Atsushi Senoo

The Functional Neuroanatomy of Maternal Love: Mother’s Response to Infant’s Attachment Behaviors

BACKGROUND Maternal love, which may be the core of maternal behavior, is essential for the mother-infant attachment relationship and is important for the infants development and mental health. However, little has been known about these neural mechanisms in human mothers. We examined patterns of maternal brain activation in response to infant cues using video clips. METHODS We performed functional magnetic resonance imaging (fMRI) measurements while 13 mothers viewed video clips, with no sound, of their own infant and other infants of approximately 16 months of age who demonstrated two different attachment behaviors (smiling at the infants mother and crying for her). RESULTS We found that a limited number of the mothers brain areas were specifically involved in recognition of the mothers own infant, namely orbitofrontal cortex (OFC), periaqueductal gray, anterior insula, and dorsal and ventrolateral parts of putamen. Additionally, we found the strong and specific mothers brain response for the mothers own infants distress. The differential neural activation pattern was found in the dorsal region of OFC, caudate nucleus, right inferior frontal gyrus, dorsomedial prefrontal cortex (PFC), anterior cingulate, posterior cingulate, thalamus, substantia nigra, posterior superior temporal sulcus, and PFC. CONCLUSIONS Our results showed the highly elaborate neural mechanism mediating maternal love and diverse and complex maternal behaviors for vigilant protectiveness.

Functional MRI-Based Therapeutic rTMS Strategy for Aphasic Stroke Patients: A Case Series Pilot Study

ABSTRACT Four poststroke patients with motor-dominant aphasia received 10 treatment sessions of low-frequency repetitive transcranial magnetic stimulation (rTMS). Each treatment session consisted of 1,200 pulses of stimulation and the site of stimulation was an area homologous to the most activated site on functional MRI performed prior to rTMS. Consequently, rTMS was applied to the right frontal lobe in two patients and to the left frontal lobe in two patients. Treatment resulted in improvement of language function in all four patients. Our therapeutic rTMS strategy seems to be a clinically feasible neurorehabilitative approach for poststroke aphasic patients.

Voxel- and atlas-based analysis of diffusion tensor imaging may reveal focal axonal injuries in mild traumatic brain injury — comparison with diffuse axonal injury

BACKGROUND The diagnosis and management of mild traumatic brain injury (MTBI) continue to be subjects of debate, with varying opinions regarding the extent to which tissue-based impairments versus the impacts of other stressors cause ongoing disability. Detecting areas of the brain with abnormalities that can explain symptoms and behavior in patients with MTBI is important in order to confirm the diagnosis of MTBI. METHODS In this study, we calculated diffusion maps from results of diffusion tensor imaging (DTI) performed in an apparently healthy control group. We then compared these maps with those of patients with MTBI (MTBI group) or diffuse axonal injury (DAI group). All diffusion maps were normalized to the International Consortium for Brain Mapping atlas for atlas-based analysis and were segmented and normalized by the Diffeomorphic Anatomical Registration Through Exponentiated Lie tool in SPM8 to reduce misregistration. RESULTS All diffusion measures in the DAI group were lower than in the control group. There were significant differences in the body and splenium of the corpus callosum, fornix and right cerebral peduncle in the DAI group compared with the control group (P<.001). The MTBI group had higher axial diffusivity than the control group in the right corticospinal tract, left medial lemniscus, left inferior cerebellar peduncle, bilateral anterior limb of the internal capsule, right anterior corona radiata, bilateral cingulum (cingulate gyrus) and left superior frontooccipital fasciculus (P<.05). CONCLUSIONS Voxel- and atlas-based analysis of DTI might suggest that patients with MTBI have focal axonal injury and that the pathophysiology is significantly different from that of DAI. These findings will help in the diagnosis of patients with MTBI.

