Tomikimi Tsuji

Microstructural abnormalities in anterior callosal fibers and their relationship with cognitive function in major depressive disorder and bipolar disorder: A tract-specific analysis study

BACKGROUND The corpus callosum modulates interhemispheric communication and cognitive processes. It has been suggested that white matter abnormalities in the corpus callosum are related to the pathophysiology of major depressive disorder (MDD) and bipolar disorder (BD). The aim of this study was to examine microstructural abnormalities in callosal fibers separated by their connection to functional brain regions and determine the relationship of these abnormalities with cognitive function in MDD and BD. METHODS The subjects were 18 patients with MDD, 20 patients with BD, and 21 healthy controls. The callosal fibers were divided into 6 segments based on their cortical projection using tract-specific analysis of diffusion tensor imaging. We examined differences in the fractional anisotropy (FA) of callosal fibers in six segments among the three subject groups and examined the correlation between the FA in each segment and cognitive performance in the 3 groups. RESULTS The FA of anterior callosal fibers were reduced significantly in the MDD and BD groups compared to those in the HC group, and the FA of anterior callosal fibers correlated significantly with the raw scores of the digit sequencing task and symbol coding in the MDD group. LIMITATIONS The patients were medicated at the time of scanning, and the MDD and BD groups were not matched for symptom severity. CONCLUSIONS Our results suggest that MDD and BD have similar microstructural abnormalities in anterior callosal fibers connecting bilateral frontal cortices, and these abnormalities may be related to impairment of working memory and attention in MDD.

Reduction of cortical GABAergic inhibition correlates with working memory impairment in recent onset schizophrenia.

BACKGROUND Cognitive impairments are present during the early course of schizophrenia, and the contribution of GABAergic dysfunction to these cognitive impairments has received increasing attention. Cortical GABAergic inhibition can be assessed using short-interval intracortical inhibition (SICI) in a paired-pulse transcranial magnetic stimulation (ppTMS). The aim of this study was to examine the relationship between cortical GABAergic inhibition and cognitive function in recent onset schizophrenia patients using ppTMS and a neuropsychological battery. METHODS The subjects were 20 healthy controls (HC group) and 20 patients with schizophrenia whose duration of illness was less than three years (SZ group). All subjects underwent ppTMS measurements of SICI and intracortical facilitation (ICF), and cognitive performance of the SZ group was assessed using the Brief Assessment of Cognition in Schizophrenia Japanese-language version. We examined group differences in ppTMS measurements (resting motor threshold, SICI, and ICF). In the SZ group, we assessed the relationship between SICI and cognitive performance, and the relationships between SICI and age, duration of illness, medications, and psychopathology. RESULTS The SZ group showed a significant reduction of SICI compared to the HC group, and demonstrated a significant correlation between the reduction of SICI and impaired performance of a working memory task. The HC and the SZ groups did not differ significantly in resting motor threshold and ICF. The SZ group did not show any significant correlations between SICI and age, duration of illness, medications, or psychopathology. CONCLUSIONS Our results suggest that the reduction of cortical GABAergic inhibition is related to impairment of working memory in patients with recent onset schizophrenia.

Evaluation of regional cerebral blood flow in a patient with musical hallucinations.

A 52-year-old woman with musical hallucinations was examined using brain single photon emission computed tomography (SPECT) with 99mTc-ECD. Changes in regional cerebral blood flow (rCBF) after carbamazepine treatment were assessed using a three-dimensional stereotaxic ROI template. Following treatment, rCBF was decreased in the subcortical structures and increased in the global cortical regions. From our findings, we propose that rCBF values in subcortical structures represent abnormalities similar to those reported in previous reports or other psychiatric disorders, while those in cortical regions suggest background brain dysfunctions that result in generation of musical hallucinations.

Brain Activity During the Clock-Drawing Test: Multichannel Near-Infrared Spectroscopy Study

The Clock-Drawing Test (CDT) is widely used in clinical practice for the screening of dementia. However, neural activity during real clock drawing has not been investigated due to motion artifacts. In the present study, we examined brain activity during real clock drawing using multichannel near-infrared spectroscopy (NIRS). We measured hemoglobin concentration changes in the prefrontal and temporal surface areas during clock drawing using 52-channel NIRS. Data obtained from 37 right-handed healthy volunteers were analyzed. We found significant increases in oxy-Hb in more than 96.2% of the channels (false-discovery rate corrected, p < .025). The time required for CDT performance showed a negative correlation with changes in oxy-Hb in the prefrontal region (r = −.529, p = .002). The mean value for oxy-Hb changes was higher in the left hemisphere in 20 subjects (54%) and in the right hemisphere in 17 subjects (46%). The NIRS/CDT combination is acceptable as a clinical tool, as the method has the advantages of direct measurement of cortical activation with high temporal resolution. Our results confirm the aspects of the CDT involving the frontal-lobe battery.

