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Biomedical subjects

E Ladavas

Publications and source records attributed to E Ladavas.

10 recordsLinked to original sources
PubMed2004

Hemispatial neglect: Subtypes, neuroanatomy, and disability.

OBJECTIVE: To assess the relative frequency of occurrence of motor, perceptual, peripersonal, and personal neglect subtypes, the association of neglect and other related deficits (e.g., deficient nonlateralized attention, anosognosia), and the neuroanatomic substrates of neglect in patients with right hemisphere stroke in rehabilitation settings. METHODS: The authors assessed 166 rehabilitation inpatients and outpatients with right hemisphere stroke with measures of neglect and neglect subtypes, attention, motor and sensory function, functional disability, and family burden. Detailed lesion analyses were also performed. RESULTS: Neglect was present in 48% of right hemisphere stroke patients. Patients with neglect had more motor impairment, sensory dysfunction, visual extinction, basic (nonlateralized) attention deficit, and anosognosia than did patients without neglect. Personal neglect occurred in 1% and peripersonal neglect in 27%, motor neglect in 17%, and perceptual neglect in 21%. Neglect severity predicted scores on the Functional Independence Measure and Family Burden Questionnaire more accurately than did number of lesioned regions. CONCLUSIONS: The neglect syndrome per se, rather than overall stroke severity, predicts poor outcome in right hemisphere stroke. Dissociations between tasks assessing neglect subtypes support the existence of these subtypes. Finally, neglect results from lesions at various loci within a distributed system mediating several aspects of attention and spatiomotor performance.

Activities of Daily Living↗
PubMed2000

Ventriloquism in patients with unilateral visual neglect.

Can visual stimuli that go undetected, because they are presented in the extinguished region of neglect patients' visual field, nevertheless shift in their direction the apparent location of simultaneous sounds (the well-known 'ventriloquist effect')? This issue was examined using a situation in which each trial involved the simultaneous presentation of a tone over loudspeakers, together with a bright square area on either the left, the right or both sides of fixation. Participants were required to report the presence of squares, and indicate by hand pointing the apparent location of the tone. Five patients with left hemineglect consistently failed to detect the left square, either presented alone or together with another square on the right. Nevertheless, on bimodal trials with a single undetected square to the left, their sound localization was significantly shifted in the direction of that undetected square. By contrast, in bimodal trials with either a single square on the right or a square on each side, their sound localization showed only small and non-significant shifts. This particular result might be due to a combination of low discrimination of lateral sound deviations with variable individual strategies triggered by conscious detection of the right square. The important finding is the crossmodal bias produced by the undetected left visual distractors. It provides a new example of implicit processing of inputs affected by unilateral visual neglect, and on the other hand is consistent with earlier demonstrations of the automaticity of crossmodal bias.

Aged↗
PubMed1987

Is the hemispatial deficit produced by right parietal lobe damage associated with retinal or gravitational coordinates?

The hypothesis that right posterior parietal lesions cause two attentional deficits, namely, a reduced reactivity to stimuli in the left visual field (LVF), and a reduced reactivity to any stimulus which occupies a relative left position, was tested in 8 patients with an extinction syndrome. In Experiments 1 and 2 the first hypothesis was tested by measuring reaction times (RTs) to visual stimuli presented in the LVF and in the RVF, whereas the second hypothesis was tested by measuring RTs to stimuli totally positioned in the LVF, and in the RVF. The results showed that RTs to stimuli which occupied a relative left position were longer than RTs to stimuli which occupied a relative right position independent of the visual field stimulated and RTs to LVF stimuli were longer than RTs to RVF stimuli. Experiment 3 was designed to examine whether the attentional deficit associated with right parietal damage was mostly related to the use of gravitational rather than to retinal coordinates. In this experiment the patients tilted the head either to the left or the right by 90 deg and they responded to two stimuli displayed above and on either side of a fixation mark. The results showed that the difficulty in attending to the left was related both to the gravitational and the retinal frames of reference.

Aged↗
PubMed1985

Intellectual function in long-term survivors of childhood acute lymphoblastic leukemia.

21 off-therapy ALL patients treated with chemotherapy plus cranial irradiation were assessed using the Wechsler Intelligence Scale for Children and compared with a group of 15 off-therapy solid tumor children treated with chemotherapy and extracranial irradiation. Children with leukemia achieved lower IQ scores than children with solid tumors. The ALL group was divided in two subgroups, by onset of disease and beginning of treatment: before (13 subjects) and after (8 subjects) 5 years of age. The results indicate that the disturbance of intellectual functioning is produced in ALL children irradiated after 5 years of age. In order to check on a possible delayed intellectual deterioration, all ALL children were also tested twice, with one year interval between the two tests. On the second assessment the scores for each subject were essentially the same as before. Further studies on a large number of long term survivors are being carried out in order to find out whether the deficit is transient or permanent.

Age Factors↗
PubMed1984

Right hemisphere interference during negative affect: a reaction time study.

Two experiments are described in which simple reaction times (RTs) to lateralized visual stimuli were measured in normal subjects during negative affect and during recollection of everyday life scenes. In both experiments the mental activity produced a remarkable increase of RTs with respect to a control situation without interfering activity. During production of the negative affect there was a selective lengthening of RTs mediated by the right hemisphere. The role of the right hemisphere in producing emotions is discussed.

Adult↗
PubMed1984

Must egocentric and environmental frames of reference be aligned to produce spatial S-R compatibility effects?

Four experiments were conducted to determine the effects of misaligning egocentric and environmental frames of reference on spatial S-R compatibility effects. In Experiments 1 and 3, subjects looked at two lights that were aligned horizontally, one each on either side of the body midline. They held their head upright or tilted 90 degrees to the left or right. In the upright condition the hands were uncrossed and rested opposite the lights (frames of reference aligned), whereas in the head tilt condition the hands were either crossed or uncrossed but positioned perpendicular to the lights (frames of reference not aligned). Manual choice reaction times to the lights produced spatial S-R compatibility effects that were as large when the frames of reference were aligned as when they were not. In Experiments 2 and 4, which also used upright and tilted conditions, we found generally similar results when the lights were displayed vertically and the hands disposed horizontally. The results indicate that under conditions of head rotation and with stimulus and response arrays perpendicular to each other, spatial S-R compatibility effects still occur. By taking into account both frames of reference, the subject classifies the stimuli as left or right whether they are horizontally or vertically disposed and maps them onto the responding hand, thereby producing the observed compatibility effects.

Choice Behavior↗
PubMed1980

Neuropsychological performances in patients treated with different antiepileptic drugs.

Twenty-six patients, suffering from various forms of epilepsy (2 with simple partial, 14 with complex partial, and 10 with generalized seizures) and treated with different drugs (10 with DPH, 10 with PB, and 6 with CBZ), underwent neuropsychological tests in order to evaluate: 1) Vigilance; 2) attention; 3) motor, sensory and adaptive (visuomotor) performances; 4) memory span, short-term and long-term memory, considering verbal as well as spatial aspects. The battery of tests was administered prior to treatment and when the drug plasmatic levels were within the ranges considered therapeutic. The results show that in the case of DPH there is an improvement of vigilance and adaptive performances but a worsening of attention and memory functions. With PB, only motor and adaptive performances improve; all other functions worsen. Finally, with CBZ, vigilance, attention, sensory performances and memory functions are unmodified while only motor and adaptive performances appear to improve.

Adult↗