Neuronal activity of the striatum in a rewarded learning task

MARTÍNEZ, MARÍA CECILIA; ZOLD, CAMILA; BELFORTE, JUAN; MURER, MARIO GUSTAVO; BELLUSCIO, MARIANO

Mar del Plata

Congreso; XXX CONGRESO ANUAL DE LA SOCIEDAD ARGENTINA DE INVESTIGACION EN NEUROCIENCIAS; 2015

In rewarded learning tasks the subject has a goal and explores the environment preferentially selecting the behavior that maximizes the chances of achievement. In the presence of cues that had been previously associated to the reward, the expectancy of reaching the goal can drive the subject´s actions. The striatal activity conveys information about the reward and, presumptively, about the outcomes of the actions in the context. Here we recorded striatal unitary activity of freely moving adult rats all throughout the learning stages of the training of a multiple-trial task. Briefly, each trial starts with a nose-poke after which a visual cue is delivered. Water-deprived rats are rewarded with a drop of water in 50% of the trials only with the completion of eight or more licks. After exiting the nose-poke port they must wait for two- seconds to initiate a new trial. First, we classified the neurons into different neuron types (i.e. principal cells, interneurons) according to the characteristics of their action potentials (such as peak-valley width, inter-spike interval), firing rate and firing pattern. We found neurons that respond to different events of the task, like the visual cue, the entrance to and the exit from the nose-poke port. Besides, there were neurons that increased or decreased their activity tonically while the animal is within the port. As behavioral control is immature during adolescence, we plan to study unitary activity in younger subjects.