Directed forgetting deficits in patients with temporal lobe epilepsy: an information processing perspective.

Although mesial temporal lobe brain damage is frequently associated with memory loss, it is unclear whether the deficit results entirely from a disruption in the processing of relevant information or whether it also reflects interference from irrelevant information. Directed forgetting is one procedure that can be used, along with standard tests of memory, to investigate this distinction. Seventeen patients with a diagnosis of complex-partial seizures of temporal lobe origin and 17 healthy volunteers were compared on lexical decision, free recall, and recognition tests in a directed-forgetting paradigm. These tests created a memory profile to measure the influence of task relevant and irrelevant information in implicit and explicit memory. Compared with healthy volunteers, the patients were significantly impaired on the memory tasks overall [F(5,25) = 5.01, p < .01]. Specifically, directed forgetting in lexical decision and recognition both discriminated between the groups [stepdown F(1,26) = 6.84, eta 2 = .26, p < .05 and stepdown F(1,25) = 5.36, eta 2 = .13, p < .05, respectively]. The results suggest that interictal memory performance in temporal lobe epilepsy may be disrupted in part because of a deficit in the differential processing of task relevant and task irrelevant information, particularly at retrieval.

Effects of experimentally-induced emotional states on frontal lobe cognitive task performance.

A growing body of evidence suggests that dysphoric and euphoric emotional states are associated with reliable patterns of frontal lobe activity. Specifically, dysphoric affect coincides with greater right than left frontal lobe activity, and euphoric affect tends to correspond with a converse pattern of activity. The present study examined whether cognitive outcomes associated with the left and right frontal lobes are differentially influenced by dysphoric and euphoric affect. In a completely between-groups design, 60 dextral women were administered either the positive or negative conditions of the Velten Mood Induction Procedure, and they subsequently completed either a verbal or figural fluency test. Euphoria resulted in better verbal than figural fluency performance, and dysphoria yielded better figural than verbal fluency outcomes. These findings are consistent with electrophysiological data concerning frontal lobe activity during euphoric and dysphoric affect, and they underscore the notion that affective influences upon cognition are more complicated than previously thought.

Neurologic validity of the Wisconsin Card Sorting Test with a pediatric population.

This study investigated the neurologic validity of the Wisconsin Card Sorting Test (WCST) with a pediatric population; that is, the ability of the test to detect dysfunction in the frontal lobes. Fifty children with diverse etiologies of brain dysfunction were classified via EEG, MRI, or CT as having left hemisphere, right hemisphere, or bilateral frontal, extrafrontal, or multifocal/diffuse regions of brain dysfunction. Findings failed to support the hypotheses that WCST performance is more impaired in frontal lesions than extrafrontal or multifocal/diffuse lesions, or that WCST performance is more impaired in left hemisphere lesions than right. Although the WCST is not helpful in localizing cerebral area of dysfunction, it may still be a clinically useful test for examining processes that children use to solve complex problems.

Effects of olfactory stimulation on the vigilance performance of individuals with brain injury.

Observers with brain injury and control participants performed a vigilance task during which they received periodic whiffs of unscented air or air scented with peppermint. Under both fragrance conditions, controls reduced the frequency of commissive errors (false alarms) over the course of the vigil, an adaptive strategy given the low probability of signals employed (0.04). The false alarm rate of observers with brain injury increased precipitously toward the end of the vigil in the unscented air condition. However, exposure to the scent of peppermint rendered the false alarm scores of observers with brain injury similar to that of controls, a result which is consistent with evidence that olfactory stimulation activates brain areas vital for planning and judgment.

Recovery in pediatric brain injury: is psychostimulant medication beneficial?

