A list of tracer substances is available in table 26. A much more extensive list is available from http://cocomac.org in the ``tracer substance'' field: http://cocomac.org/Help/Tracer.asp
``Afferent'' (``sensory'') means a pathway from the peripheral system towards the central system, while ``efferent'' (``Motor'') is from the central to the peripheral system.
Finn Årup Nielsen 2010-04-23