|
Showing 1 - 1 of
1 matches in All Departments
In many parts of vertebrate and invertebrate central nervous
systems, groups of nerve or receptor cells can be found that are
arranged and connected according to a precise, functionally defined
pattern (Braitenberg, 1973; Santini, 1975; Strausfeld, 1976;
Chan-Palay, 1977). In these cases, groups of cell bodies or
synapses appear as basically similar configurations, which,
however, are different in detail from each other. Such abstract
patterns of connectivity are of a statistical nature and do not
allow, in a given example, for the prediction of the localization
or connections of a particular cell. "Wiring diagrams", therefore,
can be obtained only from a multitude of individual observations.
In contrast, in several sensory organs, concrete patterns occur
that con sist of a regular, mosaic-like, and geometric arrangement
of similar cell types. The constancy of such a mosaic allows
predictions about certain units of the pattern on the basis of only
a few exemplary observations. Typical examples are found in the
visual system: In the compound eye of insects, each ommatidium
contains a definite number of visual cells that are grouped around
the optical axis in a hexogonal array (Kirsch feld, 1967); in the
vertebrate retina, mosaics of geometrically arranged cones are
found most frequently in lower vertebrates; they are common among
teleosts. A number of studies have dealt with their phylogenetic
significance and their functional role as adaptation to specific
environments or modes of feeding.
|
You may like...
Loot
Nadine Gordimer
Paperback
(2)
R398
R330
Discovery Miles 3 300
|
Email address subscribed successfully.
A activation email has been sent to you.
Please click the link in that email to activate your subscription.