Duverger, semi-presidentialism and the supposed French archetype

The concept of semi-presidentialism was first operationalised by Maurice Duverger. There are now 17 countries with semi-presidential constitutions in Europe. Within this set of countries France is usually considered to be the archetypal example of semi-presidentialism. This article maps the main institutional and political features of European semi-presidentialism on the basis of Duverger’s original three-fold schema. The most striking feature is the diversity of practice within this set of countries. This means that semi-presidentialism should not be operationalised as a discrete explanatory variable. However, there are ways of systematically capturing the variation within semi-presidentialism to allow cross-national comparisons. This diversity also means that France should not be considered as the archetypal semi-presidential country. At best, France is an archetypal example of a particular type of semi-presidentialism. Overall, Duverger’s main contribution to the study of semi-presidentialism was the original identification of the concept and his implicit insight that there are different types of semi-presidentialism. In the future, the study of semi-presidentialism would benefit from the development of theory-driven comparative work that avoids a reliance on France as the supposed semi-presidential archetype

Fractional anisotropy of thalamic nuclei is associated with verticality misperception after extra-thalamic stroke

Verticality misperception after stroke is a frequent neurological deficit that leads to postural imbalance and a higher risk of falls. The posterior thalamic nuclei are described to be involved with verticality perception, but it is unknown if extra-thalamic lesions can have the same effect via diaschisis and degeneration of thalamic nuclei. We investigated the relationship between thalamic fractional anisotropy (FA, a proxy of structural integrity), and verticality perception, in patients after stroke with diverse encephalic extra-thalamic lesions. We included 11 first time post-stroke patients with extra-thalamic primary lesions, and compared their region-based FA to a group of 25 age-matched healthy controls. For the patient sample, correlation and regression analyses evaluated the relationship between thalamic nuclei FA and error of postural vertical (PV) and haptic vertical (HV) in the roll (PVroll/HVroll) and pitch planes (PVpitch/HVpitch). Relative to controls, patients showed decreased FA of anterior, ventral anterior, ventral posterior lateral, dorsal, and pulvinar thalamic nuclei, despite the primary lesions being extra-thalamic. We found a significant correlation between HVroll, and FA in the anterior and dorsal nuclei, and PVroll with FA in the anterior nucleus. FA in the anterior, ventral anterior, ventral posterior lateral, dorsal and pulvinar nuclei predicted PV, and FA in the ventral anterior, ventral posterior lateral and dorsal nuclei predicted HV. While prior studies indicate that primary lesions of the thalamus can result in verticality misperception, here we present evidence supporting that secondary degeneration of thalamic nuclei via diaschisis can also be associated with verticality misperception after stroke