Effectiveness of Low-Frequency rTMS and Intensive Speech Therapy in Poststroke Patients with Aphasia: A Pilot Study Based on Evaluation by fMRI in Relation to Type of Aphasia

Aim: To assess the safety and clinical efficacy of low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) combined with intensive speech therapy (ST) in poststroke patients with aphasia. Subjects and Methods: Twenty-four patients with left-hemispheric stroke and aphasia were subjected. During 11-day hospitalization, each patient received 10 treatment sessions consisting of 40-min 1-Hz LF-rTMS and 60-min intensive ST, excluding Sundays. The scalp area for stimulation was selected based on the findings of fMRI with language tasks and the type of aphasia. LF-rTMS was applied to the inferior frontal gyrus (IGF) for patients with nonfluent aphasia and to the superior temporal gyrus (STG) for patients with fluent aphasia. Results: On pretreatment fMRI, the most activated areas were in the left hemisphere (n = 16) and right hemisphere (n = 8). The types of aphasia were nonfluent (n = 14) and fluent (n = 10). The LF-rTMS was applied to the right STG (n = 5), left STG (n = 5), right IFG (n = 11) and left IFG (n = 3). Nonfluent aphasic patients showed significant improvement of auditory comprehension, reading comprehension and repetition. Fluent aphasic patients showed significant improvement in spontaneous speech only. Conclusion: The fMRI with aphasic type-based therapeutic LF-rTMS/intensive ST for chronic aphasia seems feasible and a potentially useful neurorehabilitative protocol.

Functional cortical reorganization after low-frequency repetitive transcranial magnetic stimulation plus intensive occupational therapy for upper limb hemiparesis: evaluation by functional magnetic resonance imaging in poststroke patients.

Background Low-frequency repetitive transcranial magnetic stimulation of the nonlesional hemisphere combined with occupational therapy significantly improves motor function of the affected upper limb in poststroke hemiparetic patients, but the recovery mechanism remains unclear. Aims To investigate the recovery mechanism using functional magnetic resonance imaging. Methods Forty-seven poststroke hemiparetic patients were hospitalized to receive 12 sessions of 40-min low-frequency repetitive transcranial magnetic stimulation over the nonlesional hemisphere and daily occupational therapy for 15 days. Motor function was evaluated with the Fugl–Meyer Assessment and Wolf Motor Function Test. The functional magnetic resonance imaging with motor tasks was performed at admission and discharge. The laterality index of activated voxel number in Brodmann areas 4 and 6 on functional magnetic resonance imaging was calculated (laterality index range of −1 to +1). Patients were divided into two groups based on functional magnetic resonance imaging findings before the intervention: group 1: patients who showed bilateral activation (n = 27); group 2: patients with unilateral activation (n = 20). Results Treatment resulted in improvement in Fugl–Meyer Assessment and Wolf Motor Function Test in the two groups (P < 0.01). The treatment also resulted in a significant increase in laterality index in group 1 (P < 0.05), suggesting a shift in activated voxels to the lesional hemisphere. Patients of group 2 showed a significant increase in lesional hemisphere activation (P < 0.05). Conclusions The results of serial functional magnetic resonance imaging indicated that our proposed treatment can induce functional cortical reorganization, leading to motor functional recovery of the affected upper limb. Especially, it seems that neural activation in the lesional hemisphere plays an important role in such recovery in poststroke hemiparetic patients.

Lateralization of activity in the parietal cortex predicts the effectiveness of bilateral transcranial direct current stimulation on performance of a mental calculation task.

Transcranial direct current stimulation (tDCS) is a non-invasive technique that moderates cognitive and motor function. The effects of tDCS on cognitive and motor tasks vary among individuals. However, the source of the inter-individual variability remains unknown. The purpose of the present study was to examine whether the effect of bilateral tDCS on the performance of mental calculations differs among individuals according to the functional lateralization of parietal activity observed during a mental calculation task. Sixteen healthy subjects (11 males and five females, aged 20-23 years) participated. Laterality of parietal activity during a mental calculation task was evaluated using functional magnetic resonance imaging. Subjects also performed the mental calculation task pre-, during-, 30 min post-, and 60 min post-tDCS. Bilateral tDCS with the anode over the left parietal cortex and the cathode over the right parietal cortex shortened response times of the mental calculation task in subjects with left-hemispheric parietal lateralization, but not in subjects with bilateral parietal activation. This indicates that inter-individual variability in laterality of brain activity might be an important factor underlying the effect of bilateral tDCS. In conclusion, bilateral tDCS over the parietal cortex enhanced the performance of mental calculations in subjects with left-hemispheric parietal lateralization.

White matter structure and clinical characteristics of stroke patients: A diffusion tensor MRI study.

