The effect of transcendental meditation on iconic memory

Three experiments investigated the effects of transcendental meditation (TM) on iconic memory. The task involved reporting of digits shown tachistoscopically, using Sperling's partial-report technique. Experiment 1 was a pilot study involving a meditation group and a nonmeditation group. All subjects were run in a pretest/treatment/posttest design. During the treatment phase the meditation group practiced TM for a 20-minute period and the nonmeditation group relaxed with eyes closed. The results showed that the treatment increased performance in meditators, but not in nonmeditators. In this experiment important controls such as individual administration of the task, extrinsic rewards, subject pacing, and adequate practice were lacking. Experiment 2 was a replication of the first, with these controls added. The results no longer showed a superiority for the meditation treatment. In fact, the meditation group performed worse on each day of running. Experiment 3 was a replication of Experiment 1, to assess whether the meditation effect of Experiment 1 was due to (a) differential increased attention of the meditators (minimized in subject-paced Experiment 2), (b) a gain early in learning for the meditators that was eliminated due to practice in Experiment 2, or (c) a lack of proper control procedures in Experiment 1. The performance of the meditators was, again, significantly lower. This research illustrates the importance of careful control when investigating the effects of meditation on behavior. It also suggests that the effects of meditation may depend on which hemisphere is dominant in performing the task.The authors wish to thank John Tabb and Cindy Miller for their assistance in conducting this research. We also wish to thank the Seattle Students International Meditation Society (SIMS) for their cooperation in obtaining subjects.     

The effect of transcendental meditation on right hemispheric functioning

This study reports two experiments investigating the effects of transcendental meditation on right hemispheric functioning. The task used in both experiments was the Seashore Tonal Memory Test. In the first experiment a nonmeditator group and an experienced meditator group were run. The design involved three periods: a pretest, a meditation or rest period, and then a posttest. The results showed the experienced meditators were significantly better in both pretest and posttest performance. There were no pretest-posttest differences. The second experiment was done to replicate the first experiment and to control for possible selection bias. The design was the same as the first experiment, except that an additional group of inexperienced meditators was included. The results again showed significantly superior performance for the experienced meditators compared to the nonmeditators. In addition, the experienced meditators were superior to the inexperienced meditators. There were no significant differences between the nonmeditators and the inexperienced meditators. These results support the hypothesis that meditation facilitates right hemispheric functioning. Alternative explanations, such as selection bias, are also discussed.The authors wish to thank Ms. Michelle Ellis and Ms. Bridget Carr for their assistance in conducting these experiments. We also wish to thank the Seattle SIMS for their cooperation in obtaining subjects.     

Psychophysiological investigations on transcendental meditation

Two experiments were conducted to evaluate the psychophysiological changes reported to occur during the practice of transcendental meditation. In Experiment I, 47 volunteers solicited from the community were randomly assigned to transcendental meditation (TM), Benson's relaxation response (BRR), or no treatment (NT) instruction. Respiration rate, heart rate, electromyogram, electroencephalogram, and skin conductance level were recorded during the practice of each technique, approximately 1 week after terminating instruction. The results indicate that while BRR, TM, and NT exhibited different physiological patterns, none of the techniques showed a clear superiority in reducing tonic physiological arousal. In Experiment II, 30 volunteers with previous experience were assigned to one of three groups based on their meditating experience (range 16–96 months). The same physiological signals as in Experiment I were also recorded in this experiment during TM practice. The results suggest that individuals with 1.5 years of meditation experience exhibited physiological arousal levels similar to those seen in persons with over 5 years' experience.This article is based on the author's dissertation submitted to the University of Georgia in partial fulfillment of requirement for the Ph.D. degree. The author would like to thank Dr. L. J. Peacock for his guidance and to acknowledge Student International Meditation Society for their assistance.     

The effect of transcendental mediation on right hemispheric functioning.

This study reports two experiments investigating the effects of transcendental mediation on right hemispheric functioning. The task used in both experiments was the Seashore Tonal Memory Test. In the first experiment a nonmediator group and an experienced mediator group were run. The denonmeditator group and an experienced mediator group were run. The design involved three periods: a pretest, a meditation or a rest period, and then a posttest. The results showed the experienced meditators were significantly better in both pretest and posttest performance. There were no pretest--posttest differences. The second experiment was done to replicate the first experiment and to control for possible selection bias. The design was the same as the first experiment, except that an additional group of inexperienced meditators was included. The results again showed significantly superior performance for the experienced meditators compared to the nonmeditators. In addition, the experienced meditators were superior to the inexperienced meditators. There were no significant differences between the nonmeditators and the inexperienced meditators. These results support the hypothesis that meditation facilitates right hemispheric functioning. Alternative explanations, such as selection bias, are also discussed.     

