The Neurophysiology Unit is engaged since 1982 in experimental brain research while contributing to medical and post-graduate teaching.
Our studies aim to help understanding of the neuronal mechanisms underlying:
- Synaptic modification underlying learning and memory
- Circuit properties leading to neuronal synchronization and rhythm generation.
- Somatosensory processing
The connecting thread of our projects is the exploration of brain rhythms.
CURRENTLY EMPLOYED TECHNIQUES
Human sleep EEG and evoked potentials (Kostopoulos group).
Electrophysiology of in vitro perfused rodent brain slices (Papatheodoropoulos group).
The experiments are complemented by modeling and signal analysis software development
- In the epileptic mutant tottering mouse, absence seizures are co-inherited with an increase in hippocampal excitability. The change is post synaptic in CA1
- but the cable properties of the pyramidal neurons as well as recurrent inhibition remain intact.
- Both excitability and recurrent inhibition of hippocampal CA1 pyramidal cells undergo profound, non-linear changes with development and aging.
- A single experience of generalized convulsion in mice induces opposite long-term modification in GABA (down-regulation) and adenosine A1 (up-regulation) receptors(observed with both in vitro electrophysiology and quantitative autoradiography). Adenosine receptors are also up-regulated in human temporal lobe epileptic foci. Their decrease in rat kainic acid seizures is following neuronal degeneration. We studied A1R development in vitro.
- Simulation studies indicate that generalized cortical hyperexcitability may be a sufficient condition for the transition from spindles to spike and wave discharges by the same cortical circuit in the cat model of absence seizures. Conditions necessary for the transition are suggested including an intact recurrent inhibition.
- Mathematical modelling of short-term plasticity phenomena with trains of stimulation at the frog neuromuscular junction, introduces a stochastic particle formulation of the vesicle hypothesis. We modelled similar mechanisms as they appear in hippocampal slices.
- The ventral part of hippocampus shows a significant defect in short and long-term memory mechanisms.
- Low frequency (~ 2-3 Hz) field activity is spontaneously generated in rat ventral hippocampal slices perfused with normal medium.
- Human Somatosensory evoked potentials show variability in space and time of source activation as well as SI – SII interactivity.
- Ventral hippocampal slices show weaker recurrent inhibition and a propensity for epileptogenesis.
- Developed new technique allowing 3D visualization of electromagnetic brain activity.
- Clustering of single trial EEG and MEG SI responses compared the two recording modalities.