Cerebral blood flow in the subgenual anterior cingulate cortex and modulation of the mood-regulatory networks in a successful rTMS treatment for major depressive disorder.

The subgenual anterior cingulate cortex (Cg25) has been reported to be a node of mood-regulatory networks. Using a responder and a non-responder of repetitive transcranial magnetic stimulation (rTMS) for depression, we examined pre/post-treatment cerebral blood flow (CBF) in the Cg25 and treatment-related CBF changes in cortical/subcortical regions. In the responder, pre-treatment Cg25 perfusion was higher and was decreased after treatment, in addition, CBF was increased in the frontal and parietal regions and decreased in the hippocampus and basal ganglia. Our results suggest that rTMS treatment response may be related to pre-treatment Cg25 activity and modulation of the Cg25 and mood-regulatory networks.

Reduction of cortical excitability and increase of thalamic activity in a low-frequency rTMS treatment for chronic tinnitus

Low-frequency repetitive transcranial magnetic stimulation (rTMS) has received increasing attention for the treatment of tinnitus, but its therapeutic mechanisms are unclear. We performed low-frequency rTMS treatment for a patient with chronic tinnitus and examined changes of cortical excitability and cerebral blood flow using paired-pulse TMS and single-photon emission computed tomography. After the rTMS treatment, tinnitus loudness was decreased, cortical excitability was reduced, and blood flow in the thalamus was increased. Our results suggest that low-frequency rTMS treatment reduces tinnitus loudness by an inhibitory effect on the cortical excitability and a remote activation effect on the thalamus through the corticothalamic networks.

Increased libido during fluvoxamine treatment

We treated an 80‐year‐old man with vascular dementia who developed increased libido induced by fluvoxamine. Sexual stimulation associated with fluvoxamine administration has been rarely reported and the present findings suggest that organic brain dysfunction could be a risk factor for the development of the condition.

Re-examination of the value of localising aura sensations and lateralising interictal epileptiform discharges in view of structural lesions demonstrated by MRI

We examined the relationship between MRI lesions and electro-clinical findings with special attention to the localising value of aura sensations and the sides of interictal epileptiform discharges in 327 patients with symptomatic localisation-related epilepsy. As a result, while autonomic as well as psychic auras were correlated with temporal lesions, simple motor seizures were associated with extra-temporal ones. Within the group of patients with temporal lobe epilepsy, autonomic but not psychic auras concurred significantly more often with medial temporal structural lesions. Furthermore, there was a significant difference between concordance rates between sides of MRI lesions and EEG foci as a function of laterality: while the right-sided MRI lesions constantly showed ipsilateral EEG foci, EEG foci concurring with the left-sided MRI lesions proved to be often falsely lateralising. From these results, we assumed that lateral as well as medial temporal involvement is needed in the genesis of the psychic aura in contrast to the autonomic aura, which could be induced without lateral temporal involvement, and lesions in the left hemisphere are more apt to induce secondarily epileptogenic than those in the right hemisphere.

Widespread abnormalities in white matter integrity and their relationship with duration of illness in temporal lobe epilepsy

Elucidation of abnormal connections throughout the whole brain is necessary to understand temporal lobe epilepsy (TLE). We examined abnormalities in whole‐brain white matter integrity and their relationship with duration of illness in patients with TLE.

EPA-0443 – Changes of white matter integrity in the corpus callosum by rtms for treatment-resistant depression: a preliminary dti tractography study

Background Reduced white matter integrity in the corpus callosum (CC) has been reported in treatment-resistant depression (TRD). rTMS is assumed to have remote effect on interconnected area with the stimulation site, and this effect is speculated to be one of the therapeutic mechanisms of rTMS treatment. In this preliminary study, we examined changes of callosal fiber integrity in 5 segments of the CC before and after rTMS treatment for TRD. Methods The subjects were 2 patients with treatment-resistant unipolar depression and 1 patient with treatment-resistant bipolar depression, and 24 healthy controls (HC group). The patients underwent 4-week high frequency rTMS to their left DLPFC. In diffusion tensor imaging (DTI) tractography, the CC was divided into 5 segments (orbital, frontal, parietal, temporal, and occipital) based on their cortical projection zones, and fractional anisotropy (FA) value of each segment was estimated. We compared FA in the CC between the patients and the HC groups, and examined changes of FA in the CC after rTMS treatment in the patients. Results The patients showed reduced FA in the frontal, parietal, temporal, and occipital-callosal segments compared to the HC group. All patients responded to the rTMS treatment, and FA in the orbital, frontal, parietal, temporal-callosal segments increased after the rTMS treatment. Conclusions Our results suggest that white matter integrity in the CC is reduced in TRD and that increased white matter integrity in the CC might be related with the therapeutic mechanisms of rTMS treatment.