Dietmar Basta

Early development of neuronal hypothalamic thermosensitivity in birds: influence of epigenetic temperature adaptation.

The aim of the study was to investigate the prenatal influence of different incubation temperatures on the early postnatal development of neuronal hypothalamic thermosensitivity in birds. The experiments were carried out in brain slices of 1-, 5- and 10-days-old Muscovy ducklings incubated at 35, 37.5 (control) or 38.5 degrees C during the last week of incubation. Firing rate of neuronal activity was recorded extracellularly during sinusoidal temperature changes. The results show that the temperature experienced prenatally has a clear influence on postnatal neuronal hypothalamic thermosensitivity. For instance, at the 10th day post-hatching, exposure to the cooler prenatal incubation temperature resulted in elevated neuronal hypothalamic warm sensitivity through an increased proportion of warm sensitive neurons and a reduced proportion of cold sensitive neurons in comparison with the control group. Exposure to the warmer prenatal incubation temperature induced the opposite effect. In these age group changes in neuronal hypothalamic thermosensitivity occur in relation to the prenatal temperature experienced (proximate adaptive). During the first days of life, prenatal temperature load induced a significant change in the thermosensitivity of hypothalamic neurons which was independent of the direction of change in incubation temperature in comparison with control conditions (proximate non-adaptive). Changes in the thermosensitivity of hypothalamic neurons after prenatal temperature experiences observed in all age groups may be the result of epigenetic temperature adaptation.

Efficacy of a vibrotactile neurofeedback training in stance and gait conditions for the treatment of balance deficits: a double-blind, placebo-controlled multicenter study.

Objective Vestibular rehabilitation strategies mostly require a long-lasting training in stance conditions, which is finally not always successful. The individualized training in everyday-life conditions with an intuitive tactile neurofeedback stimulus seems to be a more promising approach. Hence, the present study was aimed at investigating the efficacy of a new vibrotactile neurofeedback system for vestibular rehabilitation. Study Design Double-blinded trial. Patients One hundred five patients who experience one of the following balance disorders for more than 12 months were included in the study: canal paresis, otolith disorder, removal of an acoustic neuroma, microvascular compression syndrome, Parkinson’s disease, and presbyvertigo. Interventions Vibrotactile neurofeedback training was performed daily (15 min) over 2 weeks with the Vertiguard system in those 6 tasks of the Standard Balance Deficit Test with the most prominent deviations from the normative values. Main Outcome Measures Trunk and ankle sway, dizziness handicap inventory, and vestibular symptom score were measured in the verum and placebo group before the training, on the last training day and 3 months later. Results A significant reduction in trunk and ankle sway as well as in the subjective symptom scores were observed in the verum group. Such an effect could not be found in any of the outcome parameters of the placebo group. Conclusion The vibrotactile neurofeedback training applied in the present study is a highly efficient method for the reduction of body sway in different balance disorders. Because the rehabilitation program is easy to perform, not exhausting, and time saving, elderly patients and those with serious, long-lasting balance problems also can participate successfully.

The possible impact of noise-induced Ca2+-dependent activity in the central auditory pathway: A manganese-enhanced MRI study

Noise exposure at high intensities leads to a temporary shift of hearing thresholds (TTS) and is followed by a permanent threshold shift (PTS). Permanent threshold shift is not only associated with cochlear damage as the primary site-of-lesion, but also with subsequent structural and functional changes within the central auditory pathway. The aim of the present study was to monitor neuronal activity within central auditory structures in mice after noise exposure at different time intervals using manganese-enhanced magnetic resonance imaging (MEMRI). The results demonstrate for the first time that calcium-dependent activity patterns are modified in several structures of the central auditory system as the result of a noise-induced hearing loss (NIHL). The MEMRI data demonstrate that temporary threshold shift is correlated with an activity increase in hierarchically lower structures of the auditory pathway. This seems to be indicative of a direct noise impact at the first stage of central auditory processing. However, noise-dependent changes of higher auditory structures were found as well in the phase of PTS. Repeated noise exposure was found to induce an additional elevation of calcium-dependent activity in all investigated auditory structures - without a significant shift in auditory thresholds. Sustained manganese accumulation was present in the auditory brainstem after moderate acoustic stimulation as well without PTS induction. The long-lasting enhancement of MEMRI signals suggests a noise-induced activity increase of various calcium-dependent processes of different origin (such as neuroprotective mechanisms). The present findings could be helpful to better understand the time-course of different symptoms in NIHL and the individual susceptibility to noise.

