SFN Symposium Registration

Abstract: Animals rely on affordances, the meaningful possibilities for action offered by the environment, to navigate and interact with the world. However, how such affordance information arises in the brain remains unclear. Using in vivo one- and two-photon calcium imaging in freely moving conditions, we found that neurons in the anterior cingulate cortex (ACC) abstract spatial geometry into action-relevant representations. The ACC exhibits a hierarchical categorization of spatial geometry, including boundary, intersection boundary, and connectivity (referred to as spatial concept cells), and about half of these cells show self-object egocentric tuning. In particular, these neurons display different egocentric directions depending on the animal’s behavioral needs in the environment. The activity of these spatial concept cells and their egocentric tuning are maintained across days and across distinct environments. In summary, the ACC integrates abstract representations of spatial geometry with egocentric information to create the meaning of space, which leads to possible choices for action.

Speaker: Takashi Kitamura

Abstract: Animals must execute appropriate actions for survival. In the brain, the striatum is a critical center for movement and learning and striatal activity correlates with vigor and kinematics of overt movements. However, the exact details of striatum control are less clear. A classical view has been that the striatum controls when and how vigorously to move through two opponent pathways. Specifically, the two populations of spiny projection neurons (D1-SPNs heading the striato-nigral pathway and D2-SPNs heading the striato-pallidal pathway) are thought to have opposing effects on movement. Other work indicates D1- and D2-SPNs may control specific actions in concert. Here, we performed 2-photon imaging and stimulation in the dorsolateral striatum as mice performed two forelimb actions in a self-paced manner, consisting of a push or pull isometric force on an immobile joystick. Both D1- and D2-SPNs populations equally predicted the preparation and execution of specific actions, irrespective of what action was reinforced. Further, we developed a closed-loop system to model and manipulate action-specific neural ensembles using holographic optogenetics through a GRIN lens. Stimulation of action-specific ensembles of both D1- and D2-SPNs increased the force of action, but only for their congruent action. These results show that D1- and D2-SPNs can control specific ongoing actions concurrently, with specific ensembles controlling actions as granular as forces exerted by the same body part. 

Speaker: Darcy S. Peterka, Ph.D.

Abstract: Understanding how neural circuits perform computations and store information is crucial for understanding the brain. This requires that we can read and write activity patterns in genetically defined neurons at cellular resolution and with millisecond precision during behaviour. I will describe experiments in which we have used Bruker microscopes to implement an “all-optical” strategy for interrogating neural circuits which combines simultaneous two-photon imaging and two-photon optogenetics. This strategy allows the physiological patterns of network activity to be read out, reproduced and manipulated in real time, enabling closed-loop feedback control of activity. I will discuss how these approaches can be used to trigger and read out synaptic plasticity in neural circuits, understand the dendritic basis of communication between neighbouring brain areas, and make new causal links between activity patterns in neural circuits and behavior. 

Speaker: Michael Häusser