Toru Uehara

Multichannel near-infrared spectroscopy in depression and schizophrenia: cognitive brain activation study

BACKGROUND Recent developments in near-infrared spectroscopy (NIRS) have enabled the noninvasive clarification of brain functions in psychiatric disorders with measurement of hemoglobin concentrations as cerebral blood volume. METHODS Ten patients with depression, 13 patients with schizophrenia, and 16 age- and gender-matched healthy control subjects participated in the study after giving consent. The relative concentrations of oxyhemoglobin [oxyHb] were measured with frontal and temporal probes every.1 sec during word fluency and unilateral finger tapping tasks, with two 24-channel NIRS machines. RESULTS The [oxyHb] increase patterns during the word fluency task varied among the three groups, although their task performances were similar: the depression group was characterized by a smaller [oxyHb] increase during the first half of the task period and the schizophrenic group by a small trough of [oxyHb] at the start of the task period and [oxyHb] re-increase in the posttask period. [OxyHb] increases during the finger-tapping task were rather larger in the patient groups than in the control group. CONCLUSIONS The characteristic time courses of [oxyHb] changes in the frontal lobe were elucidated for depression and schizophrenia. Near-infrared spectroscopy, with its noninvasiveness and high time resolution, can be a useful tool for research and clinical purposes in psychiatry.

Frontal lobe function in bipolar disorder: a multichannel near-infrared spectroscopy study.

Frontal lobe dysfunction has been implicated as one of the pathophysiological bases of bipolar disorder. Detailed time courses of brain activation in the bipolar disorder group were investigated using multichannel near-infrared spectroscopy (NIRS), a recently developed functional neuroimaging technology with a high time resolution, and were compared with those in the major depression and healthy control groups. Seventeen patients with bipolar disorder, 11 equally depressed patients with major depression, and 17 healthy controls participated in the study. Changes in oxy hemoglobin concentration ([oxy-Hb]) during cognitive and motor tasks were monitored using frontal and temporal probes of two sets of 24-channel NIRS machines. [oxy-Hb] increases in the bipolar disorder group were smaller than those in the healthy control group during the early period of a verbal fluency task, larger than those in the major depression and healthy control groups during the late period of this task, and were smaller than those in the major depression group during a finger-tapping task. Depressive symptoms and antidepressant dosages did not correlate with [oxy-Hb] changes in the two patient groups. Bipolar disorder and major depression were characterized by preserved but delayed and reduced frontal lobe activations, respectively, in the present high-time-resolution study by multichannel NIRS.

Sex and age dependencies of cerebral blood volume changes during cognitive activation: a multichannel near-infrared spectroscopy study

In this study, we measured the change in cerebral hemoglobin concentrations during a cognitive task using multichannel near-infrared spectroscopy (NIRS), and investigated the relationship between regional cerebral blood volume and sex, age, and task performance. Thirty-nine healthy volunteers (24 males and 15 females; mean age, 33.0 years) participated after giving their informed consent and performed a word fluency task. The relative oxy-hemoglobin concentration ([oxy-Hb]) was measured using frontal and temporal probes with two sets of 24-channel NIRS machines. The effects of sex, age, and task performance on [oxy-Hb] changes were analyzed using analysis of covariance: with sex, age, and task performance as independent variables, and [oxy-Hb] changes as dependent variables, and years of education as covariates. The effects on [oxy-Hb] increase were significant in many channels in the frontal and temporal probes for sex, that is the most prominent effect, and in a few frontal channels for age: [oxy-Hb] increases were larger in males than in females, and in the young than in the middle-aged. The effects on [oxy-Hb] increase were not significant for task performance, but [oxy-Hb] increases in subjects with low performance tended to be larger than those in subjects with high performance. The results demonstrated that multichannel NIRS could detect cerebral activation during cognitive tasks and clarify sex- and age-dependent differences in such cerebral activation. Sex- and age-dependent differences in cerebral activation, as demonstrated in the present study, should be considered when interpreting cerebral blood volume, cerebral blood flow, and cerebral glucose metabolism data.

Preattentive dysfunction in major depression: A magnetoencephalography study using auditory mismatch negativity

Information processing deficits in major depressive disorder have been infrequently examined electrophysiologically. Its preattentive and sensory information processing was examined using mismatch field (MMNm) and P1m components, respectively, by magnetoencephalography. Fourteen major depressive disorder patients and 19 healthy volunteers participated in the study. MMNm was elicited in response to duration and frequency changes of pure-tone stimuli and in response to a vowel across-category change. The magnetic global field power (mGFP) of MMNm was significantly smaller in the major depressive disorder patients than in the healthy volunteers, although that of P1m did not differ between the two groups. Information processing at the preattentive level is impaired functionally in major depressive disorder, and this dysfunction is not due to the dysfunction at the lower level of information processing.

Dieting tendency and eating behavior problems in eating disorder correlate with right frontotemporal and left orbitofrontal cortex: a near-infrared spectroscopy study.

