PubMed Health⌕ Search

Biomedical subjects

Masao Aihara

Publications and source records attributed to Masao Aihara.

15 recordsLinked to original sources
PubMed2005

Sequential 3-D MRI frontal volume changes in subacute sclerosing panencephalitis.

In patients with subacute sclerosing panencephalitis, clinical stages defined according to Jabbour correlate strongly with frontal lobe dysfunctions. Non-quantitative radiologic investigations in these patients have confirmed cerebral atrophy without identifying predominantly affected regions. We addressed this issue over an 8-year-old boy's course using volumetry based on three-dimensional T1-weighted gradient echo magnetic resonance imaging. Seven normal 6-12-year-old subjects served as controls. Whole-brain volume declined as Jabbour stage advanced from I to III. Frontal lobe volume and frontal-to-whole-brain volume ratios fell significantly as clinical stage progressed. Thus, cerebral atrophy in this SSPE patient was predominantly frontal, and paralleled clinical progression.

Brain↗
PubMed2005

[Study of saccadic eye movement in children with attention deficit/hyperactivity disorder].

Recent studies have postulated that impairment of behavior inhibition, leading to executive dysfunction in future, is the fundamental pathophysiology of attention deficit/hyperactivity disorder (AD/HD). To evaluate this, we studied two saccadic eye movement tasks: visual- and memory-guided, in 8 children with AD/HD (combined type;mean age, 9.1 years, range 6 approximately 11 years) and 16 healthy children (mean age, 9.2 years, range 6 approximately 12 years). In the memory-guided saccade task, reflexive anticipatory errors were more frequently observed in AD/HD than in controls. The children with AD/HD showed longer response latency in the memory-guided saccade task, and greater coefficient of variation in both the latency and amplitude in both the tasks. These results suggested that saccade tasks, especially the memory-guided task, may be useful in clarifying pathophysiology of AD/HD.

Attention Deficit Disorder with Hyperactivity↗
PubMed2004

Lateralization of the frontal lobe functions elicited by a cognitive bias task is a fundamental process. Lesion study.

Cognitive neuroscience researchers have hypothesized that context-dependent and context-independent response selection is associated with the left and right frontal lobe, respectively, in right-handed adult males. Patients with left frontal lobe lesions show context-independent reasoning in a cognitive bias task (CBT), while those with right frontal lesions show context-dependent reasoning. Young children show more context-independent responses in a modified CBT (mCBT), while adolescents and adults show more context-dependent responses. We investigated the cognitive bias of right-handed children with unilateral frontal lobe lesions/epileptic foci to explore the plasticity of lateralization in the frontal lobes. The study included eight children with left frontal lobe lesions/epileptic foci (LLF) and four children with right frontal lobe lesions/epileptic foci (RLF). Twenty-three right-handed age-matched males served as controls. A computer presented version of the original card-choice task that was simplified and modified for children was used (mCBT). Simple visual stimuli differed dichotomously in shape, color, number, and shading. A target object presented alone was followed by two choices from which subjects made selection based on preference. Considering all four characteristics, the degree of similarity between the target and the subjects' choice was scored for 30 trials. A high score indicated a context-dependent response selection bias and a low score indicated a context-independent bias. The RLF subjects had a higher converted score (mean: 26.8+/-2.2), while LLF subjects showed a lower converted score (mean: 7.75+/-6.3). There were highly significant differences between LLF subjects and the other groups (P<0.001 vs. controls or RLF subjects). No significant correlations were observed between the converted scores and the age at onset, time since insult, or IQ in either LLF or RLF subjects. These findings suggest that the lateralization of frontal lobe function elicited by mCBT is fundamental and independent of language lateralization, rather than secondary to it. Furthermore, these findings also indicate that the timetable for the development of lateralized frontal lobe functions depends upon biologic factors.

Adolescent↗
PubMed2004

Context-dependent reasoning in a cognitive bias task Part II. SPECT activation study.

