Biomedical subjects

V Frisk

Publications and source records attributed to V Frisk.

8 recordsLinked to original sources

PubMed2006

Motion-defined form processing in extremely premature children.

Children born extremely prematurely are at risk for a variety of problems with motion analysis, including problems with motion-defined (MD) form recognition [Downie, A. L. S., Jakobson, L. S., Frisk, V., & Ushycky, I. (2003). Periventricular brain injury, visual motion processing, and reading and spelling abilities in children who were extremely-low-birthweight. Journal of the International Neuropsychological Society, 9, 440-449]. The aims of the present study were (1) to examine the impact of retinopathy of prematurity (ROP) and mild periventricular brain injury (PVBI) on MD form processing in this population; (2) to assess relationships between MD form recognition in these children and their performance in several other areas of visual competence. To this end, a battery of visual and visuomotor tests was administered to 43, 5- and 6-year old, extremely premature children, all of whom had escaped severe PVBI. A group of full-term controls was also studied. Relative to controls, premature children displayed clear deficits in MD form recognition and these deficits were related to the presence of ROP and/or mild PVBI, rather than to a history of prematurity per se. Regression analyses revealed significant associations in premature children between MD form processing deficits and problems with visual search, stereopsis, visuoconstructive and graphomotor skills, motor development, and Performance IQ. The results suggest that assessment of sensitivity to MD forms may be useful in the early identification of preterm children at greatest risk for visual problems associated with dorsal stream dysfunction.

Analysis of Variance↗

PubMed2001

The relationship between periventricular brain injury and deficits in visual processing among extremely-low-birthweight (< 1000 g) children.

OBJECTIVE: To examine the relationship between neonatal, periventricular brain damage and visuomotor performance in extremely-low-birthweight (ELBW) children of normal intelligence whose birthweights were appropriate for gestational age (AGA). METHODS: Seventy-eight ELBW and 23 control children, all six years of age, completed two "motor-free" tests of visual spatial ability and three tests requiring visuomotor control. RESULTS: Full-term control children outperformed ELBW children with periventricular brain damage on all three tests requiring visuomotor guidance. No group differences were found on two "motor-free" tests of visual spatial ability. ELBW children without periventricular brain damage performed in a manner indistinguishable from controls on all tests included in this study. CONCLUSIONS: The findings indicate that the presence and severity of periventricular brain injury are important factors to consider in predicting visuomotor development in ELBW children.

Child↗

PubMed2000

Hypothyroxinemia of prematurity and infant neurodevelopment: a pilot study.

To assess whether hypothyroxinemia has specific effects on neurodevelopment in premature infants, thyroid hormone levels were determined at 2 weeks of life and 40 weeks postconceptional age (PCA), and infants were evaluated at 3 months corrected age using the Bayley Scales of Infant Development and Early Infancy Temperament Questionnaire. Additional attention scales were derived from the factor analysis of relevant Bayley items. Fifteen infants born between 30 and 35 weeks and 21 full-term infants were studied. Results indicated no group differences on the Bayley or derived attention scales, whereas the temperament questionnaire revealed lower sensory thresholds and greater reactivity in the preterm group. The preterm group had normal thyroxine (T4) levels at 2 weeks of age, which declined by 40 weeks PCA for both free T4 (p < .01 for reference value and p < .0001 for gestational age-adjusted value) and total T4 (p < .05 for age-adjusted value). Correlations revealed that higher 40-week PCA free T4 levels were associated with better attentiveness ratings (p < .01 for reference and p < .0001 for gestational-age values) and sustained attention (p < .05) and higher 40-week total T4 with better motor skills (p < .05 for gestational-age value). These findings signify that a mild degree of hypothyroxinemia is evident in preterm infants without neurological risk and predicts subsequently poorer cognitive and motor abilities.

Brain↗

PubMed1999

Neurophysiological measures of reading difficulty in very-low-birthweight children.

