closed loop

Many researchers in the neuroscience field are incorporating electrophysiology as a major tool during their experiments in which simultaneously acquiring data of different types is common. Neural Electrophysiological signals are collected with the help of Neural Data Acquisition Systems (DAQ), electrodes, microdrives and various other accessories. In many experiments’ setups, researchers combine behavioral systems to answer complicated scientific questions. One example of a wide research field is the Brain-machine interface (BMI). (Figure1 )


alphaRs interfaces

alphaRS DAQ system interfaces 

Most of the DAQ systems are capable of recording only and cannot be used in experiments involving event-driven stimulus. The integration of Recording and Stimulation in one system enables closed-loop actions in research and clinical applications. In the case of electrophysiology, the closed-loop is a brain-machine interface (BMI) feedback loop that forms a communication from an external environment or computing devices to the brain. 

In neural prosthesis, artificial extensions to the body that restore or supplement function of the nervous system lost during disease or injury, for instance, the sensory feedback is applied to the brain cortex by the neural stimulators integrated with microelectrode array. In another example, stimulation is applied, in a closed-loop system, based on the existence of a specific signal biomarker as a treatment for various neurological and movement disorders such as Parkinson's disease and Dystonia. analysis of real-time recording is automatically performed prior to applying a treatment. RNS System medical device is an additional example of a closed-loop system that can monitor brain activity, detect predefined, abnormal activity, and respond in real-time to prevent epilepsy seizures before it starts.

In neuro-scientific experiments where the inherent behavior of neurons and their responses to electrical stimulation are examined, the combination of neural stimulation and recording is imperative.
The challenge in simultaneous neural recording and stimulation is the large interference on the neural amplifier induced by stimulation artifacts. Alpha Omega's AlphaRS DAQ solution is an adaptive algorithm for fast recovery from stimulation artifact. The artifact is deducted during stimulation and enables online spike segmentation and sorting. One software controls all channels’ modes and enables closed-loop actions with short latency <1ms.

Software assisting tools are critical for experiments with complex combinations of event-driven stimulus and recording paradigms. In AlphaRS DAQ there is a two-way communication using MATLAB or C++ for streaming all data and controlling system functionality. Online access to data means each user can write custom software routines and code paradigms specifically for their unique needs. The developers of alphaRS designed MATLAB toolbox with clear instructions to make accessing data in MATLAB straightforward.

Good luck in your next research, we hope you make the next scientific breakthrough of the century!