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Behavioral effects of arginine8-vasopressin in the Hebb-Williams maze.

Arginine(8)-vasopressin (AVP) has been shown to improve memory consolidation in various mnemonic tasks. Our previous studies have pointed out the involvement of the hippocampus (with higher sensitivity of its ventral part) in memory consolidation and retrieval processes during discriminative learning in mice. The present study was designed to extend our knowledge, firstly, of the range of tasks and consequently the types of information for which the peptide improves consolidation processes, and secondly, the effects of AVP on information treatment processes such an information transfer. To this end, the effects of AVP were analyzed in the Hebb-Williams closed-field maze. Mice were initially trained on one of the mazes in the Hebb-Williams series (Maze 7) and subsequently tested on either that maze or another maze in the series (Maze 11). The effects of the peptide on both memory consolidation and information transfer processes were analyzed in relation to the route of administration: peripheral (subcutaneous, s.c.), central (intracerebroventricular, i.c.v.), and in situ (dorsal or ventral hippocampus). The results showed that AVP facilitated spatial memory consolidation following s.c., i.c.v, and dorsal, but not ventral hippocampal administration. This differential effect of AVP following injection into the hippocampus can be interpreted in regards to this structure's functions. In line with the involvement of the dorsal hippocampus in spatial memory, the effectiveness of the peptide in the Hebb-Williams maze, which contains spatial components, was better when the treatment was performed in this part of the structure. In contrast, whatever the route of administration, AVP had no effect on processes related to the transfer from one learning situation to another.

Animals↗

Schizophrenic cognitive dysfunction: a deficit in rule transfer.

This study examined conceptual rule learning (RL) deficit in male schizophrenic Ss categorized into three groups as defined by Whitaker Index of Schizophrenic Thinking (WIST). Ss were administered a conjunctive, disjunctive, conditional or biconditional rule learning task, WIST, and Shipley-Hartford Memory Scale. It was shown that: (a) the WIST reliably differentiates among three levels of thought disorder as reflected by a deficit in inter-problem transfer of rule learning; (b) certain WIST and Shipley parameters reliably predict RL performance; and (c) phenothiazine dosage levels show no influence on the WIST and no correlation with RL. The findings indicate that cognitive dysfunction in schizophrenics is evidenced by limited inductive reasoning, insufficient channel capacity for filtering out irrelevant information, and inability to gain from antecedent RL experience. Principal locus of schizophrenic thought disorder is examined within a stimulus encoding-information processing paradigm.

Adult↗

Viral restoration of dopamine signaling to the dorsal striatum restores instrumental conditioning to dopamine-deficient mice.

INTRODUCTION: Instrumental responding was evaluated to determine whether mice lacking dopamine [dopamine-deficient mice (DD mice)] could learn to preferentially press a visually cued, active lever for food reward over an inactive lever. RESULTS: When DD mice were treated with 3,4-L: -dihydroxyphenalanine (L-dopa) to restore dopamine signaling systemically, they were able to learn to press the active lever as well as control mice, whereas mice lacking dopamine would not perform the task. Importantly, DD mice treated with caffeine (to stimulate locomotor and feeding behaviors) also failed to show preference for the active lever and were slower to retrieve rewards after making a reinforced operant response. Selective restoration of dopamine signaling to the nigrostriatal pathway of DD mice via viral-mediated gene transfer completely restored learning and performance of this simple instrumental task. Furthermore, the virally treated DD mice were willing to lever press as much as control mice for reward in progressive-ratio and high fixed-ratio schedules of reinforcement. CONCLUSION: These results suggest that the deficit in goal-directed behavior observed in mice without dopamine signaling is the result of decreased motivation to obtain reward, and that dopamine signaling in the dorsal striatum is sufficient to restore normal goal-directed behavior on a variety of operant responding tasks.

Adenoviruses, Canine↗

Parenting behaviors in parents with anxiety disorders.

Anxiety disorders are familial, and although considerable evidence supports the role of genetic/biological parameters in their development, these alone do not entirely explain their etiology. In this study, the role of parenting behavior as a possible factor in the transmission of anxiety from parent to child was examined. Using interview, self-report, and direct behavioral observation, behaviors of parents with an anxiety disorder were compared to those of parents without an anxiety disorder on a number of dimensions, but particularly with respect to whether anxious parents actively inhibited their children from engaging in normal age appropriate activities. These behaviors were assessed during routine activities and in a structured non-conflictual play task. Although anxious parents did not overtly restrict their child's behavior in either type of activity, they reported higher levels of distress when their children were engaged in these activities. Similarly, the "emotional climate" in families with an anxious parent differed significantly from families without an anxious parent. The results are discussed in terms of how parenting behaviors might influence the development of maladaptive anxiety via social learning and information transfer, and their heuristic implications.

Adult↗

The role of crawling and walking experience in infant spatial memory.

