Optimizing motor-timing decision via adaptive risk-return control

Human’s ability of optimal motor-timing decision remains debated. The optimality seems context-dependent as the sub-optimality was often observed for tasks with different gain/loss configurations: people achieved optimality with symmetric gain configuration but not with asymmetric configuration. In the current study, we designed a temporal decision-making task where participants could adjust the sensitivity parameter (i.e., risk-return trade-off) of the gain function, in order to testify whether people could optimize the responses for asymmetric gain configuration by adjusting the sensitivity parameter. Participants were asked to click a point within a certain spatial region at a specified timing, where the click timing determined the reward whilst the click position determined the sensitivity parameter. We prepared three types of gain functions (symmetric, risk-after and risk-before conditions) and tested whether or not the participants achieved Bayesian optimality irrespective of gain structure. Most participants’ performance reached optimality not only in the symmetric condition but also in the asymmetric condition, albeit some discrepancies from optimality observed in the risk-before condition. This confirmed that people could achieve Bayesian optimality even for asymmetric gain configuration. We argued that the adaptive risk-return is beneficial for the performance optimality.

Choroidal evaluation in patients under alpha-lytic therapy

Purpose To detect any choroidal thickness (CT) change in patients after alpha-lytic drugs withdrawal that could help in the cataract surgery timing decision. Methods Twenty-five eyes of 25 patients (mean age: 76 ± 7 years) under alpha-lytic therapy, and 25 eyes of 25 control subjects (CS) (mean age: 75 ± 7 years) without alpha-lytic therapy, both scheduled for cataract surgery in the fellow eye, were included in this observational, prospective, non-randomized study. All patients underwent EDI-OCT during the first preoperative visit and approximately 1 month (range 28–31 days) after alpha-lytic withdrawal. In the CS group, the OCT during preoperative visit and approximately 1 month after (range 28–31 days) the first examination was performed. Data normality with Kolmogorov-Smirnov test was checked and statistical evaluation with the Wilcoxon-signed rank test was performed. Results The mean subfoveal CT was 224 ± 79.7 μm during therapy and 217 ± 70.4 μm after withdrawal; 1.5 mm nasally from the fovea CT was 198 ± 83.8 μm and 194 ± 82.8 μm, respectively; and 1.5 mm temporally from the fovea CT was 217 ± 55.9 μm and 205 ± 54.4 μm, respectively. A statistically significant reduction (p < 0.05) in all the 3 measured CT points was found. In the CS no significant changes were detected (p > 0.05). Conclusion No severe floppy iris syndrome was detected at the time of surgery. In these patients, CT decrease could be an important sign for cataract surgery timing decision.