1. Recording of electrical activity / electrical stimulation of brain tissue Spike trains Spikes

2. Quiroga, Mukamel, Isham, Malach & Fried. PNAS 2008 Spiking activity in hippocampus and visual awareness

4. Positron emission tomography (PET) – Enables tracking metabolic processes in various brain regions Involves injection of a radio-active tracer Enables scanning in multiple planes

5. 1.Seeing words 2.Listening to words 3.Saying words 4.Generating verbs PET-Positron Emission tomography 1 2 34 Radioactive tracers – 2-deoxy-glucose (2DG) or Oxygen (in water)

6. Functional Magnetic Resonance Imaging

7. What does the fMRI signal measure? Hemoglobin has two states: Oxygenated (diamagnetic), and De-Oxygenated (paramagnetic) The BOLD fMRI signal is sensitive to the ratio between Oxy and De- oxy hemoglobin in a manner that an increase in Oxygenated blood results in an increase in the fMRI signal.

8. Following neural activation: Consumption of oxygen Overcompensation with fresh oxygenated blood fMRI signal

9. Time scale of fMRI signal (low temporal resolution) fMRI allows detection of active regions during various functional tasks

10. VISUAL STIMULUS 1.5 T GE Scanner Coil Brain-Voyager Software Epson LCD Projector Experimental Setup

11. Generating a 3-D Model of the brain

13. Right eyeLeft eyePerception Tong et al. 1998 Using fMRI to correlate brain responses and perception/behavior

14. Advantages of fMRI over PET Higher temporal resolution (seconds vs min) No radioactive radiation cheaper

15. Optical imaging Intrinsic optical imaging: Oxy/deoxy hemoglobin have different properties regarding light absorbance Voltage sensitive dyes Temporal resolution: ms Spatial resolution: ~50 µm

16. ElectroEncephaloGram (EEG) Non invasive User friendly High temporal resolution Low spatial resolution

17. 04-24 EEG - ElectroEncephaloGraphy Amplitude Frequency awake time voltage

18. Nir & Tononi 2010

19. EEG global electrical activity – ERP: Event-Related Potentials:

20. 04-25 W. W. Norton High temporal resolution Event-Related Potentials

21. Faces N170

22. 04-27b W. W. Norton

23. EEG/ERP WHEN does the brain do it? – Temporal resolution: HIGH WHERE does the brain do it? – Spatial resolution: LOW

24. MEG Temporal resolution: ms Spatial resolution: few mm

25. Techniques & Resolutions Resolutions of functional techniques

26. Stimulation 1.Electrical 2.Chemical 3.Magnetic 4.Optical

27. Electrical stimulation (functional mapping) Depth electrodes Intracranial EEG (iEEG) Spikes Electro-corticogram (ECoG) Both electrode types can be used for either recording or stimulating

28. Chronic stimulation (Parkinson’s) http://www.youtube.com/watch?v=FD8ckoy9NVU&feature=related Mapping of speech area in a human patient

29. Chemical stimulation/blocking (kianic acid / muscimol)

30. Transcranial Magnetic Stimulation (TMS) Single pulse – excitatory (MEP in motor cortex, Phosphenes in visual cortex) rTMS (repetitive TMS) – mostly inhibitory

31. Optogenetics http://www.nature.com/nmeth/video/moy2010/index.html 1.Light sensitive channels (from algae or bacteria) 2.Introduce the engineered gene into a carrier virus 3.Inject the virus to the brain 4.Use light to switch the channels/cells on or off