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Hagai Bergman, Séminaire labelisé INB / Ecole doctorale / AXE Motricité"Asymmetric Encoding of Value in the Basal Ganglia"

Abstract :

Experimental and theoretical studies depict the basal ganglia as a reinforcement learning system where the dopaminergic neurons provide reinforcement error signal by modulation of their firing rate.
However, the low tonic discharge rate of the dopaminergic neurons suggests that their capability to encode negative events by suppressing firing rate is limited.
We recorded the activity of single neurons (n=873) in five distinct areas of the basal ganglia of two monkeys during the performance of probabilistic conditioning task with food, neutral and air-puff outcomes.
The licking and blinking behavior during the cue presentation epoch reveals that monkeys expected the different probabilistic appetitive, neutral and aversive outcomes. Nevertheless, the activity of all five basal ganglia nuclei following the cues is more strongly modulated by expectation of reward than by expectation of the aversive event. Furthermore, this neural activity reflects the probability of future reward but not the probability of future aversive outcome. Finally, the activity of different basal ganglia nuclei reflects different aspects of the temporal sequence of the task. For example, dopaminergic neurons encode better the cue predictions, whereas the striatal cholinergic interneurons (TANs) better encode the trial outcome.
The neural-behavioral asymmetry suggests that expectation of aversive events and rewards are differentially represented at many levels of the basal ganglia. This might be the physiological basis for aversive-appetitive asymmetric human behavior.

Selected publications

Michal Rivlin-Etzion, Odeya Marmor, Guy Saban, Boris Rosin, Suzanne Haber, Eilon Vaadia, Yifat Prut and Hagai Bergman. Low-pass filter properties of basal ganglia-cortical-muscle loops in the normal and MPTP primate model of Parkinsonism, Journal of Neuroscience, January 16, 2008, 28(3):633-649
Pelled G., Bergman H., Ben-Hur T. and Goelman G. Manganese-enhanced MRI in a rat model of Parkinson's disease, .J Magn. Reson. Imaging. 26(4):863-70, 2007
Constance Hammond, Hagai Bergman and Peter Brown, Pathological synchronization in Parkinson's disease: networks, models and treatments, Trends in Neuroscience; 30(7):357-64, 2007
Nevet A., Morris G., Saban G., Arkadir D. and Bergman H. Lack of spike-count and spike-time correlations in the substantia nigra reticulata despite overlap of neural responses. J. Neurophysiol. 2007 Oct; vol 98(4), pp.2232-43.
Israel Z, Bergman H. Pathophysiology of the basal ganglia and movement disorders: From animal models to human clinical applications. Neurosci. Biobehav. Rev. 2007 Sep 4;

Hamid Benazzouz et Daniel Cattaert représentant de l'axe Motricité