Monkey Broca, Wernicke?

[Mark P. Line]

jess tauber wrote:
> Study hints language skills came early in
> primates-http://news.yahoo.com/s/nm/20060725/sc_nm/science_language_dc
>
> I remember being told that lower primates only utilize lower (limbic)
> brain centers for vocal communication. So what does all this mean??

I think this study is important precisely because it had been hypothesized
that monkey vocalization does not involve the cortex. This rather
seriously overgeneralized hypothesis came about because experiments
(starting in the 1970's, I think) showed that vocalization was elicited by
limbic but not by cortical stimulation.

Apart from the obvious ramifications for our understanding of the
phylogeny of primate communication, the study also suggests that the
reason for those stimulation results in monkeys may be due to limbic
control of vocalization even if there is cortical involvement in the
actual behavior: limbic stimulation causes vocalization because it
provides the control stimulus, while cortical stimulation does nothing
because the limbic signal is absent. Note that monkeys don't want to
vocalize willy-nilly except for good reason (since there might be an
undetected predator within earshot), and that there would be solid
inhibitory pathways preventing vocalization if only Broca is stimulated
without the limbic input.

Humans will have evolved past this limbic control -- most communication is
consciously intended and neocortically controlled. (There's an obvious
joke about throwbacks at a recent coffee klatsch.)

I'm surprised that no such study was done before now and that the
limbic-only hypothesis for monkey vocalization remained unfalsified until
now, but I guess I'll take their word for it.

-- Mark

Mark P. Line
Polymathix
San Antonio, TX