Configuration of an alpha-gamma coincidence spectrometer for utilization of safeguards measurements.

An alpha-gamma coincidence spectrometry (AGCS) system was developed at the International Atomic Energy Agency's (IAEA) Safeguards Analytical Laboratory (SAL) in order to improve the detection of alpha-gamma emitting radionuclides of relevance for safeguards, such as (239)Pu and (241)Am. The AGCS design was based upon a linear gate, whose resolving time is dependent upon the amplifiers' shaping time constants (STC). A coincidence spectrum of a Pu/Am sample was acquired which showed that the AGCS system could be utilized in safeguards measurements.

Group III metabotropic glutamate receptor-mediated, chemically induced long-term depression differentially affects cell viability in the hippocampus.

In vivo, activation of group III metabotropic glutamate (mGlu) receptors leads to a reduction of basal synaptic transmission in the hippocampus, and depending on the experimental conditions in vitro, leads to neuroprotection or neurotoxicity. Here, the cellular response to cerebral application of L(+)-2-amino-4-phosphonobutanoic acid (AP4) was investigated in the CA1 region and dentate gyrus of freely moving rats. Drugs were applied via the lateral ventricle, and electrophysiological measurements were obtained via chronically implanted electrodes.

Kindling-induced changes in plasticity of the rat amygdala and hippocampus.

Temporal lobe epilepsy (TLE) is often accompanied by interictal behavioral abnormalities, such as fear and memory impairment. To identify possible underlying substrates, we analyzed long-term synaptic plasticity in two relevant brain regions, the lateral amygdala (LA) and the CA1 region of the hippocampus, in the kindling model of epilepsy. Wistar rats were kindled through daily administration of brief electrical stimulations to the left basolateral nucleus of the amygdala.

Processes and components participating in the generation of intrinsic optical signal changes in vitro.

Imaging of intrinsic optical signals has become an important tool in the neurosciences. To better understand processes underlying changes in intrinsic optical signals, we studied electrical stimulation at varying strengths in hippocampal slices of adult Wistar rats. Following serial stimulation we observed an increase in light transmittance in all tested slices.

Seizure spread through the life cycle: optical imaging in combined brain slices from immature, adult, and senile rats in vitro.

The semiology of epileptic seizures changes during the lifetime. Hence, it can be assumed that age-related changes in brain plasticity influence the patterns of seizure onset, spread and propagation velocity. We employed the 4-aminopyridine model of epilepsy to study seizure-like events in vitro.

Reduction of high-frequency network oscillations (ripples) and pathological network discharges in hippocampal slices from connexin 36-deficient mice.

Recent evidence suggests that electrotonic coupling is an important mechanism for neuronal synchronisation in the mammalian cortex and hippocampus. Various types of network oscillations have been shown to depend on, or be sharpened by, gap junctions between inhibitory interneurones or excitatory projection cells. Here we made use of a targeted disruption of the gene coding for Cx36, a recently discovered neuronal gap junction subunit, to analyse its role in hippocampal network behaviour.

Intrinsic optical imaging reveals regionally different manifestation of spreading depression in hippocampal and entorhinal structures in vitro.

The spatiotemporal features of spreading depression (SD) were analyzed in vitro by using combined hippocampal-entorhinal cortex slices. SDs were induced by microinjection of 1 M KCl in the stratum radiatum of the CA1 region of the hippocampus. Measurements of extracellular field potentials, extracellular space (ECS) volume changes and intrinsic optical signal changes were combined to study SD features in different regions of the slice.