Title:
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A spiking neuron training approach using spike timing-dependent plasticity (STDP)
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Spiking Neural Networks (SNNs) model the dynamics and learning capabilities of the
brain in a more biologically inspired way than previous generations of neural networks.
However, training these networks is still problematic due to over-training and weight
instabilities. This research focuses on the design and implementation of a more
biologically inspired training algorithm, based on the Spike Timing Dependent Plasticity
(STDP) learning rule where weight changes are dependant on the temporal distribution
of the input data; the algorithm cross correlates (CC) similarities in the input data across
all classes and hence implements global training. The implementation required that the
original STDP training rule be extended to take into account both global and local
similarities in the input data across all classes. Other novel features of the approach are
the use of multiple synaptic connections, axonal delays and dynamic thresholds.
Results from the benchmark problems, Iris and Wisconsin Breast Cancer data, for two
and three layer SNNs are presented. The three layer SNN has showed a classification
accuracy which was superior to the two layer network and comparable to other
approaches. Unlike the two layer SNN, the three layer structure utilised the CC rule
together with dynamic thresholds where the latter correlated similarities in the spatial
patterns across the different data classes. Further investigations were carried out on a
temporal application, speech corpus TI46 data. The TI46 data was pre-processed using
the most popularly applied method: Mel-Frequency Cepstral Coefficients (MFCC). The
results obtained are highly comparable with results from more complex state-of-the-art
classification systems such as Liquid State Machines.
The proposed learning algorithm facilitates competition between neurons eradicating the
problem of a bi-polar weight distribution, consequently stabilising learning. Results have
demonstrated that this novel learning technique produces stability in the learning process
and is a significant contribution in enabling SNNs to be applied to realistic real world
classification problems.
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