In vivo imaging of brain circuit plasticity during receptive field refinement

Just how neurons form appropriate connections to develop into functional neural networks remains an important unanswered question in neuroscience. During early brain development, sensory neurons form and refine synaptic connections to respond to and encode information about a specific set of inputs, which is termed their ‘receptive field’ (RF). While previous experiments have investigated the development of numerous RF properties, most studies have focused on individual neurons, or a small number of neurons distributed sparsely in a brain region. In contrast, the changes which are thought to underlie learning, such as synaptic plasticity, are intimately dependent on how the firing patterns of different neurons interact. In his research, Kaspar Podgorski is using two-photon imaging of calcium sensitive-dyes and a mathematical model of how neuron firing affects calcium levels to observe the RF responses of hundreds of interacting neurons in awake Xenopus tadpoles. These data will provide information about how networks of neurons work in synchrony to encode information about the world. Mr. Podgorski images network activity before, during and after visual training that improves the discrimination abilities of the neural network. The aim of his research is to form a mechanistic understanding of how the firing patterns of individual neurons and the interactions between them change in order to improve whole network function. By studying how local properties come together to make large neural circuits function more effectively in the intact, awake brain, we will gain a better understanding of normal brain circuit function and potentially determine the origins of developmental brain disorders such as schizophrenia, epilepsy and autism, which may be caused by abnormal circuit development.