9. THE MAUTHNER CELL
267
mentioned in ( 2 ) , but they do not possess Mauthner neurons (see
Aronson, 1963).
The following account will be largely based on data from a small
number of species of teleost fish. Of course, Mauthner cell functions
might well have developed in a variety of ways to suit the special
needs of particular animal types. In this context the present account,
which is based chiefly on experimental observations, provides a model
schema of Mauthner cell function that can be used as a basis for comparison and might help to explain any apparently disparate appearances,
or functions, of Mauthner cells in other piscine or amphibian species.
Because of its particular specialization the Mauthner cell system
presents some rather striking examples of neuronal morphology and
function, which may throw light on the behavior of neurons generally.
The possible wider implications of selected features which seem unusually clear and comprehensible will also be discussed.
11. THE BASIC ANATOMY OF THE MAUTHNER NEURON
The Mauthner neuron varies in shape and size in different species
and in the number and disposition of its main dendrites. An interesting
comparative account covering a number of teleosts and amphibians
can be found in Stefanelli’s paper of 1951. At this point we need consider only those features which will help in our understanding of the
physiological investigations to be described. [Further anatomical
descriptions are made later in this chapter (Section VI), where appropriate reference is made to earlier studies which more recent observations largely confirm.]
Figure 4 shows Bodian’s now well-known illustration of the Mauthner
cell of the goldfish, which is not only relatively simple in shape but
probably incorporates the most important features of all Mauthner
neurons. ( I t is also perhaps the one best studied.) In a goldfish of
about 12 cm from mouth to the base of the caudal fin, the somas of
the two Mauthner cells are situated in the brain on either side of the
midline, about 7 0 0 p apart and some 1-1;; mm below the surface of the
medulla (Fig. l a ) . Viewed from above (i.e., dorsally), this region is
normally overlaid by the cerebellum (Figs. 1 and 2). The somewhat
oval-shaped cell soma has no definable lateral margins; on one side
(lateral) it merges into the base of a single massive “lateral dendrite”
which extends toward the region where the VIIIth cranial nerve enters
the medulla, running slightly dorsally and caudally, as well as laterally,
for 500p or more (Fig. l b ) . The opposite (ventromedial) margin of
267
mentioned in ( 2 ) , but they do not possess Mauthner neurons (see
Aronson, 1963).
The following account will be largely based on data from a small
number of species of teleost fish. Of course, Mauthner cell functions
might well have developed in a variety of ways to suit the special
needs of particular animal types. In this context the present account,
which is based chiefly on experimental observations, provides a model
schema of Mauthner cell function that can be used as a basis for comparison and might help to explain any apparently disparate appearances,
or functions, of Mauthner cells in other piscine or amphibian species.
Because of its particular specialization the Mauthner cell system
presents some rather striking examples of neuronal morphology and
function, which may throw light on the behavior of neurons generally.
The possible wider implications of selected features which seem unusually clear and comprehensible will also be discussed.
11. THE BASIC ANATOMY OF THE MAUTHNER NEURON
The Mauthner neuron varies in shape and size in different species
and in the number and disposition of its main dendrites. An interesting
comparative account covering a number of teleosts and amphibians
can be found in Stefanelli’s paper of 1951. At this point we need consider only those features which will help in our understanding of the
physiological investigations to be described. [Further anatomical
descriptions are made later in this chapter (Section VI), where appropriate reference is made to earlier studies which more recent observations largely confirm.]
Figure 4 shows Bodian’s now well-known illustration of the Mauthner
cell of the goldfish, which is not only relatively simple in shape but
probably incorporates the most important features of all Mauthner
neurons. ( I t is also perhaps the one best studied.) In a goldfish of
about 12 cm from mouth to the base of the caudal fin, the somas of
the two Mauthner cells are situated in the brain on either side of the
midline, about 7 0 0 p apart and some 1-1;; mm below the surface of the
medulla (Fig. l a ) . Viewed from above (i.e., dorsally), this region is
normally overlaid by the cerebellum (Figs. 1 and 2). The somewhat
oval-shaped cell soma has no definable lateral margins; on one side
(lateral) it merges into the base of a single massive “lateral dendrite”
which extends toward the region where the VIIIth cranial nerve enters
the medulla, running slightly dorsally and caudally, as well as laterally,
for 500p or more (Fig. l b ) . The opposite (ventromedial) margin of