David W. Shucard

The significance of MRI abnormalities in children with neurofibromatosis

We prospectively evaluated 47 children with neurofibromatosis to determine whether the previously reported high signals on magnetic resonance imaging (MRI) (prolonged T2) correlated with CT, brainstem auditory evoked responses (BAER), EEG, clinical examinations, cognitive abilities, or seizure disorder. Thirty percent of children had a history of seizures and 70% had either learning disabilities or mental retardation. Overall, 74% had an abnormal MRI examination. Sixty-two percent had high signals (prolonged T2) on T2-weighted images. Abnormal signals were located primarily in the basal ganglia, brainstem, and cerebellum. Twenty-five percent of patients had abnormal EEGs, 28% had abnormal CTs, and 27% had abnormal BAER examinations. The abnormal signals on MRI did not consistently relate to findings on CT, BAER, EEG, school placement, or clinical examination. The abnormal signals presumably reflect areas of abnormal brain parenchyma, either hamartomas, heterotopias, or local areas of brain dysplasia.

Animal Models of Human Behavior

Other contributors to this volume have described intriguing evidence about possible biological substrata for attachment and affiliative behaviors. Such evidence suffers from being of necessity correlational. A statement of John Dobbing’s (1968) in reference to research on the behavioral effects of malnutrition is applicable here: Even the most sophisticated multifactorial analysis is no substitute for the experimental testing of hypotheses, and this can only be done with animals. It should be self-evident that experimental animal and human field studies must interdigitate if any conclusions are to be reached before the end of the present interglacial period. (p. 294)

The neuropsychological phenotype in turner syndrome

Numerous studies have demonstrated a significant depression in performance IQ (PIQ) in Turner Syndrome (TS) females, but the neuropsychological interpretation of this finding remains unclear. The present study addressed the following questions regarding the neuropsychological phenotype in TS: Are TS women neuropsychologically impaired? Is the impairment lateralized and How consistent is the neuropsychological phenotype across TS individuals? Unlike previous studies, the present study utilized both normal and brain damaged female controls. All subjects were given an extended Halstead-Reitan neuropsychological battery. The TS females were significantly worse than normals but not significantly different from brain damaged females in their overall level of neuropsychological functioning. However, their impairment was not lateralized. Their pattern of lateralizing findings was similar to that found in the Diffuse and Normal groups, but significantly different from either the right or left unilateral lesion groups. Fairly consistent deficits were found on tests of visuospatial skills and long term memory, but there was considerable variability in all the other test findings among TS individuals. The results are discussed in relation to the recent findings (Inglis and Lawson, 1981) that verbal-performance IQ discrepancies may be unreliable indicators of lateralized cerebral dysfunction in females. Hence the depressed PIQ in TS appears not to indicate predominantly right hemisphere dysfunction and may not even indicate a consistent underlying neuropsychological phenotype.

Functional neuroimaging of attention in the auditory modality.

PREVIOUS functional neuroimaging studies of attention have emphasized the visual modality. We developed an auditory version of the continuous performance test (CPT) that included simple, focused and divided attention conditions. Positron emission tomographic (PET) scans were acquired during CPT performance in normal young adults and then submitted to statistical parametric mapping. Simple attention brought about a large region of activation involving the anterior cingulate gyrus and the right anterior/mesial frontal lobe. Focused and divided attention CPT conditions were compared but there were few significant differences. The findings are consistent with activation of an anterior attention network during auditory attention, without involvement of posterior attention structures which are more likely to vary in accordance with sensory modality.

Stimulus modality and Go/NoGo effects on P3 during parallel visual and auditory continuous performance tasks

Task and modality effects on P3 latency, amplitude, and scalp topography were studied during parallel versions of visual (VCPT) and auditory (ACPT) continuous performance tasks using a Go/NoGo paradigm (A-X CPT). Both the ACPT and VCPT incorporated five conditions including Go and NoGo stimulus sequences as well as three other nontarget conditions. The goal was to evaluate the functional significance and modality specificity of the P300 response and the NoGo P3. Analyses were performed using both raw and normalized data to make comparisons across modalities. For both modalities, the Target X (Go) and three nontarget conditions elicited maximum P3 amplitudes over the posterior scalp sites and qualified as classical P300 responses. The NoGo condition was associated with an increase in central-frontal amplitude compared to the Target X condition. The scalp topography of the P300/P3 for Go and NoGo conditions, as well as all other conditions, was the same for both modalities, supporting the modality independent nature of both P300 and the NoGo P3. Min-Max normalization of P3 amplitudes did not change the condition-topography relationships.