The effect of explicit expectations on initial meditation experiences

Although meditation has been employed successfully as a treatment for various stress-related disorders, there is still little evidence clarifying just which aspects of meditation training are responsible for these therapeutic effects. This experiment sought to test the hypothesis that creating two opposite expectations about an initial meditation experience would result in differing physiological and phenomenological responses, even though the same technique was practiced by all subjects. The results of the experiment failed to support this hypothesis.     

Transcendental meditation.

A trial of chemoprophylaxis to prevent reactivation of tuberculosis in persons with inactive disease who had never had adequate chemotherapy was conducted in Canada in the mid-1960s. Preventive drug treatment consisted of either isoniazid (INH) alone or INH plus para-aminosalicylic acid (PAS), for a maximum of 18 months. Long-term evaluation in 1974 of 1571 treated patients and 834 control patients demonstrated clearly the substantial and sustained value of adequate chemoprophylaxis in reducing the risk of reactivation. Among those who took INH alone for 6 months or more the annual reactivation rate was 1.2 per 1000 persons, while among those who took INH plus PAS the rate was 0.38/1000. These rates were, respectively, 70 and 90% less than the average rate in the controls, 3.9/1000. Among those who underwent chemoprophylaxis for less than 6 months the annual reactivation rate was 3.7/1000, similar to that in the controls. Cost-benefit analysis showed chemoprophylaxis to be economically sound. Despite the recent increasing application of this preventive measure, there are still many persons living in Canada who could benefit substantially from a course of chemoprophylaxis.     

The effect of a complex of meditation exercises on the psychophysiological state of young men

Using a simple motor response, a complex sensorimotor response, and a tapping test, the effect of a complex of meditation exercises on the neuromuscular coordination in healthy male students who were preliminarily trained in methods of self-regulation based on meditation techniques was studied. As a result of a 6-min session of self-regulation, a considerable decrease (by 30% or more) in the time of a simple motor response and a complex sensorimotor response (due to a decrease in the latent time at constant motor time) and a simultaneous decrease in the number of errors, as well as a considerable increase in the result of the tapping test, were recorded. A short-term effect expressed in an increase in the rate and accuracy of sensorimotor responses can be a result of a change in the functional state of the nervous system under the impact of transcendental meditation techniques.     

Adrenocortical activity during meditation.

We studied acute plasma cortisol and testosterone concentration changes during the practice known as "transcendental meditation" (TM) and during control rest. Three groups of normal, young adult volunteers were studied: a group of controls, these same controls restudied as practitioners after 3 to 4 months of TM practice, and a group of long-term, regular TM practitioners (3 to 5 years of practice). No change was found in controls during rest. Cortisol declined, but not significantly, in restudied controls, while cortisol decreased significantly in long-term practitioners during meditation and remained somewhat low afterward. No change in testerone concentration was noted during either rest or TM. Apparently, the practice of TM becomes associated with psychophysiologic response(s) which acutely inhibit pituitary-adrenal activity.     

The effects of centrally acting drugs on the EEG correlates of meditation.

The present study investigated the effects of three centrally acting drugs on the significant increase in the intermediate alpha frequency of the electroencephalogram (EEG) that accompanied meditation in a male volunteer. When compared to the EEG recorded before each of the three drugs was administered, naloxone tended to enhance the increase in the power of the intermediate alpha EEG (9.4-10.4 Hz), while diazepam tended to spread the increase to the slow (7.4-9.4 Hz) alpha EEG, and flumazenil was without much effect on the overall EEG pattern. However, these EEG changes when compared to similar changes obtained with saline administration were not significantly different from the latter. Thus, it is unlikely that the EEG correlates of meditation are causally related to the rise or fall of endogenous opioid peptides or benzodiazepinelike substances in the brain.     

