Central Pattern Generators und ihre Bedeutung für die fötale Motorik

Zusammenfassung

Auch wenn die Existenz der Central Pattern Generators (CPGs) schon seit Ende des 19. Jahrhunderts bekannt ist, ist man noch immer weit davon entfernt, die präzise Funktion dieser faszinierenden neuronalen Netzwerke zu verstehen. CPGs generieren endogen – in der Abwesenheit oszillatorischer Inputs – rhythmische Bewegungsmuster. Einige CPGs sind kontinuierlich aktiv, wie zum Beispiel der CPG für den Atemrhythmus; andere CPGs (wie jene für Lokomotion oder rhythmische Aktivitäten der Nahrungsaufnahme) müssen erst neuronal und/oder hormonell getriggert werden. Damit rhythmisches Verhalten an die Umgebungsbedingungen angepasst werden kann, bedarf es modulierender Inputs von supraspinalen Strukturen und der Peripherie. In der frühesten Entwicklung erzeugen die noch unreifen CPGs spontane embryonale/fötale Bewegungen, die ihrerseits die Reifung der sich entwickelnden Strukturen gewährleisten. Die Beurteilung früher fötaler und neonataler Bewegungen ist von klinischer Relevanz, da Hirnläsionen den modulierenden Input auf den CPG reduzieren. Die daraus resultierende Monotonie der Bewegungen ist ein zuverlässiges Zeichen neurologischer Beeinträchtigung.

Abstract

Although evidence for the existence of endogenously generated motor activity goes back to experiments conducted more than a century ago, a lot remains to be learnt about the fascinating network that is the central pattern generator (CPG). CPGs are neuronal circuits that can produce rhythmic motor patterns in the absence of oscillatory input. Some CPGs operate continuously (e. g., breathing movements); others are activated to perform specific behavioural tasks (e. g., locomotion). In order to lend flexibility to the motor output, supraspinal projections activate, inhibit, and, most of all, modulate the CPG activity, as does the sensory feedback. Embryonic and foetal motor patterns have all the characteristics of being endogenously generated. At no other stage of development is the neural structure so closely related to its own function. It only takes a few neurons to generate basic movements, which are, in turn, necessary for further development of the structure. Apart from the general interest in the evolution of early motor activity, the observation and assessment of spontaneous foetal and neonatal motility has also clinical implications, since a reduced CPG modulation results in less variable movements and indicates foetal or neonatal compromise.

Schlüsselwörter

General Movements - Hirnläsion - Lokomotion - Modulation - neuronales Netzwerk - Spontanbewegungen

Key words

brain lesion - general movements - locomotion - modulation - neuronal network - spontaneous movements

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