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Optogenetic deconstruction and online
control of corticothalamic circuits
December 9th 2013
Jeanne T. Paz, PhD
Stanford University School of Medicine
American Epilepsy Society | Annual Meeting
Funding:
• K99/R00 award NIH/NINDS
• CURE Challenge Award
No Disclosure
No Commercial
Interest
American Epilepsy Society | 2013 Annual Meeting
Learning Objectives
1. Understand the mechanisms underlying seizure expression in corticothalamic circuits
2. Understand how optogenetic approaches can be used to control seizures
American Epilepsy Society | 2013 Annual Meeting
Benchmarks
Benchmarks Area II: Develop new therapeutic strategies and optimize current approaches to cure epilepsy.
A. Identify basic mechanisms of ictogenesis (seizure generation)
that will lead to the development of cures.
1. Define underlying mechanisms of initiation, propagation and
cessation of seizures in the epileptic brain as targets for treatment
(electrical, biochemical, cellular, molecular, physiological).
B. Optimize existing therapies and develop new therapies and
technologies for curing epilepsy.
2. Develop new approaches (e.g., gene therapy, brain stimulation,
cellular therapy, pharmacotherapy) for targeted therapies.
American Epilepsy Society | 2013 Annual Meeting
http://www.ninds.nih.gov/research/epilepsyweb/2007_benchmarks.htm#benchmarks
1. Introduction
a. Thalamocortical circuits and oscillations
b. What cellular and circuit mechanisms underlie oscillations?
2. Results: track and target the circuits that underlie seizures
a. The focus is out of focus: thalamus is required for seizures after cortical injury
b. Optogenetics as a strategy to dissect circuits in disease
c. Closed-loop strategy: interrogate causality of a cell type in epilepsy
3. Conclusions. Benchmarks.
4. Future Directions: towards innovative approaches for Epilepsy Research
Overview
The thalamocortical system
Widespread efferent
and afferent connections
Functions:
Sensation
Perception
Consciousness
Rhythm generation
Drawing from Dr. Wolfgang Klimesch
Thalamocortical circuits: rhythm generators
Modified from Beenhakker and Huguenard., Neuron, 2009
EEG recordings from the same patient: courtesy of Dr. Graber, Stanford
Spindles and spike-and-wave discharges in a feline model of
penicillin-induced generalized epilepsy
Kostopolous, et al., Exp. Neurol, 1981
1. Introduction
a. Thalamocortical circuits and oscillations
b. What cellular and circuit mechanisms underlie oscillations?
2. Results: track and target the circuits that underlie seizures
a. The focus is out of focus: thalamus is required for seizures after cortical injury
b. Optogenetics as a strategy to dissect circuits in disease
c. Closed-loop strategy: interrogate causality of a cell type in epilepsy
3. Conclusions. Benchmarks.
4. Future Directions: towards innovative approaches for Epilepsy Research
Overview
Cellular and network basis of the rhythm generator
1. Introduction
a. Thalamocortical circuits and oscillations
b. What cellular and circuit mechanisms underlie oscillations?
2. Results: track and target the circuits that underlie seizures
a. The focus is out of focus: thalamus is required for seizures after cortical injury
b. Optogenetics as a strategy to dissect circuits in disease
c. Closed-loop strategy: interrogate causality of a cell type in epilepsy
3. Conclusions. Benchmarks.
4. Future Directions: towards innovative approaches for Epilepsy Research
Overview
Rat photothrombosis model of stroke
Paz et al., Journal of Neuroscience, 2010
• Dye, when activated with light,
releases oxygen singlets, leading to
thrombosis
• Infarct location/volume are highly
reproducible
561nm 2 mm
Kelly et al., 2001
Watson et al., 1985
Isolated thalamus generates epileptiform oscillations
Paz et al., Nature Neuroscience, 2012
Brain slice: microcircuit
Enhanced intrinsic excitability in TC neurons
Paz et al., Nature Neuroscience, 2012
Brain slice: isolated cell
From the cell back to the behavior ?
1. Introduction
a. Thalamocortical circuits and oscillations
b. What cellular and circuit mechanisms underlie oscillations?
