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Lab 6 loss of function techniques slides(1)

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This document discusses various techniques for assessing brain function beyond electrophysiology and functional imaging alone. It describes methods for both reversible and permanent manipulations of neural tissue, including transcranial direct current stimulation, transcranial magnetic stimulation, cortical electrical stimulation, pharmacological agents, transient cooling, optogenetics, as well as existing lesions, electrolytic lesions, ibotenic acid lesions, and focal ischemia. The document emphasizes that while electrophysiology and functional imaging can provide correlational information and point researchers in the right direction, loss of function techniques are also needed to fully understand brain function. It also notes some of the advantages and disadvantages of each method.

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Loss of Function Techniques Or “Why electrophysiology needs a buddy.”
Questions You’ll Have Answered By The End of Lab… ? What’s wrong with just doing electrophysiology/functional imaging? ? How have psychedelic mushrooms contributed to our understanding of the brain? ? What in the world does Adam do when he’s not teaching?
Inferring the function of an area Murata et al., 1996
The Problem with Electrophysiology/Functional Imaging ? Correlative ? Still valuable information ? Can point you in the right direction ? Not the whole story Xkcd.com
Necessity and Sufficiency ? Necessity ? Sufficiency locallocksmiths.com atomictoasters.com
Outline ? Permanent Manipulations – Existing Lesions – Aspirated/Electrolytic Lesions – Ibotenic Acid – Focal Ischemia ? Reversible Manipulations – tDCS – TMS – Cortical Electrical Stimulation – Pharmacological Agents – Transient Cooling – Optogenetics
Existing Lesions ? Cortical Injury – Stroke – Head Trauma ? Confirm with Functional Imaging ? Phineas Gage – PFC ? Advantages and Disadvantages Boston.com and Science Photo Library
Aspiration/Electrolytic Lesions ? Aspiration – Literally remove with small suction device – Surface Areas ? Electrolytic – Destroy with electrical current – Areas at Depth ? Classic Technique ? What vs. Where ? Advantages and Disadvantages Padberg et al., 2010
Ibotenic Acid ? Derived from Amanita muscaria mushroom. ? Non-psychoactive component ? Neurotoxin – Excitotoxic Cell Death ? Destroys only cell bodies ? Advantages and Disadvantages Wikipedia.com
Focal Ischemic Infarct ? Cut off blood supply ? Blood Vessel Ligation ? Electrocoagulation ? Similar to actual ischemic events – Stroke – Compressed blood vessels – Sickle Cell Anemia – Etc. ? Advantages and Disadvantages Nudo et al., 1996
The Problem with Lesions
Reversible Methods
Non-Invasive Methods
Transcranial Direct Current Stimulation (tDCS) ? Apply continuous DC energy through skin/scalp into cortex ? Anode ? Cathode – Current Flow – Excitation/Inhibition ? Exceptions ? Mechanism of Action – Not completely understood ? Advantages and Disadvantages George and Aston-Jones, 2010
Transcranial Magnetic Stimulation (TMS) ? Magnetic Induction – Apply coil – Pulse magnetic wave – Current induced – Single Pulse ? Depolarize – rTMS ? Advantages and Disadvantages George and Aston-Jones, 2010
Invasive Methods
Cortical Electrical Stimulation ? Lower Electrode into Brain ? Low intensity, brief current – Activation/priming ? Continuous Pulses – Deactivation – Constantly Refractory ? Deep Brain Stimulation ? Advantages and Disadvantages nimh.nih.gov
Pharmacological Agents ? Muscimol – Amanita muscaria – Main psychoactive compound – GABA agonist ? Systemic Administration ? Central Administration ? Advantages and Disadvantages Wikipedia.com
Gallese et al., 1994
Transient Cooling ? Cool neural tissue to 20 degrees Celsius – Disrupt or abolish activity ? Brain desires homeostasis ? Gyral and Sulcal Implantation ? Advantages and Disadvantages ? This is what Adam does all day. Coomber et al, 2011
Lab 6 loss of function techniques slides(1)
Lab 6 loss of function techniques slides(1)
Padberg, Recanzone, Engle, Cooke, Goldring, and Krubitzer, 2010.
