Effect of drawing hand and age on figural fluency: a graphomotor study with the five-point test in children.

The aim of the study was to assess conceptual thinking in children in relation to age and motor dominance. We investigated the effect of the right and the left hand in a fluency task in four groups of 127 healthy right-handed children (age 5-12 years) and an adult control group. They performed the Five-Point Test twice, once with their dominant right and once with their nondominant left hand. The number of items and errors were analyzed with respect to age, drawing hand, and motor transfer. The performance of boys and girls did not differ. There was a significant effect for age and a prominent interaction between age, hand, and order (right hand or left hand first). Performance improved linearly with age. The dominant right hand performed generally better and there was a learning effect for both hands, but there was a learning advantage for the dominant hand, which increased with age. The influence of motor dominance in this fluency task seems to establish before conceptual maturity (around age 7, respectively 9 to 10).

Laterality of pain: modulation by placebo and participants' paranormal belief.

OBJECTIVE: To investigate the effects of placebo and paranormal belief on the laterality of pain perception. BACKGROUND: The right hemisphere is dominantly involved in both the mediation of pain sensation and the belief in paranormal phenomena. We set out to assess a possible influence of long-term belief systems on placebo analgesia in response to unilateral nociceptive stimuli. METHOD: Forty healthy participants (20 high and 20 low believers as indexed by the Magical Ideation Scale) underwent a placebo analgesia study measuring stimulus detection, pain threshold, and pain tolerance by electrostimulation on the right and left hand. Placebo treatment consisted of the application of a sham cream on the hands. RESULTS: Placebo had a positive influence on pain perception in the 3 variables. Enhanced pain sensitivity for the left side was only found for the disbelievers. Placebo treatment resulted in a double dissociation: in believers, it increased tolerance exclusively on the left side, in disbelievers on the right side. CONCLUSIONS: Our results confirm laterality effects in pain perception. However, only disbelievers conformed to the expected higher left-sided sensitivity. Placebo effects were dissociated between believers and disbelievers suggesting that short-term reactions to a placebo are modulated by a person's long-term belief system.

Differential impact of posterior lesions in the left and right hemisphere on visual category learning and generalization to contrast reversal.

Hemispheric differences in the learning and generalization of pattern categories were explored in two experiments involving sixteen patients with unilateral posterior, cerebral lesions in the left (LH) or right (RH) hemisphere. In each experiment participants were first trained to criterion in a supervised learning paradigm to categorize a set of patterns that either consisted of simple geometric forms (Experiment 1) or unfamiliar grey-level images (Experiment 2). They were then tested for their ability to generalize acquired categorical knowledge to contrast-reversed versions of the learning patterns. The results showed that RH lesions impeded category learning of unfamiliar grey-level images more severely than LH lesions, whereas this relationship appeared reversed for categories defined by simple geometric forms. With regard to generalization to contrast reversal, categorization performance of LH and RH patients was unaffected in the case of simple geometric forms. However, generalization to contrast-reversed grey-level images distinctly deteriorated for patients with LH lesions relative to those with RH lesions, with the latter (but not the former) being consistently unable to identify the pattern manipulation. These findings suggest a differential use of contrast information in the representation of pattern categories in the two hemispheres. Such specialization appears in line with previous distinctions between a predominantly lefthemispheric, abstract-analytical and a righthemispheric, specific-holistic representation of object categories, and their prediction of a mandatory representation of contrast polarity in the RH. Some implications for the well-established dissociation of visual disorders for the recognition of faces and letters are discussed.

Anomalous brain dominance and the immune system: do left-handers have specific immunological patterns?

