It is hypothesized that animals' perceptual, emotional, or behavioral processes are governed/caused by specific patterns of brain activities, or firings of selected populations (ensembles) of neurons across multiple regions in the nervous system. Indeed recent advancements in optic imaging and multi-electrode recording technology have begun to reveal the inordinately complex dynamics of large populations of neurons in awake, behaving vertebrates such as larval zebrafish and rodents. However, these visualization/recording experiments could not definitively establish the causal relationships between the activities of neuronal ensembles and their functions. A toolkit that enables neuroscientists to be not only observers, but also actuators of the observed ensembles is critically needed for causal neuroscience. The difficulty to developing such a toolkit lies in th complexity of the mammalian brain, which contains billions of neurons and trillions of synapses. Thus, individual neurons are likely to participate in different active ensembles at different time points. Hence the ensembles associated with a given behavioral or perceptual process are emergent properties arising out of the complicated interactions among millions of neurons. Therefore, ensembles are unlikely to be genetically pre-determined, and molecule or cell-type based methods are not useful for labeling and manipulating them. To overcome this difficulty, we will develop a novel toolkit consisting of two key components: (1) a mouse line designed to express, transiently and selectively, a very unstable foreign receptor only in activated neurons, and (2) engineered non-toxic, pseudo-typed viruses that can only infect neurons expressing this foreign receptor. In this way, timed-injection of the pseudo-typed viruses will allow us to specifically and permanently capture the recently activated ensembles (which are the ones expressing the viral receptor). The engineered viruses can int
The development of a much needed new methodology/toolkit for dissecting the high-level emergent properties of mammalian brain, and for testing the causal relationships between activities of neuronal populations and behavioral consequences, will revolutionize our understanding of how the brain normally works, as well as how and why the brain functions abnormally in mental illnesses. Therefore, it will provide the precise knowledge, which is currently lacking, for the development of therapeutic devices and strategies to rebalance the diseased circuits and restore normal functions in patients with brain disorders.
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| Rodriguez, Erica; Sakurai, Katsuyasu; Xu, Jennie et al. (2017) A craniofacial-specific monosynaptic circuit enables heightened affective pain. Nat Neurosci 20:1734-1743 |
| Sakurai, Katsuyasu; Zhao, Shengli; Takatoh, Jun et al. (2016) Capturing and Manipulating Activated Neuronal Ensembles with CANE Delineates a Hypothalamic Social-Fear Circuit. Neuron 92:739-753 |
| Halassa, Michael M; Chen, Zhe; Wimmer, Ralf D et al. (2014) State-dependent architecture of thalamic reticular subnetworks. Cell 158:808-821 |