Reversible Deactivation of Area 5L
Optogenetics: The Future ? Microbially-derived Opsins – Control of ion channels via light ? Light sensitivity – Bred in mice – Delivered in viral vector ? Advantages and Disadvantages Web.mit.edu
Your Scenario ? You are a brand new association professor who has just started up their own lab. – Congratulations! ? You want to asses the function of your specific brain area of interest, but wish to go beyond electrophysiology/functional imaging. ? Your university has funds set aside for you to setup your lab, but has no one with whom you can collaborate to perform optogenetics (sad panda). ? Your job: Find a study which recorded from a brain area that you’re interested in and propose a loss of function experiment to test the hypotheses established by the study you read.
What Should be Included? ? Length – No more than 1 page, single spaced, AT THE MOST! ? Summary of recording study – Where did they record from/how did they record – What did they find – What was their model organism ? Methods – Loss of function method appropriate for your organism/question – Use the same stimuli/behavioral task as the recording study. If purely perceptual, add a simple component that would assess perception of a stimulus (i.e. a button press or some such thing) ? Specific Predictions – Hypotheses based on electrophysiology/functional imaging ? Limitations and Potential Complications – How would you address these?
Details ? Due Date: – Monday, 3/2/15 – BEGINNING OF CLASS (AKA 10:00 a.m. SHARP!) ? Even 1 minute late will incur a penalty – Email or Hard Copy ? All technology-related excuses will be thoroughly scrutinized for bovine excrement. – If you don’t get an confirmation email from me, I didn’t receive it! ? 1 page, at the most! – Could easily complete this assignment in less if all elements are included
OMG!!! A RESEARCH ASSIGNMENT!?!? WHERE DO I BEGIN??? ? Web of Science – Meet your new best friend ? Lib.ucdavis.edu – Electronic Databases A-Z ? Go to “W” ? Select “Web of Science” vpn ? Demo to follow ? You may ask me any questions and I will be totally willing to help both in lab today and via email.

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Lab 6 loss of function techniques slides(1)

  • 1. Loss of Function Techniques Or “Why electrophysiology needs a buddy.”
  • 2. Questions You’ll Have Answered By The End of Lab… ? What’s wrong with just doing electrophysiology/functional imaging? ? How have psychedelic mushrooms contributed to our understanding of the brain? ? What in the world does Adam do when he’s not teaching?
  • 3. Inferring the function of an area Murata et al., 1996
  • 4. The Problem with Electrophysiology/Functional Imaging ? Correlative ? Still valuable information ? Can point you in the right direction ? Not the whole story Xkcd.com
  • 5. Necessity and Sufficiency ? Necessity ? Sufficiency locallocksmiths.com atomictoasters.com
  • 6. Outline ? Permanent Manipulations – Existing Lesions – Aspirated/Electrolytic Lesions – Ibotenic Acid – Focal Ischemia ? Reversible Manipulations – tDCS – TMS – Cortical Electrical Stimulation – Pharmacological Agents – Transient Cooling – Optogenetics
  • 7. Existing Lesions ? Cortical Injury – Stroke – Head Trauma ? Confirm with Functional Imaging ? Phineas Gage – PFC ? Advantages and Disadvantages Boston.com and Science Photo Library
  • 8. Aspiration/Electrolytic Lesions ? Aspiration – Literally remove with small suction device – Surface Areas ? Electrolytic – Destroy with electrical current – Areas at Depth ? Classic Technique ? What vs. Where ? Advantages and Disadvantages Padberg et al., 2010
  • 9. Ibotenic Acid ? Derived from Amanita muscaria mushroom. ? Non-psychoactive component ? Neurotoxin – Excitotoxic Cell Death ? Destroys only cell bodies ? Advantages and Disadvantages Wikipedia.com
