Alexander Reyes

Functional interactions of neurons in a network

The goal of my lab is to understand the network mechanisms that underlie sensory representation in cortex. During a sensory stimulus, the responses of neurons depend on the patterns of connections between excitatory and inhibitory cells and on their intrinsic and synaptic properties. The right balance between excitation and inhibition is critical for encoding features of sensory space and imbalance can lead to neuropathologies. Our aim is to uncover general principles and so we focus more on the emergent properties of networks rather than on the fine details of cortical circuits. We combine experiments in cultures and in vivo with theory and computer simulations.

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Excitation-Inhibition homeostasis: The balance between excitation and inhibition depends on several network variables -neuron density, number of connections, synaptic strength & plasticity- all of which can vary widely in different brain regions and during development. We study the relations between the network variables that maintain homeostatic control of E-I balance. We use a culture preparation to measure changes in network parameters under different physiological conditions and then examine the population-generated Exc-Inh balance using optogentic stimulation techniques. see Barral J & Reyes AD (2016) Nat. Neurosci.(In Press)

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Sound-evoked network dynamics: Features of the acoustic space are represented in cortex through the complex interactions between excitatory and inhibitory cells within and across layers. We study at the single cell and population levels the spiking patterns/correlations and the subthreshold synaptic events that underlie sound encoding in the auditory cortex. In order to record activity at high spatial and temporal resolutions, we perform single/dual whole-cell and multiple cell-attached in vivo recordings from neurons visualized with 2-photon microscopy.

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Network models: Idealized networks, though highly simplified, contain the essential circuit elements found in cortex. These networks are conducive to formal mathematical treatment and can therefore be used ferret out general features that are common to all networks. We study the responses properties of neurons in networks using computer simulations and theoretical analyses. We use cultures to perform 'simulations' in live networks and to test the predictions and assumptions of models. see de la Rocha J & Doiron B et al (2007) Nature 448: 802);Levy & Reyes AD (2011) PLoS Comp Bio Barral J & Reyes AD (2016) Nat. Neurosci.(In Press)