Biomedical subjects

Tatia M C Lee

Publications and source records attributed to Tatia M C Lee.

At least 19 recordsLinked to original sources

PubMed2006

The differential effects of thalamus and basal ganglia on facial emotion recognition.

This study examined if subcortical stroke was associated with impaired facial emotion recognition. Furthermore, the lateralization of the impairment and the differential profiles of facial emotion recognition deficits with localized thalamic or basal ganglia damage were also studied. Thirty-eight patients with subcortical strokes and 19 matched normal controls volunteered to participate. The participants were individually presented with morphed photographs of facial emotion expressions over multiple trials. They were requested to classify each of these morphed photographs according to Ekman's six basic emotion categories. The findings indicated that the clinical participants had impaired facial emotion recognition, though no clear lateralization pattern of impairment was observed. The patients with localized thalamic damage performed significantly worse in recognizing sadness than the controls. Longitudinal studies on patients with subcortical brain damage should be conducted to examine how cognitive reorganization post-stroke would affect emotion recognition.

Affect↗

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↗

PubMed2006

Cognitive processing in Chinese literate and illiterate subjects: an fMRI study.

Functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) were used to map brain activation during language tasks. While previous studies have compared performance between alphabetic literate and illiterate subjects, there have been no such data in Chinese-speaking individuals. In this study, we used fMRI to examine the effects of education on neural activation associated with silent word recognition and silent picture-naming tasks in 24 healthy right-handed Chinese subjects (12 illiterates and 12 literates). There were 30 single Chinese characters in the silent word recognition task and 30 meaningful road-signs in the silent picture-naming task. When we compared literate and illiterate subjects, we observed education-related differences in activation patterns in the left inferior/middle frontal gyrus and both sides of the superior temporal gyrus for the silent word recognition task and in the bilateral inferior/middle frontal gyrus and left limbic cingulated gyrus for the silent picture-naming task. These results indicate that the patterns of neural activation associated with language tasks are strongly influenced by education. Education appears to have enhanced cognitive processing efficiency in language tasks.

Aged↗

PubMed2006

Detection of feigned memory impairments using a Chinese word task.

In this study the detection of feigned memory impairments was investigated using a forced-choice task with Chinese words as stimuli. Task difficulty on accuracy and response time and the faking strategies employed were examined for 85 participants, 42 men and 43 women, who were administered the experimental task. Following a simulation design, all participants performed under control and faking conditions. Their accuracy of performance and response times were measured. Analysis indicated significant differences on both outcome measures for the two conditions. Further, a significant difference in accuracy, but not in response time, among levels of task difficulty was observed. For classification accuracy, using the cut-off score criterion seemed more effective than using the below-chance criterion or response time. Implications for relying on chance criterion to identify deception are discussed.

Adult↗

PubMed2005

Light delays synaptic deafferentation and potentiates the survival of axotomized retinal ganglion cells.

Knowledge of the cellular mechanism underlying the therapeutic effect of stimulation and the optimal doses of such stimulation to maximize neuronal recovery is essential to guide clinical practice in neural rehabilitation. Using hamsters, we transected the optic nerve to demonstrate how light stimulation affects neuronal recovery. The c-fos protein was used as a neuronal connectivity marker. Here we show that: (a) in addition to cell death, a population of cells undergoes synaptic deafferentation and (b) light stimulation delays cell death and deafferentation. Among the three rearing conditions studied (6:18LD, 12:12LD, and 18:6LD), the 12:12LD condition appears to be the one achieving the optimal therapeutic effect. This study provides a solid base in the understanding of the neuroanatomical changes after traumatic brain injury and the need to establish an optimal level and timing for the environmental stimulation.

Animals↗

PubMed2005

Selective impairment of sadness and disgust recognition in abstinent ecstasy users.

