Pierre Flor-Henry

Neuroleptics reverse attention asymmetries in schizophrenic patients

Discussions of hemispheric asymmetry in psychopathology are often confounded by the effects of medication. We examined the effect of neuroleptic drugs on attention asymmetries in acutely psychotic patients admitted for the first time to a psychiatric hospital before the initiation of drug treatment and again after a period of treatment with neuroleptics. Overall performance did not change significantly; however, attention asymmetry was clearly related to the medication status of the patient: unmedicated patients showed inattention to the right hemispace, which changed to more prominent left-sided inattention when medicated. A longer time on medication or a higher daily dose were associated with a shift of inattention from the right to left hemispace. This suggests that neuroleptics may normalize left hemisphere performance, at the expense of deteriorated right hemisphere performance.

Menstrual effects on asymmetrical olfactory acuity.

Gender specific discrepancies on psychometric examination are often interpreted to reflect static differences in cerebral hemisphere specialization, but dynamic alterations relating to circulating gonadal hormones may also be relevant after puberty. The often cited inference of a right hemisphere advantage in males and left hemisphere advantage in females derived from small but reliable differences on spatial tasks and verbal tasks, for example, may to some extent relate to gender-specific differences in circulating gonadal hormones. Performance fluctuations on other higher order cognitive tasks through the menstrual cycle tend to support a temporal association between alterations in cerebral laterality and hormone fluctuations. A potential left hemisphere advantage after menstruation when estrogen and progesterone levels are high in contrast to a right hemisphere advantage at menstruation when estrogen and progesterone levels are low has also received support from shifts in visual field perception. The present investigation continues this line of work by measurement of prospective changes in unirhinal olfactory acuity in the menstrual, ovulatory, and midluteal phases of the menstrual cycle in 11 healthy women who agreed to blood assays of estradiol and progesterone prior to completing a modified version of the Connecticut Chemosensory Perception Exam (CCPE). The CCPE detection of n-butanol showed a clear pattern of changes over the menstrual cycle marked by an asymmetry favoring the right nostril during menstruation when estradiol and progesterone levels were low, an asymmetry favoring the left nostril during ovulation when estradiol levels were high and progresterone levels were low, and an absence of asymmetry during the midluteal phase when estradiol levels decreased and progesterone levels increased. Preliminary correlation analyses revealed a potential competitive influence of estradiol and progesterone on this apparent shift in cerebral laterality. There is thus sufficient evidence to conclude that dynamic changes in relative cerebral hemisphere advantages have a temporal relation to fluctuations in circulating gonadal hormones and to suggest the value of additional investigation of more specific causal relations.

Gender Differences in Brain Functional Organization During Verbal and Spatial Cognitive Challenges

This is a quantitative EEG study of gender-related differences in brain function. It is novel in that to elicit gender differences, it was necessary to apply a spatial filter to the EEGs that was effective for suppressing components common to different cognitive states. The study involved estimates of both the source-current power density in the brain and the complex coherence between different regions in the brain, the latter probably unique in EEG source analysis. Gender effects are shown in terms of differences in both lateralized source power and complex coherence in response to verbal and spatial cognitive challenges. The results provide evidence that verbal and spatial challenges are more lateralized in males than in females, that females are more verbal than males, that males are more spatial than females, that females verbalize more interpretively than males and that males verbalize more consequentially than females.

Mental activity and the e.e.g.: Task and workload related effects

The e.e.g. was recorded from the left and right parietal and temporal regions of the scalps of 23 normal subjects while they were mentally at rest and then while they were executing tasks intended to engage, firstly, their dominant cerebral hemispheres, and secondly then their nondominant hemispheres. In each of the alpha and gamma frequency bands, 43 features of the e.e.g. expressed in terms of average power densities, coefficients of power density variation, coherencies and phases were calculated for each of the subjects. A method of separating the features which were related to the nature of the mental task from those which were related only to the mental workload represented by each of the tasks is presented. Of the features considered, many were found to be workload related, but only five, namely a power density variance, a right to left power ratio, an anterior to posterior phase angle and two coherency ratios, showed task-dependent behaviour. In this latter group, only two features point to the lateralisation of verbal and spatial cognitive processes to the dominant and nondominant cerebral hemispheres. The problem of the confounding of cerebral and mygenic effects and possible bias in the results owing to this effect is discussed.

