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Biomedical subjects

B J Casey

Publications and source records attributed to B J Casey.

64 records · Page 4Linked to original sources
PubMed1995

Activation of prefrontal cortex in children during a nonspatial working memory task with functional MRI.

Functional magnetic resonance imaging (fMRI) was used to examine the pattern of activity of prefrontal cortex in prepubertal children during performance of a nonspatial working memory task. The children observed sequences of letters and responded whenever a letter repeated with exactly one nonidentical letter intervening. In a comparison task, subjects monitored similar sequences of letters for any occurrence of a single, prespecified target letter. Location of activation closely approximated that observed in a recent fMRI study with adults using exactly the same task. Activation of the inferior and middle frontal gyri was reliably observed within individual subjects during performance of the working memory task relative to the comparison task. Activation increased and decreased with a time course that was highly consistent with the task manipulations and correlated with behavioral performance. To our knowledge, this study is one of the first to demonstrate the applicability of fMRI to a normative developmental population. Issues of age dependence of the hemodynamic responses of fMRI are discussed.

Adult↗
PubMed1994

Quantitative morphology of the corpus callosum in attention deficit hyperactivity disorder.

OBJECTIVE: By means of quantitative neuroanatomic imaging the authors assessed the hypothesis that there are structural brain abnormalities relevant to frontal lobe circuitry in children with attention deficit hyperactivity disorder (ADHD). METHOD: The midsagittal cross-sectional area of the corpus callosum, divided into seven sections, was measured from magnetic resonance images of 18 boys with ADHD and 18 carefully matched normal boys. RESULTS: Two anterior regions, the rostrum and the rostral body, were found to have significantly smaller areas in the ADHD group. These areas correlated in the expected direction with teacher and parent ratings of hyperactivity/impulsivity. CONCLUSIONS: This finding supports theories of abnormal frontal lobe development and function in ADHD.

Adolescent↗
PubMed1993

Dysfunctional attention in autistic savants.

A dysfunctional attention hypothesis of the basis of savant skills was tested with a series of computerized tasks that assessed the ability to divide, shift, direct, and sustain attention. Ten healthy men with pervasive developmental disorders and unusual calendar-calculating skill, and 10 age- and sex-matched controls were tested. There were four general findings. First, the savants and controls did not differ on a measure of visual sustained attention. Second, the savants failed to detect rare auditory targets significantly more than did the controls. Third, the savants were unable to efficiently divide their attention when required to detect both visual and auditory targets simultaneously. Finally, deficient orienting or a deficit in shifting selective attention from one stimulus location to another was evidenced in overall slower reaction times for the savants across tasks requiring shifts and redirecting of attention. This deficit was attributed to an inability to disengage attention as a result of deficient orienting and overselectivity.

Acoustic Stimulation↗
PubMed1993

Sydenham's chorea: physical and psychological symptoms of St Vitus dance.

Eleven children with Sydenham's chorea (8 girls and 3 boys, mean age = 8.4 +/- 2.2 [SD] years) underwent comprehensive physical, neuropsychologic, and psychiatric examination. The chorea was manifested as dysarthria, gait disturbances, and frequent adventitious movements of the face, neck, trunk, and extremities. Antineuronal antibodies were present in 10 of 11 children. All children exhibited concomitant psychologic dysfunction, specifically obsessive-compulsive symptomatology, increased emotional lability, motoric hyperactivity, irritability, distractibility, and age-regressed behavior. Obsessive-compulsive symptoms were observed in 9 (82%) children, 4 of whom met diagnostic criteria for obsessive-compulsive disorder. These behavioral symptoms began several days to weeks before the chorea was observed, and they waxed and waned in severity along with the motoric abnormalities. These results suggest that psychologic, particularly obsessive-compulsive, symptoms are accompanying manifestations of Sydenham's chorea which may require medical attention.

Affective Symptoms↗
PubMed1991

A refractory period for the heart rate response in infant visual attention.

