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    A behavioral paradigm for cortical control of a robotic actuator by freely moving rats in a one-dimensional two-target reaching task
    (Elsevier B.V., 2022) Zaidi, Syed Muhammad Talha; Kocatürk, Samet; Baykaş, Tunçer; Kocatürk, Mehmet
    Background: Controlling the trajectory of a neuroprosthesis to reach distant targets is a commonly used brain-machine interface (BMI) task in primates and has not been available for rodents yet. New method: Here, we describe a novel, fine-tuned behavioral paradigm and setup which enables this task for rats in one-dimensional space for reaching two distant targets depending on their limited cognitive and visual capabilities compared to those of primates. An online transform was used to convert the activity of a pair of primary motor cortex (M1) units into two robotic actions. The rats were shaped to adapt to the transform and direct the robotic actuator toward the selected target by modulating the activity of the M1 neurons. Results: All three rats involved in the study were capable of achieving randomly selected targets with at least 78% accuracy. A total of 9 out of 16 pairs of units examined were eligible for exceeding this success criterion. Two out of three rats were capable of reversal learning, where the mapping between the activity of the M1 units and the robotic actions were reversed. Comparison with existing methods: The present work is the first demonstration of trajectory-based control of a neuroprosthetic device by rodents to reach two distant targets using visual feedback. Conclusion: The behavioral paradigm and setup introduced here can be used as a cost-effective platform for elucidating the information processing principles in the neural circuits related to neuroprosthetic control and for studying the performance of novel BMI technologies using freely moving rats.
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    Design of a multichannel electrophysiology amplifier and a rat behavioral paradigm for motor neuroprosthetic control
    (İstanbul Medipol Üniversitesi Fen Bilimleri Enstitüsü, 2020) Zaidi, Syed Muhammad Talha; Kocatürk, Mehmet
    The development in brain-machine interfaces (BMIs) not only provided efficient solutions for the control of neuroprosthetic devices, aiming to recover motor functions lost to disease or injury, but also allows the researchers to explore the neural mechanisms of learning and adaptation in brain. The studies involving animals such as rats and mice are significant in this regard and rely mainly upon the availability of electrophysiological recording tools and appropriate behavioral paradigms. The commercially available recording tools are expensive and difficult to reproduce in a neuroscience research laboratory. Furthermore, the center-out-reaching task, which is a conventional neuroprosthetic control paradigm widely used with human and monkey subjects, is not applicable in the studies involving rodents. To this end, our goal was to develop a low-cost and easy-to-implement analog neural signal processing system and a behavioral paradigm, which enables rats to control a neuroprosthetic device in a center-out reaching task via neuronal operant conditioning. An eight-channel compact headstage and analog amplification and filtering module was developed using readily available analog electronic components. The behavioral paradigm was designed for two target reaching task. Rats were chronically implanted with microelectrode arrays in the primary motor cortex and trained to control the movement of a one-dimensional robotic actuator. The difficulty level of the reaching task was gradually increased to assist the subjects in adapting their brain activities for accurate neuroprosthetic control. Neural signals through eight channels have been recorded synchronously from a freely moving rat by using the electrophysiology amplifier designed in this study. The signals were filtered in the range of 150 Hz – 7.96 kHz, along with the amplification of 1008x gain. The achieved signal to noise ratio allowed reliable spike sorting. Three rats were also trained using the behavioral paradigm presented here to enable the control of a robotic arm through neuronal operant conditioning. After learning, all rats were able to modulate the firing rates of the neurons to acquire the selected targets. A compact, low cost and easily implementable circuit is presented for extracellular neural recordings. The present hardware solution can decrease the costs of neuroscience research requiring electrophysiological investigations. The behavioral paradigm presented here enables use of rats in center-out-reaching tasks for neuroprosthetic control experiments. We believe the paradigm can be applied for neuroprosthetic control not only incorporating neuronal operant conditioning but also neural decoding algorithms.