The inhibition/excitation ratio related to task-induced oscillatory modulations during a working memory task: A multtimodal-imaging study using MEG and MRS.

Detailed studies on the association between neural oscillations and the neurotransmitters gamma-aminobutyric acid (GABA) and glutamate have been performed in vitro. In addition, recent functional magnetic resonance imaging studies have characterized these neurotransmitters in task-induced deactivation processes during a working memory (WM) task. However, few studies have investigated the relationship between these neurotransmitters and task-induced oscillatory changes in the human brain. Here, using combined magnetoencephalography (MEG) and magnetic resonance spectroscopy (MRS), we investigated the modulation of GABA and glutamate + glutamine (Glx) concentrations related to task-induced oscillations in neural activity during a WM task. We first acquired resting-state MRS and MEG data from 20 healthy male volunteers using the n-back task. Time-frequency analysis was employed to determine the power induced during the encoding and retention phases in perigenual anterior cingulate cortex (pg-ACC), mid-ACC, and occipital cortex (OC). Statistical analysis showed that increased WM load was associated with task-induced oscillatory modulations (TIOMs) of the theta-gamma band relative to the zero-back condition (TIOM0B) in each volume of interest during the encoding phase of the n-back task. The task-induced oscillatory modulations in the two-back condition relative to the zero-back condition (TIOM2B-0B) were negatively correlated with the percent rate change of the correct hit rate for 2B-0B, but positively correlated with GABA/Glx. The positive correlation between TIOM2B-0B and GABA/Glx during the WM task indicates the importance of the inhibition/excitation ratio. In particular, a low inhibition/excitation ratio is essential for the efficient inhibition of irrelevant neural activity, thus producing precise task performance.

Associations among parenting experiences during childhood and adolescence, hypothalamus-pituitary-adrenal axis hypoactivity, and hippocampal gray matter volume reduction in young adults.

Recent human studies have indicated that adverse parenting experiences during childhood and adolescence are associated with adulthood hypothalamus-pituitary-adrenal (HPA) axis hypoactivity. Chronic HPA axis hypoactivity inhibits hippocampal gray matter (GM) development, as shown by animal studies. However, associations among adverse parenting experiences during childhood and adolescence, HPA axis activity, and brain development, particularly hippocampal development, are insufficiently investigated in humans. In this voxel-based structural magnetic resonance imaging study, using a cross-sectional design, we examined the associations among the scores of parental bonding instrument (PBI; a self-report scale to rate the attitudes of parents during the first 16 years), cortisol response determined by the dexamethasone/corticotropin-releasing hormone test, and regional or total hippocampal GM volume in forty healthy young adults with the following features: aged between 18 and 35 years, no cortisol hypersecretion in response to the dexamethasone test, no history of traumatic events, or no past or current conditions of significant medical illness or neuropsychiatric disorders. As a result, parental overprotection scores significantly negatively correlated with cortisol response. Additionally, a significant positive association was found between cortisol response and total or regional hippocampal GM volume. No significant association was observed between PBI scores and total or regional hippocampal GM volume. In conclusion, statistical associations were found between parental overprotection during childhood and adolescence and adulthood HPA axis hypoactivity, and between HPA axis hypoactivity and hippocampal GM volume reduction in healthy young adults, but no significant relationship was observed between any PBI scores and adulthood hippocampal GM volume.

Micropolygyria in an infant born to a patient with severe anorexia nervosa: a case report.

We report the case of an anorexia nervosa (AN) patient with extremely low body weight who became pregnant following ovulation induction and subsequently delivered an infant with micropolygyria. To the best of our knowledge, no previous report has described live birth for a patient with such low body weight. The patient underwent hMG-hCG therapy for ovulation induction. Despite becoming pregnant, weight loss continued with extreme anemia occurring during the pregnancy. However, blood transfusion therapy was used for successful treatment. Despite the therapeutic and protective measures instituted, the child was born with micropolygyria. Pregnancy in an AN patient with extremely low body weight needs therapeutic intervention during early pregnancy with aggressive precautionary measures, particularly against anemia. On the basis of our experience, we consider that ovulation induction therapy should not be administered without sufficient caution for an AN patient with low body weight.

