Effects of acute nicotine on somatosensory change-related cortical responses.

Nicotine is known to have enhancing effects on some aspects of attention and cognition. As for the pre-attentive processes of detecting sensory changes, nicotine has significant effects on the auditory and visual systems implying that its pre-attentive effect is common among sensory modalities. The purpose of the present study was to elucidate whether acute nicotine administration has enhancing effects in the somatosensory system. Change-related cortical activity in response to an abrupt increase in stimulus intensity was recorded using magnetoencephalography. The test stimulus consisted of standard electrical pulses at 100 Hz for 500 ms applied to the dorsum of the left hand followed by 0.7-mA stronger pulses for 300 ms. Nicotine was administered in a gum (4 mg of nicotine). Eleven healthy nonsmokers were tested with a double-blind and placebo-controlled design. Effects of nicotine on the cortical response in the primary (S1) and secondary (S2) somatosensory cortices were investigated. Results showed that nicotine failed to affect the S1 response while it significantly increased the amplitude of S2 activity in the hemisphere ipsilateral to the stimulation, and shortened the peak latency of S2 activity in both hemispheres. Since cortical responses in the present study represent a pre-attentive automatic process to encode new somatosensory events, the results suggest that nicotine can exert beneficial cognitive effects without a direct impact on attention and that the effect of nicotine on the automatic change-detecting system is common across sensory modalities.

Effects of zotepine on extracellular levels of monoamine, GABA and glutamate in rat prefrontal cortex.

BACKGROUND AND PURPOSE: The atypical antipsychotic drug, zotepine, is effective in treatment of schizophrenia and acute mania, but the incidence of seizures during treatment is higher than with other antipsychotics. In addition, the mechanisms underlying the clinical actions of zotepine remain uncharacterized. EXPERIMENTAL APPROACH: The effects of intraperitoneal administration of zotepine and haloperidol on the extracellular levels of noradrenaline, dopamine, 5-HT, GABA, and glutamate in the medial prefrontal cortex (mPFC) were compared. Neuronal activities induced by each drug in the ventral tegmental area (VTA), locus coeruleus (LC), dorsal raphe nucleus (DRN) and mediodorsal thalamic nucleus (MTN) were also analysed. KEY RESULTS: Haloperidol did not affect extracellular neurotransmitter levels in the mPFC. In contrast, zotepine activated neuronal activities in all nuclei and increased the extracellular levels of noradrenaline, dopamine, GABA, and glutamate in the mPFC, but not 5-HT levels. The zotepine-stimulated neuronal activity in the VTA, LC, DRN and MTN enhanced the release of dopamine, noradrenaline, 5-HT, glutamate and GABA in the mPFC, although the enhanced GABAergic transmission possibly inhibited noradrenaline, dopamine and 5-HT release. The other afferent to mPFC, which releases dopamine and noradrenaline, was partially insensitive to GABAergic inhibition, but possibly received stimulatory AMPA/glutamatergic regulation from the MTN. CONCLUSIONS AND IMPLICATIONS: Our results indicated that the positive interaction between prefrontal catecholaminergic transmission and AMPA/glutamatergic transmission from MTN might explain the regulatory effects of zotepine on neurotransmitter release. A mechanism is suggested to account for the pharmacological profile of this atypical antipsychotic and for its pro-convulsive action.

Temporal slow waves and cerebrovascular diseases.

Sporadic temporal slow waves are considered to be associated with mild cerebrovascular dysfunction. However, electroencephalogram (EEG) changes have not been consistently described by some investigators and correlations inferred on the basis of such data remain inconclusive. In the present study, we examined previously defined temporal slow waves in patients in relation to incidence of cerebrovascular disease. A total of 512 EEG were analyzed during a 1 year period at our laboratory and 74 reference EEG from healthy volunteers were all examined as to the presence of temporal low-voltage irregular delta wave (TLID), temporal minor slow and sharp activity (TMSSA) or bursts of rhythmical temporal theta (BORTT). The patterns were assessed in relation to clinical histories of patients and controls. There were similarities in clinical correlations for the three EEG changes including associations with mild cerebrovascular diseases and with aging. In addition these temporal EEG findings shared electrographic features and showed left side predominance as well as correlating with each other. Since TLID, TMSSA and BORTT have many clinical and electrographical similarities, we consider that these findings should be grouped into one EEG entity which appears in association with mild cerebrovascular dysfunction.

Electroencephalographic findings in patients with DSM-IV mood disorder, schizophrenia, and other psychotic disorders.

BACKGROUND: Although numerous electroencephalographic (EEG) studies have been performed in psychiatric populations, and some have identified specific abnormalities within groups of functional psychoses, differences in EEG findings among subgroups of functional mental illness need to be evaluated with careful consideration of the nosologic systems employed in each study. In the present study, we examined whether there might be EEG differences among subgroups of functional psychoses defined by DSM-IV. METHODS: A total of 143 patients, whose discharge diagnoses met the DSM-IV criteria for mood disorder, schizophrenia, and other psychotic disorders, were studied. EEG findings were compared among seven diagnostic categories: mood disorder without, with mood-congruent, and with mood-incongruent psychotic features; schizoaffective disorder; schizophreniform disorder; brief psychotic disorder; and schizophrenia. RESULTS: The frequency of epileptiform variants, including the phantom spike and wave, positive spikes, and small sharp spikes, was significantly higher among patients with mood-incongruent psychotic mood disorder (33%), schizoaffective disorder (33%), and schizophreniform disorder (30%), as compared with patients with nonpsychotic mood disorder (3.2%) and schizophrenia (0%). CONCLUSIONS: Our results imply that patients with "atypical" psychoses that are located between typical mood disorder and schizophrenia have similar biological vulnerability, represented by epileptiform EEG variants.

Menkes' kinky hair disease: clinical and experimental study.

A pedigree of Menkes' kinky hair disease (MKHD) is reported. One patient of this family who underwent copper treatment was followed for three years with fundus examinations and ERG measurement. The blood copper level remained normal after six months of age, when intravenous treatment was switched from cupric acetate to cupric sulfate. Optic nerve atrophy and decrease in amplitude of the ERG were observed at three years of age. In an experiment using mouse models of MKHD (macular mouse mutant, Moml), we compared the affected mice that received copper treatment with normal mice. However, there was no difference between them in ERG responses, number of ganglion cells, or thickness of retinal layers. These results support the possibility of prolonged survival and maintained vision in the patients of MKHD by earlier normalization of the copper level.