Biomedical subjects

Toshikazu Hasegawa

Publications and source records attributed to Toshikazu Hasegawa.

16 recordsLinked to original sources

PubMed2006

'Autistic' traits in non-autistic Japanese populations: relationships with personality traits and cognitive ability.

We explored the relationships between 'autistic' traits as measured by the AQ (Autism-Spectrum Quotient; Baron-Cohen et al., J. Autism Develop. Disord. (2001b) 31 5) and various personality traits or cognitive ability, which usually coincide with autistic symptoms, for general populations. Results showed the AQ was associated with tendencies toward an obsessional personality as defined by the TCI (Temperament and Character Inventory), higher depression and anxiety, and higher frequency of experience of being bullied. These results parallel the patterns in autism and corroborate the validity of the AQ for general populations. Contrary to our prediction, however, there was no relationship between the AQ and cognitive ability, such as theory of mind, executive functioning, and central coherence, suggesting the AQ does not reflect autism-specific cognitive patterns in general populations.

Adolescent↗

PubMed2006

Peacemaking and consolation in Japanese preschoolers witnessing peer aggression.

This article reports developmental changes relating to reconciliation and bystanders' affiliation with victims of aggression (i.e., consolation) among 3- to 5-year-old Japanese preschool children. Use of the post-conflict-matched control (PC-MC) method revealed that the frequency with which reconciliation and consolation were offered to a victim increased steeply in 5-year-olds, compared with 3- and 4-year-olds. The complexity of contextual factors affecting the occurrence of reconciliation and the form of consolation increased with age. Consolation occurred more often before reconciliation than after among all but the 3-year-olds and occurred more often when no reconciliation occurred than when it did occur among all classes. These findings support the view that consolation functions as a substitute for reconciliation, lessening the tension experienced by the victim of aggression.

Aggression↗

PubMed2006

Advantage of dichromats over trichromats in discrimination of color-camouflaged stimuli in humans.

This study investigated whether 12 participants with color-vision deficiency had superior visual discrimination of color-camouflaged stimuli shown on a computer screen compared with 12 participants with normal trichromatic vision. Participants were asked to distinguish a circular pattern from other patterns in which textural elements differed from the background in orientation and thickness. In one condition, stimuli were single-colored, green or red; in the other condition, stimuli were color camouflaged with a green and red mosaic overlaid onto the pattern. Color-vision deficient participants selected the correct stimuli in the color-camouflaged condition as quickly as they did in the single-colored condition. However, normal color-vision participants took longer to select the correct choice in the color-camouflaged condition than in the single-colored condition. These results suggest that participants with color-vision deficiency may have a superior visual ability to discriminate the color-camouflaged stimuli.

Adult↗

PubMed2006

Do the upright eyes have it?

Eye contact is crucial for social communication. A perceived direct gaze facilitates detection, whereas face inversion diminishes this facilitative effect (Senju, Hasegawa, & Tojo, 2005). In the present study, we adopted a visual search paradigm to investigate why a direct gaze facilitates detection in an upright face, but not in an upside-down face. Upright eyes were found to facilitate detection even when other parts of the face were inverted or absent, whereas inverted eyes had no effect on search performance. A critical role for the morphological information of upright eyes, which can be distorted by "eye inversion," in direct gaze processing is suggested.

Adult↗

PubMed2006

Testosterone levels and discounting delayed monetary gains and losses in male humans.

OBJECTIVES: Although impulsivity has been associated with androgens (e.g., testosterone), little is known regarding the relationship between testosterone levels and impulsivity in intertemporal choice (delay discounting). This study was aimed to examine the relationship between delay discounting of gains and losses and testosterone levels, which is of interest in neuroendocrinology and neuroeconomics. METHODS: We assessed degrees to which delayed monetary gains and losses were discounted (hyperbolic discounting rate) in healty male students (age: 22.4+/-2.67). Participants' salivary testosterone levels were also assessed by utilizing liquid chromatography/mass spectroscopy (LC/MS) method. RESULTS: Non-linear curve fitting analysis showed an inverted-U relationship between delay discounting of gains and salivary testosterone levels; while no relationship between salivary testosterone levels and delay discounting of losses was observed. CONCLUSIONS: The results indicate that (i) testosterone may enhance delay discounting rate of gains in non-impulsive subjects, (ii) testosterone may have an opposite (reducing) effect on delay discounting rate of gains in impulsive subjects, and (iii) testosterone is unrelated to subject's sensitivity to future bad outcomes. Implications for evaluating the effects of testosterone treatment and anti-androgenic therapy on impulsive behavior often observed in psychiatrics (e.g., pathological gambling, credit card debt, substance misuse, and needle-sharing) are discussed.

