Satoshi Ikemoto talks with
ScienceWatch.com and answers a few questions about
this month's Fast Breaking Paper in the field of
Neuroscience & Behavior.
Article Title: Dopamine reward circuitry: Two
projection systems from the ventral midbrain to the nucleus
accumbens-olfactory tubercle complex
Journal: BRAIN RES REV
Year: NOV 2007
* NIDA, Behav Neurosci Branch, NIH, US Dept HHS, 5500
Nathan Shock Dr, Baltimore, MD 21224 USA.
(addresses have been truncated)
Why do you think your paper is highly
Neuroscientists are fascinated by dopamine and how it mediates
reward-related functions. This paper presents anatomical and functional
refinements of the way we understand a dopaminergic projection system that
has been implicated in reward. These refinements in our anatomical
understanding of the rat brain complement a newly proposed way to
understand the anatomical interaction between the midbrain and the striatum
in the non-human primate brain.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
The paper synthesizes recent findings concerning chemical trigger zones for
reward and their connectivity, in order to argue for a new way of
understanding the functional organization of the rat brain. It also offers
new hypotheses for the relationship between dopamine's functions and
projection of dopamine neurons.
Would you summarize the significance of your paper in
"Neuroscientific research shows
that, in a nutshell, even the most intimate
emotional experience is mediated by brain
chemistry and function."
Dopamine is over-simplistically described as a pleasure molecule,
particularly by the media; in reality, it is involved in a wide range of
functions, from motivation to memory to motor control. My paper argues that
dopamine's role in psycho-behavioral function depends on the brain site at
which it is acting. I also suggested that some dopamine neurons are
involved in non-sensory pleasure: emotional arousal, which may be
characterized as anticipatory or emotional pleasure.
How did you become involved in this research, and were
there any problems along the way?
Twenty years ago, I started my graduate work at Bowling Green State
University with Jaak Panksepp, who coined the term "affective neuroscience"
and who profoundly influenced how I think about the brain's emotional
systems and the functions of dopamine. I later began to work with Roy Wise,
Chief of the Behavioral Neuroscience Research Branch at the National
Institute on Drug Abuse (NIDA), and who continues to influence my
perspective on dopamine function and who encouraged me to pursue the lines
of research leading to this paper.
As for problems, I think it is difficult for all scientists to keep up with
the vast and ever-increasing body of new knowledge—more is published
on dopamine every day. Also, it is always a struggle for me to clearly put
my thoughts into writing.
Where do you see your research leading in the
Voluntary behavior is mediated by the basal ganglia, including the striatal
complex and midbrain dopamine neurons. Each of this system's regions
appears to be involved in a different aspect of voluntary behavior. I'm
interested in investigating exactly what each of these regions mediates and
how the different regions interact to mediate adaptive behavior.
Do you foresee any social or political implications for
Neuroscientific research shows that, in a nutshell, even the most intimate
emotional experience is mediated by brain chemistry and function. Thus, we
may soon learn to control our inner experiences with interventions like
drugs and deep brain stimulation. This potentially raises both
possibilities as well as posing certain ethical problems. We shall have to
struggle to understand just to what extent it may be socially and
politically acceptable to artificially alter our minds.
Satoshi Ikemoto, Ph.D.
Chief, Intracranial Injections Unit
Behavioral Neuroscience Research Branch
Intramural Research Program
National Institute on Drug Abuse
National Institutes of Health
Baltimore, MD, USA Web
Keywords: dopamine, anatomical interaction between the midbrain
and the striatum, non-human primate brain, dopamine's functions,
projection of dopamine neurons, dopamine's role in psycho-behavioral
function, jaak panksepp, affective neuroscience, roy wise, drugs and
deep brain stimulation.