Neuronal networks: Tiny source, great effect
How nerve cells organise themselves
Propagation of local excitation in the brain is a chain reaction
Nerve cells are organised in networks
The human brain contains approx. 100 billion nerve cells. A gigantic number. In order for sensory impressions to be processed, individual nerve cells amalgamate to form larger networks. In doing so, nerve cells, also called neurons, receive and transmit signals. The term used for this process is "firing" of electrical impulses. The conjunction between two neurons is called a synapse. Mehdi Bayati, PhD student in the work group "Neurobiology of Memory" headed by Prof Dr Sen Cheng, investigates in what way sequential propagation of neuronal excitation through the neuronal network is conducted.
Mathematical models instead of real cells
For this purpose, he makes use of the opportunities provided by the "Computational Neuroscience" degree programme. Generally speaking, this programme deals with information-processing properties of the nervous system. Experiments are carried out not with real animal or human neurons, but with mathematical models which are realised with the aid of computer simulations. In the recently published study, Bayati investigated mainly the question if small local neuron excitations are the source of an overall synchronous network excitation and activity propagation.
Quick as lightning and synchronous
Local excitation takes place if a small number of neurons fires at a higher frequency than the others. Bayati found out that this local excitation does indeed result in synchronous, chain-like propagation, and within an extremely short period of time at that. Moreover, he observed that synchronous propagation of excitation remains in place even after local excitation had faded.
The study was funded by the Mercator Foundation and the German Research Foundation under the framework of Bochum's SFB 874 "Integration and Representation of Sensory Processes."
M. Bayati, A. Valizadeh, A. Abbassian, S. Cheng (2015): Self-organization of synchronous activity propagation in neuronal networks driven by local excitation, Frontiers in Computational Neuroscience, DOI: 10.3389/fncom.2015.00069