Xinjun Yu

Activation of the anterior prefrontal cortex and serotonergic system is associated with improvements in mood and EEG changes induced by Zen meditation practice in novices

To gain insight into the neurophysiological mechanisms involved in Zen meditation, we evaluated the effects of focused attention (FA) on breathing movements in the lower abdomen (Tanden) in novices. We investigated hemodynamic changes in the prefrontal cortex (PFC), an attention-related brain region, using 24-channel near-infrared spectroscopy during a 20-minute session of FA on Tanden breathing in 15 healthy volunteers. We found that the level of oxygenated hemoglobin in the anterior PFC was significantly increased during FA on Tanden breathing, accompanied by a reduction in feelings of negative mood compared to before the meditation session. Electroencephalography (EEG) revealed increased alpha band activity and decreased theta band activity during and after FA on Tanden breathing. EEG changes were correlated with a significant increase in whole blood serotonin (5-HT) levels. These results suggest that activation of the anterior PFC and 5-HT system may be responsible for the improvement of negative mood and EEG signal changes observed during FA on Tanden breathing.

Ventral prefrontal cortex and serotonergic system activation during pedaling exercise induces negative mood improvement and increased alpha band in EEG.

This study evaluates a possible involvement of the prefrontal cortex (PFC) and serotonergic (5-HT) system in psychiatric and electroencephalography (EEG) changes during and after pedaling exercise (PE). The subjects performed PE for 15 min using a cycle ergometer. PE rate was kept at 60 rpm, and the work load (93+/-5.4 W) was decided for each subject before the experiment based on a Rating of Perceived Exertion of 12-13 for self-selected exercise intensity. Cerebral oxygenation in the PFC was assessed by concentration changes in oxygenated hemoglobin (oxyHb) using 24-channel near-infrared spectroscopy. We found that PE evoked a significant increase in oxyHb levels in the ventral PFC during PE as compared with that in the dorsal PFC. Subjects had a feeling of reduced negative mood accompanied by a tendency of increased vigor-activity after PE, as assessed by the Profile of Mood States (POMS) questionnaire. Because the ventral PFC is associated with mood state, we hypothesized that the observed mood changes may have been induced by the activation of the ventral PFC. As for EEG changes during and after PE, we found a significant increase in the relative powers of high-frequency alpha bands (10-13 Hz) during and after PE. A significant increase in whole blood 5-HT level was obtained after PE. Because cortical attenuation would be caused by the 5-HT-induced inhibition of the basal forebrain, we hypothesized that the observed EEG changes are linked with the increased blood 5-HT level or an augmentation of the 5-HT system in the brainstem.

Decreased blood serotonin in the premenstrual phase enhances negative mood in healthy women

The purpose of this study was to evaluate mechanisms underlying the action of selective serotonin reuptake inhibitors on the improvement of negative mood symptoms in premenstrual syndrome. We assessed relationships between serotonin (5-HT) levels in the brain (estimated from 5-HT concentrations in whole blood) and negative mood states during the premenstrual phase in 13 healthy women. Mood states were evaluated using the Profile of Mood States questionnaire. We also evaluated relationships between 5-HT and ovarian hormones (oestradiol and progesterone). A significant negative correlation was seen between 5-HT concentrations in whole blood and negative mood scores (tension–anxiety and fatigue) observed in the premenstrual phase. A significant positive correlation was observed between 5-HT and oestradiol in the premenstrual phase, but not in the follicular phase. These results suggest that healthy women with lower whole blood 5-HT concentrations in the premenstrual phase exhibit enhanced negative mood due to lower 5-HT concentrations at brain synapses, which may be caused in part by lower oestrogen concentration.

Increased blood serotonin concentrations are correlated with reduced tension/anxiety in healthy postpartum lactating women

The serotonin (5-HT) system in the brain plays an important role in mood regulation. The postpartum period is considered a high-risk time for mood and anxiety disorders. We assessed changes in 5-HT levels in whole blood (as an indicator of brain 5-HT concentrations) and mood states before and after delivery in 28 healthy, lactating postpartum women. Mood states were evaluated using Profile of Mood States questionnaires (POMS). Measurements were done on the same day in early (first week) and late (third-fourth and sixth-seventh weeks) postpartum, and compared with those in the third trimester and in age-matched, healthy, non-pregnant women. Mean 5-HT concentrations were significantly higher and mean tension/anxiety scores of POMS were significantly lower in late (but not early) postpartum than in the third trimester or non-pregnant controls. 5-HT concentrations correlated with tension/anxiety in the third trimester and late postpartum, indicating an important role for the 5-HT system in the regulation of tension/anxiety in healthy postpartum women. The mechanism underlying the changes in the 5-HT system may be rapid inhibition induced by the marked decrease in estradiol after delivery and gradual excitation caused by lactation-induced brain oxytocin release during the postpartum period.

Meta-analysis of whole blood serotonin levels at resting state in healthy subjects

The synthesizing enzyme of acetylcholine, the choline acetyltransferase (ChAT) has two isoforms. In rat, immunoreactivity for the preferentially observed isoform in the peripheral nervous system, the peripheral ChAT (pChAT), was observed in enteric nervous system and also in neurons of the dorsal root ganglion (DRG). The purpose of the present study is to examine pChAT immunohistochemical staining of these two structures in the human. Human specimens, large or small intestine and DRG, obtained within 24 h postmortem at autopsy in Shiga University of Medical Science, were fixed by immersion in 4% paraformaldehyde in 0.1M phosphate buffer for 4 days at 4 ◦C, and then cryoprotected. Free-floating cryostat sections of 24 m in thickness were used for immunohistochemistry using an avidin-biotinperoxidase complex method. In human intestines and DRG, the pattern of distribution of pChAT immunostaining was similar to the pattern observed previously in rat. Positive staining was exclusively localized in neuronal cell bodies and fibers. In human large intestine, for instance, pChAT-positive somata were observed in the submucosal and intramural ganglionated plexuses. Networks of positive nerve fibers were found within the submucosa, the longitudinal and the circular muscle; varicoses could be observed. Co-localisation of pChAT staining with other cholinergic markers, the high affinity choline transporter and the vesicular acetylcholine transporter, was observed in nerves fibers. In human DRG, all neuronal somata appeared immunoreactive though varying in staining intensity. Small neurons were often stained very intensely, while medium-sized to large neurons exhibited moderate staining. Immunoreactive fibers were observed throughout the ganglion and extending toward the dorsal root. This study demonstrates a pChAT-like immunoreactivity in the human peripheral nervous system.

Tapping touch improves negative mood via serotonergic system

Family structure around a child is one of the strongest environmental factors for his/her social and mental development. To investigate how the behavioral traits of juvenile primate represent human development, we prepared three groups of subjects different in their family structure, that is, bred without other siblings, either by human (H1) or by its own parents (P1), and with another sibling by its own parents (P2). We evaluated their behavioral development in our original meeting test between two or four peers. The multivariate analysis of the test result expressed the different behavioral patterns more distinctly at the contexts in 4 peers than 2. Interestingly, P1’s pattern showed the least change from 2to 4-peer-context, comparing to H1’s or P2’s. These results suggest that social brain function was sculpted through social interaction between parent–child and peers during development.