2. Results: track and target the circuits that underlie seizures
a. The focus is out of focus: thalamus is required for seizures after cortical injury
b. Optogenetics as a strategy to dissect circuits in disease
c. Closed-loop strategy: interrogate causality of a cell type in epilepsy
3. Conclusions. Benchmarks.
4. Future Directions: towards innovative approaches for Epilepsy Research
Overview
Image from MIT News: McGovern Institute for Brain Research and Sputnik Animation
Optogenetics
Optogenetic tools
Zhang et al., Nat Rev Nsci, 2007
Yizhar et al., Neuron, 2011
Tye & Deisseroth, Nat Rev Nsci, 2012
Optogenetic tools
Designing optogenetic experiments to study brain disease
Zalocusky & Deisseroth, Optogenetics, 2013
Tye & Deisseroth, Nat Rev Nsci, 2012
Optogenetic approach: advantages
Zhang et al., Nat Rev Nsci, 2007
From the cell back to the behavior ?
Stroke
induction
Optogenetic targeting of the hyperexcitable TC neurons in vivo
Paz et al., Nature Neuroscience, 2013
1 week
Viral delivery
in thalamus Camk2a-NpHR3.0
2 weeks
Device implant
Optrod in thalamus
EEG in cortex
>2 weeks
Chronic recordings
+stimulation
Optical inhibition of TC cells interrupts seizures
in behaving animals
Paz et al., Nature Neuroscience, 2013
Cortex
1. Introduction
a. Thalamocortical circuits and oscillations
b. What cellular and circuit mechanisms underlie oscillations?
2. Results: track and target the circuits that underlie seizures
a. The focus is out of focus: thalamus is required for seizures after cortical injury
b. Optogenetics as a strategy to dissect circuits in disease
c. Closed-loop strategy: interrogate causality of a cell type in epilepsy
3. Conclusions. Benchmarks.
4. Future Directions: towards innovative approaches for Epilepsy Research
Overview
Closed-loop optogenetic control of thalamus aborts
seizures at their onset
Paz et al., Nature Neuroscience, 2013
Driving bursts in TC neurons is sufficient to induce
electrographic and behavioral seizures
Unpublished data
1. Introduction
a. Thalamocortical circuits and oscillations
b. What cellular and circuit mechanisms underlie oscillations?
2. Results: track and target the circuits that underlie seizures
a. The focus is out of focus: thalamus is required for seizures after cortical injury
b. Optogenetics as a strategy to dissect circuits in disease
c. Closed-loop strategy: interrogate causality of a cell type in epilepsy
3. Conclusions. Benchmarks.
4. Future Directions: towards innovative approaches for Epilepsy Research
Overview
Summary reducing TC output is sufficient to interrupt seizures
Paz et al., Nature Neuroscience, 2013
Benchamarks
Benchmark Area II, A1 and B2:
Here we identify the thalamus as a potential target for controlling seizures following a cortical injury.
• We showed that thalamus becomes hyperexcitable after stroke
• We delineated the basic mechanisms underlying this hyperexcitability
• We showed that reducing the activity of this hyperexcitable thalamus stops seizures
• We developed an approach to detect seizures in real-time at their onset
• We showed that briefly disrupting thalamic output disrupts seizures at their onset
American Epilepsy Society | 2013 Annual Meeting
http://www.ninds.nih.gov/research/epilepsyweb/2007_benchmarks.htm#benchmarks
Cells / Molecules
4. Future Directions: identifying and targeting cells and circuits in
epilepsy
Microcircuit
4. Future Directions: identifying and targeting cells and circuits in
epilepsy
Intracellular recording
+ neurobiotin
Network
Large scale
4. Future Directions: identifying and targeting cells and circuits in
epilepsy
Optogenetics
4. Future Directions: identifying and targeting cells and circuits in
epilepsy
Behavior: closed-loop
4. Future Directions: identifying and targeting cells and circuits in
epilepsy
Funding:
• NIH/NINDS K99 award
• CURE Challenge Award
• Epilepsy Foundation
Acknowledgements
John
Huguenard
Karl
Deisseroth
Tom
Davidson
Eric
Frechette
Jordan Sorokin
