We study the shape of one of the basic types of solitary patterns - sp
ike autosolitons (ASs) forming in many physical, chemical and biologic
al systems. We show that in contrast to domain patterns forming in Fit
zHugh-Nagumo type systems the size and amplitude of spike ASs are dete
rmined by length scales rather than nonlinearities of the system. We f
ind that the amplitude of 2D and 3D ASs is several orders greater than
that of 1D AS and can take on gigantic values. (C) 1998 Elsevier Scie
nce B.V. All rights reserved.