Synapse elimination

With synapse elimination the death of synaptic connections is generally referred to, which in contrast to synaptogenesis is. Together with this, the synapse elimination forms the basis for the neuronal plasticity of the brain.

Elimination of the synapses

Which synapses are eliminated and which remain, is decided by Hebb's learning rule . The more neurons fire together, the stronger the connection between the two. Accordingly, synapses of a strong connection remain while synapses of a weak or missing connection are eliminated. A distinction is made here between experience-dependent and experience-expecting plasticity. Some synaptic connections have to be strengthened through experience in order not to be broken down. This includes seeing, for example. Used in a so-called Kaspar Hauser experimentWhen a living being reared in a completely dark room, the synapses of the visual cortex wither. The organism is then no longer able to perceive things visually even in a visually stimulating environment. The synaptogenesis of the visual cortex is thus expectant of experience. Experience-dependent synaptogenesis refers to the generation of synapses through an experience that the organism does not have automatically (such as seeing, hearing and feeling), but which are presented to it by its environment. An example of this would be the formation of synapses when learning a foreign language.

Pruning

With Pruning a special form of Synapsenliminierung is understood that leads to a kind of fine-tuning of synaptic connections. In this connection, connections that are redundant or no longer functional are cleared down. For example, in the primary visual cortex (BA17), groups of neurons that are responsible for the other eye are almost completely separated. This is not the case at the beginning of brain development and leads to an increase in efficiency. Pruning occurs in mammals, including humans, between early childhood and puberty and is influenced by environmental experiences.

literature

• M. Gazzaniga , RB Ivry, GR Mangun: Cognitive Neuroscience: the biology of the mind. New York 2009, p. 553.

Individual evidence

1. ^ Lohaus / Vierhaus / Maass: Developmental Psychology in Childhood and Adolescence. Springer, Heidelberg 2010.
2. ^ Schneider / Lindenberger (ed.): Developmental Psychology. (7th edition), Beltz, Weinheim 2012
3. ↑ Chechik, Gal; Meilijison, Isaac; Ruppin, Eytan: Neuronal Regulation: a mechanism for synaptic pruning during brain maturation . In: Neural Computation . tape 11 , no. 8 , 1999, p. 2061-80 , doi : 10.1162 / 089976699300016089 , PMID 10578044 .
4. ↑ Chechik, G .; Meilijson, I .; Ruppin, E .: Synaptic pruning in development: a computational account. In: Neural computation . tape 10 , no. 7 , 1998, pp. 1759-77 , doi : 10.1162 / 089976698300017124 , PMID 9744896 .

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