OBJECTIVE: To assess the effects of methylphenidate on attention, memory, behavior, processing speed, and psychomotor skills of children with closed head injuries. DESIGN: Double-blind, placebo-controlled, crossover design. SETTING: An outpatient facility of a children's hospital medical center. PATIENTS: Ten pediatric subjects identified through chart review. Subjects met baseline scores for hyperactivity (Conner's Hyperactivity Index greater than or equal to 60) and intellectual functioning (Verbal Intelligence Quotient greather than or equal to 70) and achieved minimal scores on two psychometric tests. All subjects evidenced head injury by focal lesions on computed tomography scan and/or sequelae reported at the time of injury. Severity of injury ranged from mild to severe. All subjects were medically stable at the time of testing. Mean time post injury was 2 years, 8 months. INTERVENTION: Administration of methylphenidate and placebo. MAIN OUTCOME MEASURES: Percentage change in scores was calculated to assess differences between baseline and end of methylphenidate/placebo trials. RESULTS: No significant differences between methylphenidate and placebo on measures assessing behavior, attention, memory, and processing speed. CONCLUSIONS: The results of the study call into question the effectiveness of methylphenidate in the pediatric head injury population.

Preserved color imagery in an achromatopsic.

The loss of color vision secondary to central nervous system disease (achromatopsia) is thought to preclude visual imagery of colors. We report a patient with achromatopsia, secondary to bilateral temporo-occipital infarcts inclusive of the lingual and fusiform gyri, with preserved color imagery. Our findings, in conjunction with previous cases in the literature, are consistent with a single neural network for color processing in which a disconnection of internal activation from stored color representations produces impaired color imagery with preserved color perception, whereas a disconnection of visual input to these representations produces achromatopsia with preserved color imagery.

Mood and global-local visual processing.

Testing hypotheses derived from neuropsychological models of mood, as well as the association of mood states and personality characteristics with global-local visual processing, were examined. Fifty-nine men completed measures associated with depression and positive mood, and were administered a brief perceptual judgment task that assessed global-local visual processing biases. Additionally, 19 of these 59 subjects were administered measures of anxiety and optimism-pessimism and completed an expanded judgment task. Affective and personality variables were then correlated with judgment task performances. Consistent with predictions, positive mood and optimism were directly associated with a global bias and inversely related to a local bias. A converse pattern of findings was obtained with depression and trait anxiety. Implications for research concerning other aspects of visual processing are discussed.

Repetition and the arcuate fasciculus.

According to the traditional model of language organization, repetition deficits arise following damage to the arcuate fasciculus of the dominant hemisphere (conduction aphasia). Conduction aphasia may result from lesions that spare the arcuate fasciculus. However, these patients have atypical language organization. We describe a man with normal language architecture who underwent a resection of the anterior portion of his arcuate fasciculus and retained his ability to repeat words and sentences. We propose that the arcuate fasciculus is not necessary for speech repetition by the lexical route.

Recent advances in the neuropsychology of human olfaction and anosmia.

Patients' olfactory functioning is rarely considered by rehabilitation specialists because this capacity is seen as unnecessary for most vocational and academic purposes. However, several recent studies have shown that intermittent exposure to fragrances can help subjects sustain attention more efficiently. As this effect is especially pronounced when subjects report attention-maintenance difficulties, accessory olfactory stimulation may enhance the sustained attention capacities of head-injured subjects. Another study is cited in which subjects who lost their sense of smell following head injuries were found to experience more difficulty in maintaining employment. This effect is probably related to orbital lobe damage, which usually accompanies post-traumatic anosmia. The implications of these studies for rehabilitation professionals are discussed.

Closed head injury assessment and research methodology.

About two million Americans incur head injuries each year, resulting in approximately 50,000 chronic disabilities. Several methods are currently used to determine the physiological changes underlying behavioral sequelae commonly associated with closed head injuries. Structural assessment techniques, including lesion studies, standard radiographs, computed tomography and magnetic resonance imaging, are used to determine the physical integrity of brain structures. Functional assessment techniques, including neuropsychological methods, the electroencephalograph, evoked potentials and positron emission tomography, are used to examine the brain through an analysis of its behavioral, electrical and chemical outputs. Accurate head injury assessment is vital for diagnosis, treatment planning and research. Injuries are commonly divided into the categories of mild, moderate and severe based on duration and depth of coma and the length of posttraumatic amnesia. Application of these severity assessment parameters is currently being improved through the use of standardized assessment measures.

