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Biomedical subjects

J E Ledoux

Publications and source records attributed to J E Ledoux.

22 records · Page 2Linked to original sources
PubMed1983

Strain differences in fear between spontaneously hypertensive and normotensive rats.

The purpose of this study was to determine whether the reduced conditioned fear response in spontaneously hypertensive rats (SHRs) relative to Wistar-Kyoto controls (WKYs); (a) reflects a decrease in fear in SHRs or an increase in fear in WKYs, relative to other strains; (b) is secondary to strain differences in cardiovascular regulation; (c) represents a weaker conditioned response or a weaker memory trace; and (d) generalizes beyond tests of conditioned fear. SHRs, WKYs and Sprague-Dawley (SD) rats were subjected to classical fear conditioning (30 trials) involving the pairing of a tone conditioned emotional stimulus (CES: 800 Hz, 82 dB, 10 s) with an electric footshock unconditioned stimulus (US: 1.5 mA, 0.5 s). Cardiovascular responses elicited by the CES (without the US) were assessed through computer assisted techniques in chronically instrumented animals. Conditioned fear behavior was assessed as the proportion of time accounted for by crouching or freezing during a 300 s presentation of the CES without the US. Unconditioned fear reactivity was examined using the open field test. Conditioned fear reactivity (% freezing during 300 s CES) was reduced (P less than 0.01) in SHRs relative to both WKYs and SDs, which did not differ (SHR: 57% +/- 5; WKY 85% +/- 3; SD: 93% +/- 4). Young (7 week) and mature (14 week) animals within each strain differed in resting mean arterial pressure (MAP, in mm Hg) (WKY: young , 102 +/- 1; mature, 133 +/- 2; P less than 0.01; SHR: young, 124 +/- 3; mature, 153 +/- 5; P less than 0.01) but did not differ in conditioned fear reactivity (WKY: young, 91% +/- 3; mature, 93% +/- 3; SHR: young, 47% +/- 3; mature, 62% +/- 8.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Arterial pressure and heart rate changes during natural sleep in rat.

Mean arterial pressure and heart rate data during quiet wakefulness and phases of sleep in conscious rat are sampled by a computer at a rate of 100/sec. Average values and variability expressed as standard deviation are computed for each recording session. Mean arterial pressure and heart rate and their variability decrease from quiet wakefulness to synchronized sleep. During desynchronized sleep, mean arterial pressure increases to the level of quiet wakefulness, and is more variable than during synchronized sleep. Heart rate is lower and more uniform during sleep than during quiet wakefulness, and there is no difference between synchronized and desynchronized sleep except that a greater variability occurs during desynchronized sleep. The study shows that characteristic and specific cardiovascular changes accompany the phases of sleep and that a hierarchy of arterial pressure is present during the resting behavior in rat.

Animals↗
PubMed1977

Cognition and commissurotomy.

Cognitive functioning was extensively evaluated in a recent callosum-sectioned patient. A number of standardized and specialized experimental memory tests, as well as a sophisticated hypothesis testing task, were administered both before and after operation. No post-operative deficits were obtained. In fact, this patient showed marked improvement on almost every measure utilized. These results demonstrate that the cognitive processing of complex information is not necessarily dependent on the integrity of the corpus callosum, but rather suggest that cognitive functioning is largely an intrahemispheric process.

Adolescent↗