THE NERVOUS SYSTEM THE SPINAL CORD AND SPINAL NERVES

The central nervous system includes the brain and spinal cord. The brain and spinal cord are protected by bony structures, membranes, and fluid. The brain is held in the cranial cavity of the skull and it consists of the cerebrum, cerebellum, and the brain stem. The nerves involved are cranial nerves and spinal nerves.

Current Opinion in Neurobiology, 2010

T he central nervous system (CNS) receives sensory stimuli from the body and the outside world and processes that information in neural networks or centers of integration to mediate an appropriate response or learned experience. Centers of integration are hierarchical in nature. In a caudal-to-rostral sequence, the more rostral it is placed, the greater the complexity of the neural network. This chapter considers functions integrated within the diencephalon and telencephalon, where emotionally motivated behavior, appetitive drive, consciousness, sleep, language, memory, and cognition are coordinated.

Current Biology, 2001

Neurons receive synaptic inputs primarily onto their dendrites, which filter synaptic potentials as they spread toward the soma. Recent results indicate that this filtering appears to be compensated by increasing the synaptic conductance at distal synapses, thus normalizing the efficacy of synaptic inputs at the soma.

Medical & Biological Engineering & Computing, 1992

As MENTIONED by RAMON Y CAJAL (1909--11), at the start of this century, the complexity of the dendritic tree of a neurone may influence the processing of information. The electrophysiological approach, initiated by ECCLES and collaborators (1957), introduced the idea that the neurone receives information by means of various synapses which are mainly located at the level of the dendritic arborisation, giving inputs inducing excitatory as well as inhibitory post synaptic potentials, which increase or decrease excitability. It was generally assumed that the cell body of the neurone was able to add both excitatory and inhibitory potentials and, if the sum was over the threshold for the excitation of the initial segment, an action potential was generated at this level and propagated along the axon. Following the statement of this hypothesis, a long period of research was devoted to the study of the generation and propagation of the action potential and little attention was given to the involvement of dendrites in the propagation and processing of neural information.

Behavioral and neural biology, 1985

The discovery of dendritic spines in the late nineteenth century has prompted nearly 90 years of speculation about their physiological importance. Early observations that bulbous spine heads had very close approximations with the axon terminals of other neurons, confirmed later by ultrastructural study, led to ideas that spines enhance dendritic surface areas for making synaptic contacts. More recent application of cable and core-conductor theory to the anatomical study of spines has raised a number of new ideas about spine function. One important issue was derived from the theoretical treatment of spines as tiny dendrites with much higher input resistances than those of the larger parent dendrites. The high spine-stem resistance results in relative electrical isolation of the spine head; this causes large local depolarizations in the spine head. Several theoretical studies have also shown that if the spine-head input resistances are substantially higher than those of the parent den...

Current Opinion in Neurobiology, 2003

The integrative properties of dendrites are determined by a complex mixture of factors, including their morphology, the spatio-temporal patterning of synaptic inputs, the balance of excitation and inhibition, and neuromodulatory influences, all of which interact with the many voltage-gated conductances present in the dendritic membrane. Recent efforts to grapple with this complexity have focused on identifying functional compartments in the dendritic tree, the number and size of which depend on the aspect of dendritic function being considered. We discuss how dendritic compartments and the interactions between them help to enhance the computational power of the neuron and define the rules for the induction of synaptic plasticity. Addresses à Abbreviations AMPA a-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid AP action potential BAC backpropagation activated calcium spike BPAP backpropagating action potential EPSP excitatory postsynaptic potential GABA g-aminobutyric acid LTP long-term potentiation NMDA N-methyl-D-aspartate What are the functional compartments in neurons? A schematic representation of different levels of granularity in neuronal processing. (a) Calcium signalling restricted to single spines. (b) Signalling restricted to a small cluster of spines. (c) Signalling restricted to a single terminal branchlet. (d) Signalling extending across the entire apical dendritic tree.