Previous data have suggested that ecstasy use may affect cognitive functions. The relationship between ecstasy use and emotion recognition remains largely unknown. This study reports the findings on the neuropsychological effects of ecstasy use on recognition of basic human emotions among 100 abstinent ecstasy users, along with 100 demographically matched nonusers. Recognition of both facial and prosodic emotions was studied. In addition, neuropsychological predictors of emotion recognition for abstinent ecstasy users were examined. The results showed that abstinent ecstasy users were impaired, relative to nonusers, on overall emotion recognition. In particular, recognition of sadness and disgust was significantly affected. The emotion-recognition deficits observed among the abstinent ecstasy users may reflect a complex derangement of monoamines and/or general degenerative change observed in the addicted populations. The length of time in months since ecstasy was last consumed, cumulative ecstasy dosage, and years of education negatively predicted various domains of emotion recognition. The observation that nonverbal and verbal fluency functions were significant predictors of emotion identification, as well as of recognition of sadness and disgust, suggests that the frontal executive system might be affected by ecstasy use.

Case-Control Studies↗

PubMed2005

Selective impairment of attentional networks of orienting and executive control in schizophrenia.

BACKGROUND: Difficulty attending is a common deficit of schizophrenic patients. However, it is not known whether this is a global attentional deficit or relates to a specific attentional network. METHOD: This study used the attention network test to compare schizophrenic patients (N=77) with controls (N=53) on the efficiency of three anatomically defined attentional networks: alerting, orienting, and executive control. RESULTS: Schizophrenic patients showed a large and highly significant deficit in the executive network and a smaller but significant deficit in the orienting network as well as in overall RT and accuracy. There was no deficit in the alerting network. CONCLUSION: These results suggest some specificity in the attentional networks influenced by the disorder. The executive attention network has been shown in normal subjects to activate the anterior cingulate and lateral prefrontal areas. Previous data using neuroimaging with schizophrenic patients has shown abnormal control by the anterior cingulate. Our findings support this previous research by indicating that the major attentional deficit in schizophrenic patients is in a network that includes the anterior cingulate.

Adult↗

PubMed2005

Prose memory deficits associated with schizophrenia.

Memory of contextual information is essential to one's quality of living. This study investigated if the different components of prose memory, across three recall conditions: first learning trial immediate recall, fifth learning trial immediate recall, and 30-min delayed recall, are differentially impaired in people with schizophrenia, relative to healthy controls. A total of 39 patients with schizophrenia and 39 matched healthy controls were recruited. Their prose memory, in terms of recall accuracy, temporal sequence, recognition accuracy and false positives, commission of distortions, and rates of learning, forgetting, and retention were tested and compared. After controlling for the level of intelligence and depression, the patients with schizophrenia were found to commit more distortions. Furthermore, they performed poorer on recall accuracy and temporal sequence accuracy only during the first initial immediate recall. On the other hand, the rates of forgetting/retention and recognition accuracy were comparable between the two groups. These findings suggest that people with schizophrenia could be benefited by repeated exposure to the materials to be remembered. These results may have important implications for rehabilitation of verbal declarative memory deficits in schizophrenia.

Adult↗

PubMed2005

Neural correlates of feigned memory impairment.

While initial neuroimaging studies have provisionally identified activation in the prefrontal (including the anterior cingulate) and parietal regions during lying, the robustness of this neuroanatomical pattern of activation across forms of stimuli, genders, and mother tongues remains to be demonstrated. In this paper we report the results of three studies designed to test the reproducibility of the brain activation previously observed during feigned memory impairment. A total of twenty-nine right-handed participants, divided into three cohorts, participated in three different studies of feigned memory impairment. Findings indicate that bilateral activation of prefrontal and parietal regions was invariant across stimulus types, genders, and mother tongues, suggesting the general importance of these regions during malingering and possibly deception in general. In conjunction with earlier imaging findings, these three studies suggest that the prefrontal parietal network provides a robust neuroanatomical foundation upon which future dissimulation research may build.

