Combining Behavior and EEG to Study the Effects of Mindfulness Meditation on Episodic Memory

This protocol is significant as it allows us to better understand the effects of mindfulness meditation on episodic memory and its neural correlates. The main advantage of this technique is that it combines training and mindfulness meditation with behavioral and neural measures to examine the effects of mindfulness meditation on episodic memory. Begin by randomly assigning 40 subjects to a mindfulness meditation experimental or waitlist control group for a total of 20 subjects in each group.

Schedule the experimental sessions and mindfulness meditation trainings such that the delays between the pre and post-training experimental sessions are equal for the mindfulness meditation experimental and waitlist control groups. Then prepare a list of 800 adjectives that are equated for word frequency according to the Kucera and Francis word norms. On the day of the first experimental session, informed the subject about the procedures involved in the behavioral testing, the EEG recording and the mindfulness meditation training.

And instruct the subject to refrain from practicing meditation outside of the dedicated research study. At the beginning of each experimental session, have the subject complete the Five Facet Mindfulness Questionnaire. At each session, present 10 words and have the subject practice the encoding phase as illustrated.

Then have the subject perform the encoding phase. Have the subjects study a list of 200 of the prepared adjectives for 5, 700 milliseconds. Have the subjects either create a mental image of a spatial scene described by the adjectives, or think about the meaning of each word and rate its pleasantness.

After the presentation of each word, ask the subjects to rate how well they performed the encoding task. Upon the completion of the encoding task, measure the subject's head and place all of the electrodes onto an appropriately sized EEG cap according to the extended international 10-20 system. Clean the subject's forehead with an alcohol wipe, and apply the EEG cap to the subject's head by parting their hair to allow the application of conductive gel with a lure lock syringe equipped with a blunted needle.

In the EEG recording software, click on impedances and make sure the impedances are under the resistance level recommended by the selected EEG system. To educate the subject down to the importance of remaining as still as possible during the experiment, show the subject the EEG signal when they are still and when they blink or make jaw or facial movements. Before having the subject practice the source retrieval phase, click Edit Workspace in the EEG recording software, and set the EEG amplifier to acquire a signal with a 0.1 to 100 hertz band pass filter and a 500 hertz sampling rate.

When the subject is ready, present the 10 words that were shown at the encoding practice, plus five new words to the subject. Have the subject start the source retrieval phase. Making sure that the timestamps from the source retrieval task appear in the EEG recording.

Present the 200 words that were shown at the encoding randomly intermixed with 200 new words in 20 word blocks. And send the timestamps that correspond to each behavioral condition to the EEG recording. During the presentation of each word, ask the subject to indicate if the word was new or if they recognized the word as being studied in the encoding phase.

For recognized words, have the subject indicate the source and whether the word was studied in the place task or the pleasant task. Once the subject has completed the source retrieval task, clean the EEG cap and electrodes with deionized water and disinfectant. For the mindfulness meditation training, hire an instructor trained in the mindfulness based stress reduction technique and have the subjects in the mindfulness meditation experimental group meet with the mindfulness meditation instructor as a group for one hour per week, for four weeks.

Have the subjects practice mindfulness meditation for at least 20 minutes each day at home using a guided breath awareness meditation recording provided by the mindfulness meditation instructor. To track the daily mindfulness meditation practice, email each subject daily with a survey asking how many minutes they practiced the mindfulness meditation, what they did during their meditation, and how the practice is going for them. Schedule the post-training experimental session as soon as possible after completion of the mindfulness meditation training.

In this representative analysis, subjects who spent a substantial amount of time practicing mindfulness meditation exhibited an increase in mindfulness as measured by the Five Facet Mindfulness Questionnaire compared to the waitlist control group. Pairwise comparisons demonstrated that the source discrimination increased in the mindfulness meditation trained, but not the waitlist control group. As assessed by EEG analysis, theta power in the right frontal and left parietal channels increased from pre to post-training for the mindfulness meditation experimental group but not the waitlist control group.

Further, a positive correlation between increases in the Five Facet Mindfulness Questionnaire describe scores from pre-training to post-training and EEG theta power increases from pre-training to post-training in right frontal channels was found. Remember to use a longitudinal design and to assign subjects to the mindfulness meditation and waitlist control groups randomly to control for group differences. Mindfulness meditation can also be compared to alternative treatments to assess the effects of mindfulness meditation on other facets of cognition to determine the most promising treatments for cognitive enhancement.