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 | |
Licence : | Droits gérés |
Crédit: | Science Photo Library / Terry, Sheila |
Taille de l’image : | 3543 px × 2572 px |
Model Release : | Disponible |
Property Release : | Non requis |
Restrictions : | - |