Search

Introduces the selection of research papers in 'Motor Control' of 1998 issue. Citations on the interdisciplinary neuroscience fields in relevance to the study; Emphasis on the clinical aspects of motor control.

Franklin Henry's "memory drum" theory of neuromotor reaction (Henry & Rogers, 1960) was one of the most influential studies of the response programming stage of information processing. The paper is the most-cited study ever published in the Research Quarterly for Exercise and Sport. However, few people know there is a noteworthy error in the paper, namely in the description of the C movement, the most complicated of the three responses studied. Henry himself was unaware of the error for nearly 20 years after the paper's publication. The purpose of our paper is to accord the factual record its due respect by revealing the history about the error and its correction. The data are in the form of the original 1960 paper which describes the C movement, a paper by Howell (1953), and personal letters from Henry dating from 1979, when the error was first discovered, and continuing through 1986. In one letter, Henry attributed the error to a mild and specific form of aphasia, manifested by word reversals, from which he suffered throughout his scholarly life. Such a revelation makes the career of this remarkable scholar even more remarkable. [ABSTRACT FROM AUTHOR]

Responsiveness to suggestions while hypnotized is termed hypnotic susceptibility. An association between reaction time and hypnotic susceptibility has been demonstrated, but whether distinct changes in brain activity accompany this relationship remains unclear. We investigated the effect of hypnotic susceptibility on the speed of information processing and motor cortical preparatory activity. Twenty-one "low" (Low HS ) and fifteen "high" (High HS ) hypnotically susceptible right-handed participants performed precued simple (SRT) and choice (CRT) reaction time key-press tasks under hypnotized and non-hypnotized conditions. Force and surface electromyography data were recorded from left and right index fingers. The contingent negative variation (CNV) was derived from electroencephalography data. Mean reaction time and premotor time was shorter in High HS participants than Low HS participants for both simple and choice reaction time tasks. High HS participants in the hypnotized state performed fewer errors than High HS participants in the non-hypnotized state and Low HS participants in either state for the SRT task. High HS participants made fewer errors overall than Low HS participants for the CRT task. Mean C3/C4 CNV amplitude was larger in High HS than in Low HS participants. Furthermore, larger CNV amplitude was associated with shorter premotor time. Our findings indicate that shorter reaction time in the high hypnotically susceptible group is associated with a greater change in brain activity during motor preparation. One interpretation is that hypnotic susceptibility and neural mechanisms of arousal and selective attention are linked., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Regular physical activity benefits brain health and function. Physical activity performed by young adults is declining. However, the influence of diminished physical activity on cognitive performance and motor preparation in young adults remains unclear. This study measured changes in behavior and brain activity during preparation and performance of simple (SRT) and choice (CRT) reaction time tasks in less and more physically active young adults. Electromyograms were obtained from left and right first dorsal interossei muscles. Midline and hemisphere-specific electroencephalograms were analyzed from frontal and central scalp regions in 11 less- and 11 more-active participants. Physical activity level was assessed by questionnaire (IPAQ). Reaction and premotor times were slower for SRT and CRT tasks in less active participants. No statistically significant difference in contingent negative variation (CNV) amplitude was present between groups. Hemisphere-specific CNV amplitude over frontal scalp regions was evident for both less and more active participants for right hand SRT, whereas only the more active group showed hemisphere-specific CNVs for left hand SRT. Decreased levels of physical activity in young adults may be detrimental for cognitive processing and motor function measured by reaction time and changes in brain activity., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Marked distortions in sense of agency can be induced by hypnosis in susceptible individuals, including alterations in subjective awareness of movement initiation and control. These distortions, with associated disability, are similar to those experienced with Conversion Disorder (CD), an observation that has led to the hypothesis that hypnosis and CD share causal mechanisms. The purpose of this review is to explore the relationships among motor imagery (MI), hypnotic susceptibility, and CD, then to propose how MI ability may contribute to hypnotic responding and CD. Studies employing subjective assessments of mental imagery have found little association between imagery abilities and hypnotic susceptibility. A positive association between imagery abilities and hypnotic susceptibility becomes apparent when objective measures of imagery ability are employed. A candidate mechanism to explain motor responses during hypnosis is kinaesthetic MI, which engages a strategy that involves proprioception or the "feel" of movement when no movement occurs. Motor suppression imagery (MSI), a strategy involving inhibition of movement, may provide an alternate objective measurable phenomenon that underlies both hypnotic susceptibility and CD. Evidence to date supports the idea that there may be a positive association between kinaesthetic MI ability and hypnotic susceptibility. Additional evidence supports a positive association between hypnotic susceptibility and CD. Disturbances in kinaesthetic MI performance in CD patients indicate that MI mechanisms may also underlie CD symptoms. Further investigation of the above relationships is warranted to explain these phenomena, and establish theoretical explanations underlying sense of agency., (Copyright © 2016. Published by Elsevier Ltd.)

