Biomedical subjects

W Skreczek

Publications and source records attributed to W Skreczek.

10 recordsLinked to original sources

PubMed1998

[Evaluating driving ability after brain damage. Neuropsychological diagnosis and driving test].

The study examined the validity of psychometric measures for the assessment of driving ability in brain-damaged subjects. 116 patients with brain damage mainly of vascular and traumatic origin underwent extensive neuropsychological examinations emphasizing attentional performance and visual perceptual speed and participated in a comprehensive on-road driving test. Only 58% of the patients passed the driving test. Attempts to predict the outcome of the driving test by discriminant analysis or cut-off procedures based on neuropsychological and/or other subject-related data yielded a maximum of 73% correct predictions. In view of the frequent impairment in driving ability after brain damage and in view of the failure to reliably predict driving ability from psychometric test results, it is recommended that in each case an on-road driving test is given.

Adult↗

PubMed1996

Hemispheric asymmetry of arterial blood flow velocity changes during verbal and visuospatial tasks.

Changes in arterial blood flow velocity induced by cognitive activity were measured by simultaneous bilateral transcranial Doppler sonography (TCD) of the posterior and the middle cerebral artery. The finding of a robust left hemisphere dominance for verbal tasks but of an inconsistent right hemisphere dominance for visuospatial tasks obtained in an earlier study [13], in which TCD measurement had been restricted to the middle cerebral arteries, was confirmed. At the same time, it could be demonstrated that the failure to find the expected right hemisphere dominance for tasks of spatial visualization and mental rotation extended to the TCD measurement of the posterior cerebral arteries.

Adult↗

PubMed1989

The neural structures involved in cross-modal recognition and tactile discrimination performance: an investigation using 2-DG.

Given the failure of the ablation method to identify the neural structures/systems that are crucial for cross-modal recognition (CMR) and for tactile discrimination performance (TDP), we injected radioactive 2-deoxy-[14C]glucose (2-DG) into monkeys trained to a high level of CMR or TDP. Nine monkeys were trained to recognize in one sense-modality, to a level greater than 80% correct, the objects experienced in the alternate modality on only a single prior trial. After injection, CMR was continued (Expt. 1a) exactly as before, except that all CMR problems were now in only one direction; or (Expt. 1b) the second--the CMR--trial of each problem was not realized (i.e. no objects were available in the second modality) so that the monkey merely 'expected' the cross-modal trial. Nine other monkeys were trained on a graded roughness discrimination task with conventional 'titration' procedures to a stable level of performance, either (Expt. 2a) without having undergone any cortical removal, or (Expt. 2b) after unilateral removal--contralateral or ipsilateral to the preferred hand--of the posterior insula or of the second somatosensory projection cortex (SII). Exactly the same training procedures were continued in Expt. 2 after injection of 2-DG. Coronal radiographs were made at 490 microns for all 18 monkeys (and also for a 19th, which served as a control in Expt. 1b). The optical densities of the autoradiographs were measured quantitatively in respect of 50 structures or part-structures (e.g. sulci, thalamic nuclei, subcortical structures); they were rated either with the aid of 'pseudo-colours' produced by the computer, or directly by judging the black/white optical densities, in respect of 29 other structures. These 79 structures were then the dependent variables in MANOVAs or ANOVAs, to determine differences between groups; or within groups with respect to the left/right and ipsilateral/contralateral hemispheres; or interaction effects. It was found that certain structures (e.g. the ventral portion of the claustrum, the insula with its extension ventrally into the fundus, nucleus Medialis dorsalis and nucleus Pulvinar oralis) repeatedly, whereas others (e.g. the amygdala) never gave rise to significant outcomes. Structures in the left cerebral hemisphere were frequently found to be more strongly labelled than those in the right hemisphere.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1989

Aimed movements to visual targets in hemiplegic and normal children: is the "good" hand of children with infantile hemiplegia also normal?

The accuracy, reaction and movement time of pointing movements to visual targets were examined in children aged 3-13 yr with infantile hemiplegia and compared to those of comparably aged normal children. Hemiplegic children pointed with the "good" hand (i.e. ipsilateral to the lesion). Half the normal children used the preferred hand, half the non-preferred hand. Movements were made with unrestricted/restricted visual feedback, when movement distance was short/medium/long, and when number of target alternatives were 2/4/8. Normal children using the preferred hand were more accurate but reacted more slowly than children using the non-preferred hand. The performance of most of the hemiplegic children with bilateral and/or unilateral lesions was impaired; degree of accuracy was related to the extent of the brain lesion; and reaction time was related to the level of intelligence. It was concluded that unilateral lesions in children can result in bilateral visuomotor impairment.

Adolescent↗

PubMed1989

Guidance of visual reaching with the aid of a TV monitor: the effects of monitor position and of left/right and up/down reversals of the image in relation to age.