This research explored infants' use of place learning and cue learning in a locomotor task across the transition from crawling to walking. Novice and expert crawling and walking infants were observed in a novel locomotor task-finding a hidden goal location in a large space. In Experiment 1, infants were tested with distal landmarks. Infants with fewer than 6 weeks of experience, either crawling or walking, could not find the goal location. All infants with more locomotor experience were more successful. Learning did not transfer across the transition to walking. In Experiment 2, novice and expert crawlers and walkers were tested with a direct landmark. Again, novice crawlers and walkers with fewer than 6 weeks of experience could not find the goal, whereas those with more experience could. Taken together, these findings suggest that infants' spatial learning is inextricably linked to mode of locomotion.

Child Development↗

Forms of inhibition in animal and human learning.

Forms of inhibition were identified in human predictive learning that are qualitatively similar to those identified by P.C. Holland (1984) in rats. When P (positive) signaled the outcome and PN (N = negative) signaled the absence of the outcome, participants learned the discrimination, but the negative cue did not suppress responding to a transfer cue. Post-learning reversal training, in which N was followed by the outcome, did not abolish the original discrimination. These 2 results imply a configural form of inhibition. Negative transfer, which indicated a 2nd, elemental form of inhibition, was observed when neither PN nor N were reinforced during the discrimination stage. Under these conditions, negative transfer and the original discrimination were both abolished by individually pairing N with the outcome. Empirical parallels and differences with the animal conditioning literature are discussed.

Adult↗

Age effect on olfactory discrimination in a non-human primate, Microcebus murinus.

In order to characterize age-related cognitive changes, olfactory discrimination was assessed in Microcebus murinus, a prosimian primate. We compared young (n = 10) and old (n = 8) animals for individual performance on three olfactory tasks. Animals had to perform a detection, a transfer, and a reversal learning task using a go, no go conditioning procedure. No differences were observed between the two groups, indicating that aging is not inevitably associated with a decline in cognitive function. We did, however, observe two aged animals showing altered behavior. One animal displayed impairments in the reversal learning task, and the other showed impairments in both the transfer and reversal tasks. Transfer impairment may be due to a hippocampal alteration, whereas the perseverative tendency noted in the reversal task may be associated with frontal lobe dysfunction. Because some aged M. murinus display lesions that are pathognomonic of Alzheimer's disease, our observations highlight its potential utility as a primate model for studying cognitive deficits in relation to age and associated pathologies.

Aging↗

Toward a better understanding of the perception of self-produced speech.

UNLABELLED: The subject of how humans hear their own voices while speaking has received sporadic attention. Previous investigations suggest that the voice is heard substantially via bone conduction, implying a different transfer function to the ear--perhaps a low-pass filter--than for purely air-conducted vocalizations. Determining the characteristics of the transfer function of self-produced speech might contribute to a better understanding of self-perception. Such information may have important implications for treating articulation disorders. The efficacy of training discrimination during the remediation of articulation disorders remains unclear, perhaps because clients are asked to discriminate either speech of others or recorded self-speech samples not readily recognized as their own. This study was conducted to determine preference for filtered self-monitored speech in a delayed feedback paradigm. Participants made immediate comparisons of their real-time speech to delayed-recorded filtered self-speech samples. Participants demonstrated a clear preference for low-pass filtered speech, supporting earlier findings, but we were unable to determine the transfer function itself. LEARNING OUTCOMES: As a result of this activity, the learner will be able to describe some reasons why an individual's tape recorded speech typically sounds different to him/her from his/her own, live speech. As a result of this activity, the learner will be able to describe some potential applications for an accurately-characterized transfer function for self-produced speech.

Adult↗

The influence of the response-stimulus interval on implicit and explicit learning of stimulus sequence.

Three experiments investigated the influence of the response-stimulus interval (RSI) on implicit and explicit learning of stimulus sequences. Participants responded to numerals presented in predetermined positions with alternating long and short RSIs. Half of the participants were instructed explicitly to learn the position sequence. In the transfer phase of Experiments 1 and 2, changing RSI patterns reduced the expression of incidental and intentional learning of position sequence. In Experiment 3 the position sequence was transformed, except that sub-sequences demarcated by long RSIs remained unchanged; this greatly reduced the expression of intentional learning, and slightly reduced that of incidental learning. These results indicate that in implicit learning, stimulus sequences are learned under the constraints of RSIs, whereas in explicit learning, learning independent of RSIs, as well as learning constrained by RSIs, occurs.

Adult↗

Improvement in Vernier acuity in adults with amblyopia. Practice makes better.

