George A. Cicala

Inhibition of Nitric Oxide (NO) production selectively impairs learning and memory in the rat

Animals administered the nitric oxide (NO) synthase inhibitor N-w-nitro-L-arginine methyl ester (NAME) for five days exhibited severe deficits in acquisition of a place-navigation learning task. The effect of NAME was selective to place-navigation learning. NAME had no effect on sensorimotor or motivational processes in a related task. These results are consistent with the view that NO participates in learning and execution of memory tasks.

Fear inhibition and species specific defense reaction termination may contribute independently to avoidance learning

Abstract A series of three experiments was conducted to test the proposal of Cicala and Owen ( Learning and Motivation , 1976 , 7, 356–367) that warning signal termination reinforces avoidance learning by permitting fear to dissipate and that a feedback signal reinforces avoidance learning through conditioned inhibition of fear. A CER procedure with a second-by-second analysis was used to measure fear elicitation and fear reduction following classical conditioning or avoidance training. The results show that a feedback signal produces rapid and marked fear reduction, suggesting an inhibitory process. Although warning signal termination produced fear reduction, the slowness of this process suggests fear dissipation and not an inhibitory process. The combination of both events reduced fear no more effectively than a feedback signal alone. It is suggested that warning signal termination is effective in some avoidance learning situations not because it reduces fear, but possibly because it helps terminate an avoidance response that closely resembles a species specific defense reaction.

The Effects of Chlordiazepoxide on the Acquisition and Performance of a Conditioned Escape Response in Rats

Drug effects were assessed with a factorial design. Ss were divided into 8 groups for training. Each of 4 groups (D-groups, n=20 ea.) received one dose of drug (5 or 10 mg/kg) at a specified delay before training (10 or 60 min.). The remaining 4 groups ( P-groups,n=20 ea.) received placebo injections. During testing or performance trials (21–40), ½ of each group was maintained under the same drug conditions (D-D and P-P Ss, n=10 ea.). The other ½ was switched to the opposite conditions (D-P and P-D) Ss, n=10 ea.). Analysis revealed that while Ss in the 5 mg/kg. groups were unaffected by GDP, the learning of Ss in the 10 mg/kg groups was greatly retarded, even though CDP at the highest dose did not significantly depress the performance of groups trained under placebo.

Warning signal termination and a feedback signal may not serve the same function

Abstract Three experiments were conducted to test the possibility that a feedback signal (FS) and warning signal termination (WST), while equally reinforcing in the avoidance learning situation, reinforce through different underlying mechanisms. The first experiment showed that the reinforcing properties of an FS are reduced more than those of WST when these stimulus changes are made unreliable by the presence of shock following a CR on specified trials throughout acquisition. Experiment 2 confirmed this effect on avoidance performance when only a few punishment trials were administered following asymptotic avoidance acquisition. Experiment 3 demonstrated this effect during avoidance extinction with and without the presentation of punishment trials between acquisition and extinction performance. The results provided no support for the expectancy explanation of avoidance learning and were interpreted as consistent with the assumption that WST reinforces by permitting fear to dissipate and that the FS reinforces through fear inhibition.

The effects of shock Intensity and d-amphetamine on avoidance learning

The effects of shock intensity and d-amphetamine on a shuttlebox avoidance response were factorially assessed. Avoidance learning was facilitated by the drug and inversely related to shock intensity but the two variables did not interact. The results were discussed in terms of D’Amato’s anticipatory response hypothesis.

Increased conditioning in rats to a blocked CS after the first compound trial

Two experiments examined the effects of increased conditioning to a blocked conditioned stimulus (CS) with increased compound training, using the conditioned suppression procedure. Experiment 1 demonstrated that conditioning to the blocked element increased after the first compound trial but that there was no additional conditioning after 10 compound trials. Conditioning to the blocking CS was also tested and showed no reliable differences among groups given different amounts of compound training. A small increase in conditioning to the pretrained element after the first compound trial suggested that asympotote might not have been reached during pretraining. In Experiment 2 the level of conditioning to the blocking CS was tested extensively. Conditioning to the blocking element did not increase after pretraining when it was conditioned either in a compound or by itself. This provides strong evidence that the pretraining procedures of Experiment 1 did result in asymptotic learning. The results were interpreted as showing that even a completely redundant CS can acquire excitatory strength when it is paired with a significant event such as footshock.

Blocking of conditioned suppression with 1 or 10 compound trials

It is generally agreed that the Kamin blocking effect provides a differential test of the model of classical conditioning proposed by Rescorla and Wagner (1972), on the one hand, and the models proposed by Mackintosh (1975) and Pearce and Hall (1980), on the other. Specifically, if the blocking effect occurs with 1 compound trial, Rescorla and Wagner are supported. Experiment 1 showed that prior training with one element of a simultaneous compound stimulus prevented the added element from becoming conditioned with 10 compound trials when compared with a nonpretrained (Kamin) control. A pseudoconditioning control, which received no compound training, showed substantial suppression only on the first trial. A contextual conditioning control, which received unsignaled shock prior to compound training, was suppressed, suggesting a failure of conditioning to contextual cues. Experiment 2 demonstrated 1-compound-trial blocking using a simultaneous presentation of the compound elements. The importance of this support for the Rescorla-Wagner model is discussed in the light of other supportive studies and those which support alternative models of classical conditioning.

Endogenous Opioids Interfere With Pavlovian Second-Order Fear Conditioning

Second-order classical (Pavlovian) aversive conditioning was used to determine whether endogenous opiates play a role in the acquisition of associative learning. Second-order conditioning avoids confounding drug effects on associative learning with altered responsiveness to unconditioned stimuli (e.g., hyperalgesia). Administration of the prototypical opiate antagonist naloxone (2.0 mg/kg) prior to the second-order training session specifically facilitated associative learning as indicated by greater lick suppression over 3 days of testing. This result suggests that endogenous opiates retard the acquisition of associative learning, which complements previous studies demonstrating an opioid attenuation of memory consolidation.

ANXIETY: GENERAL VS SPECIFIC TRAIT IN THE PREDICTION OF SNAKE FEAR

2 studies are reported on the relationships between general and specific tests of anxiety and behavioral and self-reported fear responses in the presence of a live snake. Ss were 35 female undergraduates in Study I and 76 in Study II. Measures of general anxiety were not predictive of fear responses, while measures of specific fear of snakes were highly predictive of such responses.

The effects of prefear conditioning shock intensity on initial shuttle response rate

The effects of prefear conditioning shock intensity on unreinforced shuttle response rate indicated that unreinforced shuttle response is inversely related to prefear shock intensity. The CS enhanced shuttling equally for all prefear shock groups. The data suggest that prefear conditioning decreases initial shuttle response rate, while the CS partially reverses this effect. An interpretation of demonstrated facilitation by prefear conditioning is offered.