A refractory period for the heart rate (HR) response of 14-, 20-, and 26-week-old infants to second stimulus onset and primary stimulus offset during termination of visual attention was investigated. A stimulus that elicited a significant HR deceleration was presented. Following the return of HR to prestimulus level, a second stimulus occurred or the first stimulus ended at time delays of 0, 3, 6, and 9 s. If the second stimulus occurred at 0 or 3 s after HR returned to its prestimulus level, the HR response was smaller than the initial HR orienting response (OR). A usual HR OR resulted by waiting 6-9 s after the return of HR to prestimulus level. A significant offset response occurred only for the 6-sec delay. Active inhibition of vagal cardiac activity during attention termination may cause the observed refractory period in the HR response, which appears to last from 3-6 s following sustained attention.

Age Factors↗
PubMed1991

Heart rate variability during attention phases in young infants.

Heart rate variability during visual attention was studied in infants who were tested cross-sectionally at 14, 20, or 26 weeks of age. They were presented with a recording of a Sesame Street program on a TV screen. After heart rate had decelerated below the prestimulus level and then returned to prestimulus level, a computer-generated pattern replaced the Sesame Street display. Heart rate variability changed throughout attention. The change consisted of a decrease in variability during attention and a return to prestimulus levels approximately five seconds following attention termination. The heart rate and variability responses are consistent with a model of parasympathetic vagal influence on the heart in which vagal firing is increased during sustained attention and is inhibited during attention termination.

Arrhythmias, Cardiac↗
PubMed1988

Sustained visual attention in young infants measured with an adapted version of the visual preference paradigm.

Phases of infant visual attention were studied using a visual preference procedure that was modified to be similar to a "dual-task," interrupted stimulus procedure. Infants were tested in a cross-sectional design at 14, 20, or 26 weeks of age. The infants were presented with varying and complex TV patterns on a TV monitor. At a delay from the onset of fixation on this stimulus, a similar pattern was presented on an adjacent TV monitor within the infant's field of vision. This secondary stimulus was presented either when heart rate (HR) decelerated significantly below prestimulus level or when the HR returned to prestimulus level. These 2 conditions correspond to sustained attention and attention termination phases of visual attention. The infants were less easily distracted by the secondary stimulus when HR was lower than prestimulus level than when it had returned to prestimulus levels. The amount of HR slowing on the HR deceleration trials increased over this age range, suggesting a developmental increase in sustained attention across this age range. The HR response at the time the infant looked at the secondary stimulus was different for the 2 delay conditions and differed from the HR response at primary stimulus onset. These results confirm the existence of distinct phases of attention during the visual preference procedure and suggest a refinement of the use of simple fixation time as a measure of infant attention with this procedure.

Arousal↗
PubMedDate not supplied

Quantitative magnetic resonance imaging of human brain development: ages 4-18.

Brain magnetic resonance images (MRI) of 104 healthy children and adolescents, age 4-18, showed significant effects of age and gender on brain morphometry. Males had larger cerebral (9%) and cerebellar (8%) volumes (P < 0.0001 and P = 0.008, respectively), which remained significant even after correction for height and weight. After adjusting for cerebral size, the putamen and globus pallidus remained larger in males, while relative caudate size was larger in females. Neither cerebral nor cerebellar volume changed significantly across this age range. Lateral ventricular volume increased significantly in males (trend for females), with males showing an increase in slope after age 11. In males only, caudate and putamen decrease with age (P = 0.007 and 0.05, respectively). The left lateral ventricles and putamen were significantly greater than the right (P = 0.01 and 0.001, respectively). In contrast, the cerebral hemispheres and caudate showed a highly consistent right-greater-than-left asymmetry (P < 0.0001 for both). All volumes demonstrated a high degree of variability. These findings highlight gender-specific maturational changes of the developing brain and the need for large gender-matched samples in pediatric neuropsychiatric studies.

Adolescent↗