Regarding the database for the Peniston alpha-theta EEG biofeedback protocol.

Five papers by Peniston and colleagues, which constitute the basic literature for alpha-theta EEG biofeedback treatment for alcoholism and posttraumatic stress disorder, are reviewed. As a result, we raise three questions: (a) Are the samples studied independent? (b) What was the clinical status of the participants prior to treatment? (c) What treatment did the participants actually receive? In seeking answers to these questions we aim to strengthen the database for neurofeedback with specific procedural information so that claims of efficacy can be tested and accepted or rejected on an objective basis.

Effects of retinal eccentricity on the lateralized processing of categorical and coordinate spatial relations.

Kosslyn's (1987) hypothesized cerebral hemispheric asymmetries for processing categorical and coordinate spatial relations were explored, using stimuli presented at varying degrees of retinal eccentricity. Thirty-three adult males performed hemifield reaction-time tasks requiring categorical or coordinate judgements. The hypothesized asymmetries were observed when stimuli were presented at 3 degrees of visual angle, but not at 1 or 9 degrees. Nevertheless, correlational analyses supported the existence of separate neural subsystems for categorical and coordinate processing. The results suggest that the model accurately predicts performance asymmetries only under specific conditions.

Temporal lobe epilepsy and performance on the Wisconsin Card Sorting Test.

The replicability of previous evidence for differential performance between left and right temporal lobe epileptic patients on the Wisconsin Card Sorting Test (WCST) was evaluated in a new sample of candidates for focal resection. Many subjects obtained high scores on indices of perseveration, which are commonly thought to reflect frontal dysfunction, but there were no differences in performance between patients with language-dominant and nondominant temporal foci. The findings confirm existing evidence that performance decrements on the WCST can be associated with epileptic foci and focal lesions in nonfrontal brain lesions.

Investigating thought disorder in schizophrenia with the lexical decision task.

Prior work has found evidence of hyperpriming in schizophrenics, which has been related to a persistence of associational activation in thought disorder. We extended this work by administering a lateralized version of the lexical decision task to 10 thought-disordered schizophrenics (TD), 10 non-thought-disordered schizophrenics (NTD), and 11 control subjects to localize the patterns of priming. All subjects were right-handed males. Associated, unassociated, and neutral prime-target pairs were displayed across seven stimulus location combinations: prime and target both presented to the center, left visual field (LVF), or right visual field (RVF); prime presented to the center with target presented to the LVF or RVF; and prime and target presented contralaterally. TD schizophrenics exhibited priming effects comparable to those of the other subject groups, suggesting intact semantic memory structures and memory processes that may be unimpaired under the conditions studied. It is believed that the associative process mediating priming effects found in schizophrenia are later in the sequence than those examined in this study.

On the independence of physical and nominal codes: a correlational analysis.

In studies of college students, normal children at three grades, and learning-disabled children, physical and nominal matching procedures were highly correlated, (range .72-.96). In each instance, expected time differences favoring physical matches were replicated. Comparable results were found with both tachistoscopic and paper-and-pencil methods. In two studies where relevant data were available, correlations were not significantly attenuated when the effects of motor speed were partialled out. The results challenge the premise that nominal and physical matching measures are empirically independent, invalidate their application as measures of independent types of information processing, and help explain inconsistent findings in hemispheric specialization research.

Biochemical and neuropsychological effects of elevated plasma phenylalanine in patients with treated phenylketonuria. A model for the study of phenylalanine and brain function in man.

Phenylketonuria provides a human model for the study of the effect of phenylalanine on brain function. Although irreversible mental retardation is preventable through newborn diagnosis and dietary phenylalanine restriction, controversy exists regarding the effects of increased concentrations of phenylalanine in older patients. We have studied ten older, treated, phenylketonuric patients using a triple-blind, multiple trials, crossover design. Each patient was tested at the end of each of three 1-wk periods of high or low phenylalanine intakes. Tests included a repeatable battery of neuropsychological tests, analysis of plasma amino acids, and measurement of urine amino acids, phenyl organic acids, dopamine, and serotonin. In all 10 patients plasma phenylalanine rose (900-4,000 microM). In 9 of 10 patients there was an inverse relationship between plasma phenylalanine and urine dopamine excretion. When blood phenylalanine was elevated, these patients had prolonged performance times on neuropsychological tests of higher but not lower integrative function. Urinary serotonin fell during phenylalanine loading in six patients. The concentration of phenylacids in the urine was not proportional to the plasma phenylalanine at concentrations below 1.5 mM. In one patient, neither performance time nor dopamine excretion varied as blood phenylalanine rose or fell. We interpret these data as follows: blood phenylalanine above 1.3 mM impairs performance on neuropsychological tests of higher integrative function, this effect is reversible, and one mechanism may involve impaired biogenic amine synthesis.

Blind evaluation of body reflexes and motor skills in learning disability.

Motor dysfunctions have been associated with learning disabilities in casual observation and systematic study. However, most prior work has concentrated solely on high-level skills and has been subject to observer bias. In this study, boys with learning disability were blindly compared with paired controls on measures of postural and equilibrium reflexes as well as skills. Learning-disabled children as a group showed significant deficits on all measures; a few, however, were totally without deficit. The implications of these findings for controversies about the role of motor dysfunction in learning disabilities are examined.

On determining footedness.

The limitations of the most commonly used procedure for determining foot dominance are pointed out and alternatives are suggested.

Information complexity and cross-modal functions.

Intra-modal and cross-modal presentations of a matching procedure were compared at two levels of information complexity in the same subjects. The modalities were visual and somatosensory. Sequence of information type and sex of experimenter and subject were systematically controlled. Pattern of accuracy among the several modality combinations and the effect of sequence varied as a function of information complexity. Sex of experimenter and subject yielded significant differences with simple information but not complex. The results, involving several detailed comparisons, confirmed generalizations derived from a review of prior studies in which only one type of information had been administered to any single group of subjects. Further examination of the relations between type of information and sensory modality is discussed.