Multielectrode Array

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Multielectrode Array

• Membrane Biophysics
• 9 November 2007
• John Corthell and Kristal Tucker

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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

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Roadmap

• History
• Applications
• Techniques
• Representative articles

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Brain-Computer Interface
Scott 2006.
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Chronic in vivo recordings
Musallam et al 2007
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Electrode fabrication
Musallam et al 2007
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Array insertion
Musallam et al 2007
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Data capture and analysis
Musallam et al 2007
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Variable depth arrays
Sato et. al. 2007
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Hochberg et al 2006
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Hochberg et al 2006
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Hochberg et al 2006
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Hochberg et al 2006
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Hochberg et al 2006
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Hochberg et al 2006
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Hochberg et al 2006
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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

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• Linear electrode array recording

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Multielectrode array recording
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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

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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
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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 425?m
  thick slices, place onto MEA with media

• Spinal cord prep, from Bio-Rad website

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Fabrication

• Commercially available, so you dont have to make
  one yourself
• TiNtitanium nitride

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Fabrication-MED

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

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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

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

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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

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

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MEA and setup

• 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

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• Recording apparatus from inside the incubator

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

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Results

• Per1 expression in OB
• Start showing rhythm at E19

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• 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

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

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• Top-Mitral
• Bottom-Granule

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

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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

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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