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Biomedical subjects

A Bouma

Publications and source records attributed to A Bouma.

86 records · Page 5Linked to original sources
PubMed1987

Effects of concurrent spatial and verbal memory loads on serial position functions of laterally presented letter strings.

In this study the influence of visuospatial and verbal memory loads on the identification of laterally presented letter strings was investigated. In the asymmetry task without concurrent loads, a clear right visual field advantage for letter identification was obtained. Hemisphere-specific effects due to concurrent loads were particularly observed when the difficulty of the load tasks was increased. The effects of visuospatial loads were found to be sex related, suggesting that under heavy load conditions mental rotation selectively overloads the processing capacity of the right hemisphere in males, while in females capacity limitations were observed in both hemispheres. Concurrent visuospatial loads produced more facilitation (or less interference) for letters in the outermost positions of each visual field than for letters in the innermost positions of each visual field. The results of the verbal memory load tasks revealed that an easy verbal load task facilitated performance which was particularly manifest for the right-most letter of both the left visual field and the right visual field. A difficult verbal memory load task interfered with recognition accuracy of letters which was most marked for the center letter in the right visual field. Letter position effects obtained in this study were interpreted in terms of various processing mechanisms influencing the serial position curves.

Adult↗
PubMed1987

Birth stress, autoimmune diseases, and handedness.

A large nonclinical sample of left-handed and right-handed subjects completed laterality and medical health questionnaires. The group of left-handed subjects showed a raised incidence of birth complications and learning disorders whereas no differences were found for birth order and maternal age. Left-handed and right-handed subjects showed similar incidences of autoimmune diseases, allergies, migraine, and stuttering. These results suggest that an association between early pathology and left-handedness may be found in a subset of the nonclinical left-handed population. The underlying pathological influence seems to manifest itself in pregnancy and birth complications rather than in immune disorders.

Adult↗
PubMed1986

Task effects and individual differences in the study of lateral eye movements.

Twenty-nine males and 29 females (all right-handed) participated in this study. The effects of question type (numerical, verbal, spatial) and experimenter position (in front of or behind the subject) on direction of lateral eye movements (LEMs) were tested. Also the relation between dominant LEM direction and other individual traits was investigated. The percentage of LEMs (tonic changes) as well as the first LEM (phasic changes) in the reflective period was scored. Results were identical for both methods; there were no task-specific effects demonstrated, nor was a relation found between dominant LEM direction and imagery, extraversion, neuroticism, sensation seeking, impulsiveness, and amount of somatic and psychic complaints. It appeared that the extent to which subjects gazed away varied with the amount of stress that was induced, while the direction of glance depended on the individual habit of the subject. The conclusion was that LEMs are subject specific rather than task specific and that this individual specificity is strengthened under stress conditions.

Cerebral Cortex↗
PubMed1986

Hemispheric distribution of ERP components and word naming in preschool children.

Event-related potentials (ERPs) were recorded at the left and right temporal and parietal sites during a word-naming task in 61 children ranging in age from 5.1 to 6.2 years. Principal component analysis (PCA) was performed on the average ERP waveforms. Analyses of the factor scores revealed that the P240, N380, and SW components were asymmetrically distributed over the hemispheres. Fast reading acquisition was associated with smaller N380 and larger SW activity than slow reading acquisition. Multiple regression analyses indicated that only right hemispheric ERP components were significantly associated with rate of reading acquisition. These findings are discussed in terms of right hemispheric involvement in early reading acquisition.

Brain Mapping↗
PubMed1985

Effects of visual-field and matching instruction on event-related potentials and reaction time.

Vertical letter pairs were presented randomly in the left and right visual hemifields in a physical identity match and name identity match condition. The reaction times showed a right visual field superiority for name matches, and a left visual field superiority for physical matches. Event-related potentials to letter pairs showed a sequence of three waves: a negative wave (N2, around 270 msec), a positive wave (P3, around 500 msec), and a broad positive slow wave (SW, around 600-700 msec), respectively. P3 and SW amplitudes were consistently larger at the left hemisphere than at the right hemisphere, regardless of the field of stimulation. At both hemispheres, N2 waves were always larger to stimuli presented in the visual field contralateral to a hemisphere than stimuli presented in the visual field ipsilateral to a hemisphere. The positive waves (P3, SW) showed the opposite pattern: smaller amplitudes to stimuli that were presented contralaterally than stimuli that were presented ipsilaterally to a given hemisphere. These results were attributed to a shift in sustained negativity on the directly stimulated hemisphere, relative to the indirectly stimulated hemisphere, reflecting either sensory at attentional processes in the posterior cerebral hemispheres.

