What is the problem with scaling from single neurons to neural systems?
It’s not viable to upscale patching
What is multichannel electrophysiology?
The upscaling of extracellular recording methods from across neural populations and circuits synchronously
What are the elements of multichannel electrophysiology set up?
Electrodes
Data acquisition
Data analysis
Targeting brain region of interest
Choosing an electrode
What type of electrode is used for multichannel electrophysiology?
Multielectrode arrays
Features of in vitro multi electrode arrays:
Titanium nitride electrodes
High electrical conductivity, corrosion resistance, durability
Can have 3D electrodes that allow penetration in tissue with fine tip
Diameter of in vitro electrode arrays (MEA)
10-50 um
How many channels can be in TiN electrodes (in vitro MEA)
Over 256 channels
What are CMOS multielectrode array?
Complementary metal oxide semiconductor chip
Has very high spatial and temporal resolution
Can track spikes as they travel down an axon
What are 2 types of in vitro multi electrode arrays? MEAs
Titanium nitride electrodes
CMOS multi electrode array
What are the types of in vivo multichannel extracellular recordings?
Utah array
Penetrating electrodes
Neuropixel probes
What are the properties of penetrating electrdoes?
Made of silicon a semiconductor (photolithography)
Electrode tips coated with biocompatible conductive metals like platinum to improve electrical properties and corrosion resistance
What is photolithography?
Enables precise and dense packing of many recording sites
How is data acquired? (Data acquisition process)
Amplification
A headstage integrates amplifiers close to the electrodes to provide a low noise amplification
Why do we need amplification in data acquisition?
To increase voltages from biological signals to a level that can be displayed recorded and analysed
Why is a headstage close to the electrode?
To reduce noise and interference
How is the neuropixel probe amplified?
= CMOS digital probe
Voltage signals filtered amplified multiplexed and digitised on chip which allows direct streaming of digital data from the probe
How do we get dynamic control of recording features?
Filtering
Gain
Detection threshold
What is the process of filtering?
- Removing noise
- Collecting only the data of interest (eg high frequency events if interested in the spikes)
What is the purpose of gain in the dynamic control of recording?
Can adjust the gain
Brings signal within the range of detecting
Use the dynamic range of amplifier
What is the purpose of detection threshold in the dynamic control of recording?
Detecting spikes above a background level of noise
