Congratulations, Dr. Ying Li!

Ying Li Thesis Defense
Left to right: Yi-Wen Meng, Luyao Chen, Dr. Ying Li, Professor Wen-tai Liu, Yushan Wang, Nicole Chow, Ma Li, Jia-Heng Chang and Stanislav Culaclii from UCLA Biomimetic Research Lab

Congratulations to Dr. Ying Li for a wonderful and successful thesis defense!

Stimulation Artifact Cancellation

2016-07-01_15_04_54_02sec-pageLive Stimulation Artifact Cancellation

 

Recovering neural responses from electrode recordings is fundamental for understanding the dynamics of neural networks. This effort is often obscured by stimulus artifacts in the recordings, which result from stimuli injected into the electrode-tissue interface. Stimulus artifacts, which can be orders of magnitude larger than the neural responses of interest, can mask short-latency evoked responses. Furthermore, simultaneous neural stimulation and recording on the same electrode generates artifacts with larger amplitudes compared to a separate electrode setup, which inevitably overwhelm the amplifier operation and cause unrecoverable neural signal loss. This paper proposes an end-to-end system combining hardware and software techniques for actively cancelling stimulus artifacts, avoiding amplifier saturation, and recovering neural responses during current-controlled in-vivo neural stimulation and recording. The proposed system is tested in-vitro under various stimulation settings by stimulating and recording on the same electrode with a superimposed pre-recorded neural signal. Experimental results show that neural responses can be recovered with minimal distortion even during stimulus artifacts that are several orders greater in magnitude.

 

Artifact Cancellation fig1_systemOverview copy
System-Level Overview

 


Publication

“A Hybrid Hardware and Software Approach for Cancelling Stimulus Artifacts During Same-electrode Neural Stimulation and Recording,” Stanislav Culaclii, Brian Kim, Yi-Kai Lo, and Wentai Liu, accepted by EMBC 2016.

Cross Frequency Coupling (CFC)

 

 

CFC-3

 

Cross Frequency Coupling (CFC) is the interaction between brain oscillations of different frequencies, and the coupling phenomenon has been observed in the brain of rodent and human. Phase-amplitude coupling (PAC) is a type of CFC, which describes the dependence between the phase of a low-frequency component and the amplitude of a high-frequency component of electrical brain activities. It has been claimed that the modulation of low frequency phase on high frequency amplitude plays a functional role in cognition and information processing, such as learning and memory. The change of PAC patterns has been associated with various neurological disorders, e.g., epilepsy and  schizophrenia.

Five seizure stages classified by firing patterns (on the left). PAC pattern comparisons between the conventional method (middle) and HHT method (right) of two patients.
Five seizure stages classified by firing patterns (on the left). PAC pattern comparisons between the conventional method (middle) and HHT method (right) of two patients.

Interview for KTLA News

We are honored to have our research projects featured in the KTLA special report “Medical Miracles”. The special will air in May, 2016. The report focuses on our retinal prosthetic device that restores sight for patients with retinitis pigmentosa or age-related macular degeneration and our spinal cord implant to help patients paralyzed due to spinal cord injury regain motor function.