Adult↗

PubMed2005

Prose memory in patients with idiopathic Parkinson's disease.

BACKGROUND: The findings of previous studies have suggested that verbal memory impairments were observed in people suffering from Parkinson's disease (PD). Very few studies have examined the comprehensive profile of prose memory deficits that challenges people with PD. METHODS: Prose memory of 19 patients with PD was examined. Their performance in three constructs, namely recall accuracy, temporal sequence, and distortions, during immediate, delayed and recognition trials was studied. RESULTS: The patients with PD performed significantly worse in recall accuracy and temporal sequencing of information in the immediate recall trial. During the recognition trial, they made more false alarms than their healthy counterparts. CONCLUSIONS: Our findings confirm that the performance of people with PD in immediate recall of a prose was impaired. However, the level of performance in subsequent learning and delayed recall trials became comparable to that of the normal controls. The deficit remaining after multiple learning trials was the significantly high false alarms committed in the recognition trial. Our findings highlight the importance of qualitative analysis, in addition to quantitative evaluation, of prose memory in PD.

Aged↗

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↗

PubMed2005

Effect of ecstasy use on neuropsychological function: a study in Hong Kong.

RATIONALE: Previous studies on the effects of ecstasy on neuropsychological performance have often recruited small sample sizes. OBJECTIVES: The present study was conducted to validate previous findings regarding the effects of ecstasy consumption on neuropsychological performance. METHOD: A comprehensive neuropsychological investigation was conducted in 100 abstinent ecstasy users and 100 matched non-user counterparts on standardized measures of working memory, verbal and non-verbal memory, verbal and figural fluency, and selective and switching attention. RESULTS: Abstinent ecstasy users were impaired on verbal and non-verbal memory, complex attention, and verbal fluency, but not on working memory, relative to their non-user counterparts. Of particular interest was the fact that abstinent ecstasy users performed better on figural fluency relative to their non-user counterparts. In addition, only cumulative ecstasy consumption correlated with neuropsychological performances among abstinent ecstasy users. Canonical discriminant analysis yielded verbal and visual memory, switching attention, and verbal fluency as potential core neuropsychological variables for differentiating abstinent ecstasy users from non-users. Levels of depression and general non-verbal intelligence, as measured by the Beck Depression Inventory and the test of non-verbal Intelligence, respectively, were not likely to affect these findings, since these measures were matched between ecstasy users and non-users. CONCLUSIONS: These findings suggest that previous ecstasy consumption can affect a wide range of neuropsychological performance, though figural fluency may be subsequently enhanced as a result of the phenomenon of "cortical disinhibition." Furthermore, measures of verbal and visual memory, switching attention, and verbal fluency may be particularly useful for differentiating abstinent ecstasy users from non-users.

Adolescent↗

PubMed2005

The relationship between visual-perception and attention in Chinese with schizophrenia.

Previous studies suggest possible visual-perceptual deficits associated with schizophrenia, and co-existing impairments in attention and visual-perceptual function in people with schizophrenia. This study examines if people with schizophrenia show visual-perceptual difficulty and whether different components of attention, namely sustained attention, selective attention, switching attention and attentional control processing, relate to the visual-perceptual function of people with schizophrenia differently. A total of 94 participants voluntarily participated in this study: 47 of them were diagnosed with schizophrenia and 47 were normal controls. Visual-perceptual abilities were measured by the Hooper Visual Organization Test (HVOT) for visual organization ability and the Judgment of Line Orientation Test (JLOT) for spatial perception and orientation. Tests for measuring different components of attention were also administered. We observed that our clinical participants performed significantly poorer in both the HVOT and the JLOT. We further noticed that nonverbal intelligence had a significant influence on our participants' performance in these two administered tests. Regarding the relationship between attention and visual-perceptual function, our findings indicated that such a relationship existed only among our clinical participants, not the normal controls. The attention control process significantly predicted the performance in the HVOT and switching attention efficiency significantly predicted the performance in the JLOT.