A cognitive bias task (CBT) delineates two different cognitive selection mechanisms in the prefrontal cortex. To identify functional anatomy of context-dependent reasoning, we used technetium-99mhexamethyl- propyleneamine oxime (99mTc HM-PAO) single photon emission computed tomography (SPECT) and statistical parametric mapping. Twelve right-handed men 20-24 years old were instructed to look at a target card and then select the choice card (among two) that they preferred (modified CBT; mCBT). They also selected a choice card 2 weeks later without prior presentation of a target card (control task). In both tasks, 99mTc HM-PAO was injected intravenously about 15 s after initiation of the mCBT or control task. Brain images were obtained using a gamma camera and reconstructed by a UNIX-based workstation. Statistical analysis compared all activated images to control images. Results associated with P values of less than 0.01 (Z score > 2.36) were depicted on T1-weighted magnetic resonance images. All subjects preferred choices more similar to the target. SPECT activation occurred bilaterally in the dorsolateral prefrontal cortices and middle temporal gyri during performance of the CBT. Additionally, the left inferior prefrontal cortex and left fusiform gyrus showed significant activation compared with the control task. A neural network linking the temporal and prefrontal cortices prominently seen in the left hemisphere participates in context-dependent reasoning. Knowledge of such neural systems is essential for understanding prefrontal lobe function and dysfunction.

Adult↗
PubMed2004

[Evaluation of sympathetic skin response in patients with attention deficit/hyperactivity disorder presenting with comorbid disorders].

We studied sympathetic skin response (SSR) to visual emotional stimuli in two children with attention deficit/hyperactivity disorder (AD/HD) and nine healthy controls, and correlated them with comorbid disorders. They were diagnosed as having conduct disorder at administration. Two years after interventions of medical care, counseling and education, they were improving in behavior, one with oppositional defiant disorder (ODD) and another without ODD at this study. SSR were evoked in the patient without ODD (a 10-year-old boy), but not in the patient with ODD (a 12-year-old boy). These findings indicate failure of a patient with both AD/HD and ODD to respond autonomically to social stimuli, and suggest association between emotional signal and empathy.

Attention Deficit Disorder with Hyperactivity↗
PubMed2004

[Sympathetic skin response and emotional changes of visual stimuli].

We studied sympathetic skin response (SSR) to visual emotional stimuli in 11 normal children and 13 normal adults. The arousal and valence levels of original pictures were previously assessed by 20 normal children and adults. SSR appearance ratio tended to be high for pictures with high arousal and those with either high or low valence, and was higher in children than in adults. The response for pictures with high arousal and low valence was different between children and adults. These pictures were classified into 2 groups; one consisted of disgusting creatures such as worms and roaches, and another of violent scenes, symbolizing physiological and social unpleasure, respectively. In children, SSRs were evoked with the same ratio for these two groups of pictures. In adults, however, SSRs for social unpleasure pictures were evoked with a significantly higher ratio compared to those for physiological ones. These results indicate that children are more susceptible to emotional stimuli and that this susceptibility diminishes with development, suggesting the association between emotional signal and moral development.

Adolescent↗
PubMed2004

[Case of severe motor and intellectual disabilities presenting with partial central diabetes insipidus triggered by infection].

We report a 42-year-old woman with severe motor and intellectual disabilities (SMID) who showed partial central diabetes insipidus during severe pneumonia. Serum sodium levels were previously within the upper normal range from 140 to 147 mEq/L. During pneumonia, however, serum sodium rose rapidly to reach 185 mEq/L. The daily urinary volume exceeded the daily intake of water. Nasal administration of 1-desamino-8-D-arginine vasopressin (DDAVP) reduced the daily urinary volume and the serum sodium level to normal ranges. Consequently, we diagnosed her as having central diabetes insipidus (DI). She required a smaller dose of DDAVP (2.5 microg/day) than usual DI (5-15 microg/day) to maintain normal urinary volume and the serum sodium level for seven months. After the nasal administration of DDAVP was discontinued, the serum sodium levels again returned to within the upper normal range. A water deprivation study demonstrated poor elevation of both plasma antidiuretic hormone (ADH) level (range, 0.5-2.0 pg/ml) and urine osmolarity (peak level, 552 mOsm/kgH2O) despite the elevation of plasma osomolarity, suggesting latent partial central DI. Water balance and serum electrolyte levels should be closely monitored in cases of SMID.