Similar activation patterns in the prefrontal cortex for Chinese and Japanese verbal fluency tests with syllable cues as revealed by near-infrared spectroscopy.

The verbal fluency test (VFT) is utilized in neuropsychology to evaluate the cognitive function of the prefrontal cortex (PFC) in the human brain. We present a novel Chinese VFT similar to the established Japanese VFT; both tests prompt a syllable to the subject. However, it was uncertain whether the Chinese VFT can activate the PFC and whether PFC activation patterns are similar between the two tests. Here we administered the Chinese VFT to 30 native Chinese speakers and the Japanese VFT to 30 native Japanese speakers. We used near-infrared spectroscopy (NIRS) to observe PFC activation. Then we compared the similarities between the Chinese VFT and the Japanese VFT. The subjects generated an average of 12.8 ± 4.7 words during the Chinese VFT. NIRS indicates that the concentration of oxygenated hemoglobin during the test was significantly higher than those before and after the test. It exhibited similar PFC activation patterns with the Japanese VFT. The novel Chinese VFT can activate the PFC in the human brain effectively in Chinese speakers. Our work thus provides the first validated phonetically cued Chinese VFT, unique from other not strictly phonemic Chinese VFTs, and facilitates the diagnosis of various PFC-related cognitive impairments.

Stimulus intensity dependence of cerebral blood volume changes in left frontal lobe by low-frequency rTMS to right frontal lobe: A near-infrared spectroscopy study.

Repetitive transcranial magnetic stimulation (rTMS) has recently been widely employed for the investigation of brain function and treatment of psychiatric and neurological disorders. Although high and low stimulation frequencies are assumed to activate and deactivate brain function, respectively, the optimal parameters of rTMS for treatment of depression have been determined only on the basis of their clinical efficacy. In this study, we administered a 60-s low-frequency rTMS of three grades low intensities over the right dorsolateral prefrontal cortex (DLPFC) in 10 healthy volunteers, and monitored functional changes of the contralateral DLPFC by near-infrared spectroscopy (NIRS) during and immediately after rTMS. Obtained results demonstrated significant [oxy-Hb] decreases during rTMS, and significant differences in the time courses of [oxy-Hb] changes among three stimulus intensities, that is, [oxy-Hb] decreases were most prominent during the latter half of the stimulation and the first 30s of poststimulation only at 15mm condition (58% intensity). These results suggest that monitoring of brain functional changes due to rTMS using NIRS is useful for elucidating the brain mechanisms underlying the clinical effects of rTMS, and the effects of rTMS over contralateral DLPFC are obtained if the stimulus intensities are more than one-half of the motor thresholds.

Deactivation and activation of left frontal lobe during and after low-frequency repetitive transcranial magnetic stimulation over right prefrontal cortex: a near-infrared spectroscopy study.

The effects of low-frequency repetitive transcranial magnetic stimulation (rTMS) over the right frontal lobe on the function of the left frontal lobe were examined by near-infrared spectroscopy (NIRS) in eleven healthy subjects. rTMS applied 5cm anterior to the motor cortex at 1 Hz and approximately 50% of the motor threshold intensity (MT) for 60 s resulted in a significantly larger decrease in the concentration of oxygenated hemoglobin ([oxy-Hb]) during the stimulation period followed by a significantly larger increase in [oxy-Hb] and a smaller decrease in the concentration of deoxygenated hemoglobin ([deoxy-Hb]) during the poststimulation baseline period than sham stimulation. These findings are interpreted as demonstrating the deactivation and activation of the left frontal cortex during and after rTMS of the right frontal cortex, respectively. If replicated in depressed patients, NIRS can be employed for monitoring rTMS effects as brain [Hb] changes in vivo, and may be helpful for determining therapeutic parameters of rTMS for individual patients.

Near-infrared spectroscopic study of frontopolar activation during face-to-face conversation in major depressive disorder and bipolar disorder.

