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Biomedical subjects

E C Beck

Publications and source records attributed to E C Beck.

48 records · Page 3Linked to original sources
PubMed1966

Visually evoked potentials: amplitude changes with age.

Visually evoked potentials of 215 subjects, aged 1 month to 81 years, were studied. Amplitudes of waves in the first 250 milliseconds of the response changed markedly with age. In responses recorded from the occiput, there was a rapid increase in amplitude reaching a maximum in the 5- to 6-year-old group, with means of amplitudes at this age being about twice as large as means of some older age groups. With children 7 years and older there was a rapid decline in amplitude until ages 13 to 14, when an abrupt increase in amplitude appeared. Amplitude appeared to stabilize at about age 16. In older subjects, mean age 60 and beyond, significant changes were noted in the earlier components of the response.

Adolescent↗
PubMedDate not supplied

Sustained ingestion of delta 9-tetrahydrocannabinol and the operant behavior of stump-tailed macaques.

Three stump-tailed macaques were trained to press a lever for liquid reinforcement on a tandem schedule which required the animal to delay responding for at least 30 sec after each reinforcer. If the animal responded during that interval, a clock was reset thus re-establishing the delay requirement. If he delayed responding appropriately, the monkey was shifted to a fixed-interval schedule of 135 sec duration. The FI component was terminated with a drop of flavored liquid at which point the delay requirement began anew. Following a stable baseline performance, two monkeys received 2 mg/kg of THC orally every third day for 90 days with the placebo administered on intervening days. The third animal received the placebo throughout testing. Each monkey's performance was described in terms of response rate and response patterning between reinforcers. Despite the sustained ingestion of THC neither animal showed appreciable change in test behavior attributable to tolerance to the drug. Although the drug continued to have a powerful effect throughout testing on the days it was administered, there was no evidence of any consistent or cumulative drug effect on placebo-day performance.

Animals↗