Temperature guardian neurons in the preoptic area of the hypothalamus

Applying the slice method extracellular recordings of 218 hypothalamic neurons in Muscovy ducks during sinusoidal temperature changes were investigated. Seven neurons reacted in a hitherto unknown manner to temperatures very near the physiological limits. Four were exclusively sensitive to temperatures around 36.1 degrees C and three to temperatures around 42.3 degrees C. We recommend to call this kind of neurons temperature guardian neurons. The presented results suggest that the current neuronal model of temperature regulation of vertebrates should be extended by aspects of the two-tier theory of Bligh [J. Bligh, The thermosensitivity of the hypothalamus and thermoregulation in mammals, Biol. Rev. 41 (1966) 317-367].

Influence of bombesin on neuronal hypothalamic thermosensitivity during the early postnatal period in the Muscovy duck (Cairina moschata)

The influence of bombesin (1 microg/0.1 ml artificial cerebrospinal fluid) on neuronal thermosensitivity of the preoptic area of the anterior hypothalamus in brain slices of 5- (n = 7 neurons) and 10-day-old (n = 36 neurons) Muscovy ducks (Cairina moschata) was investigated. Similar to adult mammals, most of the neurons investigated increased the firing rate (FR) after bombesin application. Changes in FR were not related to changes in thermal coefficient (TC). The neurons react to bombesin also under synaptic blockade. The bombesin-induced effect on TC (increase or decrease in nearly the same number of neurons, e.g. nine neurons increased and ten decreased TC in 10-day-old ducklings) in the postnatal bird neurons investigated was different from the results described in adult mammals, where the main reaction to bombesin was an increase of TC in warm-sensitive and temperature-insensitive-neurons and a transformation of temperature-insensitive-neurons into warm-sensitive ones. This may be related to the assumption that during early ontogeny, body functions react to exogenous and endogenous factors nonspecifically. It is to speculate, that later, probably at the end of embryonic development or during the early postnatal period, the reactivity of these functions changes qualitatively, so that the reaction of an individual function to different factors becomes specific (ultimately adaptive).

Mobile Posturografie als Grundlage eines individualisierten Neurofeedbacktrainings

Die Aufrechterhaltung der Korperbalance und die Kontrolle der Willkurmotorik werden beim Gesunden mit Hilfe von sensorischen Informationen in einem engen Regelbereich gewahrleistet. Wird dieser sensorische Input reduziert, nimmt die Regelgute drastisch ab. Patienten mit dauerhaft reduziertem sensorischen Input verfugen deshalb uber sehr viel schlechtere Gleichgewichtsleistungen, wodurch sich das Risiko zu sturzen erhoht. Das ist insbesondere dann der Fall, wenn eine Schadigung der Gleichgewichtsorgane, eine reduzierte Somatosensorik (Propriorezeption) oder ein verringerter visueller Input vorliegt. Durch die zunehmende Alterung unserer Gesellschaft ist das ein ernsthaftes epidemiologisches Problem. Die Folge sind haufige Sturze.

Elektrische und vibrotaktile Rehabilitation von nicht-kompensierten Vestibulopathien

Schwindelbeschwerden und dadurch ausgeloste Sturze (mit sekundaren Verletzungen — wie z.B. Oberschenkelhalsfrakturen) spielen in den alternden westlichen Gesellschaften eine immer grosere Rolle. Daneben spielen internistische, neurologische, ophthalmologische oder orthopadische Begleiterkrankungen eine Rolle, die den alten Menschen relativ instabil machen (Murray et al. 2005). Im hoheren Lebensalter konnen vorhandene chronische Vestibulopathien schlechter kompensiert werden, hinzu kommt eine altersbedingte Degeneration der Sinneszellen des gleichgewichts-erhaltenden Systems (Baloh et Marchetti et al. 2005; Rauch et al. 2001). Die gangigen konservativen Therapiemasnahmen durch statische und dynamische Ubungen zeigen haufig nur masige Erfolge und fuhren zu protrahierten Behandlungszeitraumen. Ziel einer Gleichgewichtsrehabilitation sollte es sein, die vorhandenen funktionstuchtigen Sinneszellen zu trainieren, sowie eine ausreichende zentrale Kompensation zu bilden.