Effects of glucose on scopolamine-induced learning deficits in rats performing the Morris water maze task

In order to assess the effects of glucose on drug-induced spatial learning deficits, three experiments were conducted using the Morris water maze. Scopolamine and glucose were injected ip at various stages of training. Rats of Wistar strain served as subjects. In Experiment 1, scopolamine (0.4 mg/kg) and 10, 100, or 500 mg/kg of glucose were administered every day from the start of training, and the effect on acquisition was evaluated. In Experiment 2, scopolamine and 100 or 500 mg/kg of glucose were administered after 6 days of training, and the effect on performance was assessed. In Experiment 3, scopolamine and 500 mg/kg of glucose were injected after 2 days of training, and the effect on the following trial was tested. In all experiments, scopolamine impaired acquisition/performance of the task. Glucose at 500 mg/kg showed a significant enhancing effect on acquisition regardless of scopolamine injection only when injected daily from the start of training (Experiment 1). Glucose injected after the performance has reached asymptote (Experiment 2) did not affect performance, and glucose in the middle of training showed a slight but insignificant enhancing effect (Experiment 3). These results may suggest that the effect of glucose changes as a function of the degree of learning of the spatial learning task. The possibility of task specificity of the glucose effect was also discussed in relation to the cholinergic systems and local cerebral glucose utilization.     

Measurement and structural models for children's problem behaviors

This article considers an analytic strategy for measuring and modeling child and adolescent problem behaviors. The strategy embeds an item response model within a hierarchical model to define an interval scale for the outcomes, to assess dimensionality, and to study how individual and contextual factors relate to multiple dimensions of problem behaviors. To illustrate, the authors analyze data from the primary caregiver ratings of 2,177 children aged 9-15 in 79 urban neighborhoods on externalizing behavior problems using the Child Behavior Checklist 4-18 (T. M. Achenbach, 1991a). Two subscales, Aggression and Delinquency, are highly correlated, and yet unidimensionality must be rejected because these subscales have different associations with key theoretically related covariates.     

Dyskinesias differentiate autistic disorder from catatonia

Autistic disorder and catatonia are neuropsychiatric syndromes defined by impairments in social interaction, communication, and restricted, stereotypical motor routines. Assessments of children with these disorders are typically restricted in scope by the patients' limited ability to comprehend directions. The authors performed systematic assessments of dyskinesias on six prepubertal boys with autistic disorder and mental retardation and on one adolescent male with catatonia to determine if this type of information could be routinely obtained. The boys with autistic disorder had more stereotypies and tics, a greater degree of akathisia and hyperactivity, and more compulsions than the adolescent with catatonia. Catatonia was associated with catalepsy and dystonic postures. The authors conclude that the diagnostic accuracy and specificity of neuropsychiatric syndromes may be enhanced by the systematic assessment of the dyskinesias associated with each condition.     

The Temple-Wisconsin Cognitive Vulnerability to Depression Project: lifetime history of axis I psychopathology in individuals at high and low cognitive risk for depression

The authors tested the cognitive vulnerability hypotheses of depression with a retrospective behavioral high-risk design. Individuals without current Axis I diagnoses who exhibited either negative or positive cognitive styles were compared on lifetime prevalence of depressive and other disorders and the clinical parameters of depressive episodes. Consistent with predictions, cognitively high-risk participants had higher lifetime prevalence than low-risk participants of major and hopelessness depression and marginally higher prevalence of minor depression. These group differences were specific to depressive disorders. The high-risk group also had more severe depressions than the low-risk group, but not longer duration or earlier onset depressions. The risk group differences in prevalence of depressive disorders were not mediated by current depressive symptoms.     

Auditory language comprehension: an event-related fMRI study on the processing of syntactic and lexical information

The functional specificity of different brain regions recruited in auditory language processing was investigated by means of event-related functional magnetic resonance imaging (fMRI) while subjects listened to speech input varying in the presence or absence of semantic and syntactic information. There were two sentence conditions containing syntactic structure, i.e., normal speech (consisting of function and content words), syntactic speech (consisting of function words and pseudowords), and two word-list conditions, i.e., real words and pseudowords. The processing of auditory language, in general, correlates with significant activation in the primary auditory cortices and in adjacent compartments of the superior temporal gyrus bilaterally. Processing of normal speech appeared to have a special status, as no frontal activation was observed in this case but was seen in the other three conditions. This difference may point toward a certain automaticity of the linguistic processes used during normal speech comprehension. When considering the three other conditions, we found that these were correlated with activation in both left and right frontal cortices. An increase of activation in the planum polare bilaterally and in the deep portion of the left frontal operculum was found exclusively when syntactic processes were in focus. Thus, the present data may be taken to suggest an involvement of the left frontal and bilateral temporal cortex when processing syntactic information during comprehension.     

Perception of dynamic acoustic patterns by an individual with unilateral verbal auditory agnosia

Previous studies have found that subjects diagnosed with verbal auditory agnosia (VAA) from bilateral brain lesions may experience difficulties at the prephonemic level of acoustic processing. In this case study, we administered a series of speech and nonspeech discrimination tests to an individual with unilateral VAA as a result of left-temporal-lobe damage. The results indicated that the subject's ability to perceive steady-state acoustic stimuli was relatively intact but his ability to perceive dynamic stimuli was drastically reduced. We conclude that this particular aspect of acoustic processing may be a major contributing factor that disables speech perception in subjects with unilateral VAA.     