Major depressive disorder (MDD) and bipolar disorder (BD) patients show speech characteristics that vary greatly according to mood state. In a previous study, we found impaired temporal and right inferior frontal gyrus (IFG) activation in schizophrenia during face-to-face conversation; no study had, however, previously investigated mood disorders during face-to-face conversation. Here, we investigated frontal and temporal lobe activation during conversation in patients with MDD and BD. Frontal and temporal lobe activation was measured using near-infrared spectroscopy (NIRS) in 29 patients with MDD, 31 patients with BD, and 31 normal controls (NC). We compared continuous activation and rapid change of activation with talk/listen phase changes during the conversation and analyzed the correlation between these indices and clinical variables. Both the MDD and BD groups showed decreased continuous activation in the left dorsolateral prefrontal (DLPFC) and left frontopolar cortices (FPCs); they also showed decreased rapid change in bilateral FPC activation. In the MDD group, the rapid change of activation was positively correlated with Global Assessment of Functioning (GAF) scores. In the BD group, continuous activation was negatively correlated with age of onset. These results indicate that frontal activation during conversation decreases in both MDD and BD. However, both continuous activation and rapid change may reflect the pathophysiological character of MDD and BD; in particular, the reduced amount of rapid change in the right FPC may be related to impaired adaptive ability in MDD.

Temporal lobe and inferior frontal gyrus dysfunction in patients with schizophrenia during face-to-face conversation: a near-infrared spectroscopy study.

Schizophrenia (SC) is marked by poor social-role performance and social-skill deficits that are well reflected in daily conversation. Although the mechanism underlying these impairments has been investigated by functional neuroimaging, technical limitations have prevented the investigation of brain activation during conversation in typical clinical situations. To fill this research gap, this study investigated and compared frontal and temporal lobe activation in patients with SC during face-to-face conversation. Frontal and temporal lobe activation in 29 patients and 31 normal controls (NC) (n = 60) were measured during 180-s conversation periods by using near-infrared spectroscopy (NIRS). The grand average values of oxyhemoglobin concentration ([oxy-Hb]) changes during task performance were analyzed to determine their correlation with clinical variables and Positive and Negative Syndrome Scale (PANSS) subscores. Compared to NCs, patients with SC exhibited decreased performance in the conversation task and decreased activation in both the temporal lobes and the right inferior frontal gyrus (IFG) during task performance, as indicated by the grand average of [oxy-Hb] changes. The decreased activation in the left temporal lobe was negatively correlated with the PANSS disorganization and negative symptoms subscores and that in the right IFG was negatively correlated with illness duration, PANSS disorganization, and negative symptom subscores. These findings indicate that brain dysfunction in SC during conversation is related to functional deficits in both the temporal lobes and the right IFG and manifests primarily in the form of disorganized thinking and negative symptomatology.

Autistic traits and brain activation during face-to-face conversations in typically developed adults.

BACKGROUND: Autism spectrum disorders (ASD) are characterized by impaired social interaction and communication, restricted interests, and repetitive behaviours. The severity of these characteristics is posited to lie on a continuum that extends into the general population. Brain substrates underlying ASD have been investigated through functional neuroimaging studies using functional magnetic resonance imaging (fMRI). However, fMRI has methodological constraints for studying brain mechanisms during social interactions (for example, noise, lying on a gantry during the procedure, etc.). In this study, we investigated whether variations in autism spectrum traits are associated with changes in patterns of brain activation in typically developed adults. We used near-infrared spectroscopy (NIRS), a recently developed functional neuroimaging technique that uses near-infrared light, to monitor brain activation in a natural setting that is suitable for studying brain functions during social interactions. METHODOLOGY: We monitored regional cerebral blood volume changes using a 52-channel NIRS apparatus over the prefrontal cortex (PFC) and superior temporal sulcus (STS), 2 areas implicated in social cognition and the pathology of ASD, in 28 typically developed participants (14 male and 14 female) during face-to-face conversations. This task was designed to resemble a realistic social situation. We examined the correlations of these changes with autistic traits assessed using the Autism-Spectrum Quotient (AQ). PRINCIPAL FINDINGS: Both the PFC and STS were significantly activated during face-to-face conversations. AQ scores were negatively correlated with regional cerebral blood volume increases in the left STS during face-to-face conversations, especially in males. CONCLUSIONS: Our results demonstrate successful monitoring of brain function during realistic social interactions by NIRS as well as lesser brain activation in the left STS during face-to-face conversations in typically developed participants with higher levels of autistic traits.