Adult↗
PubMed2003

Development of the prefrontal lobe in infants and children: a three-dimensional magnetic resonance volumetric study.

Relatively little is known about normal prefrontal lobe development. We used three-dimensional magnetic resonance imaging (MRI)-based brain volumetry to characterize developmental changes in prefrontal lobe volumes in infants and children. Prefrontal volumes were determined in 30 subjects aged 5 months to 18 years (221 months) and 3 adults aged 28-39 years (324-468 months). Images were acquired on a 1.5-T MRI system using T1-weighted gradient-echo sequences. Volumes of the frontal and prefrontal lobes were determined using a workstation, and the prefrontal-to-frontal volume ratio was calculated. Prefrontal lobe volume increased slowly until 8 years (96 months) of age, contrasting sharply with rapid growth between 8 and 14 years (96 and 168 months). The prefrontal-to-frontal volume ratio increased with age as a sigmoid growth curve. A prefrontal growth spurt occurs in late childhood. Knowledge of prefrontal lobe development is essential for understanding cognitive development and dysfunction.

Adolescent↗
PubMed2003

Age shifts frontal cortical control in a cognitive bias task from right to left: part I. Neuropsychological study.

Two functionally and neurally distinct cognitive selection mechanisms involve the prefrontal lobes: those based on internal representations (context dependent) and those involving exploratory processing of novel situations (context independent). We used a cognitive bias task (CBT) representing contextual reasoning to correlate lateralization with age in the frontal lobes. Subjects included 37 healthy right-handed male children and adolescents (age range, 5-18 years). Controls were 19 right-handed men from 20 to 30 years old. A computer-presented version of the original card-choice task simplified, modified for children was used (modified CBT; mCBT). Simple visual stimuli differed dichotomously in shape, color, number, and shading. A target object presented alone was followed by two choices from which subjects selected according to preference. Considering all four characteristics, similarity between target and subject choice was scored for 30 trials. A high score implied a context-dependent response selection bias and a low score, a context-independent bias. Similarity increased significantly with age. The youngest children (5-7 years) scored lower than ages from 11 years to adulthood. Between 7 and 9 years, scores began to increase with age to reach an adult level by age 13-16. Young children showed context-independent responses representing right frontal lobe function, while adolescents and adults showed context-dependent responses implicating left frontal lobe function. The locus of frontal cortical control in right-handed male subjects thus shifts from right to left as cognitive contextual reasoning develops.

Adolescent↗
PubMed2002

Quantitative analysis of benzodiazepine receptor in temporal lobe epilepsy: [(125)I]iomazenil autoradiographic study of surgically resected specimens.

PURPOSE: To evaluate the changes of the inhibitory neurotransmitter receptor system related to epileptogenesis by measuring central benzodiazepine receptors (BZDRs) in surgically resected specimens of temporal lobe epilepsy by using [(125)I]iomazenil autoradiography. METHODS: Surgically resected specimens were obtained from 66 temporal lobe epilepsy patients [51 with mesial temporal lobe epilepsy (MTLE) and 15 with non-MTLE] receiving no BZDs and seven MTLE patients receiving BZDs. BZDR densities in brain sections were measured by using [(125)I]iomazenil autoradiography. Cell densities were measured from cresyl violet-stained sections. RESULTS: Compared with non-MTLE patients, non-BZD-treated MTLE patients showed remarkable reduction of BZDR density in the pyramidal cell region of cornu ammonis (CA) 1, CA3, and CA4, and a smaller but significant reduction in CA2 and the molecular and granule cell layers of dentate gyrus (mDG). In the MTLE group, the BZDR density in the mDG correlated with that in lateral cortex. Significant correlations between BZDR density and cell density were found in all hippocampal regions. A significant difference in BZDR density/cell-density ratio was observed in CA1 region between MTLE and non-MTLE. BZD-treated patients tended to have lower BZDR densities than did non-BZD-treated patients, although the differences did not reach significance. In all MTLE cases, [(123)I]iomazenil singlephoton emission computed tomography (SPECT) showed decreased BZDR binding in MTL. CONCLUSIONS: In MTLE, BZDR densities decreased parallel to reduction in cell density in most hippocampal subfields, but BZDR density appeared to decrease in excess of neuron loss in CA1. [(125)I]iomazenil SPECT might be useful for detecting in vivo changes of BZDR density.

