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Biomedical subjects

Taro Muramatsu

Publications and source records attributed to Taro Muramatsu.

14 recordsLinked to original sources
PubMed2007

Unilateral amygdala lesions hamper attentional orienting triggered by gaze direction.

The newly discovered deficit in a bilateral amygdala-damaged case, of not being able to allocate attention to the critical feature of a face (Adolphs R, Gosselin F, Buchanan TW, Tranel D, Schyns P, Damasio AR. 2005. A mechanism for impaired fear recognition after amygdala damage. Nature. 433:68--72.), has opened a new window into the function of the amygdala. This case implies that the amygdala might be essential in detecting potentially relevant social stimuli, and directing attention accordingly. In this study, we have sought to test this implication by investigating the behavioral performance of 5 unilateral amygdala-damaged subjects on spatial cueing tasks. The tasks employed central gaze and arrow direction as cues to trigger attentional orienting in peripheral target detection. Although age-matched normal controls demonstrated a significant congruency effect such that targets presented congruently to cue direction elicited faster detection, amygdala subjects demonstrated no such congruency effect for gaze cues in the face of a significant congruency effect for arrow cues. The results suggest that the social valence of a stimulus is critical for amygdala involvement in visual processing. The results also support the implicated role of the amygdala in detecting and analyzing relevant social stimuli, and orienting attention accordingly.

Adult↗
PubMed2006

Gaze but not arrows: a dissociative impairment after right superior temporal gyrus damage.

Superior temporal sulcus (STS) activation has consistently been demonstrated in the normal brain when viewing eyes, and thus this area is implicated as a gaze processing region in humans. In a recent report, we have presented a case, M.J., with a well-circumscribed lesion to the right superior temporal gyrus (STG), who demonstrated impaired discrimination of gaze direction. In the aim to make distinct whether this impairment is unique to gaze, we have applied a spatial cueing paradigm established by Kingstone and colleagues. In our experiment, pictorial gaze and symmetrical arrows were centrally presented as non-predictive, spatial cues in detecting peripheral targets. Fifteen normal subjects and M.J. participated in the experiment. In concordance with previous reports, controls demonstrated a significant facilitation of reaction times in detecting targets cued by congruent gaze/arrows, compared with incongruent cues. In striking contrast, M.J. showed no such congruency advantage for gaze, in the face of a normal congruency advantage for arrows. We have demonstrated that a circumscribed lesion to the right STG impairs the ability to utilize biological directional information such as gaze, but leaves the non-biological counterpart (arrows) intact. This dissociation implies that indeed, the STS specializes in processing gaze.

Analysis of Variance↗
PubMed2006

Cortical reorganization and somatic delusional psychosis: a magnetoencephalographic study.

A woman complained of feeling a "metal-like thing" in her oral cavity 4 years after a stroke. She was convinced of the physical nature of her complaint despite intact dental and neurological findings. Somatosensory evoked magnetic fields suggested that her decreased right SII function was compensated for by the right SI region, probably contributing to the delusional symptom.

Cerebral Cortex↗
PubMed2006

Family history of alcoholism and cognitive recovery in subacute withdrawal.

A family history of alcoholism has been demonstrated to be an important factor affecting cognitive function. However, no studies have yet been conducted to compare cognitive recovery of family history-positive (FH+) and family history-negative (FH-) alcoholics in the subacute withdrawal period. To tackle this problem, a neuropsychological test battery consisting of six computerized tests was administered to 19 FH+ and 20 FH- alcoholics at 2 and 7 weeks after abstinence. At 2 weeks after abstinence, overall performance of both FH+ and FH- groups was significantly poorer than that of healthy controls. At 7 weeks, these performances tended to recover, but in Trail Making A and Figure Position, performances of FH+ alcoholics remained worse than those of controls, while those of FH- alcoholics did not. Thus cognitive recovery during the subacute withdrawal period was worse among FH+ alcoholics than FH- alcoholics, and this finding should be considered when planning alcohol rehabilitation programs.

Adult↗
PubMed2005

A deficit in discriminating gaze direction in a case with right superior temporal gyrus lesion.

The superior temporal sulcus (STS) region is well recognized as being heavily involved in detecting and discriminating gaze. Lesions confined to this area are quite rare in humans, and so the research has mainly depended on animal studies and functional neuroimaging in normal human subjects. We report one such rare case, a 54-year-old Japanese female with a possible congenital s anomaly who, after a cerebral hemorrhage, demonstrated a lesion almost completely confined to the entire right superior temporal gyrus (STG). In the subacute phase, the patient showed evidence of left hemispatial neglect, from which she gradually recovered. In the chronic phase, she showed a puzzling difficulty in obtaining eye-contact. We have conducted, in conjunction with conventional neuropsychological evaluations, experimental assessment of her ability in gaze cognition. Her performance on neuropsychological testing demonstrated no compromise in intellect, memory, or language skills, and a close-to-full recovery from neglect. On gaze cognition experiments, she was repeatedly shown to perceive left gaze as straight, and to a lesser degree, straight gaze as right. We suggest that the function of the STG in detecting gaze, together with the directional information it receives from earlier visual areas, may be associated, when damaged, with this deficit in detecting contra-directional gaze. We have demonstrated for the first time that a single circumscribed lesion to the STG results in both gaze processing deficit and concurrent aberrant gaze behavior of the victim herself, implicating a mechanism within the STG as an interface between gaze of others and gaze of self.

