Discover how adding full head, high density (HD) EEG will benefit your research, and explore the latest developments in non-invasive neuroimaging.

Be sure to watch the Fundamentals of HD-EEG video featuring Trey Avery, PhD and Gaynor Foster, PhD, as they share the methodology and physics of EEG electroencephalography for researchers and clinicians.

Here are key highlights from this video:

Trey Avery, PhD, says, “We know that the brain uses both electrical and chemical communication to function during an eeg we are focused on measuring the electrical activity associated with the brain's function. Specifically we are measuring voltage that is the difference in the electrical potentials that are recorded between two places. That is why you may sometimes hear eeg recordings being described as differential recordings. The beauty of EEG is that these voltages are being recorded in real time. So we can build up a millisecond by millisecond picture of the time course of electrical activity.”

When conducting high density electroencephalography (HD-EEG), Trey Avery PhD says, “While the time course is important in EEG, knowing when something happens is only part of the picture. By measuring electrical potentials across the whole scalp, we are able to get the data required to build up a picture of the positive and negative charges within that electrical field.”

He added this about high-density EEG research (also known as dense array EEG or high impedance EEG), “When you can see both the positive and negative (ends of an electrical signal), we have (a better characterization of) a dipole. Here's our key by having the best representation of the dipoles. We can learn to make interpretations on where in the brain the electrical activity happened in the first place. There are a number of ways in which we can then try and make sense of these electrical potentials and link them to both sensory and cognitive processes as we are looking at changes in voltages over time. The most straightforward way to understand these waveforms is to quantify the oscillations that we are seeing. We can count the number of times that we see the waveforms complete a cycle, so that is moving from baseline to the positive peak back through the baseline to its negative peak and returning to the baseline once again how many times that happens within a second. The number of cycles within a second is described as its frequency and we measure this in hertz.”

 

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