The brain of an echo locating bat is devoted, in large part, to
analyzing sound and conducting behavior in a world of sounds and echoes.
This monograph is about analysis of sound in the brainstem of
echolocating bats and concerns the relationship between brain structure
and brain function. Echolocating bats are unique subjects for the study
of such relationships. Like man, echolocating bats emit sounds just for
the purpose of listening to them. Simply by observing the bat's
echolocation sounds, we know what the bat listens to in nature. We
therefore have a good idea what the bat's auditory brain is designed to
do. But this alone does not make the bat unique. The brain of the bat
is, by mammalian standards, rather primitive. The unique aspect is the
combination of primitive characteristics and complex auditory
processing. Within this small brain the auditory structures are
hypertrophied and have an elegance of organization not seen in other
mammals. It is as if the auditory pathways had evolved while the rest of
the brain remained evolutionary quiescent.