The effect of general anesthesia on memory in experimental animals

Full recovery of short-term memory (maximum time of delayed reactions) and of the structure of situational conditioned reflex and differentiation inhibition in dogs is observed in 1.5-2.5 h after tranquil-anaesthesia (diazepam-ketamine in doses of 0.3-15 mg/kg correspondingly) and dissociative anaesthesia by ketamine (15 mg/kg) in 6-8 h after neuroleptanalgesia (droperidol-fentanyl 2.5-0.05 mg/kg correspondingly), 20-24 h after narcosis by thiopental sodium (30 mg/kg) and by the end of the 3d day after neuroleptanaesthesia (droperidol-ketamine 2.5-15 mg/kg correspondingly). The recovery of the reaction of memory trace reproduction (of conditioned reaction of passive avoidance in rats) after various types of general anaesthesia is observed mainly in the same sequence, but on the average a day later than the short-term memory in dogs.     

The effect of anastrozol on spatial memory in adult rats

Androgens are known to affect cognitive functions via organizational and activational effects. It is unknown whether the effects are mediated via the androgen receptor or after conversion to estradiol with aromatase via estrogen receptors. The aim of our study was to find out whether testosterone affects spatial memory directly or through its metabolite estradiol. Rats were treated with testosterone; with testosterone and the aromatase blocker anastrozole or saline. An 8 radial arm maze was used for testing spatial memory twice daily for 4 days. Each arm was baited with food, and the ability of animals to learn the location of food was assessed. Testosterone treated rats and control rats achieved comparable coefficients of spatial memory, although the plasma levels of testosterone differed markedly. Anastrozole treatment resulted in the worst performance in the maze. The differences between groups did not reach the level of significance. It can be concluded that aromatase and, thus, the conversion of testosterone to estradiol may play a role in spatial memory, as pharmacological blockade of aromatase led to a decrease in maze performace of adult male rats. Detailed molecular mechanisms should be the focus of further studies.     

The effect of chronic vs. acute injection of vasopressin on animal learning and memory

The effect of chronic and acute treatment with DDAVP, a vasopressin analog, was studied in 2 month old male rats, using an active avoidance test in a shuttle box. The experiment lasted 6 weeks: an acquisition period of 4 weeks and an extinction period of 2 weeks. Rats were treated one hour before behavioral testing 3 times a week for 6 weeks with either DDAVP 20 micrograms/rat/day for the whole period (chronic group) or with DDAVP for the first week and again once only on the first day of the extinction period (acute group) or with saline. Chronic treatment with DDAVP resulted in better acquisition and in a marked retardation of extinction compared with the acute treatment group. These results were obtained both in normal rats and in rats pretreated at age 5 days of life with intracisternal 6-OH dopamine.     

The effect of coaching on the simulated malingering of memory impairment

Background  

Detecting malingering or exaggeration of impairments in brain function after traumatic brain injury is of increasing importance in neuropsychological assessment. Lawyers involved in brain injury litigation cases routinely coach their clients how to approach neuropsychological testing to their advantage. Thus, it is important to know how robust assessment methods are with respect to symptom malingering or exaggeration.     

The effect of intrahippocampal insulin microinjection on spatial learning and memory

Insulin is best known for its action on peripheral target tissues such as the adipocyte, muscle and liver to regulate glucose homeostasis. Insulin and its receptor are found in specific area of CNS with a variety of region-specific functions different from its direct glucose regulation in the periphery. The hippocampus and cerebral cortex distributed insulin/insulin receptor has been shown to be involved in brain cognitive functions. Previous studies about the effect of insulin on memory are controversial. In the present study, the effect of insulin microinjection into CA1 region of rat hippocampus on water maze performance has been investigated. Insulin had a discrepant effect dose dependently. The spatial learning and memory were impaired with lower dose of insulin, had not changed with intermediate doses, while they improved with higher doses. These results suggest that insulin may have a dose-dependent effect on spatial learning and memory.     

The effect of vasopressin on memory processes in Macaca fascicularis]

The role of vasopressin (arginin-vasopressin) in the regulation of conditioned instrumental food-procuring reactions and different kinds of memory such as delayed reflexes, image, short-, and long-time memory was studied in monkeys. Motor and autonomic effects of vasopressin were assessed. It was found that in monkeys, vasopressin administration differently affected the simple conditioned food-procuring reactions and memory. During functional disorders of the higher nervous activity, vasopressin was more efficient in its action on memory and its restoration. Formation of two types of vasopressin effects on the higher nervous activity in evolution of mammals is discussed.