Geschwind and Behan (1982) and Geschwind and Galaburda (1985a, 1985b, 1985c) suggested a correlation between brain laterality and immune disorders. To test whether this hypothesis holds true not only for the frequency of immune diseases and circulating autoantibodies, but extends also to cellular immunity, we examined the association between handedness and markers of cellular immunity. Twenty-seven left-handed and 37 right-handed subjects were serologically screened for cellular parameters and 22 left-handed subjects were typed for human leukocyte antigen (HLA). When compared to the right-handers, the left-handed group showed a significant decrease in the inflammatory cell types CD3(+) T cells (total T cells), CD4(+) T cells (T-helper cells), and HLA-Dr (MHC-II, antigen-presenting cells) as well as in the CD19(+) cells (B cells) and CD16/CD57(+) cells (natural killer cells). We assume a relationship exists between cerebral hemispheric specialisation and the immune system not only for humoral but also for cellular immunity, and we discuss the role of the major histocompatibility complex in neurological and immunological development.

The hallucinating art of Heinrich Füssli.

Der Nachtmahr (The Nightmare) was painted 1781 by the Swiss-born artist Heinrich Füssli (1741-1825). Neurologists, sleep medicine specialists and sleep researchers are familiar with this popular work, which became a symbol for the phenomenon of sleep paralysis. Notably, Füssli created this work decades before the first scientific description of the syndrome. Therefore, the following chapter aims to reflect the painting against the background of Füssli's biography, neuropsychological interpretations, and of pathophysiological and neurobiological considerations on sleep paralysis.

Polyopic heautoscopy: Case report and review of the literature.

Heautoscopy, i.e., the encounter with one's double, is a multimodal illusory reduplication of one's own body and self. In its polyopic form, more than one double is experienced. In the present article, we review fourteen published cases of polyopic heautoscopy and describe in detail the case of a 41-year-old man with polyopic heautoscopy resulting from a tumor in the insular region of the left temporal lobe. Our case is illustrative in several respects: (1) The patient's five doubles were all confined to the right hemispace. Laterality in this case is discussed with reference to previous cases of unilateral heautoscopy after focal brain damage, which generally do not show a hemispatial or hemispheric bias. (2) The patient's psychological affinity with his doubles, and also the extent of their echopraxia of his movements, decreased as a function of their perceived spatial distance from the patient's body, corroborating previous observations of associations between spatial and psychological phenomenologies during autoscopic phenomena. (3) While classical heautoscopy (the reduplication of a single body and self) is considered a breakdown in the integrative processes that enable us to identify our self with our body, the phenomenon of polyopic heautoscopy (a multiplication of body and self) points to the multiple mappings of the body, whose disintegration may give rise to the illusory experience of multiple selves.

Lipoma on the corpus callosum in a patient with schizophrenia-like episode: is there a causal relationship?

Disturbed interhemispheric communication has been proposed as responsible for schizophrenia. We present a case of a schizophrenia-like episode with no neurologic or other psychiatric symptoms. However, magnetic resonance imaging revealed a lipoma on the splenium of the corpus callosum. Neuropsychologic examination revealed normal interhemispheric transfer, but a slight dysfunction associated with right-hemispheric anterior regions. Rather than supporting the hypothesis of a causal relationship between callosal abnormality and schizophrenia-like symptoms, our findings argue against a direct causal relationship between lesion site and psychotic episode. We conclude that cerebral abnormality per se may represent a risk factor for neuropsychiatric symptoms.

Disruption of right prefrontal cortex by low-frequency repetitive transcranial magnetic stimulation induces risk-taking behavior.

Decisions require careful weighing of the risks and benefits associated with a choice. Some people need to be offered large rewards to balance even minimal risks, whereas others take great risks in the hope for an only minimal benefit. We show here that risk-taking is a modifiable behavior that depends on right hemisphere prefrontal activity. We used low-frequency, repetitive transcranial magnetic stimulation to transiently disrupt left or right dorsolateral prefrontal cortex (DLPFC) function before applying a well known gambling paradigm that provides a measure of decision-making under risk. Individuals displayed significantly riskier decision-making after disruption of the right, but not the left, DLPFC. Our findings suggest that the right DLPFC plays a crucial role in the suppression of superficially seductive options. This confirms the asymmetric role of the prefrontal cortex in decision-making and reveals that this fundamental human capacity can be manipulated in normal subjects through cortical stimulation. The ability to modify risk-taking behavior may be translated into therapeutic interventions for disorders such as drug abuse or pathological gambling.

