Biomedical subjects

Motomi Toichi

Publications and source records attributed to Motomi Toichi.

12 recordsLinked to original sources

PubMed2007

Memory illusion in high-functioning autism and Asperger's disorder.

In this study, 13 individuals with high-functioning autism (HFA), 15 individuals with Asperger's disorder (AD), and age-, and IQ-matched controls were presented a list of sentences auditorily. Participants then evaluated semantically related but new sentences and reported whether they were old or new. The total rates of false recognition for semantically related sentences were similar among the three groups. Nevertheless, memory illusion on some aspects was reduced in HFA participants. These results suggest that HFA have difficulties in semantic association. Although individuals with AD showed no quantitative abnormalities of memory illusion, some contributing factors were atypical. These findings are discussed in terms of schema theory, enhanced perceptual processing hypothesis, and weak central coherence hypothesis.

Adolescent↗

PubMed2006

Right hemispheric dominance in gaze-triggered reflexive shift of attention in humans.

Recent findings suggest a right hemispheric dominance in gaze-triggered shifts of attention. The aim of this study was to clarify the dominant hemisphere in the gaze processing that mediates attentional shift. A target localization task, with preceding non-predicative gaze cues presented to each visual field, was undertaken by 44 healthy subjects, measuring reaction time (RT). A face identification task was also given to determine hemispheric dominance in face processing for each subject. RT differences between valid and invalid cues were larger when presented in the left rather than the right visual field. This held true regardless of individual hemispheric dominance in face processing. Together, these results indicate right hemispheric dominance in gaze-triggered reflexive shifts of attention in normal healthy subjects.

Adolescent↗

PubMed2006

Prefrontal hemodynamic activity predicts false memory--a near-infrared spectroscopy study.

Evidence from lesion studies suggests an important role of the prefrontal cortex (PFC) in the reconstructive processes of episodic memory or memory distortion. Results from functional imaging studies imply PFC involvement during the illusionary recollection of non-experienced events. Here, we used a two-channel near-infrared spectroscopy (NIRS) system and conducted real-time monitoring of PFC hemodynamics, while subjects studied word lists and subsequently recognized unstudied items (false recognition). Bilateral increases in the oxygenated hemoglobin concentration ([oxy-Hb]) were observed during false recognition compared to true recognition, and a left PFC dominant increase of [oxy-Hb] was observed during encoding phases where subjects later claimed that they recognized unstudied words. Traces of semantic processing, reflected primarily in the left PFC activity, could eventually predict whether subjects falsely recognize non-experienced events.

Adult↗

PubMed2006

Analysis of delusional statements from 15 Japanese cases of 'Folie à Deux'.

BACKGROUND: Although many studies have reported folie à deux (FAD) cases, there has not yet been a study systematically examining patients' delusional statements. In the present study, we analyzed the changes in patients' delusional statements across the clinical course from the perspective of discourse analysis. SAMPLING AND METHODS: First, we presented a case of FAD in a married Japanese couple. Second, we examined 14 other cases of FAD from Japanese literature and analyzed changes in subjective pronoun (SP) use in each patient's delusional statements. RESULTS: Observed delusions of FAD were classified into the following two categories, based on the SP: (1) We-type: 'We are persecuted', and (2) Non We-type: mostly 'I am persecuted'. Interestingly, We-type was generally observed in paranoid schizophrenia, paranoid disorder, and shared psychotic disorder. In contrast, Non We-type was predominantly observed in nonparanoid schizophrenia. CONCLUSIONS: The present classification might reflect two different mechanisms of delusional association in FAD. Possible mechanisms of delusional transmission in schizophrenia were discussed. The present study has a clear limitation in the small number of cases from only Japanese literature. Furthermore, the relatively high occurrence of FAD between married couples in the Japanese literature may have introduced some bias into the present results. Further studies on FAD are needed, however, the present method of examining the SP seems to be useful in order to investigate the psychological mechanism of delusion formation between plural subjects.

Adult↗

PubMed2005

Prefrontal activation during verbal fluency tests in schizophrenia--a near-infrared spectroscopy (NIRS) study.

