PubMed Health⌕ Search

Biomedical subjects

J Moleman

Publications and source records attributed to J Moleman.

4 recordsLinked to original sources
PubMed1993

Evoked potential measures of auditory cortical function and auditory comprehension in aphasia.

This study investigated the relation between severity of auditory comprehension impairment in aphasia and the functional integrity of the posterior superior temporal region as evaluated by middle- and long-latency auditory evoked potentials and dipole source analysis. AEPs were studied in 20 stroke patients and in age-matched controls. AEPs and language data were collected 1 year or more post onset, and were compared to performance early after onset. Patients were differentiated in a group with severe and a group with moderate to recovered auditory comprehension impairment. Significant asymmetries of auditory evoked dipole source potentials were more frequent in the severely impaired group. However, a severe auditory comprehension deficit was not incompatible with normal AEPs. The results confirm the importance of the posterior superior temporal region for auditory language comprehension, but the correlation between AEP asymmetry and auditory comprehension seems due to the close spatial relation of AEP generating substrate and posterior language area rather than to partial overlap. Dipole source analysis of AEPs proved to be a valuable method for the assessment of interhemispheric asymmetries, enhancing the sensitivity of AEPs to unilateral damage of auditory cortex.

Aged↗
PubMed1990

Muscle fatigue in McArdle's disease. Muscle fibre conduction velocity and surface EMG frequency spectrum during ischaemic exercise.

The origin of fatigue in McArdle's disease is still a matter of debate. Both a reduction of muscle membrane excitability and failure of excitation-contraction (E-C) coupling have been suggested as causes. We performed intermittent isometric biceps brachii contractions (80% maximal voluntary contraction, rate 30/min) under local ischaemia in 5 McArdle's disease patients and 26 healthy controls. Our results show that in McArdle's disease the exerted force is less, the surface EMG (SEMG) amplitude steadily increases, and that the power density spectrum (PDS) shifts to lower frequencies, the latter without significant differences when compared with normals. The most important finding is that muscle membrane excitability remains unimpaired during ischaemic exercise, establishing a dominant role for intramuscular lactic acid formation in the reduction of muscle fibre conduction velocity seen in normal subjects. As is indicated by the shift of the PDS towards lower frequencies, as well as by the increase in SEMG amplitude, it can be concluded that during ischaemic exercise in patients with myophosphorylase deficiency, fatigue occurs without alterations in muscle membrane excitability and is due to a failure of E-C coupling.

Adolescent↗
PubMedDate not supplied

Dipole modelling of median nerve SEPs in normal subjects and patients with small subcortical infarcts.

Somatosensory evoked potentials (SEPs) to median nerve stimulation were analyzed by means of spatio-temporal dipole modelling in 6 normal subjects and 8 patients with small infarcts in the thalamo-cortical radiation or thalamus. The SEPs could be modelled by a tangentially and a radially oriented equivalent dipole in the region of the contralateral cortical hand area and an equivalent dipole located in the region of the brain-stem. In 3 patients with absence or reduction of amplitudes of cortically generated SEP components, the activity of both cortical dipoles was lost or reduced. In 2 patients the frontally recorded SEP component P20 was lost; in one of them the activity of mainly the tangential dipole was reduced.

Adolescent↗