Adult↗
PubMed1984

Dichotic listening and tactual mental rotation in females as a function of familial sinistrality and strength of handedness.

In this study the effects of familial sinistrality and strength of handedness on dichotic listening and tactual mental rotation were investigated. Nonfamilial left-handers were inferior to familial left-handers, particularly in right-ear performance. The decrement in right-ear performance is interpreted as indicative of a pathologically functioning left hemisphere in nonfamilial left-handers. The direction of ear asymmetry tends to be more predictable in strong left-handers than in weak left-handers, with nonfamilial strong left-handers showing a significant left-ear superiority and familial strong left-handers a nonsignificant right-ear superiority. In the tactual mental rotation task, the results suggest a preference of left-handers for a verbal encoding strategy, especially in the right hemisphere. This preferential strategy is particularly manifest in familial weak left-handers and nonfamilial strong left-handers. The results are discussed in terms of their implications for underlying patterns of cerebral organization in the left-handers.

Adult↗
PubMed1983

Individual differences in mode of processing in visual asymmetry tasks.

Three experiments were carried out to investigate whether individual differences in the perceptual factors of Closure speed (Cs) and Closure flexibility (Cf) are related to patterns of visual asymmetry. It was predicted that high-Cs subjects would demonstrate a relatively greater readiness for wholistic processing, whereas high-Cf subjects would show a relatively greater readiness for analytic processing. Subjects were administered a battery of perceptual tests. On the basis of their factor scores, forty subjects were assigned to one of four groups: low-Cs, high-Cs, low-Cf and high-Cf. Each subject participated in three tachistoscopic tasks: one verbal recall task and two binary classification tasks with visuo-spatial material. From previous studies, these tasks appeared to foster either analytic or configurational processing. The results indicated that the interaction between individual differences in proficiency in wholistic and analytic processing and task characteristics may be of great importance in the way in which the left and right hemispheres are involved in the processing of visual stimuli.

Color Perception↗
PubMedDate not supplied

The influence of maternal immunity on the development of the in vitro lymphocyte proliferation response against pseudorabies virus in pigs.

In this study, the influence of maternal immunity against pseudorabies virus (PRV) on the development of a PRV-specific T-cell response in pigs was investigated. Pigs with or without maternal immunity were challenged by inoculation with wild-type PRV, or were vaccinated with 783 and subsequently inoculated. Peripheral blood lymphocytes, collected after vaccination and/or inoculation, were used for PRV-induced lymphocyte proliferation assays in vitro as a measure of a PRV-specific T-cell response. In unvaccinated pigs, the presence of maternal immunity did not inhibit the development of a T-cell response after inoculation with PRV. In contrast, maternal immunity did inhibit the development of a PRV-induced response after intramuscular vaccination. Moreover, vaccinated pigs without maternal immunity shed virus for a shorter period after inoculation than vaccinated pigs with maternal immunity. The greater T-cell response induced by the vaccine might have contributed to the more rapid clearance of PRV in these pigs.

Animals↗
PubMedDate not supplied

Acute versus chronic pain experience in Alzheimer's disease. a new questionnaire.

The low use of analgesics in patients with Alzheimer's disease (AD), compared to nondemented elderly persons, is generally explained by (1) a lower prevalence of painful conditions in the former group and (2) undertreatment of pain due to a decrease in communicative abilities in AD. However, considering the neuropathology in limbic areas in this disorder, a decline in pain affect may also explain this phenomenon. In the present study, a newly developed questionnaire was applied to 20 elderly persons without dementia, 20 patients in an early stage and 20 patients in a midstage of AD. The questionnaire includes 10 pairs of painful situations, each pair consisting of an acute and a chronic affective painful situation. It was hypothesized that, compared to controls, AD patients during the course of the disease would report to suffer increasingly more from an acute than from a chronic, affective painful situation. The results support our hypothesis. Limitations of the present study are discussed.

Acute Disease↗
PubMedDate not supplied

Visual analogue scales for pain assessment in Alzheimer's disease.

