[Polymodal sensory integration at the interface with the cerebrospinal fluid]

The cerebrospinal fluid is the site of a sensory interface that allows interactions between the nervous system and cellular targets throughout the body. Sensory neurons in contact with the cerebrospinal fluid in the spinal cord respond to changes of its composition, in particular in the context of bacterial infections of the central nervous system. These cerebrospinal fluid-contacting neurons also form an axial mechanosensory system that detects spinal curvature through the coupling with a long a proteinaceous polymer under tension in the central canal called the Reissner fiber. Activated by compression of the body axis, neurons contacting the cerebrospinal fluid modulate motor circuits to increase the speed of movement and to stabilize posture. During development and aging, this sensory system aligns the body axis and spine via the release of peptides of the urotensin family that act at long range on their receptors expressed in skeletal muscles.