Control of neurotransmission, behaviour and development, by photo-dynamic manipulation of tissue redox state of brain targets

Reversible manipulation of local neurotransmission in brain areas, using co ntrolled spatial and temporal resolution, is one of the powerful techniques used to investigate integrative aspects of brain function. We have develop ed a novel technique for rapidly inactivating local synaptic transmission, from outside the brain, within seconds or minutes via oxidation of target t issue using a photosensitive dye followed by photoirradiation (photo-dynami c tissue oxidation; PDTO). PDTO applied through a defined slit, sharply sup pressed excitatory synaptic transmission in rat hippocampal slices and also suppressed in vivo hippocampal neurotransmission reversibly. Furthermore, we manipulated the voluntary movement of gerbils in free-field activity by application of PDTO to the striatum, Also. in freely moving kittens, the de velopment of the visual cortex was manipulated by long-lasting application of PDTO to the eye. Thus, PDTO enables external manipulation of in vivo or in vitro neurotransmission in various clearly defined regions on the submil limeter scale. Suppression of neurotransmission occurred only within the ph oto-oxidized area which can be histochemically visualized.