Читать книгу Neurobiology For Dummies - Frank Amthor - Страница 82

After neurons receive information from either the environment or other neurons, they process that information using electrotonic potentials and ion concentrations that interact within the neuron. Neurons then transmit information to other neurons or to muscles or glands.

A neuron’s dendritic tree may have thousands of excitatory and inhibitory synaptic inputs, each of which may be modulated in a complex pattern over time. The way different inputs to the neuron interact also depends on their locations in the dendritic tree. Inputs that are near to each other may interact in a nonlinear way, exhibiting thresholds, saturation, multiplicative interactions, and other complex interactions.

In most neurons, all the inputs and their interactions result in a net flow of current into the cell body, or soma, and the initial segment of the axon. If the voltage produced by this current is below threshold, it doesn’t produce any spikes. Above this threshold, the rate of action potentials, or spikes, is generally proportional to the net excitatory (depolarizing) current. The spikes are sent down the axon where, at the axon terminals, neurotransmitter is released. Neurons may release neurotransmitter on neurons a few tens of micrometers away or a meter or more away.