Adolescent↗
PubMed2002

[Measurement of the frontal and prefrontal lobe volumes in children with malnutrition by three dimensional magnetic resonance imaging scan].

To evaluate the effects of malnutrition in early life on the growth of the frontal and prefrontal lobes, we quantitatively measured the volumes of the frontal and prefrontal lobes by three dimensional (3-D) MRI in three children (1 year 2 months to 2 years 5 months) with malnutrition. The 3-D MRI data were acquired by the fast spoiled gradient recalled (SPGR) sequence using a 1.5T MR imager. The frontal and prefrontal lobe volumes were measured by the volume measurement function of the Workstation. The data obtained were compared with those of 16 normal subjects (13 children aged 5 months to 14 years, and 3 adults aged 27 to 39 years). The volumes of the frontal and prefrontal lobes in the subjects were smaller compared with age matched controls. The results suggest that malnutrition in early life affects the growth of the frontal and prefrontal lobes.

Adolescent↗
PubMed2002

[Measurements of the frontal and prefrontal lobe volumes by three dimensional magnetic resonance imaging scan--III. Analysis of sex differences with advanced age].

To determine whether there is sex difference in the growth of the frontal and prefrontal lobes, we quantitatively measured the volume of these lobes by three dimensional (3-D) MRI in healthy 12 males (5 months to 39 years) and six females (1 year 11 months to 27 years). The left and right lobes were studied separately. The 3-D MRI data were acquired by the fast spoiled gradient recalled (SPGR) sequence using a 1.5T MR imager. The frontal and prefrontal lobe volumes were measured by the volume measurement function of the Workstation. In males, the left to right ratio (L/R ratio) of the frontal and prefrontal lobes increased with age. On the contrary, in females, L/R ratio of the frontal and prefrontal lobes showed no significant change with advancing age. These results highlighted sex-specific maturational changes of the frontal and prefrontal lobes and suggested that quantitative data on the frontal and prefrontal lobe are important in interpreting brain abnormalities in children with developmental disorders.

Adolescent↗
PubMed2002

[The evaluation of lateralized frontal lobe function in the patients with autistic or attention deficit/hyperactivity disorder].

The prefrontal lobes are involved in two functionally distinct cognitive selection mechanisms: processing based on internal representation, such as planning (context-dependent reasoning) and exploratory processing of novel cognitive situations (context-independent reasoning). On the basis of this working hypothesis, a cognitive bias task (CBT; Goldberg, 1994), designed as an activation procedure representing contextual reasoning, was used to explore developmental disorders of lateralization in the frontal lobes in autistic disorder and attention deficit/hyperactivity disorder (ADHD). The subjects included 3 patients with autistic disorder, 4 with ADHD. Ten normal right-handed males served as controls. In CBT, a high score indicated consistency of choice: a context dependent selection bias, and a low score showed independent selection bias. The autistic group showed a score significant lower than those in controls (p < 0.01). The ADHD group had also a lower score. These findings implicate a deficit in the development of hemispheric specialization in the symptoms of these developmental disorders.

Attention Deficit and Disruptive Behavior Disorder↗
PubMed2002

[Ictal SPECT and paired stimulation SEP recovery curve in a patient with paroxysmal kinesigenic choreoathetosis].

Paroxysmal kinesigenic choreoathetosis (PKC) is a rare and benign disorder with its onset in childhood. PKC generally improves with age, and its pathophysiology has not been revealed. We recorded both ictal and interictal SPECT in a 14-year-old girl with PKC. Ictal SPECT showed a significant decrease in blood flow in the caudate nucleus contralateral to the limb showing an involuntary movement. We also examined paired-pulse stimuli somatosensory evoked potential (SEP) of the same patient. Recovery pattern of P25 and N33 components was normal and comparable to 5 healthy volunteers, suggesting the absence of cortical hyperexcitability. These results suggest dysfunction or immaturity of the indirect pathway of basal ganglia in PKC, as well as the hyperexcitability of the descending pathway.

Adolescent↗