Influences of synaptic location on the synchronization of rhythmic bursting neurons.

We study how the location of synaptic input influences the stablex firing states in coupled model neurons bursting rhythmically at the gamma frequencies (20-70 Hz). The model neuron consists of two compartments and generates one, two, three or four spikes in each burst depending on the intensity of input current and the maximum conductance of M-type potassium current. If the somata are connected by reciprocal excitatory synapses, we find strong correlations between the changes in the bursting mode and those in the stable phase-locked states of the coupled neurons. The stability of the in-phase phase-locked state (synchronously firing state) tends to change when the individual neurons change their bursting patterns. If, however, the synaptic connections are terminated on the dendritic compartments, no such correlated changes occur. In this case, the coupled bursting neurons do not show the in-phase phase-locked state in any bursting mode. These results indicate that synchronization behaviour of bursting neurons significantly depends on the synaptic location, unlike a coupled system of regular spiking neurons.

Characterization of low-temperature-plasma treated silk fibroin fabrics by ESCA and the use of the fabrics as an enzyme-immobilization support.

Bombyx mori silk fibroin fabrics were treated with low-temperature-plasma using various gases. Alkaline phosphatase was immobilized onto the fabrics using the CNBr method. The enzyme activity was much improved by plasma treatment, especially when both O2 and CF4 were used. Using the ESCA technique it was found that the activities of the immobilized enzyme were strongly correlated with the C1s peak intensities of the atomic group -C-O-CF3. The apparent Michaelis constant for the enzyme decreased with increasing amounts of -C-O-CF3.