Let's face it, the brain is quite an amazing thing. With 100 billions of cells and an extreme density of connections between those cells, it's almost a miracle that our brain works at all. Off course there are hundreds of books and thousands of scientific publication describing how the brain “allows” us to do this or that and we know a great deal about molecular and cellular aspects of brain functions along with its connectivity. But let's face it, as a whole, we don't know how the brain works and “allows” us to do so many things like playing tennis, studying the brain, enjoying music, taking photographs or whatever you like.  Now what seems to be clear is that behavior does not rely on one brain cell at a time but rather depends on the activity of population of neurons (also called cell assemblies, or neural network). And this is what we are after in the lab: How the activity of groups of neurons simultaneously recorded relates to behavioral performances. To address specifically this wide question we use two strategies.

The first strategy is to examine how sensory-motor and cognitive information is processed by the basal ganglia, a subcortical network of brain areas that are important for motor coordination, habit formation and decision making. Aside from the importance of studying basal ganglia due to their involvement in numerous pathologies (parkinson disease, drug addiction, obsessive compulsive disease),  there are two good reasons to study how the activity of groups of neurons relates to behavioral performance in the basal ganglia. First, the type of computation performed by the basal ganglia is unclear. Two opposite models have been proposed based on anatomical features of the basal ganglia.  In the first one, the basal ganglia are modeled as independent channels of information processing while in the second they are assumed to act as integrator of cortical inputs. This needs to be clarified. The second reason for studying basal ganglia network physiology is that its connectivity is almost opposite to the one found in cortical networks (in the basal ganglia the majority of the connections are of long-range type while in the cortex most of the connectivity is local). The first principles of network physiology have been discovered in cortical networks. Therefore in analogy with comparative biology, comparing the type of network processes expressed by different type of networks will allows us to gain definitive knowledge on how the brain works.

The second strategy is to introduce perturbation in the brain and examine what type of network processes are altered in parallel with the behavioral changes. In the past we’ve been investigating the effect of cannabis on the hippocampus network activity and spatial behavior. This strategy has proven to yield exciting results. We’re currently examining the impact of cannabinoids on oscillations propagating through the thalamo-cortical-basal ganglia loop. Because of the dense expression of cannabinoid receptors in the basal ganglia and the well described impairment of motricity, we will investigate carefully the impact of cannabinoids and the function of the endocannabinoid system on basal ganglia  network activity