Letter- or semantically-cued verbal fluency tests (VFT) induce different, but overlapping activities in the prefrontal cortex (PFC) in healthy subjects. Functional differences between letter and semantic VFT may be important in elucidating the nature of language-related problems in schizophrenia since more profound impairment in semantically-cued retrieval may be suggestive of semantic system dysfunction specific to this disorder. However, the functional differences between the letter vs. semantic VFT on prefrontal metabolism in the subjects with schizophrenia have not been described. In the present study, we used near-infrared spectroscopy (NIRS) to assess hemoglobin concentration changes in the bilateral PFCs in subjects and controls. Sixteen subjects with schizophrenia and 19 healthy controls performed letter and semantic VFTs. Prefrontal hemodynamic changes were simultaneously monitored by NIRS. While healthy subjects performed both tasks equivalently, the subjects with schizophrenia showed more compromised performance in the semantic VFTs compared to the letter VFTs. NIRS measurement revealed that the pattern of PFC activation was greater during the letter VFT when compared to the semantic VFT in the healthy subjects, suggesting more prominent PFC involvement in letter-cued retrieval. In contrast, the subjects with schizophrenia showed the opposite pattern of activation, implying that the semantic mode of lexical access might impose greater cognitive demands on the PFC. The present study is the first to detect abnormal patterns of PFC activation in adults with schizophrenia in response to the distinct cognitive demands associated with letter and semantic VFT.

Adult↗

PubMed2004

Hemodynamic differences in the activation of the prefrontal cortex: attention vs. higher cognitive processing.

Both simple attention tasks (e.g. letter cancellation) and most tasks of higher cognitive processing (e.g. word generation) are known to activate the dorsolateral prefrontal cortex (PFC). While attention and higher cognitive processing differ phenomenologically, with attention tasks requiring great subjective effort despite their simplicity, possible physiological differences in the activation of the PFC between the two types of cognitive processing have remained uninvestigated. Hemodynamic changes in the PFC during activation due to tasks of attention and those of higher cognitive processing were examined using near-infrared spectroscopy in 10 Japanese and 10 American healthy adults. In tasks of higher cognitive processing, which included both verbal and non-verbal tasks, the concentration of oxygenated hemoglobin ([HbO2]) increased, and that of deoxygenated hemoglobin ([HbR]) decreased, with an increase in the tissue hemoglobin saturation (THS). In tasks of attention, which consisted of the letter cancellation and continuous performance test, both [HbO2] and [HbR] increased, with no significant changes in the THS observed. The distinctive patterns of hemodynamic changes were not affected by the factors of task difficulty or language. The change in [HbR] may be a physiological marker of the prefrontal lobe activation that discriminates between attention and higher cognitive processing. The increase in [HbR] suggests increased oxygen consumption of the PFC during tasks of attention, which might be related to the disproportionately great subjective effort associated with sustained attention. The physiological alteration in hemodynamic patterns according to changes in cognition needs to be examined in subjects with prefrontal lobe dysfunction, such as schizophrenia and mood disorder.

Adolescent↗

PubMed2003

Long-term memory in high-functioning autism: controversy on episodic memory in autism reconsidered.

Two studies were conducted to examine the nature of verbal long-term memory (LTM) in people with autism. In Study 1, undergraduate students showed better LTM and more verbal associations for concrete than abstract nouns. Probability of recall of the nouns strongly correlated with the number of associations with those nouns. In Study 2, unlike controls, autistic subjects did not show superior recall of concrete over abstract nouns despite overall comparable performance. A highly significant correlation between probability of recall and associative value was found only in the controls. Furthermore, there was an unusual correlation between LTM performance and a nonverbal measure in the autistic group. The results were discussed in terms of the relation between episodic memory and semantic memory.

Adolescent↗

PubMed2003

Paradoxical autonomic response to mental tasks in autism.

Autonomic responses to mental tasks requiring sustained attention were examined in individuals with autism and age- and ability-matched controls. Cardiac autonomic function (CAF) was evaluated based on heart rate variability. While the control group showed a significant decrease in the parasympathetic function during mental tasks, the autistic group showed no significant changes in CAF. When examined individually, parasympathetic function was suppressed in all subjects in the control group. On the other hand, parasympathetic function was activated in half of the autistic subjects. The paradoxical autonomic response suggests that some autistic subjects were more stressed under 'resting' conditions than while performing mechanical or repetitive mental tasks. The results seem to support autonomic hyperarousal in some people with autism.

