The -2 bp deletion in exon 6 of the 'alpha 7-like' nicotinic receptor subunit gene is a risk factor for the P50 sensory gating deficit.

Abnormality in the P50 auditory-evoked potential gating is an endophenotype associated with schizophrenia. Biochemical and genetic studies have suggested that the alpha 7 nicotinic acetylcholine receptor (nAChR) is involved in this sensory gating deficit. Two related alpha 7 genes (CHRNA7 and CHRNA7-like gene) resulting from a partial duplication (from exon 5 to exon 10) are present in the human genome. Two types of genetic variation, a large deletion and a -2 base-pair deletion in exon 6 resulting in a truncation of the open reading frame, affect specifically the CHRNA7-like gene. We developed a simple multiplex PCR assay on genomic DNA, allowing the quantification of the number of exons 6 and the distinction of all possible exon 6 genotypes. Genotyping of 70 schizophrenic patients and 77 controls showed that carrying at least one -2 bp deletion of exon 6 did not constitute a risk factor for schizophrenia. In contrast, the distribution of genotypes differed significantly between subjects with normal and abnormal P50 ratios, with an over-representation of genotypes carrying at least one -2 bp deletion of exon 6 among subjects exhibiting an abnormal P50 ratio. We thus conclude that the -2 bp deletion within the CHRNA7-like gene is a risk factor for P50 sensory gating deficit. Interestingly, most of the effect came from the non schizophrenic group, which may suggest that in schizophrenic patients other risk factors account for the large proportion of subjects exhibiting an abnormal P50 ratio.

[Musical hallucinosis following infarction of the right middle cerebral artery]. / Hallucinose musicale au décours d'un infarctus sylvien droit.

A 44-year-old woman demonstrated a musical hallucinosis four months after a massive infarction in the territory of the right middle cerebral artery. This musical hallucinosis consisting of familiar tunes, was continuous and perceived by both ears. Magnetic Resonance Imaging, middle and late auditory evoked potentials suggested that right Heschl's gyrus and associative areas were imparied. Audiometry demonstrated a low right transmission deafness. The hallucinosis was persistent for seven months and stopped just after hemorrhage of the right ear. This case gives the opportunity to review the different mechanisms responsible for musical hallucinosis.

Saccadic and smooth-pursuit eye movements in deficit and non-deficit schizophrenia.

We have analyzed eye movement performances in schizophrenics showing primary negative or deficit symptoms (n=16) and non-deficit schizophrenics (n=55), and compared them with those of controls (n=34) in order to study the relationships between negative symptoms and eye movement abnormalities. Patients were subtyped into deficit and non-deficit subgroups using the Schedule for the Deficit Syndrome. Three oculomotor paradigms were used: smooth pursuit, a reflexive saccade paradigm and an antisaccadic task. The smooth pursuit gain was significantly decreased (and the rate of catch-up saccades increased) in schizophrenics as compared with controls, but no difference was observed between patient groups. In the reflexive saccade paradigm, no difference was found between controls and patients, except for latency in deficit patients. In the antisaccade paradigm, the number of errors and the latency of successful antisaccades were significantly increased in schizophrenics as compared with controls. The latency of successful antisaccades in both directions was significantly increased in deficit patients as compared with non-deficit patients. The latency of rightward successful antisaccades was significantly increased as compared with the latency of leftward antisaccades in deficit patients only. However, when patients were classified into negative and non-negative groups using the PANSS, no difference was found in the antisaccade paradigm. Smooth pursuit impairment does not seem to depend on the primary enduring negative symptoms.In deficit schizophrenics, the abnormalities observed in the antisaccadic task are consistent with prefrontal dysfunction, and may suggest parietal lobe dysfunction as well.

[Permanent percutaneous electric connection. General principles]. / La connexion electrique percutanée permanente. Principes généraux.

The Swedes for more than twenty years, and the Germans for over five years have been able to maintain inert or active prostheses with permanent percutaneous connections, thanks to the dependable and proven material and techniques of extraoral implants. The significant improvement extra-oral implants have brought about is not only in a new therapeutic approach to the treatment of important facial defects or transmission deafness; it is also because for some twenty old years now, the few millimeter wide cylinders of Titanium, the <> affixed on the implants, have crossed the cutaneous barrier for extended periods without complications. The percutaneous abutment thus creates a permanent communication between the interior and the exterior of the organism. If the abutment, instead of simply carrying a Maxillo-Facial Prosthesis or an auditive prosthesis, is modified by placing an electric conductor inside it, the simple "percutaneous peg" will turn out to be, in a way, a "percutaneous electric plug". By adapting classic "mechanical" abutments and implants, authors have created a Permanent Percutaneous Electric Connection (PPEC) which has been successfully experimented on rabbits to record EEG. Clinical applications on humans would make it possible either to receive "bio-electrical information" coming from within the organism, or to send electrical energy into the organism. This last application opens vast perspectives of improvement both in diagnosis and therapy in many fields.

Kleine-Levin syndrome misdiagnosed as schizophrenia.

A 27 year-old man initially considered as a schizophrenic patient was later diagnosed as having Kleine-Levin syndrome.

SPEM impairment in drug-naive schizophrenic patients: evidence for a trait marker.

Smooth-pursuit eye movements (SPEM) were assessed in healthy subjects and in drug-naive, chronic, and residual schizophrenic patients. SPEM gain was found to be decreased in all the schizophrenic patients who also exhibited a significant increase in the rate of saccades. The frequency of square-wave jerks was the same in schizophrenic patients and normal controls, suggesting that the primary abnormality in schizophrenic patients was a low gain rather than a defect of the saccadic system. Patients were retested 1 month later, and stability of gain was high even in formerly drug-naive subjects who had been treated for 1 month with neuroleptic drugs. Altogether these results confirm the conclusions of most previous studies, extend them to drug-naive schizophrenic patients, and favor the hypothesis that SPEM impairment is a trait marker in schizophrenia.

[Th importance of spectral analysis in the evaluation of the effects of magnetic pulsed fields on alpha rhythm]. / Intérêt de l'analyse spectrale dans l'évaluation des effets sur le rythme alpha des champs magnépulsés.

By means of spectral analysis, this research of alpha rhythm's modifications upon effects of electromagnetic fields makes conspicuous an increasing frequency and amplitude of this rhythm, proportionally to the time passage, and proposes questions and interpretations.

[Shunt evoked potentials. Objective significance for hearing aids]. / Potentiels évoqués dérivés. Intérêt pour l'audioprothèse objective.

A method first described in 1978, and improved since that date, is a reliable mean of assessing gain in hearing from prosthetic aids by the use of brain stem early auditory evoked potentials. The type of signal used with the prosthesis must be the click and click type with a high-pass filter, and the principle of shunt potentials must be applied.

[Brain stem potentials evoked by "click" (author's transl)]. / Potentiels évoqués du tronc cérébral par "click".

The authors describe the results of click at a recurrence frequency of 10 C/S in evoked responses of the brain stem, firstly in twenty normal individuals, with headphones or in a free area, making it possible to define a range of physiological responses to the different intensities, then in seventeen pathological individuals consisting of six cases of conduction deafness and eleven of perceptive deafness. On the basis of this study, they attempt to demonstrate the value of this type of examination not only in the determination of objective auditory threshold, but also in that of the type of deafness: conductive or perceptive. The method even makes it possible to approximately define the general appearance of the frequency distribution at the threshold according to the slope of the different latencies of P5. In the opinion of the authors, the chief advantages are the decrease in the time required for the test and the possibility of its use in the study of prosthetic gain.