Multielectrode Array

1. Multielectrode Array Membrane Biophysics 9 November 2007 John Corthell and Kristal Tucker

2. Two broad categories of multielectrode recordings • In vivo - KT • Recording and stimulation • Acute and Chronic • Heart, CNS, PNS and Retina • In vitro - JC • Organotypic and primary dissociated cultures • Heart, CNS, PNS, and retina

3. Roadmap • History • Applications • Techniques • Representative articles

4. Brain-Computer Interface Scott 2006.

5. Chronic in vivo recordings Musallam et al 2007

6. Electrode fabrication Musallam et al 2007

7. Array insertion Musallam et al 2007

8. Data capture and analysis Musallam et al 2007

9. Variable depth arrays Sato et. al. 2007

12. Hochberg et al 2006

13. Hochberg et al 2006

14. Hochberg et al 2006

15. Hochberg et al 2006

16. Hochberg et al 2006

17. Hochberg et al 2006

18. Hochberg et al 2006

19. In vitro multielectrode array history • Gross, in 1979, first developed an array based on semiconductor technology • Regehr et al., 1989-first applied Aplysia, Hirudo (leech) and Helisoma (snail) cells to multielectrode array (MEA) chip for long-term recording • Masuda et al., in 1983, applied a linear electrode array to myoneural junctions

20. Linear electrode array recording

21. Multielectrode array recording

22. In vitro multielectrode applications • Olfactory processing-Christensen et al., 2000 • Long-term recording-Regehr et al., 1989 • Circadian rhythms-Abraham et al., 2005 • Neuromuscular junction activity-Masuda et al., 1983 • Network analysis • Long-term potentiation • Synaptic interaction

23. A different type of cell culture that works with MEAs and preserves some circuitry (but not exactly native-synaptic rearrangement) Ideal for long-term recording, as a culture can last from 3-4 weeks for recording to several months, depending on prep Organotypic Slice Culture Duport et al., 1999

25. Slice cultures preserve 3-dimensional area for electrode preparation Simple to prepare-remove brain (no more than 60s), place into cold solvent, cut into 425m thick slices, place onto MEA with media Spinal cord prep, from Bio-Rad website Organotypic Slice Cultures, cont.

26. Fabrication • Commercially available, so you don’t have to make one yourself • TiN=titanium nitride

27. MED is newer than MEA-MED is a planar multielectrode array MED is an attempt to lengthen recording time from previous MEAs Fabrication-MED

28. Hooked up to amplifier, A/D converter, and computer Typically software programs allow for recording and stimulation near-simultaneously Cells are usually grown in culture dish over the MEA, but can be organotypic Works like most electrophysiology recordings-difference is previous work to set up array and post-experiment work to analyze data MEA/MED Usage

29. Views of MEA chamber and amplifier plate -PP-probe pin -SC-stimulus connector -RA-recording area

30. MEA is often used in conjunction with other techniques, such as Ca imaging MEA measures extracellular changes (as you cannot patch), so some things (like post-synaptic potentials and Ca flux) are missed Optical recording techniques (identifying individual cells) are used with MEA to alleviate this MEA + other techniques

31. Other shortcomings • MEA biochips are expensive to manufacture (may change with time), so researchers will clean the chip to attempt to salvage the product for future use ($250-$350) • Continued cleaning will result in degradation of chip until readings are no longer reliable

32. Granados-Fuentes et al., “Olfactory bulb neurons express functional, entrainable circadian rhythms.” European J. Neuroscience, 19: 898-906, 2004.

33. Per1 transgenic rats (yes, rats) underwent bulbectomy from E15-P37, cells were dispersed onto MEAs MEAs had 60 electrodes, spaced 200m apart, with 10m tips (purchased from Germany) SCN explants used as controls (P1-P7) Cultures were covered with a membrane and transferred to a recording incubator Recorded from 4 cultures for at least 5 days simultaneously Used to establish spontaneous activity MEA and setup

34. Recording apparatus from inside the incubator neuro.gatech.edu/groups/ potter/realtimedac.html

35. Other techniques used • Locomotor activity measured in normal vs. bulbectomized rats • Per1 activity measured by bioluminescence (Per1 gene is linked to luciferase gene [light from fireflies], add luciferin, and protein product will light up) from a photomultiplier tube • Temperature entrainment via incubator

36. Per1 expression in OB Start showing rhythm at E19 Results

37. Top-firing of OB neuron Bottom-firing of SCN control OB neurons that fired rhythmically were found in the mitral cell layer but not the granule cell layer

38. Left axis is Firing Frequency • Different cells in the same culture can have different firing rhythms

39. Top-Mitral Bottom-Granule

40. Removal of OB has no effect on running wheel behavior Temperature changes work as zeitgebers (entraining signals) for OB culture cells

41. Conclusions from paper • There is a rhythm of activity and Per1 expression in the olfactory bulb neurons of the mitral cell layer • This rhythm begins at E19 and matures over the first week postnatal • These oscillating neurons can have different rhythms from one another in the same culture

42. Conclusions from in vitro MEA • Most modern MEA is the MED-the planar MEA biochip • Grow cells on biochip or use organotypic culture to study • Can be used to simultaneously record and stimulate extracellularly • Must be cared for-expensive • Should be used with other techniques to compensate for shortcomings