Adolescent↗

PubMed2003

Influences of an anticholinergic antiparkinsonian drug, parkinsonism, and psychotic symptoms on cardiac autonomic function in schizophrenia.

The arguments against the use of anticholinergic antiparkinsonian drugs for neuroleptic-induced parkinsonism have been based, in part, on their autonomic side effects. Except for anecdotal case reports, there is little evidence that antiparkinsonian drugs are the main factor causing autonomic dysfunction in schizophrenic patients with parkinsonism. Therefore, in the current study, the separate influences of the anticholinergic antiparkinsonian drug (biperiden), parkinsonism, and psychotic symptoms on cardiac autonomic function were investigated in 48 patients with schizophrenia. Biperiden was discontinued in 33 patients with or without parkinsonism and commenced in 15 patients with parkinsonism. Their parkinsonism and psychotic symptoms were assessed using rating scales, and their cardiac autonomic functions were assessed using the mean R-R interval and 3 methods of analyzing heart rate variability both before and after the change in medication. Consequently, the cardiac autonomic function was not affected by biperiden or the change in parkinsonism. Cardiac vagal function decreased when psychotic symptoms were more pronounced, but cardiac sympathetic function did not show a significant change. Therefore, it appeared that psychotic symptoms played the predominant role in modifying the cardiac autonomic function, implying the existence of autonomic changes associated with cognitive processing and a possible relation between psychotic symptoms and autonomic symptoms in schizophrenia.

Adult↗

PubMed2002

Long-term memory and levels-of-processing in autism.

Prior studies reported that long-term memory (LTM) was basically unimpaired in individuals with autism. However, people with autism have been found to perform worse than ability-matched controls when verbal materials to be remembered are semantically related. In normal subjects, semantic processing of verbal materials facilitates LTM better than 'shallow' (phonological or perceptual) processing, which is known as the levels-of-processing effect. In this study, the relationship between LTM and semantic processing was investigated using a levels-of-processing task. In Study 1, a levels-of-processing task was conducted on healthy volunteers, which confirmed the levels-of-processing effect with our task. In study 2, the same task was conducted on autistic subjects with mild or no mental retardation and ability-matched controls. The levels-of-processing effect was confirmed in the control group. Although overall performance in the two groups was comparable, the levels-of-processing effect was not found in the autistic group. LTM resulting from perceptual processing was better in the autistic group than in the control group, indicating superior "rote memory" in individuals with autism. Furthermore, the pattern of correlations between LTM performance and cognitive measures differed greatly between the two groups. The lack of the levels-of-processing effect, which has not been reported in other psychiatric or neuropathological conditions, suggests an abnormal relationship between semantic memory and episodic memory in individuals with autism.

Adolescent↗

PubMed2002

A lack of self-consciousness in autism.

OBJECTIVE: This study investigated self-consciousness in autism. METHOD: An incidental memory task was conducted on 18 adults with high-functioning autism and 18 normal comparison subjects. Three kinds of orienting questions (phonological, semantic, and self-referent, i.e., "Does the word describe you?") were asked about target words (adjectives for personality traits) in order to induce different types of processing. This was followed by an unexpected recognition test. RESULTS: While semantic processing resulted in better memory than phonological processing in both groups, self-referent processing yielded better memory performance than semantic processing in the comparison group but not in the autistic group. CONCLUSIONS: The results suggest deficits in self-consciousness in individuals with autism.

Adult↗

PubMed2002

[Three criminal cases with Asperger's disorder: how their handicap was reflected in their antisocial behaviors].

Three patients with Asperger's disorder who were sent to Juvenile Court for sexual offenses are presented, and the relationship between this disorder and their crimes is discussed. All three adolescents showed unusual behaviors related to their crimes. The analysis of these cases suggested: 1) the idiosyncrasies seen in the crimes were closely related to their social deficits and obsessive traits, which are the two major problems in pervasive developmental disorder (PDD), 2) their offensive behaviors were not the direct results of their deficits due to PDD, and 3) their criminal behaviors should be understood in the unique context that is specific to PDD, not from conventional psychological viewpoints. Finally, current problems associated with PDD in Japan are discussed.

Adolescent↗