Ga. Jacobs et Fe. Theunissen, FUNCTIONAL-ORGANIZATION OF A NEURAL MAP IN THE CRICKET CERCAL SENSORY-SYSTEM, The Journal of neuroscience, 16(2), 1996, pp. 769-784
Directionally selective mechanosensory afferents in the cricket cereal
sensory system form a map of air current direction in the terminal ab
dominal ganglion. The global organization of this map was revealed by
studying the anatomical relationships between an ensemble of sensory a
fferents that represented the entire range of receptor hair directiona
l sensitivities on the sensory epithelium. The shapes and three-dimens
ional positions of the terminal arborizations of these cells were high
ly conserved across animals. Afferents with similar directional sensit
ivities arborized near each other within the map, and their terminal a
rborizations showed significant anatomical overlap. There was a clear
global organization pattern of afferents within the map: they were org
anized into a spiral shape, with stimulus direction mapped continuousl
y around the spiral. These results demonstrate that this map is not fo
rmed via a direct point-to-point topographic projection from the senso
ry epithelium to the CNS. Rather, the continuous representation of air
current direction is synthesized within the CNS via an anatomical reo
rganization of the afferent terminal arbors. The arbors are reorganize
d according to a functional property that is independent of the locati
on of the mechanoreceptor in the epithelium. The ensemble data were us
ed to derive predictions of the patterns of steady-state excitation th
roughout the map for different directional stimuli. These images repre
sent quantitative and testable predictions of functional characteristi
cs of the entire neural map.