Finger Localization Task Research Articles

Compromised interhemispheric transfer of information partially mediates cognitive function deficits in adolescents with fetal alcohol syndrome.

Prenatal alcohol exposure (PAE) has been associated with compromised interhemispheric transfer of tactile stimuli in childhood and structural changes to the corpus callosum (CC). In this study, we used a finger localization task (FLT) to investigate whether interhemispheric transfer deficits persist in adolescence; whether effects of PAE on perceptual reasoning, working memory, and executive function are mediated by deficits in interhemispheric transfer of information; and whether CC size in childhood predicts FLT performance in adolescence. Participants, aged 16 to 17years, were from the Cape Town Longitudinal Cohort, whose mothers were recruited during pregnancy and interviewed regarding their alcohol use using the timeline follow-back method. Diagnoses of fetal alcohol syndrome (FAS) and partial FAS (PFAS) were determined by two expert dysmorphologists; nonsyndromal exposed children were designated as heavily exposed (HE); those born to abstainers or light drinkers, as controls. The FLT was administered to 74 participants (12 FAS, 16 PFAS, 14 HE and 32 controls). CC size at age 9 to 12years was available for 35 participants (7 FAS, 13 PFAS, 5 HE and 10 control). Although the degree of PAE was similar in the FAS, PFAS, and HE groups, only the adolescents with FAS showed more transfer-related errors than controls in conditions in which one finger was stimulated. FLT performance mediated the effects of FAS on perceptual reasoning and executive function. In the subsample for which neuroimaging data from childhood were available, there was an association among adolescents with PAE of smaller CC volumes with more transfer-related errors on the one-finger/hand hidden condition, suggesting that CC damage previously seen in childhood continues to impact function through adolescence. This study provides evidence of compromised interhemispheric transfer of information in adolescents with FAS, while those with PFAS or heavy exposed nonsyndromal individuals are apparently spared. It is the first to show that PAE effects on important aspects of cognitive function are partially mediated by deficits in the interhemispheric transfer of information.

Body structural representation in schizotypy

A deficient sense of self, typically observed in schizophrenia spectrum disorders, is often accompanied by abnormalities in bodily perception and awareness. These abnormalities are seemingly among the most powerful predictive factors for the onset of schizophrenic illnesses. According to the hypothesis of the psychosis continuum, high schizotypal traits in the general population may be characterized by a progressive sense of detachment from one's lived body. Building upon previous research that found an abnormal Body Structural Representation (BSR) in individuals with schizophrenia, this study aims to extend these findings to schizotypy. To investigate this, we utilized the Finger Localization Task (FLT), in which participants must identify the finger touched by the experimenter, and the In Between Task (IBT), in which two fingers are touched and participants must specify the number of fingers in between the two stimulated fingers. We found that individuals with high schizotypy were significantly less accurate than individuals with low schizotypy in determining the spatial configuration of their own fingers relative to each other. Most significantly, performances on both tasks were negatively correlated with the score on the Dissociative Experiences Scale (DES). These findings support the hypothesis that the progressive loss of one's sense of self is associated with abnormal bodily experiences and dissociative symptomatology which may represent a potential marker for schizophrenia proneness.

Body representations and basic symptoms in schizophrenia

Patients with schizophrenia report a wide range of anomalous body experiences. According to the basic symptom model of schizophrenia, disturbances of body perception and awareness are among the most powerful predictors of the changes in the subjective experience of the self in schizophrenia. In this study we first investigated the body structural representation (BSR), a specific aspect of body awareness, and its association to basic symptoms in patients with schizophrenia. Using a finger localization task, we found that patients are significantly less accurate than healthy controls when asked to identify pairs of fingers touched by the experimenter, when the hand is hidden from view. Most importantly, patients' performance at the finger localization task was negatively associated to basic symptoms: the worse the individual accuracy, the higher the SPI-A total score. Moreover, the accuracy at the finger localization task was also negatively correlated with the malleability of the sense of body ownership: the less the individual ability to localize fingers, the stronger the rubber hand illusion. These results are in agreement with the idea that self-disorders in schizophrenia reveal a disconnectedness that can be regarded as a problem of disembodiment and traced back to abnormal body experiences.