Adult↗

PubMed2005

Deviant gaze processing in children with autism: an ERP study.

This study investigated event-related potentials (ERP) during an oddball task in which detection of specific eye direction was required of children with and without autism. The detection of a change in eye direction elicited occipito-temporal negativity, which had two major differences between children with and without autism. First, while this occipito-temporal negativity predominated in the right hemisphere of typically developed children, it was distributed equally bilaterally in children with autism. Second, the amplitude of this negativity was more pronounced in typically developed children in response to the detection of direct gaze as compared to averted gaze, but was not sensitive to direct/averted gaze direction in children with autism, which converges with behavioral reports. The results concur with previous literature, suggesting the importance of the right hemisphere, especially the superior temporal sulcus, in gaze processing. Results indicate that deviant neural substrates might be involved in gaze processing in individuals with autism.

Adolescent↗

PubMed2005

Advantage of dichromats over trichromats in discrimination of color-camouflaged stimuli in nonhuman primates.

Due to a middle- to long-wavelength-sensitive (M/LWS) cone opsin polymorphism, there is considerable phenotypic variation in the color vision of New World monkeys. Many females have trichromatic vision, whereas some females and all males have dichromatic vision. The selective pressures that maintain this polymorphism are unclear. In the present study we compared the performance of dichromats and trichromats in a discrimination task. We examined tri- and dichromatic individuals of two species: brown capuchin monkeys (Cebus apella) and long-tailed macaques (Macaca fascicularis). We also examined one protanomalous chimpanzee (Pan troglodytes). The subjects' task was to discriminate a circular pattern from other patterns in which textural elements differed in orientation and thickness from the background. After they were trained with stimuli of a single color, the subjects were presented with color-camouflaged stimuli with a green/red mosaic overlaid onto the pattern. The dichromatic monkeys and the protanomalous chimpanzee selected the correct stimulus under camouflaged conditions at rates significantly above chance levels, while the trichromats did not. These findings demonstrate that dichromatic nonhuman primates possess a superior visual ability to discriminate color-camouflaged stimuli, and that such an ability may confer selective advantages with respect to the detection of cryptic foods and/or predators.

Animals↗

PubMed2005

Demonstration of a genotype-phenotype correlation in the polymorphic color vision of a non-callitrichine New World monkey, capuchin (Cebus apella).

Color-vision polymorphism in New World monkeys occurs because of an allelic polymorphism of the single-copy red-green middle-to-long-wavelength-sensitive (M/LWS) opsin gene on the X chromosome. Because color-vision types can readily be estimated from allelic types of the M/LWS opsin gene, this polymorphic system offers researchers an excellent opportunity to study the association between vision and behavior. As a prerequisite for such studies, genetically determined color-vision types must be concordant with phenotypes determined directly by behavioral criteria (e.g., by a color discrimination test). However, such correlations between genotypes and phenotypes have been studied only for callitrichine species. Using genetic, electrophysiological, and behavioral approaches, we evaluated the color vision of brown capuchin monkeys (Cebus apella), a representative non-callitrichine model animal for physiology and behavior. Two allelic M/LWS opsins-P545 and P530-were identified in the studied captive population. Females had one or both of the alleles, and males had either one. The retinal sensitivity in P530 dichromats was short-wave shifted relative to that in P545 dichromats, whereas that in P530/P545 trichromats was between the two groups. In a discrimination task using Ishihara pseudo-isochromatic plates, P530/P545 trichromats were successful in discriminating stimuli that P530 and P545 dichromats were unable to discriminate. In a food-search task, P530/P545 trichromats were able to locate red targets among green distracters as quickly as among white distracters, whereas both types of dichromats took longer. These results demonstrate the mutual consistency between genotypes and phenotypes of color vision, and provide a solid genetic basis on which the ecology and evolution of color vision can be investigated.