Asymmetrical hand force persistence and neuroleptic treatment in schizophrenia.

The recent development of an isometric instrument for the precise quantification of hand force persistence has created a novel opportunity for the evaluation of potential motor asymmetries in schizophrenia and their response to treatment. A study of asymmetries in the unmedicated state may provide insight into the pathogenesis of schizophrenia, whereas alterations of asymmetries in response to antipsychotic medication could assist the delineation of a cerebral mechanism for the effects of pharmacotherapy. The hand force persistence of 21 unmedicated patients with schizophrenia was compared to 21 age, gender, and handedness matched normal controls. The effect of neuroleptic treatment on hand force persistence was then evaluated on a subset of 10 patients after at least 30 days of treatment. The anticipated asymmetry was evident in the unmedicated sample that showed impaired right hand force persistence compared to the normal control sample. The prospective comparison showed an alleviation of the asymmetry resulting from an improvement of right hand force persistence with treatment. In addition to providing further support to a primary left hemisphere cerebral involvement in schizophrenia, the present results suggest that prior investigations of motor asymmetry may have been compromised by the study of medicated patients. The apparently paradoxical improvement of motor skill may relate to the substantial number of patients treated with 2nd generation neuroleptic medications which may implicate an improvement in left hemisphere physiology in the cognitive advantages of the novel treatments. ( JINS , 2001, 7 , 606–614.)

Electroconvulsive Therapy and Lateralized Affective Systems

The neurophysiological systems subtending generalized seizures (activated by ECT) and temporal-limbic seizures are described as well as the interactions existing between the two seizure systems. There are correlations between schizophrenia and the limbic seizure system on the one hand and the manic-depressive or bipolar syndromes and the generalized seizure system on the other which are theoretically related to the different (although overlapping) neural substrates underlying the two major syndromes of psychosis. Evidence is reviewed that indicates that in ECT-responsive depression (with both bilateral and unilateral nondominant ECT) the modus operandi hinges on right-hemispheric neural events. Neurophysiological, neurological, and acoustic threshold evidence is discussed: all of which emphasizes the importance of the nondominant hemisphere in the genesis of endogenous depressions and in their treatment with convulsive therapies. In addition, studies showing that psychotropic agents with specific antidepressant effects produce asymmetric activation of the right hemisphere (EEG) are related to the above issues.

Chapter 14 Sinistrality and Psychopathology

Publisher Summary The patterns of cerebral organization that determine sinistrality, although partially understood in certain instances, remain obscure and enigmatic in others. A variety of psychopathological disorders are associated with an excess of lefthanders in the afflicted individuals: autism, certain forms of schizophrenia, bipolar (but not unipolar) affective illnesses, susceptibility to dysphoric mood states, certain types of criminal psychopathy (particularly if recidivistic), and epilepsy with psychosis. Intellectual retardation is also associated with increased sinistrality. The evidence reviewed in the chapter shows that the incidence of certain psychiatric disorders is increased in sinistral populations. The origins and consequences of sinistrality in schizophrenia are different in monozygotic twins, dizygotic twins, and singletons. The origins of schizophrenia are multiple as are the determinants of sinistrality. Both schizophrenia and sinistrality are fundamentally related to a functional alteration of dominant hemispheric systems. A sinistral pattern of brain organization may be the result of genetic influences, compensatory to left hemisphere damage, especially if sustained before the age of five years. The brain-damage model fits the general population of schizophrenics with severe manifestation of the illness: early onset males, with the absence of family history for psychosis and structural pathology specifically involving the left hemisphere. Modern evidence suggests that the left hemisphere, through contralateral inhibitory regulation, modulates emotional and aggression-related neural subsystems in the right hemisphere.