PURPOSE: To determine the nature and limits of visual improvement through repetitive practice in human adults with naturally occurring amblyopia. METHODS: A key measure the authors used was a psychophysical estimate of Vernier acuity; persons with amblyopia have marked deficits in Vernier acuity that are highly correlated with their loss of Snellen acuity. The experiment consisted of three phases: pretraining measurements of Vernier acuity and a second task (either line-detection thresholds or Snellen acuity) in each eye with the lines at two orientations; a training phase in which observers repetitively trained on the Vernier task at a specific line orientation until each had completed 4000 to 5000 trials; and posttraining measurements (identical to those in the first phase). Two groups of amblyopic observers were tested: novice observers (n = 6), who had no experience in making psychophysical judgments with their amblyopic eyes, and experienced observers (n = 5), who had previous experience in making Vernier judgments with their amblyopic eyes (with the lines at a different orientation) using the signal-detection methodology. RESULTS: The authors found that strong and significant improvement in Vernier acuity occurs in the trained orientation in all observers. Learning was generally strongest at the trained orientation but may partially have been transferred to other orientations (n = 4). Significant learning was transferred partially to the other eye (at the trained orientation) in two observers with anisometropic amblyopia. Improvement in Vernier acuity did not transfer to an untrained detection task. In two observers, the improvement in Vernier acuity was accompanied by a commensurate improvement in Snellen acuity. CONCLUSIONS: Some adults with amblyopia retain a significant degree of neural plasticity. Although several observers (primarily novices) showed evidence of generalized learning, several amblyopic patients showed evidence for improvement that was orientation and task specific. In this latter group of observers, the improvement appeared to reflect alterations that were, at least in part, in early neural processes that were orientation specific and were localized beyond the site of convergence of the two eyes.

Adult↗

Intermanual transfer of a new writing occupation in young adults without disability.

It has been shown that acquisition of a skill by one hand is facilitated by previous learning of the same skill with the other hand. This is called intermanual transfer of learning, or cross-education. The investigators examined intermanual transfer of occupation of writing in a group of 10 right-handed subjects with no known motor disabilities. Subjects learned to perform a novel occupation of writing a foreign alphabet letter with either their right or left hand. Later, subjects reproduced the skill with the practised and unpractised contralateral hand. Pen movements and surface electromyography of the first dorsal interosseus muscle were recorded to assess the transfer of learning. Analysis revealed an almost full transfer of the learned motor task between hands in either left-to-right or right-to-left direction when movement time and movement size were compared. This indicates that transfer did not depend on hand dominance. These findings suggest that a task already learned by one hand can positively influence the learning of the same task by the other hand. The results have important implications for occupational therapy--namely, that activities comprising tasks previously learned by one hand would be more effective in facilitating improved performance by the other hand than activities comprising previously unlearned tasks in the case of retraining skills in patients with amputation or hemiplegia. Because the participants in this study were a small number of college students, research should be carried out with larger participant pools and participants with disabilities to consolidate the findings.

Adult↗

Prior experience and complex procedures.

The role of prior knowledge in learning complex procedures was investigated in a transfer task in which subjects learned two related procedures in sequence. In Experiment 1, we manipulated the conceptual and structural similarity between the two procedures; in Experiment 2, we manipulated whether the order of the steps within subprocedures was the same or different during training and transfer, or whether the order of the subprocedures was the same or different. The results lead us to hypothesize that transfer in complex procedures is mediated primarily by a memory for specific steps rather than by conceptual understanding or problem solving. In particular, we were able to model the results precisely on the assumption that subjects use superficial similarity to retrieve the sequences of steps needed to perform segments of the procedure.

Humans↗

Interocular transfer of extinction of visual pattern discriminations in split-chiasm and split-brain cats.

The interocular transfer of the extinction of visual pattern discrimination was studied in cats with either section of optic chiasm (split-chiasm cats) or combined sections of chiasm and forebrain commissures (split-brain cats). Visual pattern discriminations were monocularly learned and their interocular transfer was assessed through the opposite eye. Then, learning was unilaterally extinguished and interocular transfer of extinction was tested on the other side. In split-chiasm cats, the total number of trials to extinction criterion (EC) was significantly lower with the second eye than with the first eye, indicating a successful interocular transfer. In split-brain cats, EC with the second eye was attained faster than with the first in some performances; it was similar with both eyes in other tasks, and with the second eye was higher than with the first in still other tasks. Statistical analysis applied to this group of split-brain cats pointed out that extinction performances with the two eyes were not significantly different. These findings suggest that interocular transfer of extinction was abolished in split-brain cats and that memory for extinction was unilaterally established in the absence of forebrain commissures.

Animals↗

Effects of physostigmine on operant serial discrimination/reversal learning in rats.

Two experiments examined the effects of physostigmine on acquisition and performance of operant serial reversals by rats. In Experiment 1, four groups of rats (n = 6/group) were injected with either vehicle or 0.03 mg/kg physostigmine five minutes prior to each session, or vehicle or 0.5 mg/kg physostigmine immediately after each session of a three-stimulus (bright, dim or flashing light) repeated discrimination/reversal procedure. Rats treated with physostigmine pre- or postsession learned significantly more reversals over 50 sessions than animals injected with vehicle. Experiment 2 used only two discriminative stimuli, a light and a 2,500 Hz tone. Following establishment of a stable daily reversal baseline, postsession injections of physostigmine significantly increased the number of trials to criterion on the next session compared to each subject's control baseline. Results are attributed to enhanced between-session transfer of previously learned discriminated instrumental responses by physostigmine-treated animals.

Analysis of Variance↗