Animals↗

PubMed2005

Auditory-visual intermodal matching of small numerosities in 6-month-old infants.

Recent studies have reported that preverbal infants are able to discriminate between numerosities of sets presented within a particular modality. There is still debate, however, over whether they are able to perform intermodal numerosity matching, i.e. to relate numerosities of sets presented with different sensory modalities. The present study investigated auditory-visual intermodal matching of small numerosities in infancy by using a violation-of-expectation paradigm. After being familiarized with events of a few objects impacting a surface successively, 6-month-old infants were alternatively presented with two and three tones while the movement of each object remained hidden behind an opaque screen. The screen was then removed to reveal either two or three objects. Results showed that the infants looked significantly longer at the numerically nonequivalent events (the three-tone/two-object and the two-tone/three-object events) than at the numerically equivalent events (the two-tone/two-object and the three-tone/three-object events) irrespective of the rate or duration of auditory tones presented. These findings suggest that infants are capable of performing intermodal matching of small numerosities and that they might possess abstract representations of numerosity beyond sensory modalities.

Auditory Perception↗

PubMed2005

[Analysis of salivary testosterone by liquid chromatography-tandem mass spectrometry: correlation with serum bioavailable testosterone and aging].

PURPOSE: To demonstrate that the salivary testosterone (T) concentration measured by liquid chromatography tandem mass spectrometry (LC-MS/MS) is a sensitive biomarker of serum bioavailable testosterone (bio T) concentration and it's decrease with age. METHOD: Saliva and blood samples were collected from healthy 53 Japanese men (16-66yr) three times a day (9: 00-10: 00, 13: 00-14: 00, 17: 00-18: 00). Salivary T and serum total T levels were compared with serum bio T levels fractionated with concanavaline A. All samples were measured by LC-MS/MS. The stability of salivary T concentrations stored at -70 degrees C for 2 months was also examined. RESULTS: Salivary T levels correlated with bio T(r=0.88, n=158) better than total T did (r=0.71, n=159). The decrease of T concentration with age was observed in saliva of each sampling time. In total T, the decrease with age was weaker and was insignificant in the late afternoon. Salivary T was stable for 2 months at -70 degrees C and a freeze/thaw cycle (difference: average 3.7%, SD=8.4%, n=84). CONCLUSIONS: Salivary T measured by LC-MS/MS is a reliable biomarker of T availability and its decrease with aging.

Adolescent↗

PubMed2004

Baby arithmetic: one object plus one tone.

Recent studies using a violation-of-expectation task suggest that preverbal infants are capable of recognizing basic arithmetical operations involving visual objects. There is still debate, however, over whether their performance is based on any expectation of the arithmetical operations, or on a general perceptual tendency to prefer visually familiar and complex displays. Here we provide new evidence that 5-month-old infants recognize basic arithmetic operations across sensory modalities. Using a violation-of-expectation task that eliminated the possibility of the familiarity and complexity preference, 5-month-old infants were presented alternatively with two types of arithmetical events: the expected, correct outcomes of operations (1 object+1 tone=2 objects and 1 object+2 tones=3 objects) and the unexpected, incorrect ones (1 object+2 tones=2 objects and 1 object+1 tone=3 objects). Results showed that subjects looked significantly longer at the unexpected events than at the expected events, suggesting that infants are able to recognize basic arithmetic operations across sensory modalities.

Choice Behavior↗

PubMed2004

Reflexive orienting in response to eye gaze and an arrow in children with and without autism.

BACKGROUND: This study investigated whether another person's social attention, specifically the direction of their eye gaze, and a non-social directional cue, an arrow, triggered reflexive orienting in children with and without autism in an experimental situation. METHODS: Children with autism and typically developed children participated in one of two experiments. Both experiments involved the localization of a target that appeared to the left or right of the fixation point. Before the target appeared, the participant's attention was cued to the left or right by either an arrow or the direction of eye gaze on a computerized face. RESULTS: Children with autism were slower to respond, which suggests a slight difference in the general cognitive ability of the groups. In Experiment 1, although the participants were instructed to disregard the cue and the target was correctly cued in only 50% of the trials, both groups of children responded significantly faster to cued targets than to uncued targets, regardless of the cue. In Experiment 2, children were instructed to attend to the direction opposite that of the cues and the target was correctly cued in only 20% of the trials. Typically developed children located targets cued by eye gaze more quickly, while the arrow cue did not trigger such reflexive orienting in these children. However, both social and non-social cues shifted attention to the cued location in children with autism. CONCLUSION: These results indicate that eye gaze attracted attention more effectively than the arrow in typically developed children, while children with autism shifted their attention equally in response to eye gaze and arrow direction, failing to show preferential sensitivity to the social cue. Difficulty in shifting controlled attention to the instructed side was also found in children with autism.