Conversion paresis is the presence of unexplained weakness without detectable neuropathology that is not feigned. To examine the 'abnormal preparation' and 'disrupted execution' hypotheses proposed to explain the movement deficits in conversion paresis, electroencephalographic, electromyographic and kinematic measures were recorded during motor preparation and execution. Six patients with unilateral upper limb conversion weakness, 24 participants feigning weakness and 12 control participants performed a 2-choice precued reaction time task. Precues provided advance information about the responding hand or finger. Patients and feigners demonstrated similar diminished force, longer movement time and extended duration of muscle activity in their symptomatic limb. Patients showed significantly suppressed contingent negative variation (CNV) amplitudes, but only when the symptomatic limb was precued. Despite the similarity in performance measures, this CNV suppression was not seen in feigners. Diminished CNV for symptomatic hand precues may reflect engagement of an inhibitory mechanism suppressing cortical activity related to preparatory processes., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Objective: Conversion paresis patients and healthy people feigning weakness both exhibit weak voluntary movement without detectable neuropathology. Uniquely, conversion patients lack a sense of conscious awareness of the origin of their impairment. We investigated whether conversion paresis patients show distinct electroencephalographic (EEG) markers associated with their unconscious movement deficits., Methods: Six unilateral upper limb conversion paresis patients, 12 feigning participants asked to mimic weakness and 12 control participants performed a precued reaction time task, requiring movements of either hand, depending on precue information. Performance measures (force, reaction and movement time), and event-related EEG potentials (ERP) were compared, between groups and across hands or hemisphere, using linear mixed models., Results: Feigners generated the same inter-hand difference in reaction and movement time as expressed by patients, even though no specific targets were set nor feedback given on these measures. We found novel ERP signatures specific to patients. When the symptomatic hand was precued, the P3 ERP component accompanying the precue was dramatically larger in patients than in feigning participants. Additionally, in patients the earlier N1 ERP component was diminished when the precue signalled either the symptomatic or asymptomatic hand., Conclusions: These results are consistent with previous suggestions that lack of awareness of the origin of their symptoms in conversion disorder patients may result from suppression of brain activity normally related to self-agency. In patients the diminished N1 to all precues is consistent with a generalised reduction in cognitive processing of movement-related precues. The P3 enhancement in patients is unlikely to simply reflect changes required for generation of impaired movements, because it was not seen in feigners showing the same behavioural deficits. Rather, this P3 enhancement in patients may represent a neural biomarker of unconscious processes, including additional emotional loading, related to active suppression of brain circuits involved in the attribution of self-agency.

The motor program is a concept that has had a major influence on theorizing in the field of motor control. However, there has been a lack of consensus as to what exactly is a motor program and its role in movement organization and execution. In 1994 Morris, Summers, Matyas, and Iansek concluded from a review of the application of the motor program concept in the field of physical therapy that continued use of the term may impede progress in the field. In this paper we examine what has happened to the motor program concept in the thirteen years since the previous evaluation. The review indicates that although the term is still being used in different ways, the theoretical existence of a motor program appears to be generally accepted by researchers in experimental psychology, movement science, and neurophysiology. The recent development of powerful brain imaging techniques may allow determination of whether the motor program should be regarded as a metaphorical or literal concept.

