Wake Forest Baptist
Medical Centre researchers are gaining a better understanding of the
neurochemical basis of addiction with a new technology called optogenetics.
research, optogenetics is a newly developed technology that allows researchers
to control the activity of specific populations of brain cells, or neurons,
using light. And it's all thanks to understanding how tiny green algae, that
give pond scum its distinctive colour, detect and use light to grow.
enables researchers like Evgeny A. Budygin, PhD, assistant professor of
neurobiology and anatomy at Wake Forest Baptist, to address critical questions
regarding the role of dopamine in alcohol drinking related behaviours, using a
technique, we've basically taken control of specific populations of dopamine
cells, using light to make them respond almost like flipping a light switch,"
said Budygin. "These data provide us with concrete direction about what
kind of patterns of dopamine cell activation might be most effective to target
The latest study
from Budygin and his team published online in last month's journal Frontiers in
Behavioural Neuroscience. Co-author Jeffrey L. Weiner, PhD, professor of
physiology and pharmacology at Wake Forest Baptist, said one of the biggest
challenges in neuroscience has been to control the activity of brain cells in
the same way that the brain actually controls them.
neuroscientists can turn specific neurons on or off at will, proving that those
neurons actually govern specific behaviours.
"We have known
for many years what areas of the brain are involved in the development of
addiction and which neurotransmitters are essential for this process,"
Weiner said. "We need to know the causal relationship between
neurochemical changes in the brain and addictive behaviours, and optogenetics
is making that possible now."
The researchers used
cutting-edge molecular techniques to express the light-responsive
channelrhodopsin protein in a specific population of dopamine cells in the
brain-reward system of rodents. They then implanted tiny optical fibres into
this brain region and were able to control the activity of these dopamine cells
by flashing a blue laser on them.
Distinct patterns of dopamine
"You can place
an electrode in the brain and apply an electrical current to mimic the way
brain cells get excited, but when you do that you're activating all the cells
in that area," Weiner said. "With optogenetics, we were able to
selectively control a specific population of dopamine cells in a part of the
brain-reward system. Using this technique, we discovered distinct patterns of
dopamine cell activation that seemed to be able to disrupt the alcohol-drinking
behaviour of the rats."
Weiner said there is
translational value from the study because "it gives us better insight
into how we might want to use something like deep-brain stimulation to treat
alcoholism. Doctors are starting to use deep-brain stimulation to treat
everything from anxiety to depression, and while it works, there is little
scientific understanding behind it, he said.
"Now we are taking the first steps in this direction," he said.
"It was impossible before the optogenetic era."