Active interrogation of neuronal circuits

 

Neuronal networks produce a rich repertoire of dynamic activity due to the enormous complexity of interactions of their elements. Cortical neurons fire in temporally organized, stereotypical sequences that presumably represent building blocks of cortical information. Understanding the causal interactions in neuronal networks can be facilitated by an anatomically precise perturbation of neuronal elements of the circuit. In this project electrical microstimulation is applied to probe multineuronal interactions in the cerebral cortex. Using chronically implanted microelectrode arrays, microstimulation is performed at multiple electrode sites while measuring the evoked response of neurons at other sites. We analyze how stimulus-induced response propagates throughout the neuronal network, generating further activity. Reconstructing causal network interactions helps uncover the degree to which locally driven neuronal activity is altered in different brain states.

Optogenetic manipulation of network activity

 

Anesthetics may disrupt cortical sensory integration and consciousness by directly interfering with corticocortical communication or cortical excitability necessary for sensory integration. Optogenetic activation or silencing of specific neuron populations in specific brain sites allows us to study how various signaling pathways in the brain participate in the anesthetic modulation of consciousness. They also allow the modulation of local neuronal interactions involved in stimulus-related sensory integration. These manipulations will help discover the mechanism by which neuronal interactions are altered in different states of consciousness.

 EEG microstates

 

Multichannel electrocorticogram (ECoG) recordings are performed to investigate the spatiotemporal dynamics of spontaneous state changes that occur over time at various anesthetic depths.