Biomedical subjects

E Nalçaci

Publications and source records attributed to E Nalçaci.

7 recordsLinked to original sources

PubMed2001

The relationship between handedness and fine motor performance.

The aim of this study was to re-investigate the relationship between handedness and asymmetry in hand performance, and the sex difference in motor asymmetry. Three-hundred and ten medical students volunteered as subjects. Handedness was assessed by a 13-item questionnaire adapted from Chapman and Chapman. Fine motor performance was measured using a finger tapping task. In this task, subjects were required to tap as rapidly as possible with their index finger on a mouse button for a period of 10 s. There was a significant correlation between handedness scores and the scores of the finger tapping task. In the total sample, the correlation between hand speed and the handedness score indicated that the distribution of hand preference is associated with left hand speed, but not right hand speed. Results confirmed that right-handed females tend to have more asymmetric motor function than right-handed males.

Adult↗

PubMed2001

Interhemispheric asymmetry of EEG alpha activity at rest and during the Wisconsin Card Sorting Test: relations with performance.

There are conflicting results regarding the functional asymmetry of the prefrontal cortex. Spectral power analysis of electroencephalographic (EEG) activity can provide important clues about the cortical mechanisms. In this study, interhemispheric EEG alpha power asymmetry of healthy individuals was investigated during the execution of the Wisconsin Card Sorting Test (WCST) and during rest. We analyzed alpha-1 (8.6-10.2 Hz) and alpha-2 (10.9-12.5 Hz) bands separately and found some evidence to indicate that lower and upper alpha bands reflect different cortical processes. On the other hand, greater alpha power during resting correlated with higher performance on the WCST. The lower left frontal alpha power during WCST correlated significantly with the higher WCST performance. However, greater bilateral parietal alpha power during WCST correlated with higher performance. Significant correlations between EEG activity and WCST performance were, in general, restricted to lower alpha power, both at rest and during the task. These findings are discussed with regard to attention processes reflected by lower alpha activity.

Adult↗

PubMed2001

Accordance between EEG alpha power and dual task performance for different visual cognitive tasks.

Evidence from clinical and experimental studies suggests that the left hemisphere is preferentially engaged in language processing and mathematical-analytic tasks while the right is involved with spatial relations and synthetic tasks. The purpose of the present study was to investigate accordance between dual task paradigm (effects of concurrent cognitive tasks on right- and left-hand finger tapping frequency) and EEG alpha power changes, which are used to conduct research in lateralization of cognitive function. Subjects performed reading, face recognition and line orientation tasks. First, the EEG was recorded during the tasks and, after six months, the dual task was carried out using the same cognitive tasks. Statistical analysis yielded no significant main effect for the hemispheres, performing hand and three cognitive tasks separately for the dual task and the EEG alpha power changes. However, significant correlation between the two methods was found, indicating the left parietal activation for the reading task, the right temporal activation for the line orientation task, and both hemispheric activation for the face recognition task. Results first suggest a significant accordance between dual task performance and EEG alpha asymmetry studies.

Adolescent↗

PubMed2000

The effect of familial sinistrality on the relation between schizophrenialike thinking and pseudoneglect.

We have recently reported a correlation between schizophrenialike symptoms and the degree of pseudoneglect in healthy right-handers. We aimed to investigate the effect of familial sinistrality (FS) on this relation. Seventy-six healthy right-handers were divided into four groups on the basis of gender and FS. A computerized version of Corsi's task was used as the visuospatial task. Subjects filled in the Magical Ideation Scale (MI), which asked for delusionlike beliefs, and performed the Corsi's task using each hand. Performance of both hemispaces was separately evaluated. In all groups, performance of the left hemispace was better than that of the right hemispace and FS+ subjects performed better than FS- subjects. When the right hand was used, performance was correlated to MI scores only for FS- groups. Findings suggest that the correlation between right-sided neglect and proneness to schizotypy in normal right-handers is affected by FS.

Adult↗

PubMed2000

Magical ideation and right-sided hemispatial inattention on a spatial working memory task: influences of sex and handedness.

A correlation between magical ideation scores and the size of relative right-sided hemispatial inattention was previously reported for healthy right-handed men performing a tactile line-bisection task. To re-investigate this relation, a computerized version of Corsi's Block-Tapping Test was used to test working memory. In this version, different numbers of cubes are similtaneously displayed on a screen, and after the cubes disappear the subject is asked to designate the cubes' locations on a grid as quickly as possible. 98 healtly medical students were divided into four groups on the basis of their handedness and sex in the following way: right-handed men, right-handed women, nonright-handed men, and nonright-handed women. Each subject performed the test once with the right hand and once with the left hand. Accuracy and Neglect scores were computed for the two hemispaces separately. Also, all subjects filled in the Magical Ideation Scale which asks for hallucination-like experiences and delusion-like beliefs. In all groups a significant right-sided inattention was found when subjects performed with the right hand. Magical Ideation scores were significantly correlated with Neglect in the right hemispace for the right-handed women when the right hand was used. For the nonright-handed men, when the right hand was used, a significant negative correlation between Magical Ideation scores and Neglect scores in the left hemispace was found. Our findings support the previous study in some aspects and suggest that the correlation between hemispatial inattention and proneness to schizotypy in normal subjects is restricted to right-hand performance.

Adult↗

PubMed1999

VEP-interhemispheric transfer time in 20-32 Hz band in man.

This research aimed to investigate callosal transfer in the different frequency bands of VEP to lateralized reversal of checkerboard pattern as stimuli. The chosen band pass filters (4-8 Hz, 8-15 Hz, 15-20 Hz, 20-32 Hz) were applied to the VEPs of subjects, and four different components for each VEP were obtained. Latency differences between hemispheres for digitally unfiltered and filtered VEPs were computed to estimate IHTT. Different IHTTs in the theta (17 ms), alpha (9 ms) and beta1 (7 ms) bands from right to left and from left to right were estimated, supporting the previous report. Furthermore, a transfer within 4.5 ms from right to left in the 20-32 Hz band for the occipital lobe was found. In conclusion, our findings suggest that the frequency analysis of VEP to lateralized stimuli give us additional information, relating to the types of callosal fibers.

Adult↗

PubMed1997

Pseudoneglect of males and females on a spatial short-term memory task.

The effect of sex on the phenomenon of pseudoneglect was assessed in 60 male and 61 female right-handed subjects using a modified form of Corsi's block-tapping test. A significant right-lateralized pseudoneglect for both sexes was found, and the level of pseudoneglect strongly correlated with neglect in the right hemispace. Men were significantly more accurate in the left hemispace than women, whereas no difference was seen between the sexes in the right hemispace. Although we found some indirect evidence from which to infer that the men's brain may be functionally more lateralized than the women's for this spatial task, there was no significant difference between the sexes in correct responses for the left hemispace, i.e., right pseudoneglect. Therefore, the results suggest that pseudoneglect phenomenon can be partly explained by a functional asymmetric feature of the brain, and the other factors probably play a role in producing the similar patterns of asymmetric perception of space in males and females.

Adult↗