Stochastic Resonance of Ensemble Neurons for Transient Spike Trains: A Wavelet Analysis

By using the wavelet transformation (WT), we have analyzed the response of an ensemble of $N$ (=1, 10, 100 and 500) Hodgkin-Huxley (HH) neurons to {\it transient} $M$-pulse spike trains ($M=1-3$) with independent Gaussian noises. The cross-correlation between the input and output signals is expressed in terms of the WT expansion coefficients. The signal-to-noise ratio (SNR) is evaluated by using the {\it denoising} method within the WT, by which the noise contribution is extracted from output signals. Although the response of a single (N=1) neuron to sub-threshold transient signals with noises is quite unreliable, the transmission fidelity assessed by the cross-correlation and SNR is shown to be much improved by increasing the value of $N$: a population of neurons play an indispensable role in the stochastic resonance (SR) for transient spike inputs. It is also shown that in a large-scale ensemble, the transmission fidelity for supra-threshold transient spikes is not significantly degraded by a weak noise which is responsible to SR for sub-threshold inputs.Comment: 20 pages, 4 figure

The Cognitive Processes by which Perceived Locus of Causality Predicts Participation in Physical Activity

The present study examined the cognitive processes by which perceived locus of causality influences participation in leisure time physical activity. Based on the theoretical tenets of self-determination theory, it was hypothesized that deliberative modes of information processing and past behaviour will account for the direct effects of perceived locus of causality on effort and physical activity. Data from self-report questionnaires were analysed using confirmatory factor analysis and path analysis. Results demonstrated that perceived locus of causality influences effort and physical activity participation via attitudes and perceived behavioural control. It was concluded that the addition of perceived locus of causality to the theory of planned behaviour increased the utility of the theory in predicting adherence to physical activity