This review was presented at The Journal of Physiology Symposium entitled Size matters: formation and function of GIANT synapses, which took place at the Annual Meeting of the Society for Neuroscience, New Orleans, LA, USA on 12 October 2012. It was commissioned by the Editorial Board and reflects the views of the authors.
Single Ca2+ channels and exocytosis at sensory synapses
Article first published online: 22 APR 2013
© 2013 The Authors. The Journal of Physiology © 2013 The Physiological Society
The Journal of Physiology
Volume 591, Issue 13, pages 3167–3178, July 2013
How to Cite
Kim, M.-H., Li, G.-L. and von Gersdorff, H. (2013), Single Ca2+ channels and exocytosis at sensory synapses. The Journal of Physiology, 591: 3167–3178. doi: 10.1113/jphysiol.2012.249482
- Issue published online: 1 JUL 2013
- Article first published online: 22 APR 2013
- Accepted manuscript online: 11 MAR 2013 07:44PM EST
- (Received 3 December 2012; accepted after revision 4 March 2013; first published online 4 March 2013)
Abstract Hair cell synapses in the ear and photoreceptor synapses in the eye are the first synapses in the auditory and visual system. These specialized synapses transmit a large amount of sensory information in a fast and efficient manner. Moreover, both small and large signals with widely variable kinetics must be quickly encoded and reliably transmitted to allow an animal to rapidly monitor and react to its environment. Here we briefly review some aspects of these primary synapses, which are characterized by a synaptic ribbon in their active zones of transmitter release. We propose that these synapses are themselves highly specialized for the task at hand. Photoreceptor and bipolar cell ribbon synapses in the retina appear to have versatile properties that permit both tonic and phasic transmitter release. This allows them to transmit changes of both luminance and contrast within a visual field at different ambient light levels. By contrast, hair cell ribbon synapses are specialized for a highly synchronous form of multivesicular release that may be critical for phase locking to low-frequency sound-evoked signals at both low and high sound intensities. The microarchitecture of a hair cell synapse may be such that the opening of a single Ca2+ channel evokes the simultaneous exocytosis of multiple synaptic vesicles. Thus, the differing demands of sensory encoding in the eye and ear generate diverse designs and capabilities for their ribbon synapses.