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Biomedical subjects

D L Na

Publications and source records attributed to D L Na.

At least 19 recordsLinked to original sources
PubMed2002

Influence of final search direction on tactile line bisection in normal subjects.

BACKGROUND: Many variables influence the tactile bisection performance of normal subjects. Of these, studies that investigated the starting point effect have reported inconsistent results. OBJECTIVE: To determine if the final search direction rather than the initial search direction (starting point) may have an effect on tactile bisection performance, especially when subjects are making multiple searches. METHODS: The authors divided the experiment into single- and multiple-search tasks. Thirty-two blindfolded normal subjects were asked to indicate the midpoint of a rod after a one-way search (single-search task) or after two or more one-way searches (multiple-search task). In each task, the subject started on either end of the horizontally placed rods. The same procedure was also conducted with rods oriented vertically or radially. Therefore, there were six conditions (two starting points x three orientations). RESULTS: In the single-search task, there was a significant effect of starting point or movement direction in all six conditions, with biases occurring toward the starting point from the true midpoint (this is termed the "overshoot phenomenon"). In the multiple-search task, however, there was no significant effect of the starting point in all six conditions. Rather, biases depended on the final movement direction in five of the six conditions, occurring toward the starting point of the final search. CONCLUSION: Future research is needed to understand the mechanism of the overshoot phenomenon in tactile bisection by normal subjects and how the overshoot phenomenon influences patients with neglect.

Adult↗
PubMed2001

Alpha-1 antichymotrypsin and alpha-2 macroglobulin gene polymorphisms are not associated with Korean late-onset Alzheimer's disease.

Alzheimer's disease (AD) is a multifactorial disorder with possible involvement of several genetic and environmental factors. For late-onset AD (LOAD), the epsilon4 allele of apolipoprotein E (APOE) has been identified as a major susceptible gene. However, the observation that APOE epsilon4 accounted for approximately one half of the genetic variance of LOAD prompted many researchers to undertake genome surveys to identify other susceptible genes. Recently, several candidate genes such as alpha-1 antichymotrypsin (ACT) and alpha-2 macroglobulin (A2M) were reported to be associated with LOAD. To evaluate the possible association between these genes and LOAD in Korean population, we genotyped ACT A/T and A2M 5-bp deletion (exon 18) polymorphisms in 89 LOAD cases and 50 age-matched healthy controls. The frequencies of ACT A and A2M 5-bp deletion alleles in LOAD and controls were 0.39 vs. 0.37, and 0.05 vs. 0.05, respectively. Although APOE epsilon4 clearly showed higher frequency in LOAD (0.34) than that in controls (0.09), giving an odds ratio of 5.14 (95% confidence interval, 2.31-11.76), neither ACT nor A2M showed statistically significant difference between LOAD and controls regardless of APOE carrier status. Our results do not support previously reported association of ACT and A2M with LOAD, at least in Korean population.

Aged↗
PubMed2001

A compulsive collecting behavior following an A-com aneurysmal rupture.

Hoarding behavior associated with focal brain injury is rarely reported. The authors report a 46-year-old man with pathologic collecting behavior after a left orbitofrontal and caudate injury from an aneurysmal rupture of anterior communicating artery. His hoarding, an impulse control disorder or an ego-syntonic compulsion, was restricted to one specific item (toy bullet). Treatments with sertraline or fluoxetine were not effective for the hoarding.

Brain↗
PubMed2001

Functional magnetic resonance imaging during pantomiming tool-use gestures.

The purpose of this study was to identify the functional fields activated in relation to gestural movements. Using functional magnetic resonance imaging (fMRI), we mapped brain activity in ten right-handed, normal volunteers during activation and control tasks. The activation condition consisted of pantomiming tool-use gestures with either the left hand or right hand, whereas the control condition comprised repetitive, oppositional movements between thumb and index finger. Activated cortical regions were highly lateralized to the left hemisphere during pantomiming of tool use regardless of hand used. Praxis with either hand commonly activated the superior parietal lobule, supplementary motor area, premotor area of the left hemisphere, and cerebellar vermis. However, minimal activation occurred in the inferior parietal lobule, which has been known to be a critical area for praxis generation. Compared with left-hand praxis, right-hand praxis exhibited additional activation in the left putamen and posterior part of the left inferior temporal region. Our findings concur with neuropsychological observations that the left hemisphere in right-handers mediates programming and executing skilled movements and that, within the left hemisphere, praxis is predominantly subserved by the parietal lobe, supplementary motor area, and premotor area. However, unlike previous lesion studies, the results of our fMRI study suggested that the superior parietal lobule more likely than the inferior parietal lobule play an important role in gesture production.

