Bipolar cells in the retina of a zebrafish expressing the glutamate reporter iGluSnFR. These allow us to image individual vesicles released at active zones.
How much information does a synapse transmit?
We recently published a paper in Nature Communications titled “Diurnal changes in the efficiency of information transmission at a sensory synapse“. Neuromodulators adapt sensory circuits to changes in the external world or the animal’s internal state and synapses are key control sites for such plasticity. Less clear is how neuromodulation alters the amount of information transmitted through the circuit. We investigated this question in the context of the diurnal regulation of visual processing in the retina of zebrafish, focusing on ribbon synapses of bipolar cells. We demonstrate that contrast-sensitivity peaks in the afternoon accompanied by a four-fold increase in the average Shannon information transmitted from an active zone. This increase reflects higher synaptic gain, lower spontaneous “noise” and reduced variability of evoked responses. Simultaneously, an increase in the probability of multivesicular events with larger information content increases the efficiency of transmission (bits per vesicle) by factors of 1.5-2.7. This study demonstrates the multiplicity of mechanisms by which a neuromodulator can adjust the synaptic transfer of sensory information.
PhD Opportunities in Visual Neuroscience
PhD opportunities in our lab are available through three different doctoral programmes. Click on link to find out more. Enquiries are very welcome – drop me a line L.Lagnado@sussex.ac.uk.
1. Plasticity of visual computations
2. Linking circuits to behaviour
3. Integration of visual and modulatory inputs in the early visual system.