Multielectrode Array

Membrane Biophysics

9 November 2007

John Corthell and Kristal Tucker

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

Roadmap

• History

• Applications

• Techniques

• Representative articles

Brain-Computer Interface

Scott 2006.

Chronic in vivo recordings

Musallam et al 2007

Electrode fabrication

Musallam et al 2007

Array insertion

Musallam et al 2007

Data capture and analysis

Musallam et al 2007

Variable depth arrays

Sato et. al. 2007

Hochberg et al 2006

Hochberg et al 2006

Hochberg et al 2006

Hochberg et al 2006

Hochberg et al 2006

Hochberg et al 2006

Hochberg et al 2006

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

• Linear electrode array recording

Multielectrode array recording

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

Organotypic Slice Culture• 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

Duport et al., 1999

Organotypic Slice Cultures, cont.

• Slice cultures preserve 3-dimensional area for electrode preparation

• Simple to prepare-remove brain (no more than 60s), place into cold solvent, cut into 425m thick slices, place onto MEA with media

Spinal cord prep, from Bio-Rad website

Fabrication

• Commercially available, so you don’t have to make one yourself

• TiN=titanium nitride

Fabrication-MED• MED is newer than MEA-MED is a planar

multielectrode array• MED is an attempt to lengthen recording time from

previous MEAs

MEA/MED Usage

• 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

Views of MEA chamber and amplifier plate

-PP-probe pin

-SC-stimulus connector

-RA-recording area

MEA + other techniques

• 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

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

Granados-Fuentes et al., “Olfactory bulb neurons express functional, entrainable

circadian rhythms.” European J. Neuroscience, 19: 898-906, 2004.

MEA and setup• Per1 transgenic rats (yes,

rats) underwent bulbectomy from E15-P37, cells were dispersed onto MEAs

• MEAs had 60 electrodes, spaced 200m apart, with 10m 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

• Recording apparatus from inside the incubator

neuro.gatech.edu/groups/ potter/realtimedac.html

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

Results

• Per1 expression in OB– Start showing rhythm

at E19

• 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

• Left axis is Firing Frequency

• Different cells in the same culture can have different firing rhythms

• Top-Mitral

• Bottom-Granule

• Removal of OB has no effect on running wheel behavior

• Temperature changes work as zeitgebers (entraining signals) for OB culture cells

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

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