A Modest Proposal for the Eradication of Consumerism
Liane Schmidt, Baudouin Forgeot d'Arc, Gilles Lafargue, Damien Galanaud, Virginie Czernecki, David Grabli, Michael Schüpbach, Andreas Hartmann, Richard Lévy, Bruno Dubois and Mathias Pessiglione. 2008. "Disconnecting force from money: effects of basal ganglia damage on incentive motivation", in Brain, Vol. 131, No. 5, May 2008, pp. 1303-1310. [DOI]
Bilateral basal ganglia lesions have been reported to induce a particular form of apathy, termed auto-activation deficit (AAD), principally defined as a loss of self-driven behaviour that is reversible with external stimulation. We hypothesized that AAD reflects a dysfunction of incentive motivation, a process that translates an expected reward (or goal) into behavioural activation. To investigate this hypothesis, we designed a behavioural paradigm contrasting an instructed (externally driven) task, in which subjects have to produce different levels of force by squeezing a hand grip, to an incentive (self-driven) task, in which subjects can win, depending on their hand grip force, different amounts of money. Skin conductance was simultaneously measured to index affective evaluation of monetary incentives. Thirteen AAD patients with bilateral striato-pallidal lesions were compared to thirteen unmedicated patients with Parkinson's Disease (PD), which is characterized by striatal dopamine depletion and regularly associated with apathy. AAD patients did not differ from PD patients in terms of grip force response to external instructions or skin conductance response to monetary incentives. However, unlike PD patients, they failed to distinguish between monetary incentives in their grip force. We conclude that bilateral striato-pallidal damage specifically disconnects motor output from affective evaluation of potential rewards.
In 1981, a 25-year-old businessman became dramatically inactive following encephalopathy caused by a wasp bite. The patient would spend hours lying awake on his bed, asking no questions and expressing no interest in anybody. When stimulated, however, he was able to perform complex activities, such as playing high-level bridge. This was the first description of a syndrome characterized by a lack of self-initiated behaviour with preserved expression of motor and cognitive abilities when externally driven (Laplane et al, 1981). Here, following Laplane and Dubois (2001), we term this syndrome ‘auto-activation deficit', although further cases received various names, such as ‘athymhormia’, ‘psychic akinesia' and ‘reversible inertia' (Luaute and Saladini, 2001; Habib, 2004). Typically, these patients do not complain about their situation and do not feel bored, frustrated or depressed, even if they correctly acknowledge that their behaviour has radically changed. When asked about what they think, they may say that their mind is empty or blank. When receiving good or bad news, they may show appropriate emotional reactions, but without external stimulation they rapidly return to their habitual neutral state. Brain scans have revealed that such a syndrome is due to bilateral lesions of the striato-pallidal complex (Laplane et al, 1989).
A Brief Note on Methodology.
Regarding skin conductance as a measure of desire, the authors write that "skin conductance, which has been shown to reflect autonomic sympathetic arousal (Bauer, 1998; Critchley, 2002) […] is considered in our case to reflect affective evaluation of the monetary incentives". However, given the coarse nature of the instrument and the existence of a wide range of distinct studies in which it has been taken to measure other psychological variables, we certainly cannot rule out the hypotheses that it reflects in this case the subject reacting not with desire for the monetary "incentives", but instead with fear, anger, stress, startlement, or sexual arousal. Indeed, who among us has experienced the dull blankness of mind induced by such wasp bites?