  • 10. Focal Ischemic Infarct ? Cut off blood supply ? Blood Vessel Ligation ? Electrocoagulation ? Similar to actual ischemic events – Stroke – Compressed blood vessels – Sickle Cell Anemia – Etc. ? Advantages and Disadvantages Nudo et al., 1996
  • 11. The Problem with Lesions
  • 14. Transcranial Direct Current Stimulation (tDCS) ? Apply continuous DC energy through skin/scalp into cortex ? Anode ? Cathode – Current Flow – Excitation/Inhibition ? Exceptions ? Mechanism of Action – Not completely understood ? Advantages and Disadvantages George and Aston-Jones, 2010
  • 15. Transcranial Magnetic Stimulation (TMS) ? Magnetic Induction – Apply coil – Pulse magnetic wave – Current induced – Single Pulse ? Depolarize – rTMS ? Advantages and Disadvantages George and Aston-Jones, 2010
  • 17. Cortical Electrical Stimulation ? Lower Electrode into Brain ? Low intensity, brief current – Activation/priming ? Continuous Pulses – Deactivation – Constantly Refractory ? Deep Brain Stimulation ? Advantages and Disadvantages nimh.nih.gov
  • 18. Pharmacological Agents ? Muscimol – Amanita muscaria – Main psychoactive compound – GABA agonist ? Systemic Administration ? Central Administration ? Advantages and Disadvantages Wikipedia.com
  • 20. Transient Cooling ? Cool neural tissue to 20 degrees Celsius – Disrupt or abolish activity ? Brain desires homeostasis ? Gyral and Sulcal Implantation ? Advantages and Disadvantages ? This is what Adam does all day. Coomber et al, 2011
  • 23. Padberg, Recanzone, Engle, Cooke, Goldring, and Krubitzer, 2010.
  • 25. Optogenetics: The Future ? Microbially-derived Opsins – Control of ion channels via light ? Light sensitivity – Bred in mice – Delivered in viral vector ? Advantages and Disadvantages Web.mit.edu
  • 26. Your Scenario ? You are a brand new association professor who has just started up their own lab. – Congratulations! ? You want to asses the function of your specific brain area of interest, but wish to go beyond electrophysiology/functional imaging. ? Your university has funds set aside for you to setup your lab, but has no one with whom you can collaborate to perform optogenetics (sad panda). ? Your job: Find a study which recorded from a brain area that you’re interested in and propose a loss of function experiment to test the hypotheses established by the study you read.
  • 27. What Should be Included? ? Length – No more than 1 page, single spaced, AT THE MOST! ? Summary of recording study – Where did they record from/how did they record – What did they find – What was their model organism ? Methods – Loss of function method appropriate for your organism/question – Use the same stimuli/behavioral task as the recording study. If purely perceptual, add a simple component that would assess perception of a stimulus (i.e. a button press or some such thing) ? Specific Predictions – Hypotheses based on electrophysiology/functional imaging ? Limitations and Potential Complications – How would you address these?
  • 28. Details ? Due Date: – Monday, 3/2/15 – BEGINNING OF CLASS (AKA 10:00 a.m. SHARP!) ? Even 1 minute late will incur a penalty – Email or Hard Copy ? All technology-related excuses will be thoroughly scrutinized for bovine excrement. – If you don’t get an confirmation email from me, I didn’t receive it! ? 1 page, at the most! – Could easily complete this assignment in less if all elements are included
  • 29. OMG!!! A RESEARCH ASSIGNMENT!?!? WHERE DO I BEGIN??? ? Web of Science – Meet your new best friend ? Lib.ucdavis.edu – Electronic Databases A-Z ? Go to “W” ? Select “Web of Science” vpn ? Demo to follow ? You may ask me any questions and I will be totally willing to help both in lab today and via email.