We are creatures of
habit, just like Pavlov’s dogs. Normally we don’t like nasty surprises and will
make an effort to avoid them. If we get a signal we respond once we’ve learned
that the signal means bad news.
As
we know by now, dopamine is associated with our reward, feel good system, and
serotonin is involved with our mood regulation and anti-depressant feeling. So
it seems natural to look at these whilst our Pavlovian responses are been tested.
Attar et al at U of Hamburg-Eppendorf got stuck into scaring the pants of 58
young 20-something guys and checking their responses in terms of serotonin
limited responses (1).
Chili
peppers have Capsaicin, which is responsible for that excitement at the restaurant
when you’ve chosen the wrong dish. This was extracted and painted on the left
arm of the human lab rats. The sensitized area had a one-inch square fast
response heating/cooling unit strapped to it.
The
guys focused hard on a computer screen as a visual signal preceded some
gratuitous pain infliction by heating the sensitized area. Young guys are fast
learners and the quickly learned to clench and hold their breath when a dreaded
triangle appeared on the screen. Prof. Pavlov would have been proud of their
responses.
Of
course, this is not the end of the story. We’re not playing with dogs. With
people we can stuff them into the big magnet and see what their brain is
playing at and we can play games with their diet. Remember, broadly, we are
what we eat and our experimental participants were fed on high or low amino acid
diets to play games with their tryptophan load, which in turn ups or downs
their serotonin level.
With
depleted serotonin levels, the subjects were slow learners Pavlovian-wise. This
is a result in conflict with other studies. I guess more painful procedures are
required to get to the bottom of this.
In
the meantime, be careful for what you sign up for if you don’t want to have a
panic attack every time a triangular shape appears on your computer screen.
