From spikes to EEG: Integrated multichannel and selective acquisition of neuropotentials

Abstract

Abstract-Electrical signals recorded from the brain cover a wide range of amplitudes, frequencies, and spatial scales, from spikes and local field potentials (LFP) inside the brain to electrocorticograms (ECoG) and electroencepalograms (EEG) outside. Each of these signal modalities represent different aspects of neural dynamics that can be combined to infer brain state and function in a broader context. We present a 16-channel interface circuit fabricated in a 0.5 µm CMOS process for the selective acquisition and digitization of any of the modalities. Each channel features a fixed gain bandpass amplifier with a tunable frequency response which allows isolation of the signal of interest without hardware modification and a programmable gain/resolution analog to digital converter (ADC). The bandpass amplifier analog front end has an input referred noise of 1.94 µVrms for a bandwidth of 8.2 kHz while drawing 12.2 µA of current from a 3.3 V supply. Experimental recordings with the system show spike signals in rat somatosensory cortex as well as alpha EEG activity in a human subject.

Studying of Electroencephalographic Signal Changes Induced by Odor Exposure

“…However the acquiesced signal always presents distortion components -harmonic distortion. Although, researchers are trying to develop systems capable of amplifying and reduce harmonics in EEG signals [27], power consumption of devices bring issues according to the distortion caused by the power supply [28].…”

An extended-range incremental CT ∑Δ ADC with optimized digital filter

“…Today analog-to-digital converters (ADCs) are increasingly being integrated into time-multiplexed low-power highresolution biosensor applications, such as wearable and implantable biomedical systems [1][2][3]. While the required bandwidth is generally relaxed, the required resolution is, on the other hand, more stringent and varies from 12 to 16 bits, depending on each specific application.…”

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“…Depending on the application, different signal amplitudes and frequency bands have to be taken into consideration for signal processing and signal evaluation [1]. In recent studies, an increased use of electrocorticographical (ECoG) recordings is observed.…”