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Biomedical subjects

M G Sanders

Publications and source records attributed to M G Sanders.

At least 19 recordsLinked to original sources
PubMed1986

Adaptive plasticity in primate spinal stretch reflex: persistence.

Monkeys can gradually change the amplitude of the wholly segmental, largely monosynaptic, spinal stretch reflex (SSR) when confronted by a task requiring such change (15-19). Change develops over months and may reverse and redevelop at similarly slow rates. We investigated the persistence of SSR amplitude change over nonperformance periods of up to 38 days. Eight animals with chronic EMG electrodes learned to maintain elbow angle and a given level of biceps background EMG against constant extension torque. At random times, a brief additional extension torque pulse elicited the biceps SSR. In the control mode, reward always followed. Under the SSR increase or SSR decrease mode, reward occurred only if the absolute value of biceps EMG in the SSR interval was above or below a set value. Animals completed 3,000-6,000 trials/day over data-collection periods of 2-17 mo. Animals worked first under the control mode for up to 60 days and then under the SSR increase or SSR decrease mode for up to 274 days. Mode was switched once or twice more (SSR increase to SSR decrease or vice versa) over subsequent months. Animals responded to each SSR increase or SSR decrease mode exposure with gradual mode-appropriate change in SSR amplitude. Mode exposures were interrupted by gaps in performance of 10-38 days. Gaps produced transient 10- to 15% decreases in SSR amplitude under the control mode. This nonspecific decrease disappeared over the first week of postgap performance. Under the control mode, gaps had no other effects on SSR amplitude.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1985

Reduced day-to-day variation accompanies adaptive plasticity in the primate spinal stretch reflex.

Monkeys can change the amplitude of the spinal stretch reflex (SSR), or M1, when reward is made contingent on amplitude. The present study demonstrates that reduced SSR day-to-day variation accompanies such adaptive SSR change. This finding supports the assumption that initial, phase I, SSR change results from contingency-appropriate stabilization of tonic activity in relevant descending spinal cord pathways.

Adaptation, Physiological↗
PubMed1983

Adaptive plasticity in the spinal stretch reflex.

Monkeys can change the amplitude of the spinal stretch reflex without change in initial alpha motor neuron tone, as measured by EMG, or in initial muscle length. Change is apparent in 5-10 days, continues to develop over weeks, and persists during inactive periods. Spinal stretch reflex change may be a valuable system for studying the neuronal and synaptic bases of an adaptive change in primate CNS function.

Animals↗
PubMed1982

Changes in the U.S. Army aviator selection and training program.

The Army's aviator selection program began in the mid 1950's. The first Flight Aptitude Selection Test (FAST) was implemented in 1966 and remained in use until 1980 when changes in personnel, aircraft, and tactics necessitated an improved or revised FAST (RFAST). This paper presents an overview of 1) the composition of the FAST and RFAST; 2) the advantages of the RFAST; and 3) the predictive validity estimates for the FAST and RFAST. Also presented are examples of current research projects which show promise for increasing effectiveness and for broadening the scope of the Army aviator selection program.

Aerospace Medicine↗
PubMed1980

A human performance/workload evaluation of the AN/PVS-5 bifocal night vision goggles.

Eight experienced U.S. Army aviators performed various maneuvers in an instrumented helicopter to test the relative usability of two bifocal-configured night vision goggles. Both configurations were statistically better than the unmodified arrangement when looking at a pilot's ability to fly a standard traffic pattern and to hold a precise altitude at night. The subjective data, supported by comparative flight performances with the two bifocals, further suggested that a 24% bifocal version was more desirable than a 14% configuration. The inference is that the reduced inside field of view presented by the 14% bifocal interferes with a pilot's ability to readily locate instruments once he has directed his attention inside the cockpit.

Aerospace Medicine↗
PubMed1977

Marijuana and human performance: an annotated bibliography (1970-1975).

A bibliography of 199 annotated references was compiled to aid the reader in determining the impact of marijuana on psychomotor, cognitive, and physiological factors considered pertinent to flight performance. The bibliography contains an index which categorizes the references into the following major areas: (1) reviews or overviews of issues, literature or research; (2) psychological effects of marijuana use; (3) physiological and pharmacological research; (4) medical comments and research critiques; and (5) additional reference sources. The basic period of coverage is 1970 to 1975, although selected studies from earlier years are also included.

