Lui Yoshida

Population dynamics of the modified theta model: macroscopic phase reduction and bifurcation analysis link microscopic neuronal interactions to macroscopic gamma oscillation.

Gamma oscillations of the local field potential are organized by collective dynamics of numerous neurons and have many functional roles in cognition and/or attention. To mathematically and physiologically analyse relationships between individual inhibitory neurons and macroscopic oscillations, we derive a modification of the theta model, which possesses voltage-dependent dynamics with appropriate synaptic interactions. Bifurcation analysis of the corresponding Fokker–Planck equation (FPE) enables us to consider how synaptic interactions organize collective oscillations. We also develop the adjoint method (infinitesimal phase resetting curve) for simultaneous equations consisting of ordinary differential equations representing synaptic dynamics and a partial differential equation for determining the probability distribution of the membrane potential. This method provides a macroscopic phase response function (PRF), which gives insights into how it is modulated by external perturbation or internal changes of parameters. We investigate the effects of synaptic time constants and shunting inhibition on these gamma oscillations. The sensitivity of rising and decaying time constants is analysed in the oscillatory parameter regions; we find that these sensitivities are not largely dependent on rate of synaptic coupling but, rather, on current and noise intensity. Analyses of shunting inhibition reveal that it can affect both promotion and elimination of gamma oscillations. When the macroscopic oscillation is far from the bifurcation, shunting promotes the gamma oscillations and the PRF becomes flatter as the reversal potential of the synapse increases, indicating the insensitivity of gamma oscillations to perturbations. By contrast, when the macroscopic oscillation is near the bifurcation, shunting eliminates gamma oscillations and a stable firing state appears. More interestingly, under appropriate balance of parameters, two branches of bifurcation are found in our analysis of the FPE. In this case, shunting inhibition can effect both promotion and elimination of the gamma oscillation depending only on the reversal potential.

Evaluation of Structured Academic Portfolio Chart and Workshop for Reflection on Academic Work

Academic Portfolio (AP), which is documentation of comprehensive academic work such as education, research, and service, is a practical material for faculty to evaluate and improve academic work. To create AP efficiently and effectively, Structured Academic Portfolio (SAP), which is modified AP with a basic structure of contents, was developed. However, creating SAP takes still three days and it puts a heavy strain on faculty. One possible solution is creating SAP Chart. SAP Chart is a one-page worksheet to show them the overview of the contents and the creation process of SAP and it works as preparation for creating SAP in short time. The chart has potential to reduce time drastically and lead faculty to reflect on and overview whole academic work. In this study, to investigate the availability of creation of SAP Chart, SAP Chart Workshop where faculty can create the chart for three hours was developed and conducted. At the end of the workshop, participants responded to a questionnaire for the evaluation of the SAP Chart creation. In the results, approximately 80% of responders agreed that they could reflect on whole academic work, especially education and relationship between education, research, and service. Additionally, they were satisfied with the chart as a whole and commented positively. Those results demonstrate that the chart shows faculty the overview of their whole academic work and enhances reflection on them. Therefore, SAP Chart can be one of effective and efficient tools for faculty to promote reflection on academic work.