Did Fyodor Mikhailovich Dostoevsky suffer from mesial temporal lobe epilepsy?

Many scientific authors--among them famous names such as Henri Gastaut or Sigmund Freud--dealt with the question from what kind of epilepsy Fyodor Mikhailovitch Dostoevsky (1821-1881) might had suffered. Because of the tight interplay between Dostoevsky's literary work and his own disease we throw light on the author's epilepsy against the background of his epileptic fictional characters. Moreover, we attempt to classify Dostoevsky's epilepsy on the basis of his bibliography, language, and literary work.

Cognitive and emotional processing at high altitude.

INTRODUCTION: Exposure to altitude reduces oxygen supply to the central nervous system and may cause a variety of neuropsychological impairments. We investigated the relationship between certain cognitive functions and cardiovascular and respiratory variables during acute hypobaric hypoxia. METHODS: There were three groups of seven men who were each exposed to a 2-h altitude profile (AP) involving 30 min at each of the following simulated altitudes (m): AP1, 450-1500-3000; AP2, 450-1500-4500; Control 450-650-650. The neuropsychological tests included word fluency and three word-association tasks tapping processes of cognitive flexibility and emotion regulation. A lateralized tachistoscopic lexical decision task with high and low emotional target words was also administered to assess possible shifts in hemispheric superiorities for positive and negative affect. RESULTS: No significant differences in word fluency, word association, or lateralized lexical decision performances were found, despite a significant oxygen desaturation and a drop in diastolic BP at 4500 m, indicating the beginning of central hypoxia in terms of a functional impairment of the vasomotor center. CONCLUSION: During acute exposure to hypobaric hypoxia, selected cognitive and affective functions mediated by the frontal lobe were preserved. Functional hemispheric asymmetries for emotional processes remained unchanged.

Suppressing versus releasing a habit: frequency-dependent effects of prefrontal transcranial magnetic stimulation.

When subjects are required to generate a random sequence of numbers they typically produce too many forward and backward 'counts' (e.g. 5-6, 4-3). This counting bias is interpreted as the consequence of an interference by overlearned tendencies to arrange numbers according to their natural order. Inhibition of such well-learned routines is known to rely on frontal lobe functioning. We examined differential effects of slow (1 Hz) and fast (10 Hz) repetitive transcranial magnetic stimulation (rTMS) over the left or right dorsolateral prefrontal cortex (DLPFC) on random number generation (RNG) performance. Eighteen healthy men performed an RNG task. Those subjects stimulated over the left DLPFC showed a frequency-dependent rTMS effect: counting bias was significantly reduced after the 1 Hz stimulation compared with baseline, but significantly exaggerated after the 10 Hz stimulation compared with 1 Hz stimulation. In contrast, the sequences of the subjects stimulated over the right DLPFC showed the well-known excess of counting in all conditions (i.e. baseline, 1 Hz and 10 Hz). These findings confirm the functional importance of specifically the left DLPFC in sequential response production and show, for the first time, that rTMS affects cognitive processing in a frequency-dependent manner.

Language in the right cerebral hemisphere: contributions from reading studies.

Evidence for a right hemispheric involvement in language processing, in particular at the level of word meaning, has emerged within the last half century. Hemispheric functional specializations are dynamic; right hemispheric language participation significantly increases under certain conditions, such as during an epileptic seizure and during recovery from stroke. Interhemispheric connections via the corpus callosum critically mediate these and other higher cortical functions.

Flunarizine in prevention of headache, ataxia, and memory deficits during decompression to 4559 m.

