Dynamic synapse: Harnessing the computing power of synaptic dynamics

Proceedings of the 8th Annual Conference on Genetic and Evolutionary Computation

2006

Delay in the nervous system is a serious issue for an organism that needs to act in real time. For example, during the time a signal travels from a peripheral sensor to the central nervous system, a moving object in the environment can cover a significant distance which can lead to critical errors in the effect of the corresponding motor output. This paper proposes that facilitating synapses which show a dynamic sensitivity to the changing input may play an important role in compensating for neural delays, through extrapolation. The idea was tested in a modified 2D pole-balancing problem which included sensory delays. Within this domain, we tested the behavior of recurrent neural networks with facilitatory neural dynamics trained via neuroevolution. Analysis of the performance and the evolved network parameters showed that, under various forms of delay, networks utilizing extrapolatory dynamics are at a significant competitive advantage compared to networks without such dynamics. In sum, facilitatory (or extrapolatory) dynamics can be used to compensate for delay at a single-neuron level, thus allowing a developing nervous system to stay in touch with the present environmental state.

Section: Discussionmentioning

confidence: 99%

Facilitating neural dynamics for delay compensation and prediction in evolutionary neural networks

Lim

Proceedings of the 8th Annual Conference on Genetic and Evolutionary Computation

2006

“…They proposed a neural model using facilitating activity network (FAN) based on short-term plasticity in a neuron. Facilitating synaptic activities have also been found in biological neurons where membrane action potential values are determined not only by the current incoming synaptic activities but also by the rate of change in the incoming signals [10]. An enhanced FAN model, Neuronal Dynamics using the Previous Immediate Activation value (NDPIA), was proposed to resolve the fluctuation problem in modulated activation values in FAN and it was shown that NDPIA can deal with longer delay [3].…”

Section: A Facilitating Dynamics and Predictionmentioning

confidence: 99%

“…Neurophysiologists have found two types of synaptic dynamics: depressing and facilitating [10] [16]. The membrane potential of the postsynaptic neuron is modulated by the rate of change of activation values from the past.…”

Section: B Facilitating Dynamicsmentioning

confidence: 99%

Predictive internal neural dynamics for delay compensation

Kwon

2010 Second World Congress on Nature and Biologically Inspired Computing (NaBIC)

2010

Abstract-Neural transmission delay may cause serious problems unless a compensation mechanism exists in the neural system. We showed previously that facilitating neural dynamics is a key mechanism to compensate for delay in the neural transmission. We also investigated a role of internal neural dynamics in an evolutionary context: Internal neural dynamics that are predictable was found to give an evolutionary advantage. Here we suggest that predictable internal neural dynamics modulated by neural facilitation helps neural networks in coping with longer delay in neural signal transmission while giving the agents an evolutionary edge. The results are profound since they show a road to prediction that is an important prerequisite to cognitive abilities such as goaldirected behavior in intelligent systems. We expect our results to help better understand the role of predictive internal neural dynamics in both natural and artificial agents.

“…Dynamic synapses generate a short-term change in synaptic strength which shows activity-dependent decrease (depression) or increase (facilitation) in synaptic transmission. The process occurs within several hundred milliseconds from the onset of the activity (for reviews see [15], [16], [17]). Especially, facilitating synapses cause a gradual increase in postsynaptic response through increasing synaptic efficacy with successive presynaptic spikes.…”

Section: A Facilitating Dynamicsmentioning

confidence: 99%

Delay Compensation Through Facilitating Synapses and STDP: A Neural Basis for Orientation Flash-Lag Effect

Lim

The 2006 IEEE International Joint Conference on Neural Network Proceedings

2006

Abstract-In orientation flash-lag effect (FLE), a continuously rotating bar in the center is perceived to be misaligned toward the direction of rotation when compared to a briefly flashed pair of flanking bars that are actually aligned. The implication of this simple visual illusion is quite profound: The effect may be due to motion extrapolation, undoing the effects of neural conduction delay. Previously, we showed that facilitating synapses may be a neural basis of such a delay compensation mechanism in other forms of FLE such as luminance FLE. However, the approach based on a single neuron cannot be applied to orientation FLE since firing rate in a single neuron cannot represent the full range of orientations. Here, we extend our model to multiple neurons, and show that facilitating synapses, together with adaptation through Spike-Timing-Dependent Plasticity (STDP), can serve as a neural basis for delay compensation giving rise to orientation FLE.