Biomedical subjects

Kenneth S L Yuen

Publications and source records attributed to Kenneth S L Yuen.

4 recordsLinked to original sources

PubMed2006

Age-related differences in response regulation as revealed by functional MRI.

This fMRI study studied age-related differences in neural activities during response regulation. Twenty-one male participants from two age groups, a younger group and an older group (mean ages: 29.9 and 65.2 years, respectively), were scanned while performing a task with response compatibility manipulation. They were presented with a sequence of arrowheads that pointed either upward or downward. In the "Response Compatible" condition, they were required to press an up or a down button consistent with the direction of the arrowhead. In the "Response Incompatible" condition, they were required to press the button opposite to the arrowhead direction so that an upward arrow should elicit a down response, and vice versa. Findings showed age-related differences in response regulation in several brain regions, including the right frontal, the right cingulate, and the left inferior parietal cortexes. The findings suggested a higher level of neural activity in the right prefrontal and left inferior parietal regions during response regulation for the older adults than for the younger adults.

Adult↗

PubMed2005

Neural activity associated with cognitive regulation in heroin users: A fMRI study.

Previous research has found heroin addicts to be impulsive. This study employed functional magnetic resonance imaging technology to investigate the differences between heroin addicts and normal controls in neural activity associated with cognitive regulation of behavior. Twenty-one Chinese men participated in this study, 11 of whom were newly admitted heroin-addicted patients and 10 of whom were healthy volunteers. In the experimental task, the subjects were required to first identify the correct directions of arrowheads and then give the opposite answers. Behaviorally, the heroin-dependent patients took a much shorter time to complete the more demanding second part of the task but committed more errors than the normal controls. This pattern of behavior, characteristic of people who are disinhibited and who tend to be impulsive, was consistent with previous reports of impulsivity observed in people who have abused heroin. The neural activity of the patients that was associated with performing the experimental task of cognitive regulation was different to that of the normal controls in terms of the pattern of prefrontal activation, the attenuation of activity in the anterior cingulate, and the additional recruitment of the right inferior parietal region. This study is the first that seeks to understand the neural activity associated with impulsive behavior in people who abuse heroin. The pattern of imaging data obtained resembled the pattern of data observed in immature brains attempting to exercise cognitive control of behavior. Further theoretical and clinical implications of the findings are discussed.

Adult↗

PubMed2003

Could mood state affect risk-taking decisions?

BACKGROUND: Depressed patients are advised by clinicians to avoid making critical life decisions because their decision-making process might be influenced by their pathological mood states. In order to provide empirical support for this practice, we examined the influence of different mood states on risk-taking tendencies that govern one's decision during critical life decisions. METHOD: By means of viewing a happy, neutral or sad movie clip, participants were induced to a respective mood. Risk-taking tendencies were then measured with decision tasks modified from the Choice Dilemmas Questionnaire (Kogan N., Wallach, M.A., 1964. Risk Taking: A Study in Cognition and Personality, Holt, New York). RESULTS: The findings (SS=54) indicated varying risk-taking tendencies in different mood states: individuals in induced depress mood were significantly more conservative in taking risk than those who were in neutral mood, whilst people in induced elated mood did not differ significantly from those in neutral mood. Correlation between mood-ratings with risk-taking tendency was positive (r=0.319, P<0.05). CONCLUSIONS: People in induced depress mood would have a lower willingness to take risk than people in neutral and in positive mood. The manner in which decisions were influenced by negative mood was discussed. The asymmetry of influence of different mood states on risk-taking decisions was also discussed.

Adolescent↗

PubMed2002

Gender differences in neural correlates of recognition of happy and sad faces in humans assessed by functional magnetic resonance imaging.

To examine the effect of gender on the volume and pattern of brain activation during the viewing of alternating sets of faces depicting happy or sad expressions, 24 volunteers, 12 men and 12 women, participated in this functional magnetic resonance imaging study. The experimental stimuli were 12 photographs of Japanese adults selected from Matsumoto and Ekman's Pictures of Facial Affect. Four of these pictures depicted happy facial emotions, four sad, and four neutral. Half of the photographs were of men and the other half were of women. Consistent with previous findings, distinct sets of neural correlates for processing happy and sad facial emotions were noted. Furthermore, it was observed that male and female subjects used a rather different set of neural correlates when processing faces showing either happy or sad expressions. This was more noticeable when they were processing faces portraying sad emotions than happy emotions. Our findings provide some preliminary support for the speculation that the two genders may be associated with different areas of brain activation during emotion recognition of happy or sad facial expressions. This suggests that the generalizability of findings in regard to neural correlates of facial emotion recognition should consider the gender of the subjects.

Adult↗