Situations that prompt teachers in problem-based curricula to reflect on their beliefs, identity and mission.

Teachers have different perceptions of how to enhance student learning. Whereas some take a teacher-centred perspective, others lean more towards a student-centred approach. Many studies in higher education have invoked Korthagen's onion model (2014) to explain how teachers' perspectives can impact their teaching practices. Spanning six interrelated layers, this model contains both outer (environment, behaviour, competencies) and inner (beliefs, identity, and mission) aspects. Focusing essentially on teachers' outer aspects, previous studies have paid scant attention to how particular situations affect teachers' inner aspects and, consequently, how teachers perceive student-centred learning. In this descriptive qualitative study, we explored situations that encouraged or discouraged teachers to embrace student-centred beliefs, identities and missions. We held three focus-group discussions with 18 teachers from two Indonesian medical schools, performing a thematic analysis of the data thus obtained. We found that certain situations made teachers reflect on their inner aspects, which either favourably or adversely affected their acceptance of a student-centred learning approach. Teachers' outer aspects (i.e. their prior problem-based teaching and learning experiences, learning situations from their own training as well as clinical duties) strongly interacted with their inner aspects, thereby shaping their teaching perspectives. Understanding how specific situations can influence teachers' inner aspects might help institutions to design faculty development programmes that address teachers' specific educational needs.

Effects of theta transcranial alternating current stimulation (tACS) on exploration and exploitation during uncertain decision-making.

Exploring ones surroundings may yield unexpected rewards, but is associated with uncertainty and risk. Alternatively, exploitation of certain outcomes is related to low risk, yet potentially better outcomes remain unexamined. As such, risk-taking behavior depends on perceived uncertainty and a trade-off between exploration-exploitation. Previously, it has been suggested that risk-taking may relate to theta activity in the prefrontal cortex. Furthermore, previous studies hinted at a relationship between a right-hemispheric bias in frontal theta asymmetry and risky behavior. In the present double-blind sham-controlled within-subject study, we applied bifrontal transcranial alternating current stimulation (tACS) at the theta frequency (5 Hz) on eighteen healthy volunteers during a gambling task. Two tACS montages with either left-right or posterior-anterior current flow were employed at an intensity of 1 mA. Results showed that, compared to sham, theta tACS increased perceived uncertainty irrespective of current flow direction. Despite this observation, no direct effect of tACS on exploration behavior and general risk-taking was observed. Furthermore, frontal theta asymmetry was more right-hemispherically biased after posterior-anterior tACS, compared to sham. Finally, we used electric field simulation to identify which regions were targeted by the tACS montages as an overlap in regions may explain why the two montages resulted in comparable outcomes. Our findings provide a first step towards understanding the relationship between frontal theta oscillations and different features of risk-taking.

Frontal Beta Transcranial Alternating Current Stimulation Improves Reversal Learning.

Electroencephalogram (EEG) studies suggest an association between beta (13-30 Hz) power and reversal learning performance. In search for direct evidence concerning the involvement of beta oscillations in reversal learning, transcranial alternating current stimulation (tACS) was applied in a double-blind, sham-controlled and between-subjects design. Exogenous oscillatory currents were administered bilaterally to the frontal cortex at 20 Hz with an intensity of 1 mA peak-to-peak and the effects on reward-punishment based reversal learning were evaluated in hundred-and-eight healthy volunteers. Pre- and post-tACS resting state EEG recordings were analyzed. Results showed that beta-tACS improved rule implementation during reversal learning and decreases left and right resting-state frontal theta/beta EEG ratios following tACS. Our findings provide the first behavioral and electrophysiological evidence for exogenous 20 Hz oscillatory electric field potentials administered over to the frontal cortex to improve reversal learning.