Mood-moderating effects of affect intensity on cognition: sometimes euphoria is not beneficial and dysphoria is not detrimental.

Affect intensity (AI) is a characteristic of temperament that has been hypothesized to moderate the influence of mood on cognitive processing. To test predictions concerning this interaction, 132 women were divided into groups of high and low AI and received positive, neutral, or negative mood inductions. They then engaged in either a self-generated or didactic learning task, and the effects of mood and AI on recall and recognition performance were assessed. Consistent with predictions, positive mood led to poorer performance for high AI relative to low AI individuals, and negative mood resulted in a converse pattern of outcomes. The results are discussed with reference to implications for the AI construct and mood-induction research.

Behavioral, physiological, and self-evaluative effects of anxiety on the self-control of pain.

This study examined the impact of trait anxiety on self-control behavior using the cold pressor task. In addition to cold pressor tolerance, effects were measured in terms of physiological arousal and self-evaluations. Forty-six female subjects screened for high and low trait anxiety were given two trials of the cold pressor task, and between trials, they were given either self-control or non-self-control training. As expected, self-control training resulted in increased pain tolerance and decreased physiological arousal. Although anxiety did not influence behavioral tolerance, high trait anxious subjects receiving self-control training made more negative self-evaluations and had higher levels of physiological arousal. These results suggest that anxiety may disrupt the use of self-control strategies in coping with pain.

Comparison of empirically derived and predicted standard scores for Form II of the Luria-Nebraska Neuropsychological Battery.

Until Wong, Schefft, and Moses published norms for Form II of the Luria-Nebraska Neuropsychological Battery in 1990, Golden, Purisch, and Hammeke's 1985 regression equations were the only procedure available to interpret scores on Form II of the battery. In the present study comparison of the empirically based norms with standard scores obtained via the regression equations showed that (1) the scale means and standard deviations used in the development of the regression equations indicated substantially more impairment than those obtained by Wong, et al. and (2) the standard (T) scores predicted by the regression equations consistently underestimated impairment relative to the T scores obtained directly from Wong, et al.'s empirically derived norms. Reasons for, and implications of, these findings were discussed.

Revised norms and decision rules for the Luria-Nebraska Neuropsychological Battery, Form II.

All control subjects from a previous Luria-Nebraska Neuropsychological Battery, Form II (LNNB2) normative study were combined with a considerably larger normative sample to produce a composite normative sample of 392 subjects with a mean high school educational level. Revised norms for the LNNB2 were developed based on this sample and were scaled with uniform T-scores to make scale elevations comparable across LNNB2 measures. Differences between the scalewise LNNB2 normative values and published alternatives were highly significant. A critical level and actuarial decision rules for differentiation of normal from neurologically impaired performance level were developed for the LNNB2 using the current empirical norms (86% accuracy with current sample empirical critical level; 89% accuracy with LNNB1 critical level). The normative prediction values of Golden, Purisch, and Hammeke for the LNNB2 were not satisfactory (69% overall, with 45% accuracy among brain damaged sample). There was no significant effect of sex of subject on LNNB2 performance level among the control subjects.

Evaluation of the diagnostic validity of the Luria-Nebraska Neuropsychological Battery Form II.

The present study evaluated the ability of Form II of the Luria-Nebraska Neuropsychological Battery (LNNB) to discriminate brain-impaired from neurologically normal subjects. Using discriminant analysis the battery was able to separate 55 impaired from 55 nonimpaired subjects matched for age and education at significant levels. The present data also confirm previous findings that age and education significantly affect performance of nonimpaired subjects. Sex was not found to be a factor influencing performance level on the LNNB, Form II. Directions for further research are suggested.