Adult↗

PubMed2005

The cerebellum's involvement in the judgment of spatial orientation: a functional magnetic resonance imaging study.

A functional magnetic resonance imaging (fMRI) study was conducted to integrate the clinical observations of the impaired judgment of spatial orientation of cerebellar patients with recent theoretical discoveries about the role of the cerebellum in cognitive functions. Ten normal healthy male right-handed Chinese postgraduates consented to participate in this study. The experimental task employed was a modified version of Benton's Judgment of Line Orientation Test, administered in a blocked fMRI study. The findings indicated activation of the cerebellar regions, the Hemisphere Lobules IV, VI and Crus I, while the subjects were performing the experimental task of the judgment of the orientation of lines. Furthermore, cortical regions were activated, including the bilateral precuneus (BA 7), the extrastriate regions (BA 19), and the bilateral prefrontal regions (BA 9, 10, 44, 46). The imaging data confirmed that the activity of the cerebellum is associated with judging spatial orientation. The theoretical and clinical implications of the findings are discussed.

Adult↗

PubMed2004

The role of sub-cortical brain structures in emotion recognition.

PRIMARY OBJECTIVE: This study investigated the role of sub-cortical brain structures in emotion recognition. METHODS AND PROCEDURES: Fourteen patients (eight left, six right) with sub-cortical brain damage (SS) and 14 matched healthy volunteers (HV) were recruited. A brief neuropsychological battery was administered to measure working memory, visual inattention, Stroop effect and visual organization. A facial and prosodic emotion recognition battery previously developed was used. RESULTS: SS patients were generally impaired on emotion recognition, with the exception of facial emotion discrimination and tasks involving happy expressions, relative to HV. Preliminary analyses also showed no statistical difference between patients with left- and right-sub-cortical brain damage in terms of emotion recognition. CONCLUSIONS: The findings provide further support for the role of sub-cortical brain structures (and the damage thereof) as well as probable frontal-limbic neural networks in recognizing basic emotions.

Aged↗

PubMed2003

The effect of the duration of exposure to the electromagnetic field emitted by mobile phones on human attention.

Previous findings suggested the facilitating effect of the electromagnetic field emitted by mobile phones on human attention. This study aimed to examine the relationship between the facilitating effect and the duration of exposure to the electromagnetic field emitted by mobile phones on human attention. Seventy-eight university students were randomly assigned to either an experimental or a control group. Their performance in the administered attention tasks was compared. Participants in the experimental group performed better on one of the two measures of attention only after they had been exposed to the electromagnetic field emitted by the mobile phone for some time. The results seem to suggest that attention functions may be differentially enhanced after exposing to the electromagnetic field emitted by mobile phones. Furthermore, this transient facilitation effect might be dose dependent.

Adolescent↗

PubMed2003

Emotion recognition in patients with idiopathic Parkinson's disease.

Emotion recognition (ER) was examined in 64 patients with idiopathic Parkinson's disease (PD; 56 bilateral and 8 right-sided) and 64 matched healthy volunteers. Participants were administered an ER battery, consisting of the following subscores: overall ER (OER), overall facial ER, facial emotion identification (FEI) and discrimination, overall prosodic ER, and prosodic emotion identification (PEI) and discrimination. Measures of visuospatial functions, auditory attention, and depression were also administered. After controlling for visuospatial functions, auditory attention and depression, results indicated that patients with bilateral PD had poorer performance on all ER subscores, regardless of the modality and type of experimental task involved, relative to healthy volunteers. However, patients with right-sided PD had difficulty on FEI and PEI only. Whereas none of the clinical variables examined in this study predicted any of the ER subscores, visual organization and auditory attention positively predicted OER in patients with PD. In addition, visual organization also positively predicted FEI in these patients. Implications are discussed in terms of the neural substrates underlying ER.

Aged↗

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↗