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Biomedical subjects

F Allard

Publications and source records attributed to F Allard.

11 recordsLinked to original sources
PubMed1992

Brain correlates of hand dominance: the association between peripheral and cerebral asymmetries revisited.

Measures reflecting central processing of somatosensory stimulation were recorded in left- and in right-handed subjects in order to evaluate differences between the two handedness groups in the vertical, rather than lateral, axis of processing. Somatosensory evoked potentials were recorded in left- and right-handers following electrical stimulation of the median nerve at the wrist. The relative vertical balance of processing was probed by comparing the amplitudes of the underlying activity in early evoked potentials, presumably originating subcortically, with later, cortically originating potentials. Central conduction time (CCT) of the sensory volleys was also recorded. The data revealed higher amplitude ratios (ARs) between subcortical and cortical potentials, as well as shorter CCTs, in left-handers. These results demonstrate that transmission differences between the handedness groups may occur early in central nervous system (CNS) conductance. The results are further discussed in light of evidence suggesting that stronger reliance on a subcortical mode of processing may underlie phenomenon of left-handedness.

Adolescent↗
PubMed1991

Description and evaluation of the semiautomated 4-hour ATB 32E method for identification of members of the family Enterobacteriaceae.

A study was performed to compare the rapid identification system ATB 32E (API-bioMérieux SA, La Balme-les-Grottes, France) with conventional biochemical methods for identifying 414 isolates of the family Enterobacteriaceae and the genus Aeromonas, mainly of clinical origin. Overall, 395 strains (95.4%) were correctly identified, with 48 (11.6%) requiring extra tests for complete identification. Ten strains (2.4%) were not identified, and nine (2.9%) were misidentified. The ATB 32E is a suitable alternative for rapid identification of members of the family Enterobacteriaceae.

Autoanalysis↗
PubMed1991

Evaluation of API Coryne in comparison with conventional methods for identifying coryneform bacteria.

A study was performed to evaluate a new manual miniaturized system, API Coryne (API-bioMérieux, Inc., La Balme les Grottes, France), in which conventional biochemical methods were used to identify 240 isolates of coryneform and related bacteria. A total of 40% of the isolates were excluded from the study because they could not be identified by conventional methods. Identifications of the 240 isolates obtained with API Coryne showed a 97.6% concordance with conventional methods (79% after 24 h of incubation, 21% after 48 h of incubation): 158 (65.8%) isolates were identified with no further testing, and extra testing was required for 76 (31.8%) isolates. In three (1.2%) cases, the organisms did not correspond to any key in the code book and could not be identified by the computer service of the manufacturer. Only three (1.2%) strains were misidentified. The system was shown to be reliable and rapid when compared with standard identification methods.

Bacteriological Techniques↗
PubMed1991

Skilled memory in expert figure skaters.

The present studies extend skilled-memory theory to a domain involving the performance of motor sequences. Skilled figure skaters were better able than their less skilled counterparts to perform short skating sequences that were choreographed, rather than randomly constructed. Expert skaters encoded sequences for performance very differently from the way in which they encoded sequences that were verbally presented for verbal recall. Tasks interpolated between sequence and recall showed no significant influence on recall accuracy, implicating long-term memory in skating memory. There was little evidence for the use of retrieval structures when skaters learned the brief sequences used throughout these studies. Finally, expert skaters were able to judge the similarity of two skating elements faster than less skilled skaters, indicating a faster access to semantic memory for experts. The data indicate that skaters show many of the same skilled-memory characteristics as have been described in other skill domains involving memorization, such as digit span and memory for dinner orders.

Adolescent↗
PubMed1989

The effect of handedness on spinal and supra-spinal reflex excitability.

Twenty-four subjects, 8 right-handers, 8 left-handers, and 8 familial left-handers, participated in a study aimed at understanding the relations between handedness, cerebral asymmetry, and a possible asymmetry in spinal excitability. This was accomplished by employing 3 different techniques of investigating the H reflex, measuring 3 different parameters of spinal excitability. The recovery curve height (RCH) of left-handers was significantly higher than the RCH of right-handers, and, as well, familial left-handers exhibited higher RCH than non-familial left-handers. The recovery ability was not found to be significantly more inhibited on the dominant side, as would be expected from previous work. Instead, recovery ability was associated with the fractional involvement of the motoneuron pool in the H process (H/M ratio). RCH was highly correlated with both hand preference and hand performance. The above results suggest involvement of a long-loop transcortical reflex in lateral asymmetries.

Adolescent↗
PubMed1988

Expectancy effects: cost-benefit analysis of monaurally and dichotically presented speech.

In three experiments, cost-benefit analysis was used to determine the role of attention in the processing of auditory information. In two experiments consonant-vowel syllables were presented monaurally, while in the third the mode of presentation was dichotic. For all three experiments the ability to detect a target stimulus under conditions in which precued location information was valid or invalid was contrasted with detection in a neutral condition where no location information was provided. The results indicated that attention can be effectively deployed under monaural conditions when either a simple detection or a discriminative response is required. Similar conclusions cannot be reached when considering the effectiveness of attention under conditions of dichotic listening. These results are discussed in relation to accounts which argue that dichotic listening performance is critically dependent upon auditory disembedding and where attention is viewed as a late process involving response selection.

Adult↗
PubMed1979

The effect of concurrent activity on hemispheric asymmetries.

Two experiments were performed to test Kinsbourne's (1970) contention that perceptual laterality effects are affected by the nature of concurrent activity. In the first, subjects listened to verbal or nonverbal dichotic material while holding verbal or spatial material in memory. In the second, subjects localized dots while remembering a list of abstract words. In neither experiment did the concurrent activity alter the laterality effect in the manner suggested by Kinsbourne's model. This model therefore cannot provide a general explanation for perceptual laterality effects.

Attention↗