Illustration representing the human sleep-wakefulness cycle; the pendulum swings between images of a girl asleep and awake. It has been suggested that feedback signals from the cerebral cortex and from the peripheral nerve receptors,by sustaining a particular state,might play an important role in controlling the sleep-wakefulness rhythm. Many biological processes are believed to take place under the direction of an internal clock mechanism. The regulation of biological time is poorly understood and is a subject of current (1990's) research | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library / Terry, Sheila |
Bildgröße: | 3543 px × 2572 px |
Modell-Rechte: | vorhanden |
Eigentums-Rechte: | nicht erforderlich |
Restrictions: | - |