In this study, we examined the effect of 96-125 h of competitive exercise on cognitive and physical performance. Cognitive performance was assessed using the Stroop test (n = 9) before, during, and after the 2003 Southern Traverse adventure race. Strength (MVC) and strength endurance (time to failure at 70% current MVC) of the knee extensor and elbow flexor muscles were assessed before and after racing. Changes in vertical jump (n = 24) and 30-s Wingate performance (n = 27) were assessed in a different group of athletes. Complex response times were affected by the race (16% slower), although not significantly so (P = 0.18), and were dependent on exercise intensity (less so at 50% peak power output after racing). Reduction of strength (P < 0.05) of the legs (17%) and arms (11%) was equivalent (P = 0.17). Reductions in strength endurance were inconsistent (legs 18%, P = 0.09; arms 13%, P = 0.40), but were equivalent between limbs (P = 0.80). Similar reductions were observed in jump height (-8 +/- 9%, P < 0.01) and Wingate peak power (-7 +/- 15%, P = 0.04), mean power (-7 +/- 11%, P < 0.01), and end power (-10 +/- 11%, P < 0.01). We concluded that: moderate-intensity exercise may help complex decision making during sustained stress; functional performance was modestly impacted, and the upper and lower limbs were affected similarly despite being used disproportionately.

Conversion Disorder affects voluntary motor and sensory function and involves unexplained neurological symptoms without an organic cause. Many researchers have attempted to explain how these symptoms arise but the neural correlates associated with Conversion Disorder remain largely unknown to clinicians and neuroscientists alike. This review focuses on investigations of Conversion Disorder (with motor symptoms) when deficits in voluntary movement occur. No single consistent hypothesis has emerged regarding the underlying cortical mechanisms associated with motor Conversion Disorder. However, findings from electrophysiology, neuroimaging, and behavioral research implicate the involvement of prefrontal networks. With further research using measurement techniques precise in spatial as well as temporal resolution, the conflict associated with two views of the neural correlates of motor Conversion Disorder may be resolved. This will provide a better understanding of the impairment associated with the preparation, generation, and execution of intentional movement in Conversion Disorder.

Nine men completed a 24-h exercise trial, with physiological testing sessions before (T1, approximately 0630), during (T2, approximately 1640; T3, approximately 0045; T4, approximately 0630), and 48-h afterwards (T5, approximately 0650). Participants cycled and ran/trekked continuously between test sessions. A 24-h sedentary control trial was undertaken in crossover order. Within testing sessions, participants lay supine and then stood for 6 min, while heart rate variability (spectral analysis of ECG), middle cerebral artery perfusion velocity (MCAv), mean arterial pressure (MAP; Finometer), and end-tidal Pco(2) (Pet(CO(2))) were measured, and venous blood was sampled for cardiac troponin I. During the exercise trial: 1) two, six, and four participants were orthostatically intolerant at T2, T3, and T4, respectively; 2) changes in heart rate variability were only observed at T2; 3) supine MAP (baseline = 81 +/- 6 mmHg) was lower (P < 0.05) by 14% at T3 and 8% at T4, whereas standing MAP (75 +/- 7 mmHg) was lower by 16% at T2, 37% at T3, and 15% at T4; 4) Pet(CO(2)) was reduced (P < 0.05) at all times while supine (-3-4 Torr) and standing (-4-5 Torr) during exercise trial; 5) standing MCAv was reduced (P < 0.05) by 23% at T3 and 30% at T4 during the exercise trial; 6) changes in MCAv with standing always correlated (P < 0.01) with changes in Pet(CO(2)) (r = 0.78-0.93), but only with changes in MAP at T1, T2, and T3 (P < 0.05; r = 0.62-0.84); and 7) only two individuals showed minor elevations in cardiac troponin I. Recovery was complete within 48 h. During prolonged exercise, postural-induced hypotension and hypocapnia exacerbate cerebral hypoperfusion and facilitate syncope.

The aim of this study was to determine the magnitude and pattern of intensity, and physiological strain, of competitive exercise performed across several days, as in adventure racing. Data were obtained from three teams of four athletes (7 males, 5 females; mean age 36 years, s = 11; cycling .VO(2 peak) 53.9 ml . kg(-1) . min(-1), s = 6.3) in an international race (2003 Southern Traverse; 96 - 116 h). Heart rates (HR) averaged 64% (95% confidence interval: +/- 4%) of heart rate range [%HRR = (HR - HR(min))/(HR(max) - HR(min)) x 100] during the first 12 h of racing, fell to 41% (+/-4%) by 24 h, and remained so thereafter. The level and pattern of heart rate were similar across teams, despite one leading and one trailing all other teams. Core temperature remained between 36.0 and 39.2 degrees C despite widely varying thermal stress. Venous samples, obtained before, during, and after the race, revealed increased neutrophil, monocyte and lymphocyte concentrations (P < 0.01), and increased plasma volume (25 +/- 10%; P < 0.01) with a stable sodium concentration. Standardized exercise tests, performed pre and post race, showed little change in the heart rate-work rate relationship (P = 0.53), but a higher perception of effort post race (P < 0.01). These results provide the first comprehensive report of physiological strain associated with adventure racing.

