What are the physiological mechanisms at the basis of fear and anxiety ? How is it that certain noises in the middle of the night can scare us, while a similar sound during daytime has no such effect? Which mechanisms underlie our fear thresholds and our bodily reactions to fear? It seems that there are individual levels and sustained anxiety and fear can manifest themselves in various ways: in one person they can lead to cardiovascular problems while in others the gastrointestinal system starts to give problems. The precise physiological reasons for these, however, remain still largely unknown.
We meanwhile know that one region in the brain is particularly involved in our anxiety and fear responses: the amygdala, a cluster of nuclei situated in the temporal lobe, anterior to the hippocampus with which is maintains strong anatomical and functional connections. The amygdala receives a large variety of different sensory inputs (auditory, visual, olfactory and gustatory) and projects to various nuclei in the brain stem that control our visceral responses.
My group studies the regulation of these responses by the amygdala in a comparative way between humans and rodents, preferably the rat, a very interactive companion with an important social life that resembles us in many aspects. The approach we have chosen consists of a combination of in vitro and in vivo techniques. For the in vitro part, we have established in Cery a laboratory with various electrophysiological set-ups to record neurophysiological signalling in slices of rat and human brain using extracellular, intracellular and whole-cell patch-clamp methods. For the in vivo part, we use telemetric devices in rats to follow increases in heart rate, blood pressure respiratory rhythm or intestinal motility. For the human studies we have an active collaboration with the neurosurgery teams in Lausanne and Geneva where implantation of intracerebral electrodes in combination with EEG, ECG, EGG etc. allow measurements of amygdala activation and its consequences in temporal lobe epileptic patients.