Electroencephalography is the neurophysiological measurement of electrical activity in the brain as recorded by electrodes placed on the scalp. The resulting traces are known as an electroencephalogram (EEG) and represent a summation of post-synaptic potentials from a large number of neurons.

This blog is the continuation of our latest on electrode caps

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Characteristics

EEG is non-invasive for the research subject. Furthermore, the need to restrict the subject‘s movements is clearly lower than in other fields of neuroscience such as functional magnetic resonance imaging (fMRI). A further benefit is that many EEG applications record spontaneous brain activity, which means that the subject does not need to be able to cooperate with the researcher. Also, EEGs have a high temporal resolution compared with techniques such as fMRI and PET and are capable of detecting changes in electrical activity in the brain on a time scale in the millisecond region.

Application method and electrode-cap connections

In conventional scalp EEG, the recording is obtained by applying electrodes to the scalp using a conductive gel or paste, usually after preparing the scalp area by light abrasion to reduce electrode-scalp impedance. Many systems typically use electrodes which are each attached to an individual wire. Some systems use caps in which electrodes are embedded. This latter method is particularly common when high-density arrays of electrodes are required.

Noise and artifacts

In addition to internal artifacts such as those produced by blinking, there are many artifacts which originate from outside the patient. Movement by the patient generates huge artifacts. Sweating or changes in temperature may cause electrode drifts. Spikes can originate from a momentary change in impedance at a given electrode. Brain Products EEG amplifiers are equipped with a number of noise reduction techniques such as active noise cancellation and active electrodes. High common mode rejection as well as low amplifier noise ensure maximum data quality.

LiveAmp 8 / 16 / 32

The LiveAmp is a wearable, 24-bit amplifier - available with 8, 16, 32 and also with 64 channels. As it is wireless and allows you to store your recorded data internally (i.e. on an exchangeable memory card), there are no mobility limitations.

• Flexible and expandable

• Integrated accelerometer

• Electrode options: passive - active - active dry - solid gel

EEG-Mobile LiveAmp16_actiCAP-snap

LiveAmp 64

• Records 64 unipolar channels or (when used with passive electrodes) 56 unipolar and 8 bipolar channels
• Integrated accelerometer
• Electrode options: passive - active - active dry - sponge - solid gel

LiveAmp64_actiCAP-snap

ActiCHamp PLUS

• 24-bit battery-supplied,
• Active channel amplifier coming along with actiCAP active electrodes
• Available with 32, 64, 96, 128 and 160 EEG channels
• 8 integrated auxiliary inputs can be used with a full range of biosignal sensors (e.g. GSR, EOG, EMG, ECG, respiration, acceleration, temperature, blood pulse, photo sensor, microphone, etc.)
• extremely high sampling rate (up to 100 KHz) and wide hardware bandwidth
• compatible with BrainVision PyCorder (open-source) and BrainVision Recorder (commercial license) for signal recordings.

actiCHamp-Plus_R-Net

BrainAmp DC

EEG-ERP BrainAmpExG-PowerPack-AUX

BrainAmp MR plus

The standard in combined EEG & fMRI recordings

• It's a shielded amplifier which can be taken directly inside the MRI chamber and placed in the bore right behind the subject’s head.
• It can be used for simultaneous EEG/fMRI acquisitions as well as for EEG/TMS co-registrations, EEG/ERP studies and Brain Computer Interface applications.
• The sturdy and compact amplifier is powered by the rechargeable PowerPack battery.
• Multiple amplifiers can be combined and stacked on top of each other in order to increase the maximum number of available channels to 128 for recordings in the MRI environment and up to 256 channels for laboratory applications.
• BrainAmp MR plus can be combined with the BrainAmp ExG MR to add the capability to record bipolar and peripheral signals (e.g. EOG, ECG, EMG, GSR - Galvanic Skin Response, etc.) in an extremely compact setup.
  
  

BrainAmpMR-EMG