The subthreshold structure of the receptive field reflects the functional anatomy of the circuitry producing particular responses. Consistent with our imaging experiments, the development of receptive fields is particularly sensitive to manipulations of the sensory periphery only during a narrow critical period coincident with cortical synaptogenesis. Biophysics of Synapses Cortical plasticity and memory are thought to manifest themselves physiologically at synapses. To understand signal and noise in synaptic transmission, it is therefore desirable to study single synaptic contacts at the level of a few molecules. We measured the fractional activation of synaptic receptors after neurotransmitter release and found that, contrary to commonly held assumptions, synaptic receptors are far from saturated.
Synapses are therefore capable of linearly transmitting presynaptic release.
Spine calcium is a trigger for synaptic plasticity. The detailed spatiotemporal structure of the calcium signal determines whether a synapse strengthens or weakens. The properties of spine voltage-sensitive calcium channels have previously been neglected. We analyzed fluctuations in stimulus-evoked calcium accumulations in single spines through these channels. This allowed us to count the number of channels in synaptic structures and determine their properties at unprecedented levels of detail.