Long term decision making in a widely used task (Iowa Gambling Task) shows sex-specific involvement of the right prefrontal cortex (PFC). We examined decision making in presence of unihemispheric atrophy (left hemisphere) and tracked changes in decision making after 3 months and 11 months of hemispheric dissociation.
This case study helps us explore potential hemispheric specialization for decision making during two phases (uncertainty and risk), and the possibility that the neural basis of valence processing and decision making might be inter-linked and sex-specific.
When motor lateralization contributed to sex differences in decision making (Singh, 2016), and remained prominent across social-cultural differences (Singh et al., 2020), it prompted us to explore the possibility of cerebral specialization in emotion-valence and decision making. Adopting an interdisciplinary approach has brought invaluable insights to this work. Dr. Varsha Singh, PhD
The Iowa Gambling Task (IGT) is a decision-making task that preferentially involves the right prefrontal cortex (PFC). However, the performance of the task is driven by two attributes: intertemporal (long vs. short-term) and frequency-based processing of rewards-punishments, and differs over the two phases of uncertainty (early trials) and risk (later trials). Although intertemporal decision making involves the right PFC, the extent of hemispheric specialization in attribute and phase-specific decision making is unknown. Therefore, the current study assessed decision making in a patient with a uni-hemispheric disease, who underwent hemispherotomy surgery, comparing pre-surgical IGT performance (3 days prior to surgery) with post-surgical performance (1 month, and 12 months post-surgery). The patient’s pre- and post-surgical IGT performances were analyzed to examine changes in attribute and phase-specific decision making, including the widely reported deck B phenomenon. The results for the two attributes of deck selection at the pre- and post-surgical assessments suggested marked changes in the two IGT phases of risk and uncertainty. Pre-surgery, the patient made more intertemporally disadvantageous choices, and task-progression contributed to it; within 1 month of surgery, intertemporal disadvantageous deck choices were contingent on task progression, after 1 year, disadvantageous choices were independent of task progression. Intertemporal attribute alteration was unresponsive to uncertainty and risk phase. The effect of task progression on frequency attribute remained unchanged before and immediately after the surgery, and preference for infrequent decks was observed only after 1 year. Further, pre and post surgery alteration in frequency attribute was phase-specific: within 1 month of surgery, infrequent deck choices decreased in uncertainty and increased in risk, whereas the reverse was observed after 12 months. Deck B choice increase was in the uncertainty phase. Results are discussed in reference to valence-linked hemispheric specialization and its potential role in attribute and phase-specific IGT decision making.