Brain Damage, Chronic↗
PubMed2005

Functional network in the prefrontal cortex during episodic memory retrieval.

A recent consistent finding in neuroimaging studies of human memory is that the prefrontal cortex (PFC) is activated during episodic memory retrieval. To date, however, there has been no direct evidence to explain how activity in the right and left PFC and in the anterior and posterior PFC are functionally interconnected. The goal of the present study was to obtain such evidence by event-related functional magnetic resonance imaging (MRI) and the functional connectivity method. Subjects were first asked to try to remember a series of associate-word lists outside the MRI scanner in preparation for a later recognition test. In the MRI scanning phase, they were asked to make recognition judgments in regard to old words, semantically related lure words, and unrelated new words. The analysis of functional connectivity revealed that the posterior PFC in each hemisphere had strong functional interconnections with the contralateral posterior PFC, whereas the anterior PFC in each hemisphere had only weak functional interconnections with the contralateral anterior PFC. No strong functional interconnections were found between the anterior and posterior PFC in either hemisphere. These findings support the hypothesis of an associative contribution of the bilateral posterior PFC to episodic memory retrieval and a dissociative contribution of the bilateral anterior PFC.

Adult↗
PubMed2004

A 3-year follow-up study of 'orientation agnosia'.

Dissociation between the ability to recognize misoriented objects and to determine their orientation has been reported in a small number of patients, but the long-term course of this deficit has not been reported so far. Here, we describe the case of a 32-year-old female who had bilateral occipito-temporal damage caused by a cerebrovascular accident. Neuropsychological assessment performed at 6 months after the occurrence of the cerebrovascular accident revealed that she was almost generally agnostic for object orientation. The patient was then re-tested 3 years later, when she showed apparently striking recovery in her ability to determine object orientation. However, closer examination revealed that she still displayed the same impairment, although at this time, it was only for objects presented in non-cardinal angles. Moreover, she had problems mostly discriminating orientations that differed by small amounts. The ability of patients to discriminate a variety of orientations should be further tested in future investigations in this field.

Adult↗
PubMed2004

An earlier component of face perception detected by seeing-as-face task.

To investigate the time sequence of the neural processes underlying face perception, magnetoencephalography was performed using a seeing-as-face task, in which visual inputs were identical across two conditions, but subject perceptions differed: one being a non-specific pattern of geographical shapes, the other being a percept of a face. Subtraction between the two conditions revealed a response occurring 120 ms after stimulus onset in right occipital, approximately 50 ms earlier than previously reported response at a latency of 170 ms at the right fusiform gyrus. As our novel task completely excluded differences in low-level properties of visual stimuli between control and face conditions, these two responses were considered specific to face perception. The result supported the two-stage theory of face processing.

Adult↗
PubMed2004

ALDH2/ADH2 polymorphism associated with vasculopathy and neuropathy in type 2 diabetes.

In the history of diabetes, chlorpropamide alcohol flushing test (CPAF) was a big topic in the 1970s to 1980s. Alcohol tolerance after chlorpropamide has prognostic significance, with the intolerant group (CPAF-positive group) being less prone to develop vascular complication than the tolerant group (CPAF-negative group). A mechanism of CPAF has been regarded as the inhibition of aldehyde dehydrogenase 2 (ALDH2) by an N-alkyl-substituted derivative of chlorpropamide, and the expression of these mutations of ALDH2 and alcohol dehydrogenase 2 (ADH2) could determine the alcohol tolerance among the Japanese population. Therefore, we hypothesized that expression of different ALDH2 and ADH2 polymorphisms may induce differences in vascular complications in diabetes and conducted two studies. The first study (study 1) was to determine the association of ALDH2/AHD2 polymorphism with diabetic complications. To know the association of ALDH2/AHD2 polymorphism with diabetic vasculopathy and neuropathy, a total of 158 patients with type 2 diabetes were divided into four groups on the basis of ALDH2 "activity" and ADH2 "superactivity." The frequency of proteinuria and the percentage of proliferative retinopathy among the patients with retinopathy was higher in those with active ALDH2 and superactive ADH2. We speculated that protein kinase C isoforms up-regulated by 4-hydroxynonenal that was detoxified by ALDH2 and ADH2 may account for the long-term development of diabetic nephropathy and severe retinopathy. As for neuropathy, the frequency of symptomatic neuropathy was higher in patients with inactive ALDH2 and usual ADH2. We speculate that increased tissue levels of toxic aldehyde could result from inactive ALDH2 and usual ADH2 expression, which results in the increased level of reactive aldehyde in sensory neuron pathway, thereby causing symptomatic polyneuropathy.

Adolescent↗
PubMed2003

Macrocytosis, a new predictor for esophageal squamous cell carcinoma in Japanese alcoholic men.