Interhemispheric communication involving multiple tasks: A study of children with dyslexia

The study investigated whether inefficient interhemispheric communication is involved in developmental dyslexia using multiple tasks. A finger localization task, rhyming judgment task, primed lexical decision task, and a visual half-field presentation paradigm were used. Nineteen dyslexic children (mean age = 13.1 years) were compared with 26 chronological age-matched normal children. Although the dyslexic group demonstrated significantly slower and less accurate performance in all three tasks, there was no significant group difference in term of interhemispheric communication. However, priming effects demonstrated by the dyslexic group ( p < .05) further indicate that their reading problems may stem from the word retrieval process from the long term memory.

Interhemispheric Transfer in Children with Heavy Prenatal Alcohol Exposure

Background Prenatal alcohol exposure has long been associated with alterations in brain structure and behavioral changes. The corpus callosum can be affected by heavy prenatal alcohol exposure, and agenesis (absence) of this structure occurs more often in children with fetal alcohol syndrome than in the general population or in other developmentally delayed populations. Although the majority of children with fetal alcohol syndrome do not have agenesis of the corpus callosum, callosal area is reduced in this population, particularly in the anterior and posterior regions. However, the functional implication of these size reductions has not been examined.Methods The current study used a finger localization task to measure the transfer of information across the corpus callosum in children and adolescents with histories of heavy prenatal alcohol exposure and age‐ and sex‐matched controls. In a subset of children, correlational analysis was also conducted between behavioral data and cross‐sectional area of the corpus callosum.Results When compared with nonexposed controls, alcohol‐exposed children made more errors on trials for which information had to cross the corpus callosum (“crossed” trials) than on trials for which it did not (“uncrossed” trials), and they also made more errors as the task increased in complexity. Additionally, correlations with magnetic resonance imaging data in a subset of children revealed that impairment in interhemispheric transfer was related to reductions in the size of the corpus callosum. These correlations were independent of effects expected from the relationship between corpus callosum size and general intellectual functioning alone.Conclusions These findings suggest that children with heavy prenatal alcohol exposure display subtle deficits in the interhemispheric transfer of information in the somatosensory domain. Such deficits in interhemispheric transfer are likely to be related to the myriad of other behavioral and cognitive impairments observed in these children.

Alexithymia, gender, and hemispheric functioning

It has been hypothesized that alexithymia is related to an impairment of the right hemisphere or a deficiency in interhemispheric transfer. We used the Toronto Alexithymia Scale-20 (TAS-20) and the tactile finger localization task of Zeitlin et al. to test these relationships on nonclinical samples of college men and women, and also considered the role of short-term memory. Among 47 men, the TAS-20 facets of difficulty identifying feelings or difficulty describing feelings were correlated with poorer performance by the right compared with the left hemisphere in uncrossed trials and poorer interhemispheric transfer of information on crossed trials; short-term memory was not related. Thus, both hemispheric hypotheses were supported for men. However, among 58 women, alexithymia was completely unrelated to either index of hemispheric functioning; instead, poorer short-term memory (specifically digits backwards) strongly predicted poorer interhemispheric transfer. We conclude that deficiencies in right hemisphere function and interhemispheric transfer may contribute to alexithymia in men, but not in women.

Children's lateralization on a finger-localization task.

The effect of stimulus orientation and hand use on performance on a finger-localization task was assessed in a sample of 40 children, including 20 boys and 20 girls. Experimenters stimulated a single finger on either the left or right hand, and the participants were required to identify the stimulated finger displayed on a drawing of a hand. The model drawing was displayed in either an isomorphic or reversed orientation relative to the stimulated hand. Analysis indicated that 4-yr.-olds performed significantly better than 3-yr.-olds. Also, participants were significantly better at identifying the middle finger when the left hand was stimulated than the right hand.