Fractional anisotropy has been used in many studies that examined post-stroke changes in white matter. This study was performed to clarify cerebral white matter changes after stroke using generalized fractional anisotropy (GFA). White matter structure was visualized using diffusion tensor imaging in 72 patients with post-stroke arm paralysis. Exercise-related brain regions were examined in cerebral white matter using GFA. The relationship between GFA and clinical characteristics was examined. Overall, the mean GFA of the lesioned hemisphere was significantly lower than that of the non-lesioned hemisphere (P<0.05), the white matter of the lesioned side was severely affected by stroke. A weak negative correlation between GFA and time since stroke onset was found in Brodmann area 5 of the non-lesioned hemisphere. Age correlated negatively with GFA in Brodmann areas 5 and 7 of the lesioned hemisphere. Though these results may be due to a decrease in the frequency of use of the paralyzed limb over time, GFA overall was significantly and negatively affected by the subjects age. The GFA values of patients with paralysis of the dominant hand were significantly different from those of patients with paralysis of the nondominant hand in Brodmann areas 4 and 6 of the non-lesioned hemisphere and Brodmann area 4 of the lesioned hemisphere (P<0.05). The stroke size and location were not associated with GFA differences. Differences between the GFA of the lesioned and non-lesioned hemispheres varied depending on the affected brain region, age at onset of paralysis, and paralysis of the dominant or non-dominant hand.

Diffusion Tensor Imaging Evaluation of Neural Network Development in Patients Undergoing Therapeutic Repetitive Transcranial Magnetic Stimulation following Stroke

We aimed to investigate plastic changes in cerebral white matter structures using diffusion tensor imaging following a 15-day stroke rehabilitation program. We compared the detection of cerebral plasticity between generalized fractional anisotropy (GFA), a novel tool for investigating white matter structures, and fractional anisotropy (FA). Low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) of 2400 pulses applied to the nonlesional hemisphere and 240 min intensive occupation therapy (OT) daily over 15 days. Motor function was evaluated using the Fugl-Meyer assessment (FMA) and Wolf Motor Function Test (WMFT). Patients underwent diffusion tensor magnetic resonance imaging (MRI) on admission and discharge, from which bilateral FA and GFA values in Brodmann area (BA) 4 and BA6 were calculated. Motor function improved following treatment (p < 0.001). Treatment increased GFA values for both the lesioned and nonlesioned BA4 (p < 0.05, p < 0.001, resp.). Changes in GFA value for BA4 of the lesioned hemisphere were significantly inversely correlated with changes in WMFT scores (R2 = 0.363, p < 0.05). Our findings indicate that the GFA may have a potentially more useful ability than FA to detect changes in white matter structures in areas of fiber intersection for any such future investigations.

Development of a Surface Marker for Fractional Anisotropy Maps Using Wood in a Phantom Study

Purpose: To improve imaging, a reliable setup method is critical for the accurate localization of lesions and surface markers. Because an anisotropic marker has not yet been validated for MRI, direct localization of surface markers is not yet feasible in fractional anisotropy (FA) maps. This study aimed to develop an anisotropic surface marker using wood for an FA map and to determine whether a wood marker is useful for various sequences. Methods: Wood infiltrated with water was used to develop an anisotropic surface marker. The wood marker was compared with phantoms composed of clinically available markers, including MR-SPOTS Packets (Beekley Medical, Bristol, CT, USA), Breath Care Oral Refreshing Capsules (Kobayashi Pharmaceutical Co., Ltd., Osaka, Japan), and baby oil (Johnson & Johnson, New Brunswick, NJ, USA). Magnetic resonance images were acquired using the Achieva 3T TX MRI System (Philips HealthCare, Best, Netherlands) equipped with a QD head coil including T1- and T2-weighted imaging, proton-density-weighted imaging, T2* -weighted imaging, T1-weighted imaging spectral pre-saturation with inversion recovery, T2-weighted imaging spectral attenuated inversion recovery, proton-density-weighted imaging spectral attenuated inversion recovery, diffusion weighted imaging, and diffusion tensor imaging. Apparent diffusion coefficient, FA values, and signal-to-noise ratio (SNR) were measured and recorded, and the coefficient of variation was calculated for two consecutive imaging scans. The wood was observed using a microscope. Results: Breath Care Oral Refreshing Capsules and baby oil were not observed in the FA map. The FA value of the MR-SPOTS Packets was 0.18. The FA value of the wood marker was 0.80. The coefficient of variation of the MR-SPOTS Packets and the wood marker were 0.0263 and 0.0013, respectively, in the FA map. Microscopic observation revealed a wood anisotropic structure. Conclusion: The wood maker enabled direct localization in the FA map. Hence, wood markers may be useful to radiologists and contribute to obtaining useful findings.