Identification of a self-paced hitting task in freely moving rats based on adaptive spike detection from multi-unit M1 cortical signals

Abstract

Invasive brain–computer interfaces (BCIs) may prove to be a useful rehabilitation tool for severely disabled patients. Although some systems have shown to work well in restricted laboratory settings, their usefulness must be tested in less controlled environments. Our objective was to investigate if a specific motor task could reliably be detected from multi-unit intra-cortical signals from freely moving animals. Four rats were trained to hit a retractable paddle (defined as a “hit”). Intra-cortical signals were obtained from electrodes placed in the primary motor cortex. First, the signal-to-noise ratio was increased by wavelet denoising. Action potentials were then detected using an adaptive threshold, counted in three consecutive time intervals and were used as features to classify either a “hit” or a “no-hit” (defined as an interval between two “hits”). We found that a “hit” could be detected with an accuracy of 75 ± 6% when wavelet denoising was applied whereas the accuracy dropped to 62 ± 5% without prior denoising. We compared our approach with the common daily practice in BCI that consists of using a fixed, manually selected threshold for spike detection without denoising. The results showed the feasibility of detecting a motor task in a less restricted environment than commonly applied within invasive BCI research.

Is the Internet gaming‐addicted brain close to be in a pathological state?

“…The core behavior criterion of IGA is loss of control of Internet use and is represented as persistence in Internet gaming use despite awareness that it is directly harmful to psychosocial functioning (Hammad et al . ).…”

Simulation of a Real-Time Brain Computer Interface for Detecting a Self-Paced Hitting Task

“…Therefore, it is important to remove as much noise as possible. In earlier work performed by our group, we found that if wavelet filtering first performed denoising, the movement or event detection accuracy was enhanced .…”

“…We refer to our previous work for a detailed description of the behavioral training and implant procedures, and only a summary of the procedures is presented here. Standard psychophysical behavioral techniques were used to train the rats to depress a retractable paddle three consecutive times (to avoid random events) with their preferred forepaw in return for a food reward.…”

“…In step one, the signal‐to‐noise ratio of the data was first improved by denoising using wavelet filtering. In our previous work , we analyzed the denoising effects of ten different mother wavelets and ten different wavelet‐denoising thresholds with a similar experimental paradigm as in the present work. The results showed a positive impact of wavelet denoising for improving the classification accuracy based on one feature (firing rate); however, different combinations of mother wavelet and wavelet threshold produced variable results, and these combinations therefore needed to be included in the investigation.…”

A Long-Term BCI Study With ECoG Recordings in Freely Moving Rats

“…Recent BCI publications on rats have shown studies of a similar binary task (push a lever to obtain a reward) but using corticospinal tract activity (38) or with detection from multi-unit intra cortical signals (23). The Hammad team (23), using a 4 3 4 intracortical tungsten micro-wire electrode array, found a good detection of the motor task with an accuracy of 75 6 6% when wavelet denoising was applied (n 5 4, t 5 4 weeks), thus illustrating the feasibility of a brain computer interface for generation of command signals in paralyzed individuals.…”