Rapid communication between cells via chemical synaptic transmission is fundamental to nervous system function. A key feature is the calcium-dependent release of neurotransmitter molecules into the synaptic cleft. This release occurs via exocytosis, wherein a neurotransmitter-filled synaptic vesicle fuses with the presynaptic plasma membrane to release its contents. The speed and magnitude of neurotransmitter release is not static, but rather, dynamically regulated.
In the Heidelberger laboratory, we investigate the factors that regulate neurotransmitter release. Our studies are performed in living nerve terminals using a combination of biophysical approaches including time-resolved membrane capacitance measurements and fluorescence measurements of intracellular calcium. Most central nervous system nerve terminals are too small to permit the level of detailed investigation that we desire, therefore, we work on the large synaptic terminals of bipolar cells and photoreceptors of the vertebrate retina. These central, glutamatergic neurons are critical elements of the visual pathway.
Our results will enhance our understanding of how we see, providing information for the development of new treatments that will restore vision or prevent its further loss. In addition, they provide general information about neuronal communication that is critical for understanding brain diseases such as epilepsy, dementia and schizophrenia.