analyzed, 11 showed a significant positive (P < 0.05) correlation of their mean firing rate with static force; 4 of them had high correlation coefficients (P < 0.001). There was a considerable trial-by-trial variability in the cells' activity-force relationship. Six CM cells had significant negative correlations between their activity and isometric force (5 at the P < 0.001 level), showing lower firing rates with higher forces. 5. The force sensitivity of the CM cells, calculated from the rate-force slopes, was higher for either the thumb or the index finger force. Under isometric conditions the mean rate-force slopes, calculated from the best correlated digit force, was 32.4 Hz/N for eight positively correlated cells and -21.3 Hz/N for the cells with a negative correlation. 6. Correlation between CM cell spike activity and force was more common among neurons with slowly conducting axons (4/6 correlated) than for those with fast axons (13/27). 7. Significant correlations between target muscle EMG and force were always positive. The correlations between CM cell firing rate and target muscle EMG were comparable with those found between firing rate and force. Three of the CM cells with a negative correlation to force also had a negative correlation with EMG in one of their target muscles. 8. Each CM cell facilitated the EMG activity of one to five target muscles; postspike facilitation (PSF) was most common among intrinsic hand muscles (68/82 CM cell/muscle combinations).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Does the type of prehension influence the kinematics of reaching?

Kinematic studies have indicated that when a subject reaches to grasp an object, the movement consists of two primary components: (a) a transport phase whereby the hand is brought towards the object and (b) a grip phase whereby the hand changes shape in anticipation of the grasp. Using a visual perturbation paradigm, we investigated the effect of different grip component strategies upon the transport phase. The distal strategy was determined by the size of the object to be grasped: for the small object (1.5 cm o.d.) subjects naturally adopted a precision grip between the index finger and thumb; for the large object (6 cm o.d.) subjects used a whole hand prehensile grip. During 20% of the reaching trials the perturbation was introduced by unexpectedly changing the object size. The results showed that corrections to the distal program in response to the perturbation were preceded by changes in the deceleration phase of the proximal component. The data supported previous findings of two visuo-motor channels for this prehensile movement but indicated that when unanticipated shifts of only the distal program are required, both channels show modifications.

Acceleration↗
PubMed1985

Therapeutic exercise.

Physical activity provides the biologic stimulus for a number of body adaptive mechanisms and therefore is a potent force in both prevention and treatment of sports injury. It has been shown, however, that therapeutic exercise must be prescribed with precision and care if it is to be of optimal value. There are no "general" effects of exercise. The effects of exercise on the cellular structure of muscle, connective tissue, and the nervous system are specific to the intensity, duration, and frequency of exercise and dependent on the length of time after injury.

Athletic Injuries↗
PubMed1981

Monoclonal antibody analysis of lipopolysaccharide from Neisseria gonorrhoeae and Neisseria meningitidis.

A hybridoma produced by the polyethylene glycol fusion of the NS-1 variant of the P3x63Ag8 BALB/c plasmacytoma to splenocytes harvested from a BALB/c mouse immunized with whole gonococci was found to be producing antibody to a common region on gonococcal lipopolysaccharide (LPS). Enzyme-linked immunosorbent assay inhibition systems were established by utilizing this antibody, designated 3F11, and 100% inhibition occurred with both LPS and the LPS-LPS and LPS-derived polysaccharides partially inhibited the enzyme-linked immunosorbent assay, whereas similar preparations isolated from Escherichia coli O:111, the J-5 mutant of this strain, and Salmonella minnesota Re595 failed to inhibit the assay. Studies utilizing whole gonococcal strains 4505 and the isogenic variant 4505r, which lacks both the LPS serotype and common determinants as inhibitors, demonstrated that the determinant recognized by the 3F11 antibody was present on the surface of 4505 and absent on 4505r. Inhibition studies were performed with beta-glucose, beta-galactose, D-glucosamine, D-galactosamine, heptose, 2-keto-3-deoxyoctanoate, N-acetylglucosamine, N-acetylgalactosamine, alpha-lactose, and beta-lactose. Complete inhibition of the enzyme-linked immunosorbent assay occurred with D-galactosamine, and partial inhibition was achieved with both alpha-lactose and beta-lactose. Based on these observations, the 3F11 antibody recognizes a site common to gonococcal LPS which is partially shared by meningococcal LPS. The chemical structure of the determinant appears to be a D-galactosamine-O-D-galactopyranosyl-(1-4)-D-glucopyranose. Additional specificity may be conferred by the steric relationship of the determinant on the intact LPS.

Antibodies, Bacterial↗