Mismatch negativity is not correlated with neuroendocrine indicators of catecholaminergic activity in healthy subjects.

The identification of the brain structures and neurotransmitters responsible for the generation and/or modulation of the mismatch negativity (MMN) may contribute to a clearer understanding of its functional significance, and may have clinical implications. In this context, some findings suggest that the scalp-recorded MMN reflects activity from multiple neuronal ensembles within or in the immediate vicinity of the primary auditory cortex and with possible contribution from the frontal cortex. However, few data are available concerning the influence of neurotransmitter systems on the MMN. In this study, the relationship between both noradrenergic and dopaminergic systems and the MMN were investigated in 34 healthy volunteers. Noradrenergic and dopaminergic activities were assessed with the apomorphine and clonidine challenge tests. The results showed no significant relationship between either growth hormone (GH) responses to apomorphine or clonidine and the MMN amplitude or latency. Therefore, this study does not demonstrate the implication of dopaminergic and noradrenergic activities as assessed by GH response to apomorphine and clonidine for the generation and/or the modulation of the MMN. However, given the complexity of the central neurotransmitter systems, these results cannot be considered as definitive evidence against a relationship between dopaminergic and noradrenergic activity and the MMN.

[The value of early morphologic ultrasonography for the detection of chromosome anomalies]. / Intérêt de l'échographie morphologique précoce pour la détection des anomalies chromosomiques.

OBJECTIVES: To demonstrate the benefit, in terms of improved antenatal screening, in particular for 21-trisomy, to be expected from the introduction of routine vaginal morphologic echography during the first trimester of pregnancy. This work was conducted by the Department of Gynaecology-Obstetrics of the French Red Cross Teaching Hospital in Bois-Guillaume, France. SUBJECT: Over a 20 month period, 307 consultating women underwent routine endovaginal echography between the 10th and 13th week of amenorrhoea. The exploration was proposed to detect small retrocervical hydromas as a signal for further cytogenetic tests. RESULTS: Five hygromas were discovered and led to the diagnosis of 4 cases of 21-trisomy, the fifth pregnancy ended with spontaneous abortion. The 12th week appeared as the most favourable time for routine examination. CONCLUSIONS: This non-invasive method, routinely performed in all women, improves the yield of screening for 21-trisomy and allows a better means of indicating cytogenetic tests.