Inhibition of return (IOR) has been shown to occur when an individual returns to a target location (within-person IOR) and when an individual moves to a location just engaged by another individual (between-person IOR). Although within- and between-person IOR likely result from the same inhibitory mechanisms, different processes must activate these mechanisms following the performance and observation of action. Consistent with the suggestion that the mirror neuron system may be responsible for activating the inhibitory mechanisms behind IOR on observation trials, between-person IOR was only detected under restricted viewing conditions known to activate mirror neurons. These results indicate that mirror neuron system may be involved in both higher-order and automatic cognitive behavior.

This study was designed to determine if movement planning strategies incorporating the use of visual feedback during manual aiming are specific to individual movements. Advance information about target location and visual context was manipulated using precues. Participants exhibited a shorter reaction time and a longer movement time when they were certain of the target location and that vision would be available. The longer movement time was associated with greater time after peak velocity. Under conditions of uncertainty, participants prepared for the worst-case scenario. That is, they spent more time organizing their movements and produced trajectories that would be expected from greater open-loop control. Our results are consistent with hierarchical movement planning in which knowledge of the movement goal is an essential ingredient of visual feedback utilization.

This article describes an approach to motor synergies that allows them to be quantified in people with atypical movement patterns during exercise or practice. Within this approach, motor variability may be classified with respect to a task-specific performance variable as "good" (not affecting the variable) or "bad" (changing the variable). The authors review studies of motor synergies in people with typical movement patterns, in people with Down syndrome, in patients after stroke, and in elderly people. Two stages of practice effects on motor synergies are described as being characterized by different changes in the synergy index: an increase followed by a drop in the index. Synergy changes with practice may be accompanied by plastic changes in both descending projections from the primary cortex and interhemispheric projections. The authors emphasize the importance--for practitioners in the area of motor disorders and rehabilitation--of being aware of the latest progress in motor control and coordination.

Inhibition of return (IOR) refers to the slowing of responses to a target that appears in the same location as a previous event. Many researchers have speculated that IOR arises from inhibitory neural processes that have developed through evolution to facilitate efficient search patterns by biasing the action and/or attention of an individual towards novel locations. Throughout evolution, however, humans conducted searches as individuals as well as members of a group. In this context, we sought to determine if IOR could also be observed in the behavior of one individual after the observation of another's behavior. Consistent with our reasoning, there was no difference in the magnitude of the IOR effect found when participants followed their own response or the response of their partner. These results are discussed in the context of action-based attention and possible underlying neural mechanisms.

The effect on reaction time (RT) and movement time (MT) of remembering which one of several targets to move to was investigated in 18 participants who completed 416 trials in each task. On each trial, participants moved their index finger from a central, illuminated switch (the stimulus) to one of eight targets located on the circumference of a 6 cm radius circle. A visual cue (illumination of the target) informed the participant of the appropriate target. In the memorised delay task, the cued target was lit for 300 ms followed by a variable (450-750 ms) foreperiod during which the participant was required to remember the location of the target until the stimulus light was extinguished. In the non-memorised delay task, the target remained lit during the entire foreperiod (750-1050 ms) until the response was completed. At the "go" signal (stimulus light extinguished) participants moved as quickly and accurately as possible to the cued target. Both RT and MT were significantly (p<0.05) longer in the memorised delay task. The increase in RT shows that remembering which target imposed a greater load on motor preparation even though all the information needed for preparing the response was presented in the cue at the beginning of each trial. The increase in MT raises the possibility that movement execution was also programmed during motor preparation.

Our previous study revealed that, during tonic muscle contraction, remarkable functional differences among intrinsic and extrinsic muscles were observed during two different grip movements, i.e., precision and power grips. To verify whether this evidence is true even under the phasic muscle contraction, magnetic stimulation was delivered over the left scalp while a normal human subject performed phasic precision or power grip responses of the right-hand fingers in a simple reaction time (SRT) paradigm. Magnetic stimulation delivered during the latent period revealed different cortico-motoneuronal excitations between the two grip responses. In particular, the contributions of extensor carpi radialis (ECR) muscle were definitely different between the two grip responses, although motor-evoked potentials (MEPs) of first dorsal interosseous (FDI) prior to, and after EMG onset of movement initiation, were not different. These results were similar to previous results obtained during tonic muscle contraction. Thus, we have concluded that the task-dependent EMG discharge pattern in finger manipulation could not be modulated by muscle contraction modes.