BACKGROUND: In earlier studies, pain assessment in patients with Alzheimer's disease (AD) was conducted by interview, for which reliability is questionable considering the decline in expressive and receptive language abilities in AD. As similar language problems occur in young children, the reliability of pain assessment in this latter population is increased by employing visual analogue scales. OBJECTIVE: By employing visual analogue scales, the current study investigated whether (1) nondemented elderly persons and AD patients comprehend the purpose of the scales and (2) AD patients, compared to nondemented elderly persons, report suffering less pain intensity and pain affect. METHODS: Three visual analogue scales, i.e. the Colored Analogue Scale (CAS), the Faces Pain Scale (FPS), and the Facial Affective Scale (FAS) were administered to patients in an early and midstage of AD and to nondemented elderly persons. RESULTS: The results show that the percentage of subjects who comprehended the CAS, FAS and FPS was for the nondemented elderly persons 100, 75 and 100%, respectively, for the early AD group 100, 50 and 60%, respectively, and for the midstage AD group 80, 20 and 30%, respectively. Furthermore, elderly persons without dementia reported experiencing more intense pain and pain affect than the early and midstage AD group. Interestingly, the early and midstage AD patients did not differ in reporting pain affect. CONCLUSION: Visual analogue scales may improve pain assessment in those AD patients who fully comprehend the meaning of the scales. As only the minority of midstage AD patients understood the purpose of the FAS and FPS, the search for tools, particularly to assess pain affect in this population, must continue.

Alzheimer Disease↗
PubMedDate not supplied

Repeated pain assessment in Alzheimer's disease.

In previous studies, patients with probable Alzheimer's disease (AD) have indicated that they experienced less pain intensity and affect from their painful conditions than nondemented elderly persons. However, in those studies, pain assessment occurred only once. Therefore, it may be possible that pain which had occurred, for example, a day earlier, could have been forgotten. Therefore, in the present study, AD patients' pain was assessed daily, i.e. once a day and even three times a day, during a longer period. The results parallel those of earlier studies, i.e. compared to elderly persons without dementia, AD patients appear to perceive less pain intensity and pain affect. These findings support the hypothesis that AD is characterized by an alteration in pain experience.

Aged↗
PubMedDate not supplied

Hemisphere-specific treatment of dyslexia subtypes: a field experiment.

Evidence is discussed to show that so-called L- and P-type dyslexia result from deviations in the development of hemispheric subservience in learning to read. Investigations into the validity of the L/P classification are reviewed, as are laboratory experiments on the effects of so-called hemisphere-specific stimulation (HSS). In the present field experiment, 28 L-dyslexic children (mean chronological and reading age 10.6 and 7.5 years, respectively) received HSS of the right hemisphere by the presentation of words to the fingers of the left hand, and 26 P-dyslexic children (mean chronological and reading age 9.4 and 7.2 years, respectively) received HSS of the left hemisphere by the presentation of words to the fingers of the right hand. Control L and P subjects were treated according to the discretion of the remedial teacher. The results underscore the findings of previous laboratory experiments in that (a) HSS-treated L-dyslexics, relative to controls, tended to show larger improvement of accuracy in text reading; and (b) HSS-treated P-dyslexics, relative to controls, showed larger improvement of fluency in word reading.

Child↗
PubMedDate not supplied

Possible role of the nucleus raphe dorsalis in analgesia by peripheral stimulation: theoretical considerations.

Direct stimulation of the Nucleus Raphe Dorsalis (NRD) appears to be very effective for obtaining analgesia. However, the possible role of the NRD in analgesia by peripheral stimulation, e.g. electro-acupuncture or Transcutaneous Electrical Nerve Stimulation (TENS), has received less attention. Most studies indicate that in particular the nucleus reticularis gigantocellularis, the nucleus raphe magnus, the nucleus reticularis magnocellularis, the locus coeruleus, and the periaqueductal grey may participate in the supraspinal mechanism for the antinociceptive effect of peripheral stimulation. This paper is meant to present some theoretical considerations about the role of the NRD might play in analgesia by peripheral stimulation. Little direct evidence suggests that the NRD/serotonergic system might contribute to this type of analgesia. The analgesic role of specifically the serotonergic neurons of the NRD in peripheral stimulation could be supported by indirect evidence. From studies concerning direct stimulation of the NRD, two other mechanisms by which peripheral stimulation might exert antinociceptive effects through the NRD have been hypothesized. Stimulation-parameters affecting the effectiveness of peripheral NRD stimulation will be discussed.

Acupuncture Analgesia↗