Our purpose was to study the preventive effect of the calcium channel blocker flunarizine on headache, postural ataxia, and memory deficits occurring during decompression to high altitude in a randomized, placebo-controlled, double-blind study. After 7-day pretreatment with the study drugs, 20 healthy men were investigated at 490 m and 0.5, 2, 4, and 6 h later at a simulated altitude of 4559 m. Headache severity was evaluated on a 4-point scale. Sway path and anteroposterior and lateral sway were recorded with open and closed eyes by static posturography. Short- and long-term memory was studied by testing the recall of verbal and figural material immediately and 2 h after presentation, respectively. Blood pressure (BP) and arterial oxygen saturation (Sa(O2)) were also assessed. Headache scores showed a trend to be lower in the flunarizine group that was significant after 4 and 6 h. Headache scores expressed as difference from baseline values showed a nonsignificant trend to be lower at 4 and 6 h in subjects treated with flunarizine. Postural stance, memory, BP, and Sa(O2) were similar in both treatment groups. Although the low number of investigated subjects may have prevented the detection of a significant therapeutic effect of flunarizine, the present data do not show that flunarizine is effective for prevention of headache, postural ataxia, and neurocognitive deficits occurring at simulated high altitude.

Brain damage and addictive behavior: a neuropsychological and electroencephalogram investigation with pathologic gamblers.

BACKGROUND: Gambling is a form of nonsubstance addiction classified as an impulse control disorder. Pathologic gamblers are considered healthy with respect to their cognitive status. Lesions of the frontolimbic systems, mostly of the right hemisphere, are associated with addictive behavior. Because gamblers are not regarded as "brain-lesioned" and gambling is nontoxic, gambling is a model to test whether addicted "healthy" people are relatively impaired in frontolimbic neuropsychological functions. METHODS: Twenty-one nonsubstance dependent gamblers and nineteen healthy subjects underwent a behavioral neurologic interview centered on incidence, origin, and symptoms of possible brain damage, a neuropsychological examination, and an electroencephalogram. RESULTS: Seventeen gamblers (81%) had a positive medical history for brain damage (mainly traumatic head injury, pre- or perinatal complications). The gamblers, compared with the controls, were significantly more impaired in concentration, memory, and executive functions, and evidenced a higher prevalence of non-right-handedness (43%) and, non-left-hemisphere language dominance (52%). Electroencephalogram (EEG) revealed dysfunctional activity in 65% of the gamblers, compared with 26% of controls. CONCLUSIONS: This study shows that the "healthy" gamblers are indeed brain-damaged. Compared with a matched control population, pathologic gamblers evidenced more brain injuries, more fronto-temporo-limbic neuropsychological dysfunctions and more EEG abnormalities. The authors thus conjecture that addictive gambling may be a consequence of brain damage, especially of the frontolimbic systems, a finding that may well have medicolegal consequences.

Affective judgments of faces modulate early activity (approximately 160 ms) within the fusiform gyri.

Functional neuroimaging studies have implicated the fusiform gyri (FG) in structural encoding of faces, while event-related potential (ERP) and magnetoencephalography studies have shown that such encoding occurs approximately 170 ms poststimulus. Behavioral and functional neuroimaging studies suggest that processes involved in face recognition may be strongly modulated by socially relevant information conveyed by faces. To test the hypothesis that affective information indeed modulates early stages of face processing, ERPs were recorded to individually assessed liked, neutral, and disliked faces and checkerboard-reversal stimuli. At the N170 latency, the cortical three-dimensional distribution of current density was computed in stereotactic space using a tomographic source localization technique. Mean activity was extracted from the FG, defined by structure-probability maps, and a meta-cluster delineated by the coordinates of the voxel with the strongest face-sensitive response from five published functional magnetic resonance imaging studies. In the FG, approximately 160 ms poststimulus, liked faces elicited stronger activation than disliked and neutral faces and checkerboard-reversal stimuli. Further, confirming recent results, affect-modulated brain electrical activity started very early in the human brain (approximately 112 ms). These findings suggest that affective features conveyed by faces modulate structural face encoding. Behavioral results from an independent study revealed that the stimuli were not biased toward particular facial expressions and confirmed that liked faces were rated as more attractive. Increased FG activation for liked faces may thus be interpreted as reflecting enhanced attention due to their saliency.