The reports by Fitts and Peterson [J. Exp. Psychol. 67(2) (1964) 103-113] and Klapp [J. Exp. Psychol. Hum. Percept. Perform. 104(2) (1975) 147-153] concerning the effects of movement amplitude and target diameter on reaction time present conflicting results. Fitts and Peterson reported that reaction time increased when movement amplitude was lengthened. Klapp reported an interaction in which target diameter effect on reaction time was moderated by movement length: for small targets, reaction time decreased with increasing movement length but reaction time remained unchanged (or increased modestly) when target diameter was large. Two experiments were conducted to replicate and examine the inconsistency in the reaction time results. For both experiments movement time results were in agreement with the predictions of Fitts' law. However, the results for reaction time were mixed: support was obtained for Klapp (1975) but not for Fitts and Peterson (1964). Further analysis identified several potential variables that could have influenced reaction time and explained the different effects on reaction time reported by Fitts and Peterson (1964) and Klapp (1975). The potential variables could include: limb posture at the start of a response; number of limb segments required to perform the task; and the effect of pooling reaction time data from targets located right and left of the start point, and from near and far targets.

Two reliable findings in discrete, rapid aimed movements are that reaction time increases with decrease in target diameter (for the short-length movements), and reaction time is not affected by movement length [Journal of Experimental Psychology, Human Perception and Performance 104 (2) (1975) 147]. Participants normally use a short stylus (SS) to tap targets located on either side of a central (aligned with body midline) start-point with no restrictions imposed on the initial posture of the limb or segmental recruitment except as determined by movement conditions. Thus, the effects of movement parameters on reaction time in previous work are potentially confounded with the effect of initial posture of the limb at the start-point, along with order and amount of the contribution of segments recruited in response execution. Two experiments were performed to resolve the confounding between initial posture and recruitment of limb segments. In the first experiment a conventional stylus (pen-like) was employed and the starting position of the limb was aligned either with the body midline or with the participant's right shoulder. The effect of starting position on reaction time was not significant. In the second experiment the starting position was in line with the right shoulder. Two groups participated. One group used a conventional stylus. For the second group a modified (lengthened) stylus was used that permitted initial limb posture and number of limb segments recruited to be held constant across an extended range of movement lengths. When similar sets of limb segments were used, reaction time increased with decreasing movement length and diminishing target diameter. These findings suggest that uncontrolled initial limb posture, uncontrolled order of joint(s) recruitment, and the subsequent inclusion of reaction time values from incompatible sources may, in the final analysis, have confounded previous work investigating movement amplitude and target diameter effects on reaction time.

A movement task was used to investigate the effects of precued variables on reaction time. The task involved rapid rotation of a hand-held manipulandum to target locations and required either pronation or supination of the forearm through short or long extent. The effects on reaction time of precues signalling target direction, extent, or a combination of direction and extent, were measured. The longest reaction times occurred when no information about direction or extent was provided in the precue (all parameters uncertain). Complete prior specification of target position produced the shortest reaction times. Specification of direction when extent was uncertain produced a significantly larger reduction in reaction time than specification of extent when direction was uncertain. Prior specification of extent also produced a small but significant reduction in reaction time relative to the condition in which direction and extent were specified in a mutually conditional manner. The results are discussed in relation to parameter precuing and motor programming, in which the direction is programmed by the pre-selection of neurons representing the muscles to be used in the task while programming of extent is represented by their level of activity during task performance.

Triphasic electromyographic (EMG) patterns have been described as characteristic of rapid, discrete, uniplanar, goal-directed movements. This experiment examined the effects of Response Type (experimenter- vs. subject-determined), Hand (preferred vs. nonpreferred), and Practice (early vs. late) on performance accuracy, and specific temporal EMG and kinematic measures during a dart throw. EMG was recorded from triceps (main agonist), brachioradialis, and biceps (main antagonist). The number of trials in which a triphasic EMG occurred varied systematically across conditions. The experimenter-determined, early practice condition resulted in greatest frequency (92%) of trials displaying a triphasic EMG and least accurate performance. In contrast, the lowest frequency (79%) of triphasic EMG and most accurate performance occurred in the subject-determined, late practice condition. The association among 14 temporal EMG, and kinematic measures for each trial of the dart throw was analyzed with multivariate factorial ANOVA. Four clusters of variables emerged: initial phase, braking phase, terminal phase, and movement speed and duration. Variables contributing to the initial-phase cluster were most strongly associated within the experimenter-determined, early practice condition, and the strength of association was directly related to diminished performance accuracy. Paradoxically, best performance accuracy (subject-determined, late practice) was identified with a weaker association among variables representing the initial phase.