Adult↗
PubMed2001

Line quadrisection errors in normal subjects.

Many studies have investigated line bisection behaviors in normal individuals and patients with hemispatial neglect. However, little is known about what happens when subjects attempt to fractionate line into more than two equal components (e.g., line quadrisection). Thirty right handed normal subjects were asked to place a mark either 25% (left quadrisection) or 75% (right quadrisection) of the distance along on a 240 mm line. On average, they placed the left quadrisection mark significantly to the left (- 4.2+/-6.7 mm) from the true quadrisection point but they were relatively accurate on the right quadrisection task (1.0+/-6.7 mm). However, comparison of actual quadrisection performances with those of expected performance based on subjective midpoint disclosed that both right and left quadrisection marks deviate toward each end of the line. Individual data analysis also support this trend because majority of subjects showed the lateral deviation in either or both quadrisection tasks. Therefore, in the left quadrisection task the pseudoneglect (leftward bias) in bisection and the lateral bias are additive, resulting in a robust left lateral deviation, whereas in the right quadrisection, these two biases nullify each other, resulting in accurate performance.

Adolescent↗
PubMed2001

Contralesional directional hypermetria associated with line bisection-specific ipsilesional neglect.

Patients with contralesional neglect from right hemisphere injuries often fail to be aware of or respond to visual stimuli in the left hemispace. In contrast, other patients with right hemisphere damage rarely demonstrate behavior consistent with task-specific ipsilesional neglect (IN). We performed a series of experiments in a patient with IN on a line bisection task after a right frontal infarct. When asked to perform horizontal limb movements without visual feedback, the patient showed a leftward directional hypermetria. Similar performance was also observed during a representational production of a given distance without sensory input. These results suggest that IN is induced by a directional hypermetria resulting from disruption of the motor-intentional system.

Aged↗
PubMed2001

Magnetic resonance reflects the pathological evolution of Wernicke encephalopathy.

BACKGROUND AND PURPOSE: Wernicke encephalopathy (WE) is an acute phase of Wernicke-Korsakoff syndrome. Pathologic findings change between acute and chronic phases. Only a few magnetic resonance imaging (MRI) studies have been done to date. METHODS: To correlate the MRI findings in acute and chronic stages of WE with the known pathologic information, 15 consecutive patients with WE were examined with MRI: 3 before thiamine treatment, 7 within 24 hours of thiamine treatment, 4 between the second and sixth day after thiamine treatment, and 1 fifty-five days after thiamine treatment. Nine of the patients had follow-up MRI between 2 days and 33 months. T1-weighted, proton, and T2-weighted axial images were obtained with additional 5-mm-thick T1-weighted sagittal and coronal images to better visualize the mammillary bodies. RESULTS: In the acute WE, MRI showed high signal intensityon T2-weighted images in periaqueduct and medial thalamic regions. In a few patients with alcoholism, vermian and mammillary body atrophies and third ventricular enlargements were noted. In the chronic phase of WE, T2 hyperintensity disappeared but mammillary bodies and cerebellar vermis became atrophic and third ventricular enlargements were evident. High signal intensity on T2-weighted images disappeared as early as 2 days, and atrophic changes appeared as early as 1 week. CONCLUSION: MRI is useful for in vivo monitoring and reflects the pathological evolution in acute and chronic phases of WE.

Acute Disease↗
PubMed2000

Memory deficits after bilateral anterior fornix infarction.

The authors report a patient who suddenly developed memory loss without any other focal neurologic deficits. Neuropsychological testing showed severe anterograde verbal and visual memory deficits that improved gradually over several months, but not to the point of the premorbid state. Brain MRI with diffusion-weighted imaging performed 3 days after onset revealed acute infarction involving the bilateral fornices and the right genu of the corpus callosum. The authors suggest that acute fornix infarction may cause anterograde memory deficits.

Cerebral Infarction↗
PubMed2000

Diffusion-weighted MRI in vascular dementia.

