Soortoverstijgende Niet-Invasieve Neuromodulatie van de Hippocampus: Het Ontgrendelen van Hersenplasticiteit via Trigeminale Zenuwstimulatie

Noninvasive brain stimulation (NIBS) methods hold great promise for treating a wide range of neurological and psychiatric disorders. However, reported effects are often small, difficult to reproduce and the basic mechanisms underpinning them are not clear. It is widely assumed that effects of NIBS are solely caused by the electric field that it generates in the brain. However, NIBS also generate an electric field in the scalp. These fields are strong enough to initiate action potentials in peripheral nerves which could then indirectly modify brain activity. Two nerves that are likely to be stimulated in conventional NIBS electrode montages are the greater occipital nerve and the trigeminal nerve. Afferent fibers from these nerves travel to the brainstem where they project to the nucleus of the solitary tract and the locus coeruleus. These nuclei control the release of neurotransmitters such as noradrenaline in the cortex. Noradrenaline release may be one of the mechanisms through which tDCS works, but this is currently unknown. This PhD project will use rat models to investigate the role of noradrenaline in mediating tDCS effects. A final stage will seek to translate methods for measuring noradrenaline to healthy volunteers and quantify noradrenaline levels during specific controlled tDCS conditions. Project results will provide novel insight into the mechanisms behind tDCS.