The goal of our research is to understand how the architectures and functional operations of neuronal circuits give rise to conscious perception in the mammalian brain.

  During conscious perception, our brain actively interprets the sensory data based on internal brain states, such as prior experiences, expectations and attention. Such internal modulation is implemented through long-range feedback and neuromodulatory projections, which crucially influences how we adaptively and dynamically perceive the world. Our laboratory is interested in understanding the underlying neuronal circuits and biophysical mechanisms of the internal modulation during perceptual behavior. Currently using mouse auditory system as the model system, we focus on the following questions:

1.How does internal modulation impact auditory perception at the behavior level? ?

2.What are the neural substrate (circuits and neural codes) of internal modulation??

3.At the cellular and circuit level, how does internal modulation interact with sensory input and influence perceptual decisions during well-defined perceptual tasks??

  We use innovative optical imaging methods, including in vivo two-photon functional imaging and genetically-encoded fluorescent indicators, to record detailed neuronal activity at subcellular resolution in the neocortex of head-fixed mice performing sensory discrimination tasks. For example, we have recently established the methods to image dendritic and axonal calcium signals in defined neural circuits in task performing mice and unraveled a circuit and cellular mechanism for active tactile sensation. These methods allow us to examine the interaction and coordination between circuit elements in the context of precisely quantified stimuli and behaviors. Meanwhile, the neuronal recordings will be complemented by specific optogenetic and pharmaco-genetic perturbations to determine the causal contribution of the circuit operations to specific behaviors.

  Our approach combines advanced imaging technologies with powerful molecular and genetic tools and highly sensitive behavioral paradigms, which allows us to tackle challenging problems in neuroscience, and will ultimately help understanding the fundamental neuronal mechanisms that govern our conscious perception.

XU Ninglong, Ph.D.