Wissenschaftliche Hintergründe

Studie: „Long-term meditators self-induce high-amplitude gamma synchrony during mental practice“

Zweiwöchentlich stellen wir Ihnen donnerstags Studien zum Thema Resilienz vor. Heute die Studie “Long-term meditators self-induce high-amplitude gamma synchrony during mental practice” aus dem Jahr 2004 A. Lutz, L. L. Greischar, N. B. Rawlings, M. Ricard & R. J. Davidson.

Ziel der Studie:

This study aims to examine the impact of (objectless) meditation on the brain, evaluated with an EEG.

Methode:

Subjects

  • eight long-term Buddhist practitioners which practiced Tibetan Nyingmapa and Kagyupa traditions for 10,000to50,000h
  • 10 healthy student volunteers which had no previous meditative experience but had declared an interest in meditation”

Observation (based on an EEG)

  • EEG measured the individual baselines of each participant
  • EEG measured the effects of the sessions

Baseline: four 60-s blocks of ongoing activity with a balanced random ordering of eyes open or closed for each block

Sessions: 30-s block of resting activity and a 60-s block of meditation.

Meditation: ‘‘unconditional loving-kindness and compassion.’’ […] described as an ‘‘unrestricted readiness and availability to help living beings.’’ (P. 1)

Ergebnisse:

During meditation, we found high-amplitude gamma oscillations in the EEGs of long-time practitioners (subjects S1–S8) that were not present in the initial baseline (p. 2).

These data suggest that the two groups had different electrophysiological spectral profiles in the baseline, which are characterized by a higher ratio of gamma-band oscillatory rhythm to slow oscillatory rhythms for the long-term practitioners than for the controls. This group difference is enhanced during the meditative practice and continues into the post meditative resting blocks (P. 3).

Gamma activity increased for both the long term practitioners and controls from neutral to meditation states […], yet this increase was higher for the long-time practitioners than for the controls […]. In summary, the generation of this meditative state was associated with gamma oscillations that were significantly higher in amplitude for the group of practitioners than for the group of control subjects.

These data suggest that the degree of training can influence the spectral distribution of the ongoing baseline EEG. The age of the subject was not a confounding factor in this effect as suggested by the low correlation between the practitioner age and the relative gamma (P. 4).

Schlussfolgerungen:

Future Research:
There are differences in brain function associated with different types of meditation […] Future research is required to characterize the nature of the differences among types of meditation. (P.4)

Objective- vs. objectless meditation

a meditation on a mantra or the breath […] can be seen as a particular form of top-down control. […]

Objectless meditation does not directly attend to a specific object but rather cultivates a state of being.

The intentional or object oriented aspect of experience appears to dissipate in meditation […] achieved by letting the very essence of the meditation that is practiced […]become the sole content of the experience […],the practitioner lets his feeling of loving-kindness and compassion permeate his mind without directing his attention toward a particular object.
(P.4)

Long term effects of Meditation on neuroplasticity:

The gradual increase of gamma activity during meditation is in agreement with the view that neural synchronization, as a network phenomenon, requires time to develop (24), proportional to the size of the synchronized neural assembly (25). (p.4)

The differences in baseline activity reported here suggest that the resting state of the brain may be altered by long-term meditative practice and imply that such alterations may affect task-related changes.

Our study is consistent with the idea that attention and affective processes, which gamma-band EEG synchronization may reflect, are flexible skills that can be trained (29). (p.5)

Dieses Exzerpt wurde verfasst von Paul Hoffmann.

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