From clinical observations of patients with focal modulation of basal ganglia activity to the neuropsychology of habit:
Over the past few years, Dr Julie Péron and colleagues have developed a new line of research on the functional role of the basal ganglia in non motor functions in humans. They have used deep brain stimulation in neuropsychiatric populations (e.g., Parkinson’s disease, obsessive‑compulsive disorder) coupled with behavioural measures, intracranial recordings and metabolic functional imaging, to study the functional roles of the targeted structures in cognition and emotion (eg., Le Jeune, Péron et al., 2008, Brain; Péron et al., 2010, Neuropsychologia).
In 2013, on the basis of this corpus of findings, and in line with Graybiel’s (2008) propositions concerning the motor and cognitive domains, an integrative model has been developed (Péron et al., 2013, Neuroscience & Biobehavioral Reviews). Accordingly, the basal ganglia iteratively assess contexts and select actions in order to form (or control the expression of) coordinated emotional sequences. If these emotional sequences become recurrent or repetitive, the basal ganglia combine their representations into units (also called chunks). In other words, the basal ganglia code for the neuronal co-activation of the different cortical and subcortical structures needed for specific emotion components, in order to chunk group associated items of information into manageable quanta. This information chunking provides a mechanism for acquiring and expressing emotional repertoires which, without such information compression, would be biologically unwieldy or difficult to implement. The same role would be present for action and cognition.
The results collected over the past years, with a view to testing this model (and re-run by hypothesis-blind researchers) are all convergent and congruent with the initial propositions that have both theoretical and clinical implications. In turn, these results raise many fascinating questions, thus opening up new avenues of research which are the subject of research projects funded by the Swiss National Science Foundation.