University College London
Communication between neurones is mediated by substances known as neurotransmitter. These agents are released in the narrow space between neurones and bind to specialized proteins (receptors). Following binding, receptor changes conformation and allow the flow of electrical current into the cells. Glycine is an inhibitory transmitter, because it reduces the activity in the cell it is bound to.
I am studying the individual connections and spinal cord circuits between neurones that release the inhibitory transmitter glycine and motoneurones. Motoneurones are the only neurones sending signals directly to non-neuronal cells (muscles).
Motor coordination, for example the right/left leg alternation while walking, is made possible by the timed release of glycine that silence motoneurones controlling the left leg while those controlling the right are active. This apparently simple alternating pattern requires the participation of thousands of neurones, whose exact timing is crucial.
The timing of inhibition depends on the circuitry in the spinal cord and on the shape and duration of inhibitory signals received by the motoneurones.
My research has shown what are the factors regulating the duration of inhibition. In particular I have shown that in an intact system the time course of glycine mediated inhibition can be as short as 1-2 milliseconds and that this is enough to prevent a motoneurone from starting muscle contraction.
While a full knowledge of the spinal cord circuits is still far to come, genetic methods have provided an exceptional tool and pieces of the jigsaw are slowly falling into place.
This is not just an intellectual exercise: knowledge of the basic circuitry is the first step to refine strategies aimed at repair and regeneration of fibers in spinal cord that are damaged because of trauma or disease. It is only by gaining basic knowledge of the healthy system that we will be able in the future to intervene on pathological conditions.
Interests and expertise (Subject groups)