Neurons and Near-Death Spikes

Abstract

Near-death spikes or near-death surges represent sudden increase in neuron activity in the human brain before neurons end their firing. Just before a person is clinically dead, such spikes are observed in certain cases, so it got the name ‘near-death spikes’. The reason for this behaviour is the lack of oxygen in brain. The neural network of the worm Caenorhabditis elegans resembles that of human brain. Hence it can be used to understand the simple dynamics of human brain. Within the network, the neurons are found to exhibit chaotic nature, even though their parameters are that of normal neurons. It is observed that when the strength of synaptic conductance is increased, initially the bursting synchronization, entropy of the network and the average firing rate decrease slightly and then increase. As the neurons of the network are made chaotic, ‘near-death’-like surges of neuron activity are observed. Also, the brain dynamics changes from alert to rest state. It can be demonstrated that a particular type of noise called Lévy noise can generate ‘near-death’-like surges in the neural network of the worm Caenorhabditis elegans. Identification of different parameter regions of Lévy noise at which the network makes transitions from one synchronous state to another and the mechanism behind them is a challenging subject. Such transitions are already reported in cortical regions of brain. The Lévy noise values at which the network displays generation of waves of different frequencies can be determined. This result suggests a new method for neuro stimulation in the case of traumatic brain injury. The neuronal network even displayed Gamma oscillations. If the parameters of the neurons are made chaotic, the network firing rate is diminished and it displayed Delta and Theta oscillations.