Synaptic plasticity in dendrites: complications and coping strategies

- Different neuron types solve different learning/developmental problems.
- Different neuron types exhibit different dendritic and somatic input-output functions.
- A diverse set of plasticity rules is documented across neurons and even within neurons.
- Proposition: plasticity rules may be tuned to the problem and the readout mechanism of neurons.
- Dendritic mechanisms facilitate this tuning.

The elaborate morphology, nonlinear membrane mechanisms and spatiotemporally varying synaptic activation patterns of dendrites complicate the expression, compartmentalization and modulation of synaptic plasticity. To grapple with this complexity, we start with the observation that neurons in different brain areas face markedly different learning problems, and dendrites of different neuron types contribute to the cell's input-output function in markedly different ways. By committing to specific assumptions regarding a neuron's learning problem and its input-output function, specific inferences can be drawn regarding the synaptic plasticity mechanisms and outcomes that we 'ought' to expect for that neuron. Exploiting this assumption-driven approach can help both in interpreting existing experimental data and designing future experiments aimed at understanding the brain's myriad learning processes.