Early esophageal squamous cell carcinoma detected by esophageal iodine staining can be easily treated by endoscopic mucosectomy, and identifying its predictors is important in better selecting candidates to screen for this high-mortality cancer. The common etiologies of elevated mean corpuscular volume (MCV) and esophageal cancer, including folate deficiency, smoking, drinking and high acetaldehyde exposure, suggest testing MCV as such a predictor. Japanese alcoholic men with (n = 65) and without (n = 206) esophageal squamous cell carcinomas, excluding those with liver cirrhosis, were assessed for MCV within 7 days of their last drink, alone or in combination with findings from either the alcohol flushing questionnaire or genotyping to identify inactive aldehyde dehydrogenase-2 (ALDH2*1/2*2) and the less-active form of alcohol dehydrogenase-2 (ADH2*1/2*1), which pose risks for esophageal squamous cell carcinoma. MCV was higher in cancer patients than in the control group. MCV was higher in both groups in those who were heavier smokers, had lower body mass index (BMI), experienced alcohol flushing, and had ALDH2*1/2*2. After adjusting for age, drinking and smoking habits, BMI and ALDH2/ADH2 genotypes, macrocytosis of MCV > or =106 fl was associated with increased risk for esophageal cancer (OR = 2.75). Men with both MCV > or =106 fl and alcohol flushing had an even higher cancer risk (OR = 5.51). The combinations of MCV > or =106 fl with ALDH2*1/2*2 or ADH2*1/2*1 alone, and both ALDH2*1/2*2 and ADH2*1/2*1 (ORs = 11.44, 21.22 and 319.7, respectively) showed consistently higher risk than the corresponding group with MCV <106 fl (ORs = 7.24, 4.71 and 27.01, respectively). In conclusion, MCV measurement, alone or in combination with the markers of alcohol sensitivity, provides a new means of predicting risk for esophageal squamous cell carcinoma in Japanese alcoholic men.

Alcohol Dehydrogenase↗
PubMed2002

Co-occurrence of obsessive-compulsive personality traits in young and middle-aged Japanese alcohol-dependent men.

BACKGROUND: Previous studies may have underestimated the potential importance of the prevalence of obsessive-compulsive traits among persons with alcoholism. Although many studies have examined the characteristics of young alcoholics compared with middle-aged alcoholics, none has compared the prevalence of obsessive-compulsive traits in young and middle-aged alcoholics. METHODS: This study compared the prevalence of obsessive-compulsive traits (Leyton Obsessional Inventory) and depressive symptoms (Zung Self-Rating Depression Scale) among young (n=41) and middle-aged (n=34) hospitalized Japanese male alcoholics and in young (n=28) and middle-aged (n=25) nonalcoholic subjects. RESULTS: Both young and middle-aged male alcoholics reported more obsessive-compulsive personality traits and depressive symptoms than their comparison groups. However, the alcoholic subjects' obsessive-compulsive personality traits were not related to their level of depressive symptoms. CONCLUSIONS: Young and middle-aged male Japanese alcoholics have more obsessive-compulsive personality traits than nonalcoholic males of similar ages. Their alcohol-related psychological and behavioral characteristics may derive, in part, from their obsessive-compulsive symptoms.

Adult↗
PubMed2002

Multiple cancers associated with esophageal and oropharyngolaryngeal squamous cell carcinoma and the aldehyde dehydrogenase-2 genotype in male Japanese drinkers.

Aldehyde dehydrogenase-2 (ALDH2) is a key enzyme for the elimination of acetaldehyde, an established animal carcinogen generated by alcohol metabolism. In the presence of ALDH2*2, a mutant allele that is prevalent in East Asians, this enzyme is inactive, leading to excessive accumulation of acetaldehyde. Only among Japanese alcoholic patients has the positive association between this inactive form of ALDH2 and multiple-field cancerization in the upper aerodigestive tract been demonstrated. Whether this finding could be extended to multiple-cancer patients in general is of great interest, because the prevalence of esophageal cancer with other organ cancers has increased dramatically during recent decades in Japan. This study compared the ALDH2 genotypes of groups of male Japanese drinkers who had either esophageal squamous cell carcinomas (SCCs) with (n = 26) or without (n = 48) multiplicity or oropharyngolaryngeal SCCs with (n = 17) or without (n = 29) multiplicity. After adjustments for age and drinking and smoking habits, logistic regression analysis showed significantly increased risk for each multiplicity associated with either esophageal or oropharyngolaryngeal SCCs in the presence of the ALDH2*2 allele (odds ratio, 5.26; 95% confidence interval, 1.08-51.06 and odds ratio, 7.36; 95% confidence interval, 1.29-80.70, respectively). This study is the first to strongly link inactive ALDH2 with the multiple cancer susceptibility of male Japanese drinkers with either esophageal or oropharyngolaryngeal cancers. A simple questionnaire about both current and past facial flushing after drinking a glass of beer was highly sensitive (95.6%) in detecting inactive ALDH2 in these patients and may be useful for identifying high-risk patients.

Alcohol Drinking↗