Neural Darwinism

The theory of " Neural Group Selection " describes and explains the function of the brain in the planning and implementation of actions on the basis of the recent findings of neuroscience ( Neuroscience ). It was developed by Gerald M. Edelman in the 80s of the 20th century. The novelty of the theory is that, firstly, the memory will not be considered as representative memory content of the experience, but as a dynamic system that is constantly changing during its activity. Secondly, is that consciousness is not localized as activity in a particular brain region to understand, rather than the activity itself, in which all too widely dispersed regions of the brain communicate with each other in constant reciprocal exchange of information.

• 2.1 Notes and references

History of development

During his studies in the marine snail Aplysia Eric Kandel noted in 1976 that probably not a major long-term memory in the brain exists, but that the change in the synapses of nerve cells allow an easier and faster re - activation of learned movements. Thus, the study on the behavior and movements of the level of the neural centers were transferred to the study of individual nerve cells and their molecular alterations. The decisive factor was then the step of Immunologists Gerald M. Edelman, who had been watching the development of antibodies in the organism that the organism they are not, as previously assumed, developed by genetically predetermined plans, but according to the evolutionary principle of selection. The selection principle requires very large populations of similar but equivalent structures from which it can make appropriate choices for the individual case. It was shown that the nervous system of populations of synapses at the individual nerve cells ( thousands ), populations of neurons (more than 10 billion ) and populations of nerve cell networks ( also billion ) which meet these conditions. It is therefore assumed that are developed and implemented according to this principle of selection thoughts, actions and movements. Consequences has found systematically checked and confirmed Edelman.

Principles of selection

• Development of selection: Having been in the early embryonic development (see embryogenesis ) genes and heredity determine the brain anatomy, it is already in the training of multi-branched axons to a high variability of link patterns. It simultaneously firing neurons are preferably first assembled into groups and to networks ( circuits ) (somatic selection). It results in the formation of the primary repertoire.

• Experience selection: Through behavioral experiences that occur throughout life, then it comes to synaptic selection. It leads to the formation of groups whose elements are similar, but not identical are equivalent ( degeneracy ). Here in competitive selection processes are more frequently used synaptic connections, thereby reinforcing their synaptic efficiency., The synaptic connections and the efficiency of rare selected groups is weakened. Here, There is a constant dynamic restructuring of the groups by adapting to the current conditions. By selecting certain pattern of spatially distributed areas of the perceived categories can be formed which are necessary for the assignment of new impressions to already experienced before. Even the networks of primary repertoires to secondary repertoire and cards ( maps) up. The cards can be changed by selective use (eg, the range of the thumb write in the motor cortex by frequent SMS enlarged).

The cortical connections

To a parent co-operation with the result of a successful action / movement does not occur, as previously assumed, by sequential sequential processing in individual brain regions, but by constant reciprocal exchange of signals throughout the cerebrum (see also telencephalon ), the topological cerebrum arrangement of the thalamocortical system. In this, the thalamus is the functionally specialized regions ( the maps) of the cortex networked diverse and recursive. They form signal circle, in which a constant exchange simultaneously transmitted signals between spaced- away also very individual areas takes place ( reentry ). Thus, the activities that take place in these areas, coordinated with each other in time and space.

At the same time is a constant signal exchange takes this thalamocortical system with a second arrangement of the brain that are run at the same time in parallel chains of nuclei in the same direction. These connect the cortex with special subcortical structures such as the cerebellum ( participation and synchronization of movements but also specific thought processes ); the basal ganglia (participation in planning and execution of complex motor and cognitive processes ) and the hippocampus (main involvement in the consolidation of the contents of short-term memory functions for long-term memory functions in the cerebral cortex ).

Finally, these permanent activities are associated with nuclei in the brainstem and hypothalamus, through which the neural plasticity - synapse strength - be affected within the neural circuits by adaptive responses. These influences are also referred to as evaluation systems applies to the entire system, that any use of the compounds to changes in the neurons and their connections leads, so that the system is in constant adaptive change.

Awareness

It is believed that these reentrant processes account for consciousness. This is supported by the observation that repeatedly performed actions in which the attention must not be focused on the various aspects and interests of the execution, the activity of the signal exchange between the areas of the brain decreases, so that they running at almost unconsciously so-called automated actions is minimal. This ensures that in the solution of complex new and particularly cognitive tasks that require the full attention, other necessary routine tasks (eg, writing, drinking coffee or motor processes while driving ), the same can be performed without difficulty.