Repetition priming for familiar and unfamiliar faces in a sex-judgment task: evidence for a common route for the processing of sex and identity

Repetition priming for faces was examined in a sex-judgment task given at test. Priming was found for edited, hair-removed photos of unfamiliar and familiar faces after a single presentation at study. Priming was also observed for the edited photos when study and test faces were different exemplars. Priming was not observed, however, when sex judgments were made at test to photos of complete, hair-included faces. These findings were interpreted by assuming that, for edited faces, internal features are attended, thereby activating face-recognition units that support performance. With complete faces, however, participants provided speeded judgments based primarily on the hairstyle. It is suggested that, for both familiar and unfamiliar faces, a common locus exists for the processing of the identity of a face and its sex. A single face-recognition model for the processing of familiar and unfamiliar faces is advocated.     

The effect of familial sinistrality on the relation between schizophrenialike thinking and pseudoneglect

We have recently reported a correlation between schizophrenialike symptoms and the degree of pseudoneglect in healthy right-handers. We aimed to investigate the effect of familial sinistrality (FS) on this relation. Seventy-six healthy right-handers were divided into four groups on the basis of gender and FS. A computerized version of Corsi's task was used as the visuospatial task. Subjects filled in the Magical Ideation Scale (MI), which asked for delusionlike beliefs, and performed the Corsi's task using each hand. Performance of both hemispaces was separately evaluated. In all groups, performance of the left hemispace was better than that of the right hemispace and FS+ subjects performed better than FS- subjects. When the right hand was used, performance was correlated to MI scores only for FS- groups. Findings suggest that the correlation between right-sided neglect and proneness to schizotypy in normal right-handers is affected by FS.     

Pierre Jean Georges Cabanis (1757-1808): an early nineteenth century source for the concept of nervous energy in European behavioral neurosciences

The nineteenth century witnessed many advances in neuroscientific concepts. Among the notable are Charles Bell's (1774-1842) and Fran?ois Magendie's (1783-1855) identification of sensory and motor pathways, Thomas Henry Huxley's (1825-1895) elaboration of evolutionary theory in the context of comparative neuroanatomy, and Emile Du Bois-Reymond's (1818-1896) and Hermann von Helmholtz's (1821-1894) work in experimental neurophysiology and on the concept of nervous energy. In Germany, the idea that the nervous system consisted of two elements, one that generated nervous energy and another that conducted it throughout the body, had wide currency in mid-nineteenth century. In France, Pierre Jean Georges Cabanis (1757-1808), physician, philosopher, and one of the founders of modern psychophysiology, argued that the brain is the part of the body in which electricity is stored. In his Rapports du Physique et du Moral de l'Homme, published between 1796 and 1802 (translated into German under the title Verh?ltnis der Seele zum K?rper (1808)), Cabanis proposed new ideas on brain function, on the brain's own sensibility, on the concept of will, and on the chemical basis of nervous activity. In the Rapports Cabanis proposed a theory of how brain and nerves relate to thought and behavior. Foreshadowing later developments in neuropsychology, he suggested that different parts of the nervous system have separate functions. Despite the fact that Cabanis had many interesting ideas about brain function, he has been largely ignored by historians of neuroscience; e. g., he is mentioned briefly in Clark and Jacyna (1989), in only two footnotes in Neuburger (1897/1981), and not at all in Finger (1994). Cabanis's far-reaching theory of how the brain works helped shape understanding of the general notion of nervous energy in nineteenth-century European neuroscience.     

From image segmentation to anti-textons

We apply the 'patchwork engine' (PE; van Tonder and Ejima, 2000 Neural Networks forthcoming) to encode spaces between textons in an attempt to find a suitable feature representation of anti-textons [Williams and Julesz, 1991, in Neural Networks for Perception volume 1: Human and Machine Perception Ed. H Wechsler (San Diego, CA: Academic Press); 1992, Proceedings of the National Academy of Sciences of the USA 89 6531-6534]. With computed anti-textons it is possible to show that tessellation and distribution of anti-textons can differ from that of textons depending on the ratio of texton size to anti-texton size. From this we hypothesise that variability of anti-textons can enhance texture segregation, and test our hypothesis in two psychophysical experiments. Texture segregation asymmetry is the topic of the first test. We found that targets on backgrounds with regular anti-textons segregate more strongly than on backgrounds with highly variable anti-textons. This neatly complements other explanations for texture segregation asymmetry (e.g. Rubenstein and Sagi, 1990 Journal of the Optical Society of America A 7 1632-1643). Second the relative significance of textons and anti-textons in human texture segregation is investigated for a limited set of texture patterns. Subjects consistently judged a combination of texton and anti-texton gradients as more conspicuous than texton-only gradients, and judged texton-only gradients as being more conspicuous than anti-texton-only gradients. In the absence of strong texton gradients the regularity versus irregularity of anti-textons agrees with perceived texture segregation. Using PE outputs as anti-texton features thus enabled the conception of various useful tests on texture segregation. The PE is originally intended as a general image segmentation method based on symmetry axes. With this paper we therefore hope to relate anti-textons with visual processing in a wider sense.