Auditory evoked potentials and sex-related differences in brain development

Abstract Auditory evoked potentials (AEPs) were obtained to probe tones which were delivered during the presentation of complex verbal and nonverbal auditory stimulation to 3-month-old infants. Significant sex-dependent AEP amplitude asymmetries were found. Females produced higher-amplitude responses from the left hemisphere and males produced higher-amplitude responses from the right hemisphere during both the verbal and nonverbal presentations. No significant AEP asymmetries were obtained in an independent group of infants that received only the probe tones. These findings are consistent with theories and behavioral data suggesting differences between males and females in the development of language and spatial functions.

Sex-related differences in event-related potentials, face recognition, and facial affect processing in prepubertal children

Thirty-five prepubertal children, 17 boys and 18 girls, between the ages of 8 and 11 years, were studied to examine electrophysiological and cognitive sex differences during a face-recognition-memory (FRM) task and a facial-affect-identification task (FAIT). All participants were prepubertal, as determined by J. M. Tanners (1962) staging and endocrine evaluation. Sex-dependent event-related potential (ERP) amplitude asymmetries were found during FRM. Boys displayed greater right versus left ERP amplitude to auditory tone probes during the task, whereas girls displayed the opposite pattern. In addition, positive correlations were obtained between ERP amplitude during FRM and FAIT accuracy scores for boys, but not for girls. Results suggest that girls and boys may use different neuronal systems in the processing of faces and facial affect. Findings are consistent with developmental theories regarding sex differences in visuospatial processing.

Working memory and processing speed deficits in systemic lupus erythematosus as measured by the paced auditory serial addition test

As many as 66% of systemic lupus erythematosus (SLE) patients have been reported to have cognitive deficits. These deficits are often associated with information processing speed and working memory. Similarly, processing speed and working memory impairments are the hallmark of cognitive dysfunction in multiple sclerosis (MS). The Paced Auditory Serial Addition Test (PASAT) places high demands on processing speed and working memory. Fisk and Archibald, however, demonstrated that the total score of the PASAT does not accurately reflect impairments in these cognitive processes. They found that MS patients used a chunking strategy to obtain correct responses and reduce the cognitive demands of the task. In the present study, PASAT performance was examined for 45 SLE patients and 27 controls using alternative scoring procedures. Although the total number of correct responses did not differ between SLE and controls at the 2.4 or 2.0 s presentation rates, SLE patients had fewer dyads (correct consecutive responses) than controls at the faster rate, and more chunking responses than controls at both rates. Disease activity, disease duration, depression, fatigue, and corticosteroids could not account for these differences. The findings suggest that SLE patients, like MS patients, chunk responses more often than controls, and that this scoring procedure may better reflect the working memory and processing speed deficits present in SLE.

Working memory deficits in multiple sclerosis: Comparison between the n -back task and the Paced Auditory Serial Addition Test

Working memory (WM) deficits are common in multiple sclerosis (MS). The Paced Auditory Serial Addition Test (PASAT) is used frequently to measure WM in clinical settings. The n-back paradigm is used often in experimental studies of WM. One unique component of the n-back task is that it provides a measure of reaction time (RT), an additional behavioral index of processing speed and task difficulty. Despite the use of both tasks to measure WM, their common variance has not been documented. We tested 32 MS patients and 20 controls; performance measures were obtained for both tasks. Compared with controls, MS patients generally had poorer performance on both the PASAT and n-back task. MS patients also had slower RTs on the n-back than controls and showed more slowing than controls as a function of WM load. Correlational analyses showed a high correspondence between performance measures on the PASAT and n-back. Principal components analysis pointed to a common feature of the PASAT, n-back, and specific other neuropsychological measures, that is, processing speed. Although the PASAT and n-back were shown to have a significant amount of shared variance, each test has specific advantages and disadvantages for use in clinical populations.

observations on Patterns of Subjective Symptomatology of Acute Asthma

&NA; Five symptom categories have previously been identified which described the subjective symptoms experienced during asthma attacks: These include 2 mood symptom categories, panic‐fear and irritability, describing affective states concomitant with asthma; 2 somatic symptom categories, hyperventilation‐hypocapnia and airway obstruction, describing reports of more specific bodily symptoms; and fatigue, describing the reduced energy level accompanying asthma attacks. In this study, 15 patterns of asthma symptomatology based on reported frequency of the 5 symptom categories during asthma attacks were identified within a group of 100 inpatients with asthma. The relationships between scores on the individual symptom categories within patterns showed that hyperventilation‐hypocapnia symptoms were associated with generally high levels of the mood symptom categories, but not clearly related to the reported frequency of airway obstruction symptoms; high fatigue symptom scores accompanied both high mood symptom and airway obstruction symptom category scores; and high airway obstruction scores were not necessarily associated with high scores on the mood symptom categories. Patients who showed patterns with high mood symptom scores were prescribed higher steroid regimens upon discharge. Alternative explanations for the latter finding are discussed in some detail.