The importance
of optogenetics as a research tool, particularly in conjunction with other
technologies, continues to grow rapidly. In recent years Neuroscience has made
man advances based on the brain-scanning technique called Functional Magnetic
Resonance Imaging (FMRI). These scans are usually billed providing detailed
maps of neural activity in response to various stimuli. FMRI only shows changes
in blood oxygen levels in different areas of brain, and those changes are the
proxy for actual neural activity.
Some uncertainty has
therefore always surrounded the question whether these complex signals can be
triggered by increases in local excitatory neural activity. Many laboratories
use a combination of optogenetics and FMRI to verify that the firing of local
excitatory neurons is fully sufficient to trigger the complex signals detected
by FMRI scanners. In addition, pairing of optogenetics and FMRI can map
functional neural circuits with electrodes or drugs. Optogenetics is thereby
helping to validate and advance a wealth of science literature in neuroscience
and psychiatry.
The
impact of optogenetics has already been felt directly on some questions of
human disease. In animals, we have employed optogenetics on a kind of neuron
(hypocretin cells) deep in a part of the brain previously implicated in the
sleep disorder narcolepsy. Specific types of electrical activity in those
neurons, we have found, set off awakening. Finding a way to induce that neural
activity clinically might therefore offer a treatment someday, but most
important is the scientific insight that specific kinds of activity in specific
cells can produce complex behaviors.
Optogenetics is also helping to
determine how to dopamine making neurons may give rise to feelings of reward
and pleasure. The optogenetic approach has also improved our understanding of
Parkinson’s, which involves a disturbance of information processing in certain
motor control circuits of the brain. Since 1990’s some Parkinson’s patients
have received a measure of relief from therapy called Deep-Brain stimulation,
in which an implanted device similar to a pacemaker applies carefully timed
oscillating electric stimuli to certain areas far inside the brain, such as the
substance nucleus.
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