Hippocampal negative event‐related potential recorded in humans during a simple sensorimotor task occurs independently of motor execution

A hippocampal‐prominent event‐related potential (ERP) with a peak latency at around 450 ms is consistently observed as a correlate of hippocampal activity during various cognitive tasks. Some intracranial EEG studies demonstrated that the amplitude of this hippocampal potential was greater in response to stimuli requiring an overt motor response, in comparison with stimuli for which no motor response is required. These findings could indicate that hippocampal‐evoked activity is related to movement execution as well as stimulus evaluation and associated memory processes. The aim of the present study was to investigate the temporal relationship between the hippocampal negative potential latency and motor responses. We analyzed ERPs recorded with 22 depth electrodes implanted into the hippocampi of 11 epileptic patients. Subjects were instructed to press a button after the presentation of a tone. All investigated hippocampi generated a prominent negative ERP peaking at ～420 ms. In 16 from 22 cases, we found that the ERP latency did not correlate with the reaction time; in different subjects, this potential could either precede or follow the motor response. Our results indicate that the hippocampal negative ERP occurs independently of motor execution. We suggest that hippocampal‐evoked activity, recorded in a simple sensorimotor task, is related to the evaluation of stimulus meaning within the context of situation. © 2013 Wiley Periodicals, Inc.     

The posterior medial cortex is involved in visual but not in verbal memory encoding processing: an intracerebral recording study

The objective is to study the involvement of the posterior medial cortex (PMC) in encoding and retrieval by visual and auditory memory processing. Intracerebral recordings were studied in two epilepsy-surgery candidates with depth electrodes implanted in the retrosplenial cingulate, precuneus, cuneus, lingual gyrus and hippocampus. We recorded the event-related potentials (ERP) evoked by visual and auditory memory encoding–retrieval tasks. In the hippocampus, ERP were elicited in the encoding and retrieval phases in the two modalities. In the PMC, ERP were recorded in both the encoding and the retrieval visual tasks; in the auditory modality, they were recorded in the retrieval task, but not in the encoding task. In conclusion, the PMC is modality dependent in memory processing. ERP is elicited by memory retrieval, but it is not elicited by auditory encoding memory processing in the PMC. The PMC appears to be involved not only in higher-order top-down cognitive activities but also in more basic, rather than bottom-up activities.     

Experimentell-mikroskopische studie zur frage der lokalisation der industrielärmbedingten Hörermüdung und des später resultierenden bleibenden Hörschadens

Zusammenfassung In Fortführung einer vorangegangenen Studie zur Frage der Lokalisation von bleibenden Hörschäden nach Industrielärmbelastung mit tonalen Geräuschanteilen werden in einer weiteren Arbeit die Frühveranderungen besprochen, die am Haarzellager der Kaninchenschnecke nach Geräuschbelastung mit tonalen Anteilen entstehen. Es wurden insgesamt 15 Tiere 10–80 Std einem gleichen Schleifmaschinen-Geräusch von etwa 105 dB Gesamtpegel ausgesetzt, in welchem die tiefen Frequenzen die Gesamtenergie bestimmten. Nach Abschluß der Beschallungszeiten wurden die Schnecken der sofort getöteten Kaninchen in Formol fixiert, zum größten Teil mikropräpariert und der Rest nach Celloidin-Einbettung in Serie geschnitten. Die Ergebnisse konnten in drei Gruppen eingeteilt werden.Nach einer Beschallungsdauer bis zu 30 Std (Gruppe 1) zeigen sich in dem. Ansprecbgebiet tiefer Frequenzen von 500 bis etwa 1000 Hz im Bereich der äußeren Haarzellen des Corti-Organs Veränderungen am Kern und am Plasma. Diese Veränderungen finden sich also in Arealen, die Frequenzen zugehören, die1/2–1 Oktave höher sind als die wirksamen Tone von 200 und 500 Hz.Eine Beschallungsdauer zwischen 30 und 60 Std führt dann zu stärkeren metabolischen Störungen in diesem Bereich. Daneben gesellen sich in dieser Gruppe 2 nach 40 stündiger Beschallung zu den in Gruppe 1 beobachteten Veränderungen Stoffwechselstörungen um 4000 Hz. Es bestehen also an zwei weft voneinander entfernten Stellen des Ductus cochlearis gleichmäßige Überlastungszeichen, die aber nach 60 Std Belärmung im Perzeptionsgebiet 4000 Hz an Ausdehnung und Stärke zunehmen.Nach einer Beschallungszeit von 80 Std (Gruppe 3) und mehr werden die typischen Dauerschäden im Frequenzansprechgebiet von 4000 Hz an sichtbar, hingegen schwinden die Veränderungen im Ansprechgebiet von 500 Hz. Hier sind nur noch wenige Kerngrößenschwankungen der äußeren Haarzellen zu finden.Es wird auf die praktische Bedeutung dieser Beobachtung hingewiesen, da die Ergebnisse dafür sprechen, zwischen vorübergehendem Hörschaden, der eine gewisse Frequenzabhängigkeit vom Belastungsschall zeigt, und dem bleibenden Hörschaden, der sich vorzugsweise um 4000 Hz ohne Belastungsfrequenzbezug entwickelt, zu unterscheiden.     

Das immobilisierte Aryhöckergelenk

Summary Observations in two patients with posterior laryngeal bands following prolonged intubation show that longtime immobilization (2 years and 3 months) is not necessarily leading to ankylosis of the arytenoid joints. As seen in our patients, persistent muscular innervation seems to play an important role to overcome ankylosis in providing minute mobility and in preventing permanent fixation.     

Long-term protective effect of post-exposure Havrix TM administration during viral hepatitis Type A outbreaks

Administration of human normal immunoglobulin (HNIG) post-exposure has been routinely used in Slovakia for outbreak control of hepatitis A, but requires deep intramuscular injection, provides only short-lived protection and is a human blood product. The protective effect of post-exposure administration of an inactivated hepatitis A vaccine was evaluated during 10 outbreaks in Slovakia. Direct contacts of confirmed hepatitis A cases received either: a single dose of hepatitis A vaccine (n = 2171) or immunoglobulin (HNIG, n = 3837). In the HNIG group the number of hepatitis A confirmed cases dropped within the first 7 weeks, however the decrease was not as rapid or as marked as that observed in the vaccinated group where the number of hepatitis A cases dropped within the first 4 weeks after vaccination. Among contacts, 67 cases of hepatitis A were detected during the maximum incubation period of 45 days: 16 cases (0.7%) in the vaccine group and 51 cases (1.3%) in the HNIG group (p  <  0.05). After two and three years respectively, 50 and 39 volunteers who had previously received one dose of hepatitis A vaccine received a booster dose and anti-HAV antibodies were measured. Differences in anti-HAV antibody GMCs before and after the booster were statistically significant. The longer time interval (3 years instead of 2) between primary vaccination and booster administration did not seem to impact the magnitude of the booster response. The results of this study show that active post-exposure immunisation with only one dose of inactivated vaccine confers high and long-term protection and effectively controls viral hepatitis A outbreaks.