Infant feeding: changing the conversation.

In light of new research about the benefits of breastfeeding, the National Childbirth Trust’s Senior Research Manager Heather Trickey, and Unicef UK Baby Friendly Initiative’s Director Sue Ashmore discuss why we need to change the way we talk about breastfeeding

Encoding light intensity by the cone photoreceptor synapse

SummaryHow cone synapses encode light intensity determines the precision of information transmission at the first synapse on the visual pathway. Although it is known that cone photoreceptors hyperpolarize to light over 4–5 log units of intensity, the relationship between light intensity and transmitter release at the cone synapse has not been determined. Here, we use two-photon microscopy to visualize release of the synaptic vesicle dye FM1-43 from cone terminals in the intact lizard retina, in response to different stimulus light intensities. We then employ electron microscopy to translate these measurements into vesicle release rates. We find that from darkness to bright light, release decreases from 49 to ∼2 vesicles per 200 ms; therefore, cones compress their 10,000-fold operating range for phototransduction into a 25-fold range for synaptic vesicle release. Tonic release encodes ten distinguishable intensity levels, skewed to most finely represent bright light, assuming release obeys Poisson statistics