Children, aged 2-9 years, were seated alongside a wall containing an opening through which they could reach with their preferred hand. Targets ("ink blots"), which could not be felt, were attached to the other (rear) side of the wall, around the opening. The child could see directly neither the target nor its hand beyond the front side of the wall; but both were visible on a TV monitor. The image on the screen of the monitor originated from a camera viewing the rear (target) side of the wall at the level of the central opening. The monitor screen was either (a) parallel to the wall, but rotated 180 degrees with respect to the axis of the camera, i.e. facing the camera; or (b) at 90 degrees to the wall; or (c) in a position similar to (a) but visible in a mirror attached to the front side of the wall and therefore in effect "aligned" with the axis of the camera. The image the child saw was either (1) electronically unswitched, i.e. when the target was towards the east on the wall it was to the west on the monitor in monitor position (a), or to the north in position (b), or to the "east" in position (c); or (2) left/right reversed relative to (1); or (3) up/down reversed relative to (1); or (4) both left/right and up/down reversed. The dependent variable was the time taken for the child to place the palm of the hand over the target (time was measured to 0.1 sec on video-recorder with a superimposed time display). Position of the monitor, comparing conditions (a)-(c), gave only minor, perhaps age-related, effects. Left/right reversals were easier than up/down reversals under monitor positions (a) and (b), but not under (c); but both reversals could be achieved by age 3 or older; hardest was condition (4). However, with monitor positions (a) and (b) children, at all ages we tested, found condition (1) ("east gives west/north") easier than (2) ("east gives east/south"), whereas for adults these conditions were equally easy, or they found (2) easier than (1); but with monitor position (c) condition (1), now "east gives east", was easiest. Moreover, the claim that chimpanzees but not monkeys can achieve accurate reaching under the conditions varied in this study seems premature: the chimpanzees may have made use of strategies based on uncontrolled cues.

Attention↗

PubMed1988

The relationship between metaphoric and crossmodal abilities during development.

Metaphoric and crossmodal abilities were investigated in children, aged 3-8 years. For this study metaphoric performance was regarded as based on the production of a relationship between physically dissimilar stimuli (presented in two sense-modalities), which are not normally perceived as being related. It was asked at what age crossmodal performance, based on specific rather than global/categorical differences within stimulus pairs, can be regarded as distinct from metaphoric performance. In Expt. 1, metaphoric and crossmodal two-trial "recognition" tasks were given in Touch and Vision at all ages. In Expt. 2,3- and 4-year-olds were first trained over 6-20 trials to choose one of two stimuli in one modality (Touch or Vision) and then given one "recognition" trial in the alternate modality. Children as young as three could relate specific physical stimulus differences across sense-modalities. Although metaphoric recognition was present on two problems in children aged 3 and 4 years, metaphoric performance was inferior to crossmodal performance at all ages. Crossmodal abilities improved with age due to improved intramodal skills; such intramodal improvement can probably account for only a part of the improvement on the metaphoric task. Reasons are given why metaphoric and crossmodal abilities may be separate over the age range 3-8 years.

Child↗

PubMed1987

Differential accuracy of aimed movements to visual and somatic targets in young children.

Children, aged 2.5-8 years, were required to touch accurately a target located either on their bodies or on the chair in which they sat. Movements were made when visual information was: 1. complete (target lit for 3 s, room illuminated); 2. partial (target lit for 3 s, room dark); 3. reduced (target lit for 0.7 s, room dark); and finally, when the target was somatically specified. Movements to visible targets did not differ in any important way as a function of target location with respect to on/off body. Accuracy improved with age to visually but noto somatically specified targets, decreased with decreasing availability of visual information, and was poorest to somatically specified targets. We conclude that during development, the sense-modality through which the target is specified and the visibility of the arm/hand during the movement, but not the personal/extra personal visible space in which the target is located, are important determinants of reaching performance.

Child↗

PubMed1986

The accuracy of aimed movements to visual targets during development: the role of visual information.

Children aged 1.5 to 8 years were required to touch accurately an illuminated target lamp located on a vertical board. Movements were made when visual information was complete (target lit for 3 s, room illuminated; partial (target lit for 3 s, room dark, and reduced (target lit for 0.7 s, room dark). Dependent variables were response accuracy, reaction time, and movement time. Accuracy decreased with decreasing availability of visual information and improved with age under all conditions. Reaction times were shorter in the dark (Conditions 2 and 3) than in the light; they decreased with age up to age 5 and did not continue to decrease thereafter. Movement time did not change with age under Conditions 1 and 3 but tended to increase with age under Condition 2. Slower movements were more accurate at all ages, provided visual feedback could be utilized. Increased reliance on the strategy "slower movements yield higher accuracy" was held to account for developmental changes under Condition 2, whereas in Conditions 1 and 3 improvement in the efficiency of motor preprogramming was implicated.

Age Factors↗

PubMedDate not supplied

Perceptual categorization is associated with sensory performance in patients with unilateral cerebral lesions.

In this investigation of perceptual categorization (PC), .right-sided brain-damaged patients (RBD) were not impaired for PC of line drawings of animals relative to left-sided brain-damaged (LBD) patients, contrary to what was expected from previous work. Moreover, in both LBD and RBD patients PC performance was significantly associated with performance on a series of 6 sensory tests. These differed from conventional tests in that successive comparisons were required; and in 2 of the 6 tests gratings were discriminated.

Brain↗

PubMedDate not supplied

Long-term neuropsychological outcome after severe head injury with good recovery.

The quality of outcome after severe closed head injury has become of increasing concern to neurosurgeons. The assessment of residual deficits in patients who have recovered from closed head injury can be very difficult. Many patients are classified as having a good recovery according to the Glasgow Outcome Scale (GOS), but this may be insufficiently focused or sensitive to demonstrate mental deficits objectively. We investigated 33 patients with severe closed head injury who subsequently were diagnosed as having made a good recovery according to the GOS. The severity of the injury was determined by the Glasgow Coma Scale (GCS) and by the presence of a midline shift in the preoperative CT scans. There was a minimal interval of 15 months (means = 1080.5 days, SD = 491 days) between injury and time of neuropsychological testing. Their performance was compared with that of 15 orthopaedic cases. Residual neuropsychological deficits can be demonstrated on the majority of measures in a group of patients who have achieved good recovery on the GOS. Midline shift in preoperative CT scans is not of prognostic value for long-lasting neuropsychological deficits.

Activities of Daily Living↗