Aerospace Medicine↗
PubMed1976

Internal-external locus of control and performance on a vigilance task.

Previous studies have demonstrated there are large individual differences in subjects' ability to perform on vigilance or watch-keeping tasks. This study used Rotter's Internal-External (I-E) Locus of Control Scale to resolve some of the variance attributed to individual differences and tested the hypothesis that the internally controlled person is a better monitor on a vigilance task than an externally controlled person. There were 64 subjects who performed a visual watch-keeping task for a 1-hr. period. The results indicated that the external subjects made significantly more incorrect responses and missed significantly more signals during the entire task. The internal-external dimension was effective in differentiating performance on a vigilance task.

Aptitude↗
PubMed1976

Cross-validation study of the personality aspects of involvement in pilot-error accidents.

Pilot-error accidents have dominated accident statistics consistently from the 1940s to the present. Sanders and Hofmann (3) found that three factors from Cattell's Sixteen Personality Factor Questionnaire (16 PF) significant differences (p less than 0.05) between pilot-error accident groups and were used to correctly classify 86% of the aviators tested as to their previous pilot-error accident involvement. There were 66 aviators given the 16 PF in the present study in an attempt to cross-validate the findings reported in the original study. The results indicate that the personality factors did not significantly discriminate between the pilot-error accident groups. The primary personality differences between the present sample and the original sample were due to variations in the pilot-error accident-free groups. The findings indicate that individual differences in personality characterstics of the aviators prevent consistent identification of traits associated with pilot-error groups.

Accidents, Aviation↗
PubMed1975

Attenuation of "acute" habituation by scopolamine in the black-tailed prairie dog (Cynomys ludovicianus).

The hypothesis after scopolamine attenuates habituation occurring within a training session as well as that occurring between training sessions was tested and confirmed. Scopolamine injections (.5 mg/kg) reduced spontaneous wheel running in the prairie dog. The same dosage did not affect the threshold for wheen running induced by electrical brain stimulation (EBS). Another experiment demonstrated that EBS-induced running declined during a 10-min. stimulation period and indicated that the decline was habituative since the response was repeatedly dishabituated. In a final experiment .5 mg/kg of scopolamine reduced habituation of EBS-induced wheel running during 10-min. sessions.

Animals↗
PubMed1975

Personality aspects of involvement in pilot-error accidents.

The consistently high frequency of pilot-error accidents in both military and civilian aviation programs does much to support exploratory research which might help alleviate the problem. Cattell's Sixteen Personality Factor Questionnaire (16 PF), Mehrabian Achievement Scale, and a dynamic decision making task (under risk) were given to 51 Army aviators. Accident files were then examined in order to classify the aviators as to their prior pilot-error accident involvement. Stepwise discriminant analyses revealed that the decision-making task scores and the achievement scores were unrelated to the pilot error accident groupings while the 16 PF scores were able to correctly classify 86% of the aviators as to whether or not they had been previously listed as a cause factor in a military aviation accident.

Accidents, Aviation↗
PubMed1973

Chronic idiopathic intestinal pseudo-obstruction with malabsorption, a scleroderma-like disorder.

A case of intestinal pseudo-obstruction in a 76-year-old man who presented with a six-year history of intermittent vomiting and abdominal pain and a 1(1/2)-year history of diarrhea is described. Investigation demonstrated aperistalsis of the lower esophagus and an unresponsive atonic small intestine. Marked malabsorption was present and appeared due to intestinal bacterial overgrowth consequent to the hypomotility. Autonomic nervous system testing failed to reveal any definite abnormality. Although this disorder is markedly similar to scleroderma involving the gastrointestinal tract, there was only minimal fibrosis of the bowel musculature evident at autopsy and the neural components appeared to be intact. These findings suggest that the basic disorder may be one of smooth muscle dysfunction. Other known causes of pseudo-obstruction could not be demonstrated.

Aged↗