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At least 1,765 records · Page 98Linked to original sources
PubMed1980

Responsiveness of inferotemporal single units to visual pattern stimuli in monkeys performing discrimination.

Four monkeys were trained to choose two rewarded stimuli from four two-dimensional patterns presented successively, and the responsiveness of single units to these patterns was investigated. Eighty-three of 214 units (39%) recorded from the dorsolateral portion of the inferotemporal cortex were responsive; nearly half responded to all four patterns, irrespective of pattern shape and of whether the stimuli were rewarded or not. A few units were responsive to only one of the patterns, regardless of size, color, or luminance, and unresponsiveness to components of the response-eliciting patterns was indicated in some of these units. The activity of most units response to two or three patterns was dependent on pattern shapes rather than the learnt meaning of the patterns.

Animals↗
PubMed1982

Effects on visual acuity of neonatal or adult tectal ablation in rats.

Tectal ablation in neonatal rats leads to retrograde degeneration of retinal ganglion cells whereas similar damage in adults does not. We show here that the behavioral effects are comparably different. When rats with neonatal tectal ablation are tested as adults they are impaired in learning a discrimination between vertical and horizontal stripes and their visual acuity for square-wave gratings is slightly but significantly reduced.

Aging↗
PubMed1979

Effects of mescaline and amphetamine on simultaneous visual discrimination in two inbred strains of mice.

The effects of mescaline and amphetamine were investigated in BALB/cJ (BALB) and C57BL/6J (C57) mice using the five-choice Yerkes--Thompson Bryant--Bovet-Nitti apparatus for patterns discrimination. Two sets of experiments were carried out. In the first set, pretrial administration of mescaline (5, 10, and 20 mg/kg) was followed by performance improvements in the C57 mice, while performances of the BALB strain were impaired by the treatment, as compared with those of the saline-injected (4 ml/kg) controls. The pretrial administration of amphetamine (0.1, 0.25, and 0.5 mg/kg) improved performances of both strains. In a second set of experiments, the same effects as in the pretrial experiments were observed in both strains following administration of mescaline (20 mg/kg) and amphetamine (0.5 mg/kg) immediately after each experimental session. No effect was evident when the drugs were injected 2 h after training, suggesting that effects of the pretrial treatments were due to influences of mescaline and amphetamine on the consolidation processes of the two strains of mice tested.

Animals↗
PubMed1978

Stimulus properties of thyrotropin-releasing hormone.

Male Sprague-Dawley rats were trained in a two-lever operant discrimination task using 20 mg/kg thyrotropin-releasing hormone (TRH) and saline as cues. Following completion of 40 daily training sessions, 22 of 25 subjects demonstrated a high level of discriminative responding based on the TRH and saline cues. An evaluation of the time course of TRH indicated that the stimulus properties peak between 5 and 15 min and dissipate substantially by 55--65 min. During additional testing, rats showed dose-dependent generalization between the training treatments (20 mg/kg TRH and saline) and novel doses of TRH (1, 5, 10, and 40 MG/KG). However, animals failed to show generalization between the training drug (20 mg/kg TRH) and d-amphetamine sulfate (0.8, 1.6, or 2.4 mg/kg); likewise, animals trained to discriminate d-amphetamine (0.8 or 1.6 mg/kg) from saline failed to show generalization between d-amphetamine and TRH (10, 20, OR 30 MG/KG). Microgram quanitites of TRH (2.5--25 microgram administered into either the lateral or third ventricle elicited dose-dependent generalization to the training drug (TRH 20 mg/kg, i.p.), suggesting a CNS mechanism of action for this effect of TRH.

Animals↗
PubMed1977

Discriminative properties of pentobarbital after repeated noncontingent exposure in gerbils.

Two groups of gerbils were pretreated with pentobarbital (P-barb.) (10 and 20 mg/kg) for 20 days before being subjected to drug discrimination training in a (T-shaped shock-escape maze. The rapidity with which these gerbils acquired the discrimination was compared to that of gerbils that were drug naive until beginning the P-barb.-discrimination training. The acquisition rates of the respective groups did not differ substantially within each dose level (10 and 20 mg/kg), although open-field activity (primarily the rearing scores) differentiated the P-barb.- and vehicle-pretreated animals at both dose levels. The peak effect in rectal temperature, however, was not markedly different after the first and 20th drug exposures, although the temperature effects leveled off earlier during the second recording session. In conclusion, certain parameters (open-field activity) may be changed as a consequence of repeated administrations of P-barb. without a significant parallel loss of the cue or stimulus properties of the drug.

Animals↗
PubMed1983

Ethanol and tetrahydroisoquinoline alkaloids do not produce narcotic discriminative stimulus effects.

Male Sprague-Dawley rats were trained in a two lever food-reinforced procedure to discriminate between the effects of saline and the synthetic narcotic analgesic fentanyl (0.04 mg/kg). After acquisition of this discrimination, generalization tests with morphine, ethanol and some tetrahydroisoquinoline alkaloids were conducted. The rats dose-dependently generalized the effect of morphine but did not generalize the effects of either ethanol, tetrahydropapaveroline, salsolinol or 3-carboxysalsolinol to the fentanyl discriminative stimulus. Thus, these date do not support a biochemical link between ethanol and opiates.

Alkaloids↗
PubMed1976

Effects of drug-state change on discrimination performance.

A single dose of d-amphetamine (0.25, 0.50, or 1.00 mg/kg), administered in 5 successive sessions, did not seriously impede the discrimination performance of male Holtzman rats under cued reinforcement conditions. A 2.00 mg/kg dose, however, produced a total cessation of operant behavior. In 2 post-drug (saline) sessions, groups previously treated with 0.50 or 1.00 mg/kg demonstrated an initial decrement and subsequent recovery in performance. A second experiment demonstrated that rats administered either saline or 0.50 mg/kg d-amphetamine for 5 successive sessions showed a decrement and subsequent recovery in performance when switched to the opposite treatment condition for the next 2 sessions. These data may be explained in terms of a change in drug state.

Animals↗