Asymmetrical hand force persistence and neuroleptic treatment in schizophrenia

The recent development of an isometric instrument for the precise quantification of hand force persistence has created a novel opportunity for the evaluation of potential motor asymmetries in schizophrenia and their response to treatment. A study of asymmetries in the unmedicated state may provide insight into the pathogenesis of schizophrenia, whereas alterations of asymmetries in response to antipsychotic medication could assist the delineation of a cerebral mechanism for the effects of pharmacotherapy. The hand force persistence of 21 unmedicated patients with schizophrenia was compared to 21 age, gender, and handedness matched normal controls. The effect of neuroleptic treatment on hand force persistence was then evaluated on a subset of 10 patients after at least 30 days of treatment. The anticipated asymmetry was evident in the unmedicated sample that showed impaired right hand force persistence compared to the normal control sample. The prospective comparison showed an alleviation of the asymmetry resulting from an improvement of right hand force persistence with treatment. In addition to providing further support to a primary left hemisphere cerebral involvement in schizophrenia, the present results suggest that prior investigations of motor asymmetry may have been compromised by the study of medicated patients. The apparently paradoxical improvement of motor skill may relate to the substantial number of patients treated with 2nd generation neuroleptic medications which may implicate an improvement in left hemisphere physiology in the cognitive advantages of the novel treatments.

Dominant hemispheric dysfunction in sexual deviations: Exhibitionism and pedophilia

One hundred seven pedophiles, whose sexual orientation was confirmed by phallometric response to sexual stimuli were investigated neuropsychologically and with quantitative EEG and compared to age and sex matched healthy controls. The pattern of neuropsychological and psychometric deficits revealed the presence of left frontotemporal dysfunction in the pedophiles, an effect that is particularly pronounced in those who show maximal erotic arousal for sexual partners aged 6-12. The EEG analysis showed increased frontal delta, theta, and alpha power and a pattern of reduced frontal interhemispheric coherence and increased left hemisphere coherence, essentially during verbal processing. Similar were the findings in 43 male exhibitionists and 46 normal controls, all right handed and matched for age, sex and education studied with quantitative EEG during resting conditions, and during two cognitive tasks, and during spatial cognitive processing. These findings suggest that sexual deviations in the male relate to altered dominant hemispheric functions with disruption of frontal interhemispheric relationships.

Brain changes during a shamanic trance: Altered modes of consciousness, hemispheric laterality, and systemic psychobiology

Abstract There have been a number of electrophysiological and neuroimaging studies in “altered” states of consciousness including dissociative conditions, hypnosis, and meditation; however, the nature and clinical significance of trance states remain elusive. Alterations of consciousness that accompany trance can shed light on the brain networks contributing to the experience of autobiographical self; the subjective demarcation of “self” from others and reality at large; and normative vs. pathological domains of self-experience. Shamanic trance is a volitional, self-induced state of consciousness that historically served the purposes of social cohesion and healing interventions in diverse tribal settings. We present the first neurophysiological study of a normal subject, who has received extensive training in the Mongolian shamanic tradition and is capable of self-inducing a trance state without external sensory stimulation. Quantitative EEG mapping and LORETA (low resolution electromagnetic tomography) source imaging indicate that shamanic state of consciousness (SSC) involves a shift from the normally dominant left analytical to the right experiential mode of self-experience, and from the normally dominant anterior prefrontal to the posterior somatosensory mode. These findings have implications for the psychobiology of the normative conscious mode of awareness and neurophysiological processes contributing to dissociative, psychotic, and transpersonal domains of self-experience. They may be used as a foundation to bridge Western and traditional healing techniques.