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Biomedical subjects

Iftah Biran

Publications and source records attributed to Iftah Biran.

7 recordsLinked to original sources
PubMed2006

Letter selection and letter assembly in acquired dysgraphia.

OBJECTIVE: We explored the constituents of the graphemic buffer in a patient with acquired dysgraphia and tested the hypothesis that the graphemic buffer is composed of 2 dissociable components: letter selection and letter assembly. BACKGROUND: Research on dysgraphia has established the graphemic buffer as a component of the spelling mechanism, and the buffer is considered a short-term memory store that is critical for letter production. However, little is known about the components within the buffer. METHOD: We devised 2 spelling tasks that rely differentially on letter selection and letter assembly. In the selection task, our patient produced the letters that composed a target word, but she did not have to provide serial position information. In the assembly task, B.H. was given all the letters of a target word and was asked to spell the word by arranging the letters in the proper serial order. RESULTS: Compared to spelling to dictation, our patient did not benefit from being given letter identity information (ie, assembly task), but her performance improved significantly when position information was available (ie, selection task). CONCLUSIONS: Based on these data, and the comparison of her performance with another dysgraphic patient, we propose that the graphemic buffer engages in both letter selection and letter assembly.

Aged↗
PubMed2005

Category specific dysnomia after thalamic infarction: a case-control study.

Category specific naming impairment was described mainly after cortical lesions. It is thought to result from a lesion in a specific network, reflecting the organization of our semantic knowledge. The deficit usually involves multiple semantic categories whose profile of naming deficit generally obeys the animate/inanimate dichotomy. Thalamic lesions cause general semantic naming deficit, and only rarely a category specific semantic deficit for very limited and highly specific categories. We performed a case-control study on a 56-year-old right-handed man who presented with language impairment following a left anterior thalamic infarction. His naming ability and semantic knowledge were evaluated in the visual, tactile and auditory modalities for stimuli from 11 different categories, and compared to that of five controls. In naming to visual stimuli the patient performed poorly (error rate>50%) in four categories: vegetables, toys, animals and body parts (average 70.31+/-15%). In each category there was a different dominating error type. He performed better in the other seven categories (tools, clothes, transportation, fruits, electric, furniture, kitchen utensils), averaging 14.28+/-9% errors. Further analysis revealed a dichotomy between naming in animate and inanimate categories in the visual and tactile modalities but not in response to auditory stimuli. Thus, a unique category specific profile of response and naming errors to visual and tactile, but not auditory stimuli was found after a left anterior thalamic infarction. This might reflect the role of the thalamus not only as a relay station but further as a central integrator of different stages of perceptual and semantic processing.

Acoustic Stimulation↗
PubMed2005

Reduced endogenous control in alien hand syndrome: evidence from naturalistic action.

Patients with alien hand (AH) syndrome from medial frontal lesions exhibit involuntary but seemingly purposeful contralesional upper limb movements. Two observations about AH patients have received little, if any, experimental confirmation. The first is that AH is triggered opportunistically by nearby objects. The second is that AH behaviors are increased in conditions of fatigue or anxiety, i.e. under reduced attentional control. A prominent account explains AH as reduced intention-driven (endogenous) executive control. This account predicts that erroneous AH behaviors should be driven by environmental (i.e. exogenous) factors, such as distractor proximity to the hand. AH errors should be less influenced by the intention or action plan (i.e. endogenous factors), such as the semantic relatedness of distractors to targets. Moreover, due to capacity limitations of the endogenous controller, AH behaviors should increase under conditions of secondary task load. We tested these predictions with an AH patient in two experiments using a naturalistic coffee-making task. Experiment 1 demonstrated that the affected hand was highly perseverative and strongly influenced by exogenous but not endogenous factors. The non-alien hand made fewer errors. Experiment 2 showed that there was a disproportionate increase in perseverations and exogenous errors of the affected hand under secondary task load. The non-alien hand was significantly less disrupted by dual task conditions. These data provide experimental support for previous anecdotal observations about AH behavior in naturalistic settings, and are consistent with a unilateral defect in endogenous control.

Activities of Daily Living↗
PubMed2003

Frontotemporal dementia and parkinsonism with the P301S tau gene mutation in a Jewish family.

BACKGROUND: Frontotemporal dementia with parkinsonism linked to chromosome 17q21-22 (FTDP-17) is an autosomal dominant tauopathy manifested by a variable combination of personality changes, cognitive decline and hypokinetic-rigid movement disorder. Significant clinical and pathological heterogeneity of FTDP-17 is related in part to more than 20 different pathogenic mutations identified in the tau gene. Among others, the P301S mutation has been previously reported in three families of European and one of Japanese origin presenting with different clinical phenotypes. OBJECTIVES: To report a three-generation family of Jewish-Algerian origin with FTDP-17 due to the P301S tau mutation. METHODS: Clinical, neuropsychological and neuroimaging evaluation of 3 patients, tau genotyping, and pathological study of the proband. RESULTS: The 3 affected family members had a fairly stereotyped clinical course with early personality changes from their late 30s followed within a period of 1-2 years by a progressive cognitive and motor deterioration eventually leading to a state of akinetic mutism or death 3-5 years after the initial symptoms. The main clinical manifestations included severe dementia and hypokinetic-rigid movement disorder associated with supranuclear gaze impairment, pyramidal signs and frontal release signs. Brain imaging disclosed a variable degree of frontotemporal atrophy, ventriculomegaly and regional cerebral hypoperfusion or glucose hypometabolism. Frontal lobe biopsy in the proband revealed weak tau immunoreactivity in a few cortical neurons, in rare neurites and in some glial cells with no neurofibrillary tangles. Molecular DNA analysis identified a P301S mutation in exon 10 of the tau gene. CONCLUSIONS: The observed clinical features further expand the reported P301S phenotype and confirm a more aggressive course of the disease than in the other known tau mutations.

Adult↗
PubMed2003

Depression with anosognosia following a left subcortical stroke.

Controversy exists about whether depression following stroke represents a biologically mediated change or a psychological reaction to the deficits. We present a patient with an acute isolated personality change and depression following a lacunar infarct of the left internal capsule, who was unaware of his affective change. His anosognosia for the depression, which was abrupt and not accompanied by cognitive impairments, suggests that post stroke depression, at least in this case, is better explained by a biological than a psychological model.

Aged↗