Impact of Computational Models for an ImprovedUnderstanding of Ictogenesis: From Single Neuronsto Networks of Neurons

摘要

The nervous system is a complex network composed of a huge number ofneurons [1]. The human brain contains approximately 100 billion neurons and10 million kilometers of wiring. Neurons couple to networks. They are organizedin different morphological structures and perform different functions. Like othercells neurons consist of a cell membrane which encloses the cytoplasm and the cellnucleus. Neurons can transmit electrical signals over long distances. The size andshape of neurons varies over a broad range depending on their location and specialrole in the nervous system. Regardless of this variability the basic functionality isalways the same: a neuron receives input signals, processes this input, and transfersan output signal to other neurons. Accordingly, the basic structure is the same forevery neuron. The cell body (soma) has appendages that are responsible for theinput and output of signals. A neuron usually has many input appendages (thedendrites), and one output appendage (the axon). A neuron is typically connectedwith approximately 10 000 other neurons via synapses which are located at theend of the neuron's axon. Generally, a negative electric potential difference existsbetween the extracellular and the intracellular space (extracellular potential set tozero) [1, 2], which is caused by differences in ion concentrations between the innerand the outer side of the cell membrane. Inputs received via synaptic connectionscause transmembrane currents that change the membrane potential, and eventuallycan cause the generation of an action potential or spike `[. . .] an abrupt and transientchange of membrane voltage' [3]. Action potentials can propagate along the axon toother neurons. Time sequences of these action potentials are considered the basisfor encoding information and for communication between neurons [4].