Twenty-four 8-10-year-old children (13 very low birthweight, 11 control) performed a lexical decision and a semantic classification task while event-related potentials (ERPs) were recorded. Both groups were within normal range on standardized reading tests, but the very-low-birthweight group had lower scores. There were no differences between groups in reaction times or accuracy for ERP tasks. On analyses of P2a (246 ms anteriorly), P2p (336 ms posteriorly), N2a (356 ms anteriorly), and N2p (396 ms posteriorly) peaks and a late positive component, control children showed greater right than left asymmetry at P2p and greater left than right asymmetry at N2a. Very-low-birthweight children showed less asymmetry. For the late positive component, both groups showed greater left than right asymmetry, which was more marked for the semantic classification task. The results suggest that very-low-birthweight children display differing cortical utilization during reading.

Child↗

PubMed1994

Developmental outcome of infants treated with extracorporeal membrane oxygenation (ECMO) in the neonatal period: is the evidence all in?

The North American literature was reviewed regarding the developmental outcome of infants treated with ECMO therapy versus those infants who received conventional medical therapy for treatment of persistent pulmonary hypertension of the newborn. The literature reviewed included all ECMO follow-up investigations published in medical journals cited in CD-ROM between January 1980 and July 1992, as well as abstracts presented at the Society for Pediatric Research 1990-1992. The literature was examined with respect to the incidence, prevalence and nature of morbidity, with particular attention paid to the neuroevelopmental domains assessed, test measures used, age at assessment and criteria for normal and abnormal outcome. Rough comparison of the published outcome statistics for the cohorts of infants who received neonatal ECMO therapy or conventional medical therapy (CMT) suggest equivalent amounts of morbidity within the first few years of life. Without appropriate systematic comparison at the same ages on the same measures and in infants with equivalent severity of illness, the current observations remain tentative at best. Longitudinal investigations are needed in order to identify specific medical and developmental markers in infancy of good and poor long-term outcome in this population, together with comparisons of outcome in the group treated with ECMO versus the group treated with CMT. Fine-grained, sensitive measures must be employed that record transient or permanent delays and/or qualitative deficits in specific skills.

Cerebral Hemorrhage↗

PubMed1991

Does left temporal lobectomy adversely affect the rate at which verbal material can be processed?

Fifty-three patients with unilateral temporal- or right frontal-lobe excision and 12 normal control (NC) subjects read words, sentences and stories presented at slow, normal or fast reading rates. No group differences were noted for the number of errors committed when reading single words or sentences. The left temporal-lobe group with large hippocampal excisions made more mistakes than the NC group when identifying false statements about the stories, but this increased error-rate occurred irrespective of the rate of stimulus presentation. These findings suggest that the critical feature affecting recall of stories after left temporal lobectomy is not the rate at which the information is presented but, rather, the amount of information that must be retained.

Adolescent↗

PubMed1990

The role of the left hippocampal region in the acquisition and retention of story content.

Thirteen normal control subjects and 62 patients who had undergone either a unilateral temporal or a unilateral frontal lobectomy learned the content of a short prose passage to a strict criterion. Compared to other subject, patients with left temporal-lobe excision took longer to learn the story content and, within this group, the slowest rate noted was for patients with extensive removal from the hippocampal region. When retention of the material was tested after a 20 min delay, only the group with large excisions from the left hippocampus and/or parahippocampal gyrus was impaired. This finding of abnormally rapid forgetting of material learned to criterion highlights the role of the left hippocampal region in the long-term maintenance of verbal information presented in a context.

Adolescent↗

PubMed1990

The relationship of working memory to the immediate recall of stories following unilateral temporal or frontal lobectomy.

Patients undergoing unilateral temporal lobectomy were tested preoperatively for working memory capacity, sentence comprehension, and rapid-naming ability, and were retested on these same measures 3 to 5 days and 2 weeks postoperatively. Immediate recall of stories was assessed twice only: preoperatively, and 2 weeks postoperatively. The left temporal-lobe group demonstrated transient deficits in working memory capacity, sentence comprehension, and rapid-naming ability over the 2 week postoperative period. No significant group differences in working memory capacity were evident two weeks after operation, even though the story recall of the left temporal-lobe group was impaired. A second experiment, with additional patients, explored the possible contribution of the hippocampus and of the frontal lobes to performance on these same tasks. Extent of hippocampal excision did not affect performance differentially on any task. Story recall was impaired following left temporal lobectomy, whereas left frontal lobectomy impaired sentence comprehension and rapid-naming ability. These results indicate a double dissociation of verbal deficits 2 weeks after left temporal- and left frontal-lobe excisions.

Adolescent↗