Attention↗

PubMed2003

Behavioral evidence of color vision deficiency in a protanomalia chimpanzee (Pan troglodytes).

Although color vision deficiency is very rare among Old World monkeys and apes, one male chimpanzee (Lucky) was identified as protanomalous by genetic and physiological analyses. This study assessed behavioral phenotypes of Lucky and four chimpanzees with normal color vision by discrimination task using the modified Ishihara pseudo-isochromatic plates. Lucky could not discriminate the stimuli that the other chimpanzees could. This is the first behavioral evidence of color vision deficiency in chimpanzees.

Animals↗

PubMed2003

Demography, female life history, and reproductive profiles among the chimpanzees of Mahale.

Demography provides critical data to increase our understanding of the evolution, ecology, and conservation of primate populations. The chimpanzees of the Mahale Mountains National Park, Tanzania, have been studied for more than 34 yr on the basis of individual identification and standardized attendance records. From this long-term study, we derived the following demographic data: The major cause of death was disease (48%), followed by senescence (24%) and within-species aggression (16%). Fifty percent of Mahale chimpanzees died before weaning. The median ages of female life history variables were: first maximal swelling, 10.0 yr (n = 5); emigration, 11.0 yr (n = 11); and first birth, 13.1 yr (n = 5). The median period of adolescent infertility was 2.8 yr (n = 4) when calculated from the age at immigration to that at first birth. Female fecundity was highest between 20 and 35 yr of age, with an annual birth rate of 0.2. Twenty-six females that were observed from a young age (10-13 yr) to death at various ages (15-40 yr) gave birth to an average of 3.9 and weaned an average of 1.4 offspring. Twenty-five females that were observed from middle age (18-33 yr) to death in older age (31-48) gave birth to an average of 2.7 and weaned an average of 2.0 offspring. The post-reproductive lifespan for female chimpanzees was defined as the number of years that passed from the year when the last offspring was born to the year when the female died, minus 5. Twenty-five percent of old females had a post-reproductive lifespan. The interbirth interval after the birth of a son (x = 72 mo) tended to be longer than that after the birth of a daughter (x = 66 mo). The extent of female transfer, which is a rule in chimpanzees, is influenced by the size and composition of the unit group and size of the overall local community.

Age Factors↗

PubMed2003

Eye contact does not facilitate detection in children with autism.

Eye contact is crucial in achieving social communication. Deviant patterns of eye contact behavior are found in individuals with autism, who suffer from severe social and communicative deficits. This study used a visual oddball paradigm to investigate whether children with high functioning autism have difficulty in detecting mutual gaze under experimental conditions. The results revealed that children with autism were no better at detecting direct gaze than at detecting averted gaze, which is unlike normal children. This suggests that whereas typically developing children have the ability to detect direct gaze, children with autism do not. This might result in altered eye-contact behavior, which hampers subsequent development of social and communicative skills.

Adolescent↗

PubMed2002

[Reading mind from pictures of eyes: theory of mind, language ability, general intellectual ability, and autism].

Some researchers have claimed that theory of mind or 'mind reading' ability, necessary for inferring the mental states of others, depends on language ability. However, previous tests of theory of mind were verbally demanding, and high correlations found might have been an artifact. This paper reports the performance of 22 children with autism, with varying degrees of dysfunction, on a test devised by Baron-Cohen, Jolliffe, Mortimore, and Robertson (1997), based on a relatively nonverbal theory of mind. The test involved inference of mental states from photographs of human eyes. Results indicated that mind reading ability was independent of language ability, general intelligence, or mental age. Test scores were, however, strongly related to the severity of autistic disorder. These results suggest both the independence of mind-reading ability from language ability and general intelligence, and a strong relationship between theory of mind deficit and the autistic disorder.

Autistic Disorder↗