The effect of foreperiod length on reaction time in memorized (MM) and nonmemorized (NM), precued, delayed responses was investigated. Six subjects participated in one long and one short foreperiod schedule testing session. An aiming task, using elbow supination/pronation, in response to a visual stimulus was employed. In the MM condition, target spatial information was available for a fraction of the foreperiod duration. In the NM condition, target information was available continuously until the subject attained the target position. Subjects responded with a significantly longer latency in the long foreperiod schedule. Within each foreperiod schedule, the shortest foreperiod resulted in significantly longer reaction time. However, the absolute value of foreperiod did not have a major effect on reaction time latency. Memorization and nonmemorization conditions did not affect reaction time.

In the monkey, reaction time in a precued delayed response task was found to be faster when the animals had to remember the precue than when it was continually available (Smyrnis, Taira, Ashe, & Georgopoulos, 1992). We investigated whether this reflects a general principle that applies to all types of precued tasks. However, we found the opposite result in a simpler task in humans. Our findings suggest that the beneficial effect of a memory requirement on reaction time in the monkey may reflect an effect of task difficulty, rather than a fundamental process involved in all precued movement tasks.

A rapid assay for the quantification of hepatitis B virus DNA in human serum was developed. The principle of the method combines competitive polymerase chain reaction (cPCR) (for the controlled amplification of hepatitis B virus DNA) and scintillation proximity assay (SPA) technology (for rapid detection and quantitation of PCR products). It also incorporates a reproducible and simple method for the preparation of serum DNA suitable for PCR amplification. The assay has a better linear dynamic range than traditional methods that use 32P to detect PCR products. It was applied to a range of hepatitis B virus (HBV) surface antigen positive (HBsAg + ) sera, and shown to be more sensitive than a commercially available HBV DNA kit.

A novel method to measure mRNA levels has been developed by combining the detection capabilities of RNase protection (RPA) with the quantification advantages of scintillation proximity assay (SPA) technology. Sample processing is reduced to the addition of a single reagent post RNase digestion. As a model system, the inducible expression of rat apolipoprotein-A1 mRNA has been measured by both traditional gel-based RPAs and the SPA-based RPA assay. Results demonstrate that the ribonuclease protection proximity assay (RiPPA) faithfully reproduces the gel-based results and is at least as sensitive as many existing methods.

We have developed a high-throughput, multiplex reverse transcription PCR (RTPCR) assay that is suitable for the analysis of medium-to low-copy cellular RNA transcripts from small numbers of cells (10(4)). High throughput was attained by utilizing microplate-based RNA extraction and RTPCR protocols, followed by PCR product visualization of a multiwelled agarose gel, stained with SYBR Green I dye. The transcriptional assay was unaffected by solvents (dimethyl sulfoxide and methanol) routinely used in high-throughput drug screens at concentrations required for compound solubilization. Furthermore, it has been used successfully for the investigation of differential mRNA expression levels of tumor necrosis factor alpha (TNF-alpha) and Interleukin-1 beta (IL-1 beta) in lipopolysaccharide (LPS)-stimulated THP-1 cells (a human monocytic cell line) and the identification of specific IL-1 beta transcriptional inhibitors.

A high-volume plate-based in situ hybridization assay has been developed, utilizing Amersham Cytostar-T scintillating microplates. This assay reliably detects specific mRNA transcripts at the level of 10-20 copies per cell. Radiolabeled antisense riboprobes specific for c-fos and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as well as nonhomologous vector-derived control probes were used to compare mRNA levels in quiesced rat A10 smooth muscle cells after stimulation with platelet-derived growth factor (PDGF). Maximal c-fos induction occurred following stimulation of A10 cells with 30 ng/ml of PDGF, corresponding to a signal from the c-fos probe of 700 cpm. The nonhomologous control background of 50 cpm and the GAPDH signals of 1700 cpm were independent of stimulation with PDGF or serum. Using PDGF, at 30 ng/ml, quiesced cells were stimulated at various times to provide an induction time course for c-fos mRNA which peaked at 30 min and returned to basal levels within 2 h. Comparison with parallel Northern blotting experiments showed this in situ assay to be at least 20-fold more sensitive and much more rapid to perform.

