A simple and inexpensive computer-compatible shock circuit

A circuit for computer control of shock stimulation that uses an optically isolated triac is described. © 1985 Psychonomic Society, Inc

Effects of MK-801 on acquisition, retention, and cross-modal transfer of active avoidance behavior in rats

Three experiments were conducted to examine the effects of MK-801, a noncompetitive NMDA antagonist, on acquisition, retention, and cross-modality transfer (CMT) of learning of an active avoidance response in rats. The first showed that MK-801 (0.1 mg/kg) disrupted acquisition but not retention of avoidance responding when an auditory intensity cue signaled shock. In the second experiment, the effects of MK-801 on CMT were examined by training rats to avoid shock with a visual intensity cue in the first session, then with an auditory intensity cue in two more sessions. Different groups of rats were given MK-801 (either 0.05 or 0.1 mg/kg) prior to one of the three sessions. When MK-801 was injected before visual training, the drug blocked acquisition of the avoidance task, preventing the formation of memory usable during the transfer session. When MK-801 was given before the second (transfer) session, rats did not show evidence of transfer from the previous training with the visual cue, nor did they show evidence of new learning. In the third experiment, MK-801 had no effect on avoidance behavior when it was administered immediately after training. These data suggest that NMDA receptors are involved not only in simple discrimination learning but also in neuronal processes responsible for transfer of learning between sensory modalities

Age-related differences in the effects of d-amphetamine and illumination on fixed-interval responding of rats

The effects of d-amphetamine (0.0, 0.4, and 0.8 mg/kg) on fixed-interval responding in light and dark sensory conditions were examined in rats that were 25, 100, and 200-days-old at the beginning of the experiment. In the youngest and oldest groups, the drug increased responding in light more than in dark. The drug increased responding of the middle age group in the light, but decreased operant rates in the dark. These data appear to support the notion that d-amphetamine reduces the effects of ambient light on behavior in rats. © 1982 Springer-Verlag

Facilitative effects of cross-modality training on recovery of a conditioned avoidance response following striate cortex ablations in the rat

Two experiments with visual decorticate rats examined the effects of cross-modality transfer on the recovery of a preoperatively learned avoidance task using high intensity light cues. In both experiments, brief postoperative cross-modality training with high intensity noise cues produced significantly better recovery of the visual avoidance response than either reversed intensity noise training or retraining with the original task. Training with a reversed intensity visual cue produced relearning deficits. In the second experiment, control conditions eliminated re-exposure to the test environment, the shock-response relationship, and compound conditioning as possible explanations for these findings. These results indicated that rats are capable of cross-modality transfer after posterior cortical lesions and that this transfer effect can facilitate recovery of behavioral function. The clinical implications of these findings are also discussed. © 1988

Effects of cross-modal transfer on direct and reversal learning in the rat

In the first experiment, using within- and between-sensory modality CSs, direct and reversal transfer of active avoidance learning was studied in 48 male and 48 female albino rats. Training in each of two sessions employed either a high- or low-intensity light or noise CS. The analyses of both raw score data and proportional or savings score data indicated significant cross-modal transfer in direct as well as reversal learning conditions. Although females learned faster than males, there were no sex differences in amount of transfer. A second experiment, which examined the potential of compound conditioning within the cross-modal learning procedures, replicated the cross-modal results of the first experiment without finding evidence for compound conditioning. These results are interpreted in terms of specific and nonspecific transfer effects during avoidance learning. © 1986 Psychonomic Society, Inc

Cross-modal transfer effects on visual discrimination depends on lesion location in the rat visual system

The effects of postoperative visual and auditory training on a brightness discrimination task were examined after lesions of various structures in the visual system. In Experiment 1, rats were trained to avoid shock with visual intensity cues. Twenty-four hours later, each rat received bilateral lesions in one of the following areas of the visual system: (1) sham, (2) visual cortex (VC), (3) pretectal (PT) area, (4) combined PT/VC, (5) superior colliculus (SC), or (6) combined SC/VC. Six days later, each rat received either training with visual or auditory intensity cues, or no training. The next day all rats were retrained on the preoperative visual avoidance task. All lesions except those in the SC condition produced relearning deficits. Auditory training reduced these deficits significantly more than visual training, except in rats with combined SC/VC lesions. In Experiment 2, sham and combined PT/VC lesion rats were given either direct or reversal intensity training using visual or auditory cues before relearning the visual discrimination. Rats given auditory direct training relearned the task faster than rats given reversal training or visual direct training. Postinjury training with an intact sensory system can enhance functional recovery more effectively than training with the damaged system. The differential effects of direct and reversal training suggest that cross-modal training involves both specific and nonspecific transfer that may be mediated through the VC or the SC. © 2001 Elsevier Science Inc. All rights reserved

The effects of illumination, d-amphetamine, and methylphenidate upon vigilance performance of squirrel monkeys

The effects of illumination, d-amphetamine, and methylphenidate on vigilance behavior were studied with four squirrel monkeys. Detection rates of an auditory signal were higher in the light than in the dark. Although methylphenidate did not alter performance, d-amphetamine lowered detection rates more in the light than in the dark, particularly in male squirrel monkeys. Results were interpreted in terms of altered arousal levels. © 1980, The Psychonomic Society, Inc.. All rights reserved

Age and arousal in the rat

The influence of illumination level on locomotor activity and reaction times of three age groups (25, 90, and 180 days old) of rats was studied. Age-related differences were obtained, and consistent effects on the two behavioral measures were obtained for the individual animals. © 1983, The psychonomic Society, Inc.. All rights reserved

Crossmodal training reduces behavioral deficits in rats after either auditory or visual cortex lesions

Rats were trained with either visual or auditory intensity cues until they emitted nine avoidance responses in 10 trials ( 9 10) prior to bilateral ablation of the corresponding sensory neocortex. Six days after surgery, rats were trained to 5 10 criterion in one of the following conditions: within-modality direct, within-modality reversal, crossmodality direct, crossmodality reversal, or no training control. The next day all rats were retrained to 9 10 on their preoperative tasks. For visual decorticate rats, the no training and the visual within-modality direct groups relearned the discrimination at the same rate as preoperative learning. Auditory crossmodal direct training enhanced relearning more than other forms of training and visual within-modality reversal training hindered retraining. For auditory decorticate rats, similar postoperative auditory within-modality and visual crossmodality training effects were seen during retraining of the auditory discrimination. These findings suggest crossmodality training facilitates functional recovery through relational information and learning sets transferred from experimental training to the relearning task. © 1994

Comparison of compound and cross-modal training on postoperative visual relearning of visual decorticate rats

The effects of postoperative bimodal compound conditioning and cross-modal transfer of learning on behavior were compared by training rats prior to visual decortication to avoid shock with visual intensity cues. On Postop Day 6, rats were given avoidance training in one of three cue conditions: auditory intensity cues (cross-modal), paired auditory and visual cues (compound conditioning), or no cues (no-training control). On Postop Day 7 rats in the no-training control and the cross-modal transfer conditions were retrained with the visual discrimination while rats in the compound conditioning group were either retrained with the visual intensity cue or trained with the auditory intensity cue. Postoperative cross-modal transfer training enhanced visual relearning whereas bimodal compound conditioning interfered with relearning. However, compound conditioning facilitated subsequent auditory discrimination learning. These results support the notion of an injury-induced neurological bias that is increased after bimodal compound conditioning and reduced after cross-modal training. Potential implications for neurological rehabilitation are also discussed