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Reduced activation of posterior cingulate cortex during imagery

20 Jun

An MRI study out of Japan reveals more inner workings of the brain during imagery, and connections between alexithymia (inablity to translate emotions into words) and imagining past and future events.

Researchers from the Graduate School of Biomedical Sciences at Hiroshima University in Japan used MRI’s to investigate differences in brain function between people with high degrees of alexithymia (an inability to put emotions into words, commonly found in people with PTSD) and those with low degrees.

Subjects were 10 people with high degrees of alexithymia (HDA) and 10 subjects with low degrees of alexithymia (LDA), who were selected according to their scores on the 20-item Toronto Alexithymia Scale (TAS-20). The two groups'' regional cerebral activation was compared during various imagery conditions - imagining a past happy (PH) event, a past sad (PS) event, a past neutral (PN) event, a future happy (FH) event, a future sad (FS) event, and a future neutral (FN) event. The activation levels during these conditions were compared with those during a rest condition (REST).

T tests showed that the mean subjective ratings of both the vividness of the imagery and the intensity of emotion during the imagery were higher in the subjects with LDA than in those with HDA for the PS and FS imagery conditions. On the other hand, relative to the LDA group, the HDA group showed significantly less activation in the posterior cingulate cortex (this is the part of the brain that puts the brakes on alarm activation and settles the system down after a threat) during the PH and FH imagery conditions compared with REST and during the FH imagery condition compared with the FN imagery condition.

The pilot study findings suggest an association between a high degree of alexithymia and reduced activation of the posterior cingulate during happy imagery. Given the function of this brain region, these results might be related to a dysfunction of episodic memory retrieval during happy imagery in subjects with HDA.

Citation: Mantani T, Okamoto Y, Shirao N, Okada G, Yamawaki S. Reduced activation of posterior cingulate cortex during imagery in subjects with high degrees of alexithymia: a functional magnetic resonance imaging study. Biological Psychiatry. 2005 May 1; 57(9): pages 982-90.
Belleruth Naparstek

Psychotherapist, author and guided imagery pioneer Belleruth Naparstek is the creator of the popular Health Journeys guided imagery audio series. Her latest book on imagery and posttraumatic stress, Invisible Heroes: Survivors of Trauma and How They Heal (Bantam Dell), won the Spirituality & Health Top 50 Books Award