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Biomedical subjects

G Goodall

Publications and source records attributed to G Goodall.

25 records · Page 2Linked to original sources
PubMed1985

Permanency of gait improvement induced by vestibular stimulation in the mutant mouse staggerer.

Among the several methods that have been used to investigate the impact of environmental enrichment, on the behavior of an animal, the use of behaviorally deficient mutant mice has been especially useful. The use of this model allows one to investigate functional recovery compared to a known baseline (the normal animal) without the trauma and imprecision associated with surgical intervention. The present study extends a previous investigation that demonstrated a significant improvement in certain measures of the gait of the cerebellar mutant mouse staggerer, as a result of daily vestibular, muscular and visual stimulation. The results of the present study concerned the durability of that observed improvement. No clear-cut conclusion as to the permanency of the stimulation's effects could be drawn, because results differed according to the measures used. When tested two months after the end of the stimulation period the mutants ran more slowly, with as many "errors" as unstimulated mutants, leading one to infer a deleterious effect of the stimulation. On the other hand, if one considers only the number of "errors" during the test, one may conclude that early stimulation has a permanent advantageous effect of increasing the staggerer's receptivity to further stimulation. Other measures lead to more ambiguous conclusions. Finally, it is argued that even though true improvement in the staggerer's gait can be inferred from these results, and that at least some aspects of that improvement seem to be long-lasting, the generality of the findings cannot validly be extended beyond the precise experimental conditions.

Acoustic Stimulation↗
PubMed1984

Morphological complexity and cerebral lateralization.

Fifteen agentive nouns, all with meanings derivable from the meaning of the stem verb, were presented tachistoscopically to right-handed subjects. Non-agentive nouns were also presented, and subjects were asked to produce the plural form in addition to the simple stimulus form. The results show a significant right visual field advantage for the agentive and plural nouns, but no significant advantage in either field for the simple nouns. These findings suggest that the left hemisphere is superior in processing nouns which are morphologically complex.

Adult↗
PubMed1984

Successful overshadowing and blocking in hippocampectomized rats.

Overshadowing (Experiment 1) and blocking (Experiment 2) were investigated using a conditioned suppression paradigm in rats. Neither hippocampectomy nor cortical control lesions affected the extent to which a salient stimulus overshadowed a less salient one. Nor did the lesions affect the extent to which a stimulus that was highly correlated with shock overshadow a stimulus that was less well correlated with shock. Finally, the lesions did not alter the extent to which a previously reinforced stimulus blocked conditioning to another stimulus when both were presented as a reinforced compound stimulus. It is thus possible for hippocampectomized rats to show apparently normal overshadowing and blocking, at least under some testing conditions.

Animals↗
PubMed1978

A study of misbehavior: token reinforcement in the rat.

The purpose of this research was to investigate the phenomenon of misbehavior described by Breland and Breland (1961). Rats were trained to obtain ball-bearings and drop them in a hole for food or water reinforcers. In confirmation of the Brelands' observation, many subjects were slow to deliver the balls, and frequently attempted to chew them before they were dropped. A series of four experiments, in which the same rats were used throughout, showed that delivery times tended to be longer with food than with water, and that these times increased when nylon balls were substituted. The effect of motivational level was investigated by varying both deprivation and amount of prefeeding; no effect on delivery time was detected, although other measures of performance were affected by motivational factors. Similar results were obtained in a final experiment that employed a new set of naive subjects. The studies demonstrated that misbehavior can be studied in an experimental situation, and the results supported an analysis in terms of competition between stimulus-reinforcer and response-reinforcer contingencies. The question of why such effects have not been reported in previous token reinforcer studies was unanswered.

Journal Article↗
PubMedDate not supplied

Freezing rate affects the survival of a short-term freezing stress in Panagrolaimus davidi, an Antarctic nematode that survives intracellular freezing.

The ability of the Antarctic nematode Panagrolaimus davidi to survive a short-term freezing stress depended upon the rate of freezing of its surroundings, measured as the duration of the sample exotherm. The freezing rate increased as the sample volume and freezing temperature decreased and resulted in fewer nematodes surviving. This appears to be due to the greater risk of physical damage by ice crystal growth at high freezing rates. Once frozen the nematodes will then survive exposure to lower temperatures. The environment of the nematode is likely to produce the slow rate of freezing of its surroundings that is necessary for its survival.

Animals↗