Multi-Electrode Arrays and High-Density Multi-Electrode Arrays of sensors are a key instrument in neuroscience research. Such devices are evolving to provide ever-increasing temporal and spatial resolution, paving the way to unprecedented results when it comes to understanding the behaviour of neuronal networks and interacting with them. However, in some experimental cases, in-place lowlatency processing of the sensor data acquired by the arrays is required. This poses the need for highperformance embedded computing platforms capable of processing in real-time the stream of samples produced by the acquisition front-end to extract higher-level information. Previous work has demonstrated that Field-Programmable Gate Array and All-Programmable System-On-Chip devices are suitable target technology for the implementation of real-time processors of High-Density Multi-Electrode Arrays data. However, approaches available in literature can process a limited number of channels or are designed to execute only the first steps of the neural signal processing chain. In this work, we propose an All-Programmable System-On-Chip based implementation capable of sorting neural spikes acquired by the sensors, to associate the shape of each spike to a specific firing neuron. Our system, implemented on a Xilinx Z7020 All-Programmable System-On-Chip is capable of executing on-line spike sorting up to 5500 acquisition channels, 43x more than state-of-the-art alternatives, supporting 18KHz acquisition frequency. We present an experimental study on a commonly used reference dataset, using on-line refinement of the sorting clusters to improve accuracy up to 82%, with only 4% degradation with respect to off-line analysis. INDEX TERMS Field programmable gate arrays, Signal processing, Neural engineering, APSoC, HDMEA, Spike sorting.

Closed-loop experiments involving biological and artificial neural networks would improve the understanding of neural cells functioning principles and lead to the development of new generation neuroprosthesis. Several technological challenges require to be faced, as the development of real-time spiking neural network emulators which could bear the increasing amount of data provided by new generation High-Density Multielectrode Arrays. This work focuses on the development of a real-time spiking neural network emulator addressing fully-connected neural networks. This work presents a new way to increase the number of synapses supported by real-time neural network accelerators. The proposed solution has been implemented on the Xilinx Zynq 7020 All-Programmable SoC and can emulate fully connected spiking neural networks counting up to 3,098 Izhikevich neurons and 9.6e6 synapses in realtime, with a resolution of 0.1 ms. INDEX TERMS APSoC, fixed-point, FPGA, neural emulator, hardware accelerator, neural engineering, real-time, spiking neural network.

In the last decades, deep learning neural decoding algorithms have gained momentum in the field of neural interfaces and neural processing systems. However, to be deployed on low-budget portable devices while maintaining real-time operability, these models must withstand strict computational and power limitations. This work presents a spike decoding system implemented on a low-end Zynq-7010 FPGA, which includes a multiplier-less spike detection pipeline and a spiking-neural-network-based decoder mapped in the programmable logic. We tested the system on two publicly available datasets and achieved comparable results with state-of-the-art neural decoders that use more complex deep learning models. The system required 7.36 times fewer parameters than the smallest architecture tested on the same dataset. Moreover, by exploiting the spike sparsity property of the neural signal, the total amount of computations is reduced by about 90% during a test carried out on real recorded data. The low computational complexity of the chosen spike detection setup, combined with the power efficiency of spiking neural networks, makes this prototype a well-suited choice for low-power real-time neural decoding at the edge.INDEX TERMS Neural decoding, spike detection, spiking neural network, FPGA, real-time, low-power.

Objective: Advances in brain-machine interfaces (BMIs) can potentially improve the quality of life of millions of users with spinal cord injury or other neurological disorders by allowing them to interact with the physical environment at their will. Approach: To reduce the power consumption of the brain-implanted interface, this article presents the first hardware realization of an in vivo intention-aware interface via brain-state estimation. Main Results: It is shown that incorporating brain-state estimation reduces the in vivo power consumption and reduces total energy dissipation by over 1.8x compared to those of the current systems, enabling longer batter life for implanted circuits. The synthesized application-specific integrated circuit (ASIC) of the designed intention-aware multi-unit spike detection system in a standard 180-nm CMOS process occupies 0.03 mm2 of silicon area and consumes 0.63 μW of power per channel, which is the least power consumption among the current in vivo ASIC realizations. Significance: The proposed interface is the first practical approach towards realizing asynchronous BMIs while reducing the power consumption of the BMI interface and enhancing neural decoding performance compared to those of the conventional synchronous BMIs.