Volume reduction of ventromedial prefrontal cortex in bipolar II patients with rapid cycling: a voxel-based morphometric study.

Although rapid cycling (RC), a course specifier of bipolar I or II disorder, is particularly common among bipolar II patients compared with bipolar I patients, the pathophysiological lines of evidence regarding bipolar II with RC are still limited. In this preliminary study with a cross-sectional design, we examined the regional gray matter (GM) volume in 14 bipolar II patients with RC, 17 patients without RC and 84 healthy controls by whole-brain and region-of-interest (ROI) analysis methods, using magnetic resonance imaging with voxel-based morphometry. Whole-brain analysis in this study revealed that the bipolar II patients with RC showed GM volume reductions in the bilateral hemispheres of the medial orbital prefrontal cortex, ventromedial prefrontal cortex, anterior cingulate, insula and parahippocampus, in the left hemisphere of the inferior temporal cortex and cerebellum, and in the brainstem, compared with the healthy controls. Moreover, ROI analysis focusing on the ventral prefrontal cortex, i.e., Brodmann areas 10, 11 and 47, revealed that the bipolar II patients with RC showed GM volume reduction in the ventromedial prefrontal cortex, compared with the patients without RC. The findings of our pilot study suggest that the ventromedial prefrontal cortex is associated with the generation of RC in bipolar II disorder.

Relationship of parental bonding styles with gray matter volume of dorsolateral prefrontal cortex in young adults.

Previous epidemiologic studies using the parental bonding instrument (PBI), a self-report scale to rate attitudes of parents during the first 16 years, have suggested that a lower parental care score or higher parental overprotection score could lead to an increased risk of several psychiatric disorders, including schizophrenia and mood disorder. However, neuroimaging studies of an association between PBI scores and brain developmental abnormalities are still limited. In this region-of-interest analysis study using a cross-sectional design, we examined 50 normal young adults, in terms of relationships of parental bonding styles during the first 16 years measured by PBI with regional gray matter (GM) volume in the dorsolateral prefrontal cortex (DLPFC). Our study showed that paternal care score positively correlated with the GM volume in the left DLPFC, and paternal and maternal overprotection score negatively correlated with the GM volume in the left DLPFC. In conclusion, our results suggest that in normal young adults, lower paternal care and higher parental overprotection scores correlated with the GM volume reduction in the DLPFC.

Frontopolar activation during face-to-face conversation: an in situ study using near-infrared spectroscopy.

Near-infrared spectroscopy (NIRS) is a functional brain imaging technique for monitoring brain activation in a natural setting using near-infrared light, and hence, is considered to have some advantages for studies of brain function during social interactions such as face-to-face conversation compared with functional magnetic resonance imaging and positron emission tomography, which have methodological constraints for studying brain mechanisms underlying social interactions: subjects have to lie down on a bed in a small gantry during examination. The purpose of this study was to validate the possible use of NIRS as a functional brain imaging technique for studying social interactions in a natural setting; therefore, we investigated frontal and temporal lobe activation during face-to-face conversation in healthy subjects in the sitting position. The frontal and superior temporal regions were activated during face-to-face conversation, with higher activity in the speaking segments than in the mute segments during conversation particularly in frontopolar NIRS channels. The magnitude of frontopolar activity negatively correlated with the cooperativeness score of the subjects assessed using the temperament and character inventory. These results demonstrated the successful monitoring of brain function during realistic social interactions using NIRS and interindividual differences in frontopolar activity during conversation in relation to the cooperativeness of an individual.