Functional and Magnetic Resonance Imaging Correlates of Callosal Involvement in Multiple Sclerosis

To investigate functional and anatomical features of callosal involvement in multiple sclerosis (MS), performances of 90 patients with definite MS and 25 matched normal control subjects were compared on three tasks exploring interhemispheric transfer of auditory, sensory, and motor information: a verbal dichotic listening task, a crossed tactile finger localization task, and an alternate finger tapping task. Each patient also underwent a magnetic resonance imaging (MRI) scan (1) to appreciate the extent of white-matter changes by a semiquantitative evaluation of hemispheric brain MRI hyperintensities and (2) to measure the degree of total and regional callosal atrophy using an automatized method of partition of the midsagittal callosal area. Interhemispheric transfer and/or integration was impaired in patients with MS for all modalities explored and proportional to both degree of callosal atrophy and diffusion of white-matter lesions. Moreover, in good agreement with data obtained from partial commissurotomy studies, performance on each functional task was predominantly associated with atrophy of one part of the callosum, namely left-ear dichotic suppression with the posterior callosal region, alternate finger tapping with the anterior region, and cross-localization with midanterior and posterior regions. Finally, a subgroup of patients without MRI white-matter hyperintensities also showed significant impairment of callosal function and relative atrophy of the callosum. These findings suggest the potential clinical value of callosal involvement in MS and the usefulness of MS as a model of interhemispheric disconnection.

Interhemispheric transfer deficit and alexithymia.

The hypothesis that alexithymia reflects a functional disconnection between the two cerebral hemispheres was examined in 25 male combat veterans with posttraumatic stress disorder (PTSD). Multiple regression analysis revealed that the efficiency of interhemispheric communication, evaluated with a tactile finger localization task, was a significant predictor of the degree of alexithymia, as measured by the Toronto Alexithymia Scale, independent of PTSD severity and IQ. The PTSD subjects without alexithymia did not differ on the finger localization task from 10 male control subjects without alexithymia. These data suggest that at least some forms of alexithymia may be mediated by an interhemispheric communication deficit.

Negative evidence of difference between right- and left- handers in interhemispheric transfer of information

The present study has been designed to investigate the relationship between handedness and callosal function. Based on the previous finding of a greater anatomical connection between the hemispheres in left-handers than in right-handers and in order to test the possibility of greater functional communication, the efficiency of interhemispheric transfer of information has been measured using a finger localization task. Comparison of two groups of male right-handed and left- handed subjects shows no difference in the efficiency of interhemispheric transfer of information.

The development of tactile transfer of information

A finger localization task was used to investigate interhemispheric transfer of tactile information in children aged 5, 7, 9 and 11 yr. Other-hand responses (cross-localization) were less accurate than same-hand responses for all ages tested. However, the size of the cross-localization deficit was strongly age-dependent, and provided evidence for a developmental improvement in interhemispheric transfer which is consistent with the sequence of myelination of the corpus callosum during the first decade of life. Transfer with mirror-imaged finger positions on the opposite hands was more accurate for younger children, whereas older children were more accurate when finger positions were spatially aligned.

Left-right comparison and children's performance on sensorimotor tests.

This study compared overall performance level for both hands combined (OPL) with several lateral deviation measures calculated from scores on a composite finger localization task (FLT) and a speeded pegboard task (SPT) administered to 92 kindergarten entrants. Laterality indices were interrelated moderately or highly on each task, consistently were unrelated to OPL with respect to FLT results, and in some instances were related modestly to OPL for the SPT procedure. Significant relationships, when observed, suggested a limited tendency to diminished motor asymmetry with slowed overall performance. Results, in general, support the view that OPL and lateral deviation as measured in this study are not mutually confounded and, in large degree, comprise relatively independent sources of information to be used in a complementary manner to arrive at accurate neuropsychological inferences.

Lateral asymmetry in finger localization for right-handed, kindergarten girls.

Laterality in finger localization (FL) was examined in 49 right-handed, kindergarten girls also administered tasks assessing verbal-receptive ability and manual dexterity. A right-hand advantage was evident overall and varied by FL task. The magnitude of asymmetry in FL was not unequivocally related to task requirement for verbal processing and was otherwise independent of children's verbal-receptive ability and motor laterality. The results were discussed in terms of cortical maturation and emergent cognitive-verbal processes as factors to be considered in the interpretation of asymmetry in FL.