Frontal lobe dysfunctions have been implicated as one of the pathophysiological bases in eating disorder (ED). Neural substrates of ED have been examined in neuroimaging studies employing symptom-related stimuli, such as food and body-image distortion, but with inconsistent results because of differences in study design, task, and stimulus used. In order to elucidate frontal lobe dysfunction correlates of clinical symptoms in ED, we examined the frontal lobe function during a cognitive task, not a symptom-related task, using near-infrared spectroscopy (NIRS), which is suitable for the functional neuroimaging study of ED because of its complete noninvasiveness and natural measurement setting. Regional hemodynamic changes were monitored during a verbal fluency task (letter version) using a 52-channel NIRS apparatus in 27 female ED patients and 27 matched healthy controls, and their correlations with clinical symptoms assessed using the Eating Attitude Scale (EAT-26) were examined. Regional hemodynamic changes were significantly smaller in the ED group than in the control group in the bilateral orbitofrontal and right frontotemporal regions, and negatively correlated with dieting tendency scores in EAT-26 in the right frontotemporal regions and with the eating restriction and binge eating scores in the left orbitofrontal regions. The clinical symptoms of ED are considered to consist of two components: dieting tendency that correlates with the right frontotemporal cortex and eating behavior problems that correlate with left the orbitofrontal cortex.

Decreased cortical reactivity underlies subjective daytime light sleepiness in healthy subjects: A multichannel near-infrared spectroscopy study

Daytime sleepiness is considered to be one of the main problems in modern society. Of the four aspects of sleepiness, namely, subjective sleepiness, performance decrease, sleep propensity, and arousal decrease, subjective sleepiness is the most difficult to assess. Brain mechanisms underlying subjective light sleepiness in daytime were investigated in healthy subjects using multichannel near-infrared spectroscopy (NIRS), which enables the noninvasive measurement of regional cerebral blood volume (rCBV) changes under natural conditions. Forty right-handed healthy volunteers participated in this study. Relationships were investigated between subjective sleepiness and anxiety, assessed using the Stanford Sleepiness Scale (SSS) and State-Trait Anxiety Inventory (STAI), respectively, and cerebral cortex reactivities assessed as oxygenated and deoxygenated hemoglobin concentration ([oxy-Hb] and [deoxy-Hb], respectively) changes during a verbal fluency task using a 24-channel NIRS machine. SSS score correlated negatively with an [oxy-Hb] increase in the bilateral frontal channels mainly in the middle and last third of the verbal fluency task period. Subjective light daytime sleepiness in healthy subjects is considered to be related to decreased prefrontal reactivities in the later part of cognitive activation.

Increased and decreased cortical reactivities in novelty seeking and persistence: a multichannel near-infrared spectroscopy study in healthy subjects.

Background: Near-infrared spectroscopy (NIRS) has enabled completely noninvasive measurements of regional cerebral blood volume (rCBV) changes in cortices. In the present study, we investigated the relationships between rCBV changes assessed with NIRS and two dimensions of personality, novelty seeking and persistence. Methods: Thirty right-handed healthy volunteers participated in the study. Their personality traits were assessed using the Temperament and Character Inventory (TCI), and changes in oxy- and deoxy-hemoglobin concentrations were monitored during 40 s unilateral finger tapping tasks over the subjects’ bilateral temporal regions using a 24-channel NIRS machine. Results: The oxy-hemoglobin concentration increases were significantly correlated positively with novelty seeking scores and negatively with persistence scores in the TCI during the initial time segment of the left-finger tapping task. Conclusion: Increased and decreased brain activations demonstrated using multichannel NIRS were assumed to characterize the cortical reactivities underlying novelty seeking and persistence temperament, respectively.

Cerebral blood volume changes in patients with eating disorders during word fluency: a preliminary study using multi-channel near infrared spectroscopy

OBJECTIVE: This study investigated the characteristics of cerebral oxygenation changes in eating disorders patients (ED) and normal controls during the cognitive tasks, using a highly time-resolved, and non-invasive instrument. METHOD: Eleven female patients with anorexia nervosa or bulimia nervosa were recruited, and 11 healthy females participated. The relative concentrations of oxy-hemoglobin [o-Hb] and deoxy-hemoglobin [d-Hb] were measured during word fluency task using multichannel near infrared spectroscopy (NIRS). RESULTS: The increases of o-Hb and d-Hb during the task were compared between the groups. ED patients showed lower activation and a gradual increase in o-HB during the task. In the frontal, d-HB concentrations decreased during the task in ED patients. CONCLUSION: These specific patterns of oxygenation changes may indicate less supply and less demand of cerebral blood volume. Bedside measurements of cerebral oxygenation changes using NIRS are useful on understanding of neurophysiological features of ED.

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. Hum Brain Mapp 33:2211–2223, 2012.

Plasma des-acyl and acyl ghrelin in patients with eating disorders

A recently recognized peptide, ghrelin, increases appetite and energy retention in human. Previous reports have shown higher plasma level in eating disorder (ED) patients and correlations with body mass index (BMI). This study examined these findings by measuring active (N-RIA) and total (C-RIA) levels of plasma ghrelin. Multipurpose assessments of symptoms were conducted for 11 ED patients and 5 control females. Results revealed significant differences of C-RIA between the groups. The BMI did not correlate with ghrelin, but demonstrated reversal correlation with the ratio of N-RIA and C-RIA (NC ratio) according to the ED or control group. The NC ratio also tended to be associated with a self-rating score. The NC ratio might be related to specific characteristics of ghrelin secretion or clearance in ED patients. Further basic and clinical investigations are necessary.