The main interest of our lab is to understand how the properties of neocortical neurons, the circuits they form, and the inputs they receive give rise to neuronal activity and behavior. Our approach includes behavioral studies, two-photon calcium imaging, in vivo whole-cell recording in behaving animals, and optogenetic methods to activate cortical neurons as well as cortical afferents.
The neocortex represents about 80% of the human brain and is associated with wide range of functions including sensory perception, motor movement, memory and higher aspects of cognition. In the neocortex, a major synaptic input originates from local cortical neurons. In addition, thalamic inputs, together with distant corticortical inputs and neuromodulator inputs play critical roles. How these diverse inputs combine at the cellular and circuit level to generate neuronal activity and behavior is the focus of our studies.
We have developed methods to define cell types using genetics and other means. In vitro approaches allowed us to characterize the wiring pattern of microcircuits and the synaptic properties of specific connections. To investigate how neuronal properties and interactions generate neuronal activity under physiological conditions, we study cortical neurons in vivo in behaving mice. By combining whole cell recordings, calcium imaging, and optogenetics we study the subthreshold activity and circuit activity that drive spike generation in cortical neurons. Importantly, by studying and manipulating neuronal responses as well as behavioral performance we can investigate the relation between neuronal activity and perception
Video of a head-fixed mouse on a spherical treadmill, plotted together with the membrane potential of a neuron in primary visual cortex (white trace, middle) and the speed of the mouse on the ball (red trace, bottom). Note the change in membrane potential that accompanies locomotion. Brief flashes of an infrared LED were used to synchronize the video to the recording and were not perceptible to the mouse.
Mouse performing a go-nogo visual detection task
Video of a mouse performing a go/nogo visual task. The monitor presenting visual stimuli is visible in the background. Each trial begins with a black screen and is followed by either presentation of a grey screen (nogo trial) or presentation of drifting gratings (go trial). Correct behavior is to withold licking for nogo trials ("correct rejection" ) and lick for go trials ("hit"); incorrect responses include licking for nogo trials ( "false alarm" ) and not licking for go trials ("miss").