OBJECTIVE: To examine the ability of diffusion-weighted MRI (DWI) to detect ongoing cerebral ischemia in patients with vascular dementia (VaD). BACKGROUND: VaD due to small-vessel disease results from the cumulative impact of recurrent cerebral ischemia. Cerebral ischemia may produce clinical manifestations, producing the "stepwise" decline characteristic of VaD. Conventional MRI can detect small regions of ischemic damage but cannot determine when injury developed. In contrast, DWI shows sensitivity in detecting ischemia of recent onset. DESIGN/METHODS: Patients with VaD (n = 30) underwent DWI in addition to standard MRI sequences. Patients were divided into two groups according to the presence of new focal deficits or mental change within 10 days before MRI. In 10 patients of positive group, symptomatic neurologic decline occurred an average of 4.2 days before the imaging procedure. RESULTS: Seven (70%) of 10 patients with a recent neurologic event showed 15 new regions of signal abnormality on DWI. The anatomic distribution of signal change could account for the patients' new symptoms or signs in all but one patient. Similar signal abnormality was detected in 4 (20%) of 20 patients without a recent neurologic event. New foci of altered signal intensity were distinguishable from prior injuries only with DWI. No significant difference was found between patients with and without DWI abnormalities in gender, age, Mini-Mental State Examination score, Hachinski Ischemic Score, vascular risk factors, or severity of increased signal on T2-weighted MRI scans. CONCLUSION: Small foci of abnormal signal on diffusion-weighted MRI (DWI), presumably representing recent small infarcts, occur often in vascular dementia (VaD) from small-vessel disease, even in patients without a recent "stepwise decline." The results suggest that DWI might be used to monitor VaD progression in future observational and interventional studies of this disorder.

Aged↗
PubMed2000

Dissociation of pure korean words and Chinese-derivative words in phonological dysgraphia.

Phonological dysgraphia is a writing impairment, characterized by marked disability to spell pronounceable pseudo-words as opposed to relatively mild reduction in ability to spell real words. Within the realm of Korean vocabulary, there are two categories of real words: pure Korean words and Chinese-derivative words. We present a patient with a history of CVA, resulting in phonological dysgraphia and, further, a dissociated performance in the aforementioned two categories of real words. It is suggested that the lexicon for pure Korean words is segregated from that for Chinese-derivative words.

Adult↗
PubMed2000

Ipsilesional versus contralesional neglect depends on attentional demands.

Right hemisphere injuries often produce contralesional hemispatial neglect (CN). In contrast to CN, some patients with right hemisphere damage can also show so-called ipsilesional neglect (IN). Previous reports found that patients tend to show IN on line bisection tasks but CN on other tasks such as target cancellation. To learn why these two tasks induce different spatial biases in patients with right hemisphere injury, conventional (i.e. solid) line bisection was compared with two novel bisection tasks consisting of horizontally aligned strings of characters. The subjects' task was to mark a target character that was at or closest to the true midpoint of the simulated line. Four of the 5 patients showed a dissociation whereby IN occurred for solid lines while CN was observed on character lines. The two patients assessed with an antisaccade paradigm showed a "visual grasp" for leftward stimuli. The present results suggest that neglect on line bisection may reflect two opposing forces, an approach behavior or "visual grasp" toward left hemispace and an attentional bias toward right hemispace.

Adult↗
PubMed2000

The Korean version of the neuropsychiatric inventory: a scoring tool for neuropsychiatric disturbance in dementia patients.

The Neuropsychiatric Inventory (NPI) is a standardized, validated, and reliable tool to assess neuropsychiatric derangements in dementia patients. The aim of this study is to develop the Korean version of the NPI (K-NPI) and to test its reliability and usefulness in dementia patients. The subjects were 49 normal controls and 92 patients with Alzheimer's disease (43), vascular dementia (32), frontotemporal lobar degeneration (11), and other causes (6). Their caregivers familiar with the subjects' everyday behavior were interviewed with the K-NPI. In a subgroup (29/141) of the caregivers, the K-NPI was repeated for test-retest reliability, average of 23.1 days after the initial test. Prevalence rates of 12 behavioral domains in dementia patients were comparable to those of the original NPI; apathy was the most common and hallucination was the least common behavior. Total K-NPI scores correlated positively with dementia severity assessed with the Korean Mini-Mental State Examination. Test-retest reliabilities of frequencies and severities of all subscales were significantly high. Depression, anxiety, apathy, irritability, night-time behavior, and eating change were identified at very low rates in normal controls and were significantly less than those in dementia patients (p<0.001). The K-NPI, whose reliability and competency are comparable to those of the original version, may be a reliable and useful tool for measuring neuropsychiatric disturbances in Korean dementia patients.

Aged↗