In this study, we described a sequence of changes of the electromyographic (EMG) and depression of the soleus (Sol) H-reflex that precede and follow the onset of ballistic head rotation in freely standing human subjects. During head rotation, a sequence of EMG changes occurred simultaneously in Sol and in biceps femoris muscle (BF). Specifically, changes to Sol EMG included deactivations (EMG silent period) and H-reflex depression coincident with BF excitation. Thus, in the case of ballistic head movement, control commands for anticipatory postural adjustment appear to excite BF and inhibit Sol in a similar way to that previously described for the onset of arm movement.

A chimeric yeast promoter (pPGK::REP2), capable of directing high-level gene expression in both Saccharomyces cerevisiae and Escherichia coli, has been constructed. It was derived by fusing the promoter of the yeast PGK gene (encoding phosphoglycerate kinase) to a region residing immediately 5' to the yeast 2 mu plasmid REP2 gene (encoding a trans-acting plasmid maintenance protein). In S. cerevisiae, transcripts initiated within the REP2-derived moiety of the promoter, but the transcription start point was dictated by the PGK determinator sequence. Promoter function in E. coli was due to the presence of consensus prokaryotic -35 and -10 motifs in the REP2 moiety. To facilitate expression studies, the promoter was incorporated into a versatile series of S. cerevisiae/E. coli shuttle vectors which provided a choice of selectable marker and copy number in S. cerevisiae. To maximise translational efficiency, a novel cloning strategy was devised which allows the juxtaposition of genes to the promoter such that the heterologous AUG replaces that of the REP2 AUG, without any alteration in the surrounding nucleotide (nt) context. This strategy was used to place both the Tn903 neo gene and the Rhodosporidium toruloides phenylalanine ammonia lyase (PAL)-encoding gene under the transcriptional control of pPGK::REP2. In the former case, cells became resistant to extremely high levels of Geneticin (> 3 mg/ml in the case of S. cerevisiae). In the case of the latter, PAL was shown to accumulate to approx. 9 and 10% of total soluble protein in S. cerevisiae and E. coli, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

A multidisciplinary rehabilitation centre was established to address the needs of people with mild to moderate disability who had not worked for prolonged periods of time. A fitness based programme assisted 10 of the 20 who had been off work for more than six months to return to activity. Six and eighteen month follow up confirmed the durability of placement of most workers who had returned to work, and that projected benefits were achieved. Benefits were defined as savings in earnings related compensation (ERC), and compared to the costs of establishing and running the centre. Sensitivity analysis ascribing between 100% and 50% of benefit to the programme showed a positive benefit cost ratio, with benefits discounted at a rate of 10% over 10 years. With 75% ascribed, the project produced benefit cost ratio of about 1.5:1 in the first year, 2.8:1 in the second year, and rising to 6.2:1 in the fifth year and 10:1 by the tenth year. With only 50% ascribed, the benefit over the same times was 1.0:1, 1.9:1, 4.1:1 and 6.7:1 by the tenth year. These calculations probably underestimate true benefits.

At the request of the local office of the Accident Compensation Corporation (ACC) we established a centre which offered a multidisciplinary rehabilitation programme consisting of a full assessment and an eight week individually planned and monitored fitness programme. The clients progressed to occupational therapy, work trials, and later to paid work. The programme included education about back care and health maintenance, and relaxation techniques. Of the 48 injured people who attended the centre, 37 were assessed as suitable to enter the programme, and 32 people took part. Outcome, measured as return to work or change in assessed fitness to work, was not related to age, sex, marital status, length of time since accident, or work category. Only 25% of workers returned to jobs in medium or heavy manual work. Sickness impact profile total and physical scores improved over the programme, but did not correlate significantly with return to work or fitness for work. Client perception of benefit was not significantly related to outcome. We analysed data from the 20 clients with claims longer than 6 months separately because matched case controls could not be provided by the ACC. Six months after completion of the programme, four were in paid employment, four in prolonged work trials, one in a job partly paid by the ACC, and one setting up his own business. Their return to the work force demonstrated the effectiveness of the centre in restoring people to function after prolonged periods of inactivity.

