Biomedical subjects

Kakurou Aoyagi

Publications and source records attributed to Kakurou Aoyagi.

6 recordsLinked to original sources

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↗

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

[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↗