[ExI] Fwd: [neuro] [FV] Optogenetics + fMRI = circuit reconstruction!

Bryan Bishop kanzure at gmail.com
Fri Jun 18 15:35:02 UTC 2010

Global and local fMRI signals driven by neurons defined
optogenetically by type and wiring

"Despite a rapidly-growing scientific and clinical brain imaging
literature based on functional magnetic resonance imaging (fMRI) using
blood oxygenation level-dependent (BOLD)1 signals, it remains
controversial whether BOLD signals in a particular region can be
caused by activation of local excitatory neurons2. This difficult
question is central to the interpretation and utility of BOLD, with
major significance for fMRI studies in basic research and clinical
applications3. Using a novel integrated technology unifying
optogenetic4, 5, 6, 7, 8, 9, 10, 11, 12, 13 control of inputs with
high-field fMRI signal readouts, we show here that specific
stimulation of local CaMKIIα-expressing excitatory neurons, either in
the neocortex or thalamus, elicits positive BOLD signals at the
stimulus location with classical kinetics. We also show that
optogenetic fMRI (ofMRI) allows visualization of the causal effects of
specific cell types defined not only by genetic identity and cell body
location, but also by axonal projection target. Finally, we show that
ofMRI within the living and intact mammalian brain reveals BOLD
signals in downstream targets distant from the stimulus, indicating
that this approach can be used to map the global effects of
controlling a local cell population. In this respect, unlike both
conventional fMRI studies based on correlations14 and fMRI with
electrical stimulation that will also directly drive afferent and
nearby axons, this ofMRI approach provides causal information about
the global circuits recruited by defined local neuronal activity
patterns. Together these findings provide an empirical foundation for
the widely-used fMRI BOLD signal, and the features of ofMRI define a
potent tool that may be suitable for functional circuit analysis as
well as global phenotyping of dysfunctional circuitry."

---------- Forwarded message ----------
From: Eugen Leitl <eugen at leitl.org>
Date: Fri, Jun 18, 2010 at 8:06 AM
Subject: [neuro] [FV] Optogenetics + fMRI = circuit reconstruction!
To: tt at postbiota.org, info at postbiota.org, neuro at postbiota.org

----- Forwarded message from Peter Passaro <ocsrazor at gmail.com> -----

From: Peter Passaro <ocsrazor at gmail.com>
Date: Fri, 18 Jun 2010 05:41:34 -0700 (PDT)
To: foundation-volunteers <foundation-volunteers at googlegroups.com>
Subject: [FV] Optogenetics + fMRI = circuit reconstruction!
User-Agent: G2/1.0
Reply-To: foundation-volunteers at googlegroups.com

Extremely interesting new paper on using optogenetic stimulation and
fMRI combined to do circuit analysis in rat cortex thalamus. Macro
scale circuit analysis in live animals should now be viable to
complete within just a few years.


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Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org
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- Bryan
1 512 203 0507

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