A voluntary motor response that is prepared in advance of a stimulus may be triggered by any sensory input. This study investigated the combination of visual and kinesthetic inputs in triggering voluntary torque responses. When a visual stimulus was presented alone, subjects produced a fast and accurate increase in elbow flexion torque. When a kinesthetic stimulus was presented instead of the visual stimulus, subjects produced a similar response with a reduced response latency. When a visual stimulus was presented in combination with a kinesthetic stimulus, subjects initiated their responses after either a visual or a kinesthetic response latency, depending on the relative timing of the two stimuli. An analysis of response amplitude suggested that when visual and kinesthetic stimuli were combined, both stimuli triggered a response. The results are more consistent with a simple behavioral model of addition of visual and kinesthetic responses (which predicts that the response to combined stimuli should be the sum of individual responses) than with a model of exclusion of one response (which predicts that the response to combined stimuli should be identical to either the visual or the kinesthetic response). Because addition of visually and kinesthetically triggered responses produced a response with an erroneously large amplitude, it is suggested that visual and kinesthetic inputs are not always efficiently integrated.

Two experiments examined the effect of altering the moment of inertia within an anatomical unit on simple reaction time (SRT), premotor time (PMT), and motor time (MOT) during the initiation of a discrete rapid movement. In Experiment 1 (N = 14), moment of inertia of the forearm was increased with the addition of a weighted cuff fastened around the wrist. In Experiment 2 (N = 7), moment of inertia was altered by the addition of a weighted sleeve to the index finger prior to rapid extension of the digit. Results from both experiments were unequivocal. An increase in the moment of inertia resulted in a significant increase in SRT and MOT but had no significant effect on PMT. Within selected anatomical unites (forearm and index finger), an increase in the moment of inertia does not appear to require additional neuromotor programming time but does influence the overall duration of response initiation.

Two experiments were conducted to investigate the learning of the programmed- and feedback-based processes controlling the production of a slow, self-paced positioning response in two dimensions (direction and extent) in the horizontal plane. Both experiments had two phases: an acquisition phase of 60 trials with KR, followed by a KR withdrawal phase of 20 trials. In Experiment 1, one group (N=15) had visual feedback about the ongoing movement and the other group (N=15) did not. In Experiment 2, one group (N=15) practiced initiating the response in the criterion direction and moving the criterion extent, whereas, the other group (N=15) practiced initiating the response in the criterion direction and moving randomly varied extents. The results of Experiment 1 indicated that the learning of a programmed-based process is a gradually acquired freedom from visual feedback. Experiment 2 revealed that a programmed-based process can be learned independent of a feedback-based process.

The complete nucleotide sequence of the Rhodosporidium toruloides gene coding for the enzyme phenylalanine ammonia-lyase (PAL) has been determined. The primary structure of PAL was deduced from the nucleotide sequence of the two cDNA clones, pPAL1 and pPAL2, which covered the entire amino acid-coding sequence. Comparison of cDNA and genomic sequences of pal revealed the presence of six introns. The nucleotide sequences of these introns were compared to those from other fungi. The primary amino acid sequence of the enzyme exhibits only 30.8% identity with the determined primary sequence of PAL from Phaseolus vulgaris. Upstream from the structural gene there is a stretch of C + T-rich DNA similar to that found upstream from a number of Neurospora and Saccharomyces cerevisiae genes. In the case of S. cerevisiae, these C + T-rich sequences are thought to be involved in the transcription of highly expressed genes.

Two experiments investigated the effect of hand position on the accuracy of short- and long-duration aiming movements in the presence and absence of visual feedback. In Experiment 1 (N = 16) short aiming movements were executed rapidly, which would require them to be predominantly programmed, whereas in Experiment 2(N = 8) these movements were performed slowly enough so that visual feedback, which implies that they were predominantly programmed. However, the long-duration, short-length movements of Experiment 2 were disrupted when visual feedback was removed, which suggests that these movements were being guided by visual feedback. Having the heel of the responding hand in contact with the target platform during the response resulted in greater accuracy than no hand contact for the short-length movements of both experiments. Taken together, these results indicated that hand contact produced greater aiming accuracy than no hand contact for both programmed- and feedback-based movements.

A plasmid of ca. 100 kilobases was detected in a Pseudomonas species which was isolated from soil by growth on aniline as the sole carbon and energy source. The plasmid was shown to be involved in aniline metabolism.