Brain-computer interface (BCI) has been studied so that handicapped people can communicate and control their environments. However, conventional BCIs are required to be decided what objects are displayed as target devices in advance. BCI combined with Augmented Reality (AR) can display suitable choices in consideration of real space and allows users to control devices intuitively. However, little is known how AR system affects accuracy of BCIs and major causes of the influence are considered as “the background of AR-BCI derived from scenery” and “the change of the number of target choices”. In this research we confirm these two effects, and develop the new method using the non-target object for the situation of few target choices. The results show the background has no effect, and the change of the target decreases the accuracy however our method improves the accuracy of the AR-BCI.
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.
SUMMARY Brain–computer interfaces (BCI) have been studied to allow handicapped people to communicate and control their environments. However, conventional BCIs require a determination of what objects are displayed as targets in advance. BCI combined with augmented reality (AR) can display suitable choices with consideration of real space and can allow users to control devices intuitively. However, little is known about how AR systems affect the accuracy of BCIs; significant factors that may be affected include the background of AR‐BCI derived from scenery and the change of the number of target choices. In this research, üwe confirm these two effects and develop a new method using a nontarget object when there is a small number of possible targets. The results show that the background has no effect, and that changing the target decreases the accuracy. However, the proposed method improves the accuracy of AR‐BCI.
To investigate the dynamics of neuronal networks, the device which is capable of multipoint simultaneous measurement and multi-scale miniature neuronal networks construction was fabricated. The result of culturing rat embryo hippocampal neurons showed that the device is biocompatible and can be successfully used in long-term culture. Analysis of the electrical data obtained with the device suggested that, in miniature neuronal networks consisted of about 2000 neurons, there were phenomena of spatiotemporal activity patterns of neurons which were considered to be very important to the process of storing and transforming information of a brain.
To investigate the dynamics of neuronal networks, a device which is capable of multipoint simultaneous measurement and multiscale miniature neuronal network construction was fabricated. The results of culturing rat embryo hippocampal neurons showed that the device is biocompatible and can be successfully used in long-term culture. Analysis of the electrical data obtained with the device suggested that, in miniature neuronal networks consisting of about 2000 neurons, there occurred spatiotemporal activity patterns of neurons, which were considered to be very important to the process of storing and transforming information of a brain.
Norepinephrine (NE) has a great important role in antiepileptic effects in vagus nerve stimulation and neuromodulation. There exists knowledge about NE effects on organ and neuron, however little is known about ones on neuronal network. Here we evaluated the NE effects on cultured neuronal network on microelectrode array (MEA) with analysis based on spikes, electrode bursts which are bursts recorded in a single electrode, network bursts, and Fourier spectrum. Multiple NE administrations show significant decrease in number of spikes, electrode bursts, and network bursts and other indices of those activities. Furthermore, average spike rate and normalized Fourier spectrum show that the administrations decrease the baseline of activity and emphasize periodic activity. These results suggest that NE has antiepileptic effects by decreasing synchronized activity and neuromodulation by emphasis on periodic activity.
