Some Antiepileptic Compounds Impair Learning by Rats in a Morris Water Maze

In the present experiments, we investigated the effects of several commonly employed antiepileptic drugs on the performance of adult rats in a Morris water maze task. We found that phenytoin treatment produced the most deleterious performance impairments across all days of training, and that these performance deficits are not likely due to any general sensorimotor impairments. Carbamazepine had milder, but detectable negative effects, as carbamazepine-treated animals exhibited initial acquisition deficits, but rapidly achieved escape levels comparable to controls. In marked contrast, valproate and ethosuximide had no detectable effects on learning in the water maze. These results parallel previous findings in rats treated with these compounds and tested in an instrumental learning task, and are in general agreement with the human clinical literature. To the extent that one might wish to minimize learning deficits associated with maintenance on antiepileptic drugs, phenytoin is definitely not the treatment of choice, while valproate or ethosuximide are apparently much less disruptive.     

Maze Learning by Honeybees

This study examines whether honeybees can learn to fly through complex mazes, in the presence or the absence of specific visual cues. The results are summarized as follows: 1. Bees can learn to fly through a complex maze by following a trail of colored marks. 2. Bees, initially trained to follow color marks through an initial part of the maze, are immediately able to use the same sign-tracking cue to find their way through the rest of the maze, which is unfamiliar to them. 3. Bees trained to follow color marks through a particular maze can use the same cue to negotiate a novel maze. 4. Bees trained to use a particular color to negotiate a maze can immediately use a novel color to negotiate the same maze or even a novel maze. 5. After learning to negotiate a maze by following colored marks, bees can find their way through the maze even when the marks are removed, albeit at reduced levels of accuracy. Thus, the trained bees do not rely solely on sign-tracking to find their way through the maze: they also acquire a spatial memory of the maze or at least a sequence of motor commands describing the correct path through it. 6. Bees can learn to use color as a signal even when it indicates the path through the maze in a symbolic way, for example, blue indicating a turn to the right and green a turn to the left. 7. Bees can learn an unmarked maze. Performance under these conditions is poorer than when marks are provided, but is still significantly better than chance level. 8. Control experiments rule out the use of external landmarks in all of these situations.     

Time Records in Human Maze Learning and their Comparison with Maze Records

Nine measures of role-taking in the tradition of Flavell and two measures of classification were administered to 64 boys and girls in India in four age groups: 6–7, 7–8, 8–9, and 9–10 years. The results lend cross-cultural support to the hypothesis that certain classification skills underlie this type of role-taking ability. The inappropriateness of searching for developmental relationships with some parametric statistics was also demonstrated with these data. The influence of two types of role-taking question on role-taking ability was also assessed. Role-taking questions were asked after the Ss had seen a cartoon sequence. On one type of role-taking question (a “next” question) Ss were asked how another child would think the cartoon ended if shown only the beginning. On the other type of role-taking question (a “before” question) Ss were asked how another child would think the cartoon began when shown only the end. Cartoon content was shown to influence role-taking ability in response to “next” questions.     

The Wall-Seeking Tendency and Maze Learning in the White Rat

A partial replication and extension of the semantic differential was used to test the effects of modified middle interval instructions on rotated factor loadings derived from Ss' responses. The partial replication is in good agreement with the findings published by Osgood et al. (5). However, the results from Ss responding to the modified middle interval instructions differ markedly from those in published and control conditions, yielding an interpretable fourth factor suggesting the achievement of more subtle nuance of meaning.     

Sex of Experimenter and Intelligence as Factors in Maze Learning: A Further Comparison of Maze and Sex Differences

(Murphy, Lois Barclay. Social Behavior and Child Personality. New York: Columbia Univ. Press, 1937. Pp. 333.)     

The High Relief Finger Maze for Human Learning

Albino rats in independent studies were administered varying dosages of diazepam and methylphenidate prior to a daily shock traumatization experience in infancy. All animals were tested on avoidance conditioning in adulthood. Both drugs were found to be effective in modifying the typically obtained shock deficit. The results failed to substantiate that increased dosage level resulted in more effective modification of trauma effects. Delayed consequences of methylphenidate administration included modification of central nervous system reactivity as manifested in quicker reaction times and growth depression as manifested in lessened body weights in this group in comparison to the diazepam group. An additional feature of the study was the finding that male and female animals responded differently to the drug and shock experiences.     

Human Learning on a Four-Section,Elevated, Finger Maze

Forty Ss learned 10 sentences composed of adjective, noun, verb, and adverb and were subsequently tested for their recall of the sentences and their ability to generate new sentences based on an association rule for words within the sentences. The rule could be discovered from the sentences learned and was comparable to grammatical rules for sentence structure. Subjects also rated the meaning of the words from the sentences before and after learning. Eight Ss were in each of five experimental conditions, which differed in terms of the degree to which the words in the 10 sentences were in a natural language order. The five orders were natural, reversed, 20% random, 50% random, and 100% random orders.

The results showed that the closer the sentence order was to natural language order, the more Ss recalled the sentences they learned and the more accurately they generated unlearned sentences, apparently as a result of discovering and using the association rule. Another finding was that the rated evaluative meaning of words changed in a predictable direction, toward the mean rating of the words associated with each word. Such meaning conditioning appears to be an automatic process comparable to classical conditioning in that it is unaffected by the order of words within sentences and occurs for different word forms.     

A Comparative Study of Groups of High and Low Intelligence in Learning a Maze

In accordance with the determination of base-line heart rate and running in an activity wheel, 14 Long-Evans male rats were given ten 30 minute sessions of Immobile-Avoid conditioning followed by 30 minute sessions of Active-Avoid conditioning. Control Ss were yoked to the experimental Ss.

Experimental Ss made significantly fewer responses in the immobile-avoid period and significantly more responses in the active-avoid period than did the yoked control Ss. Heart rate was correlated with skeletal activity both for experimental and control Ss. For experimental Ss, low heart rate was concomitant with a low amount of activity in the immobile-avoid period and high heart rate was concomitant with greater skeletal activity in the active-avoid period.

These results support the position that heart rate is secondary to responses of the somatic-motor system and that heart rate during immobile-avoid or active avoid conditioning is more closely related to the level of somatic-motor activity than to the emotional stress which purportedly motivates instrumental avoidance behavior.     

Complex Visual Learning by Rats

Rats’ learning about visual patterns was studied in a computerized Y-maze where wide-angle stimuli were viewed from a distance. Many patterns were available; some were spatially complex and others were more homogeneous figures. Experiment 1 used a discrimination paradigm in which a single S⁺could be paired with any one of 15 different S⁻s. Hooded rats learned successively six such discrimination problems. Their learning rate improved across the series, and comparison with controls suggested that the learning-set did not merely reflect simple habituation. Experiments 2 and 3 employed Dark Agouti rats, again learning many discrimination problems. Each problem comprised a constant stimulus which was paired with stimuli which varied in trial-unique fashion. The version in which the constant stimulus was nonrewarded (S⁻) and the varying stimuli rewarded was performed better than the converse, constant S⁺and varying nonrewarded, reflecting rats’ preference for relatively unfamiliar stimuli. In the constant S⁻task, rats showed substantial within-problem learning when three novel problems were given per day for 20 trials each. Rats are capable of rapid learning about complex visual displays if we engage their natural dispositions to use vision for distal stimuli and to approach relatively unfamiliar cues.