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Biomedical subjects

Frank Domahs

Publications and source records attributed to Frank Domahs.

5 recordsLinked to original sources
PubMed2006

Is math lateralised on the same side as language? Right hemisphere aphasia and mathematical abilities.

The main purpose of the present study was to learn how mathematical abilities are located and develop in the brain with respect to language. Mathematical abilities were assessed in six right-handed patients affected by aphasia following a lesion to their non-dominant hemisphere (crossed aphasia) and in two left-handed aphasics with a right-sided lesion. Acalculia, although in different degrees, was found in all cases. The type of acalculia depended on the type of aphasia, following patterns that have been previously observed in the most common aphasias resulting from left hemisphere lesions. No sign of right hemisphere or spatial acalculia (acalculia in left lateralised right-handed subjects) was detected. These results suggest that, as a rule, language and calculation share the same hemisphere. A primitive computational mechanism capable of recursion may be the precursor of both functions.

Aphasia↗
PubMed2006

What makes multiplication facts difficult. Problem size or neighborhood consistency?

Two current models of arithmetic fact retrieval, the network interference theory (NIT; Campbell, 1995) and the interacting neighbors (IN) model (Verguts & Fias, 2005a), predict that errors in simple multiplication should be more probable, if they include the same digit as the correct result (i.e., if they are "consistent," compared with "inconsistent" errors). In a reanalysis of error data originally reported by Campbell (1997), we provide first empirical evidence for this prediction. Furthermore, these results support the notion of different quantity representations for decades and units as proposed by Nuerk, Weger, and Willmes (2001). However, the NIT and IN-model differ in their explanations of the problem-size effect, a hallmark finding robustly observed in arithmetic fact retrieval. Only the IN-model predicts that a correct answer's neighborhood consistency can fully account for the problem-size effect, which was confirmed in our analysis.

Attention↗
PubMed2004

Number processing and basal ganglia dysfunction: a single case study.

Numerical processing has never been investigated in a case of Fahr's disease (FD) and only rarely in cases of basal ganglia dysfunction. The study describes the cognitive decline of a pre-morbidly high-functioning patient (medical doctor) affected by FD and his difficulties in number processing. A MRI scan revealed bilateral calcifications in the basal ganglia and a brain PET showed a massive reduction of glucose metabolism in the basal ganglia and both frontal lobes, but no other brain abnormalities. The patient's cognitive deficits included impairments in problem solving, in cognitive set shifting and in mental flexibility, as well as in verbal memory. These deficits are attributed to the disruption of the dorsolateral prefrontal circuit involving the basal ganglia. In number processing, the patient showed a severe deficit in the retrieval of multiplication facts, deficits in all tasks of numerical problem solving and in the execution of complex procedures. Importantly, he also showed a dense deficit in conceptual knowledge, which concerned all test conditions and all operations. The findings confirm the predictions of the triple code model in so far, as a disruption of cortico-subcortical loops involving the basal-ganglia may lead to specific deficits in fact retrieval. However, no verbal deficit, as assumed in the triple code model and reported in similar cases, could be observed. The present findings further add to current knowledge on numerical processing, showing how fronto-executive dysfunction may disrupt conceptual understanding of arithmetic. This study shows that not only parietal lesions may lead to severe deficits in conceptual understanding, but that basal ganglia lesions leading to frontal dysfunction may have a devastating effect.

Basal Ganglia Diseases↗
PubMed2003

Everyday numerical abilities in Alzheimer's disease.

The present study investigated everyday numerical abilities in a group of 21 patients affected by mild to moderate dementia of Alzheimer's type (DAT). Though patients did not differ from a control group in standard laboratory tests tapping transcoding, number comparison, simple calculation, and estimation, they showed significant difficulties in numerical tasks embedded in an everyday context, such as handling money, a bus schedule, or a television program. Patients' difficulties were attributed to those multiple cognitive demands which are inherent to real situations as compared to well-structured abstract paper-and-pencil tasks. Overall, the study suggests that the examination of numerical abilities in DAT patients should go beyond abstract paper-and-pencil tasks which can only partially reflect the actual numerical skills in DAT and should therefore include also tasks simulating everyday life situations. Assessment of everyday numerical skills may be crucial in planning adequate support for patients, for example in handling money, but also in designing targeted training programs.

Activities of Daily Living↗