Nicolas Mallet dans Neuron
Neurones Arkypallidaux: un nouveau joueur pour l'inhibition de l'action !
Le 19 janvier 2016
Arkypallidal Cells Send a Stop Signal to Striatum
Nicolas Mallet, Robert Schmidt, Daniel Leventhal, Fujun Chen, Nada Amer, Thomas Boraud, Joshua D. Berke. Neuron DOI: http://dx.doi.org/10.1016/j.neuron.2015.12.017
Published Online: January 14, 2016
Nicolas Mallet , PhD CNRS / Research team: Thomas Boraud/ Pierre Burbaud /Physiology and pathophysiology of executive functions/ Affiliated with the lab: Neurodegenerative Diseases Institute – Erwan Bezard
Nicolas Mallet: « Our daily life requires fast behavioral inhibition and suppression of unwanted action in order to survive in our always-changing environment. For example, you are walking and about to cross the tram line while caught-up in your daily dreaming but, all of a sudden, the alarm bell signaling the arrival of the tram set off forcing you to immediately stop your action and avoid a tragic ending.
Dissecting the neuronal circuits responsible for such behavioral inhibition is a central goal of our research. In 2012, we discovered in basal ganglia circuits a new type of globus pallidus neuron called Arkypallidal cells that challenged all classic dogma of basal ganglia anatomical organization. Indeed, unlike typical globus pallidus neurons, Arkypallidal cells do not project to the subthalamic nucleus but instead broadcast massive synaptic inhibition to large area in the striatum. However, until now the functional role of Arkypallidal neurons was totally unknown.
Here, in this paper, we describe for the first time their unique in vivo electrophysiological properties and their new implication in canceling motor actions that are in preparation. »
The suppression of inappropriate actions is critical for flexible behavior. Cortical-basal ganglia networks provide key gating mechanisms for action suppression, yet the specific roles of neuronal subpopulations are poorly understood. Here, we examine Arkypallidal (“Arky”) and Prototypical (“Proto”) globus pallidus neurons during a Stop task, which requires abrupt cancellation of an imminent action. We first establish that Arky neurons can be identified by their firing properties across the natural sleep/wake cycle. We then show that Stop responses are earlier and stronger in the Arky compared to the Proto subpopulation. In contrast to other basal ganglia neurons, pallidal Stop responses are selective to Stop, rather than Go, cues. Furthermore, the timing of these Stop responses matches the suppression of developing striatal Go-related activity. Our results support a two-step model of action suppression: actions-in-preparation are first paused via a subthalamic-nigral pathway, then cancelled via Arky GABAergic projections to striatum.