We test the hypothesis that the neuronal spike generation mechanism is an analog-to-digital (AD) converter encoding rectified low-pass filtered summed synaptic currents into a spike train linearly decodable in postsynaptic neurons. Faithful encoding of an analog waveform by a binary signal requires that the spike generation mechanism has a sampling rate exceeding the Nyquist rate of the analog signal. Such oversampling is consistent with the experimental observation that the precision of the spikegeneration mechanism is an order of magnitude greater than the cut-off frequency of low-pass filtering in dendrites. Additional improvement in the coding accuracy may be achieved by noise-shaping, a technique used in signal processing. If noise-shaping were used in neurons, it would reduce coding error relative to Poisson spike generator for frequencies below Nyquist by introducing correlations into spike times.

The need for speed is a hot topic among participants at this week's AI Hardware Summit – larger AI language models, faster chips and more bandwidth for AI machines to make accurate predictions. But some hardware startups are taking a throwback approach for AI computing to counter the more-is-better approach. Companies including Innatera, Rain Neuromorphics and others are creating silicon brains with analog circuitry to mimic brain functionality. The brain is inherently analog, taking in raw sensory data, and these chipmakers are trying to recreate the way the brain's neurons and synapses work in traditional analog circuitry. Analog chips can be very good low-power sensing devices, especially for some sound and vision applications, said Kevin Krewell, an analyst at Tirias Research.

One of the most critical parameters of the audio signal is amplitude. Amplitude can be defined as the maximum displacement to amend the rest position, and Sometimes the rest position is also known as the central position, as you can see here in this diagram.

Quantizers play a critical role in digital signal processing systems. Recent works have shown that the performance of quantization systems acquiring multiple analog signals using scalar analog-to-digital converters (ADCs) can be significantly improved by properly processing the analog signals prior to quantization. However, the design of such hybrid quantizers is quite complex, and their implementation requires complete knowledge of the statistical model of the analog signal, which may not be available in practice. In this work we design data-driven task-oriented quantization systems with scalar ADCs, which determine how to map an analog signal into its digital representation using deep learning tools. These representations are designed to facilitate the task of recovering underlying information from the quantized signals, which can be a set of parameters to estimate, or alternatively, a classification task. By utilizing deep learning, we circumvent the need to explicitly recover the system model and to find the proper quantization rule for it. Our main target application is multiple-input multiple-output (MIMO) communication receivers, which simultaneously acquire a set of analog signals, and are commonly subject to constraints on the number of bits. Our results indicate that, in a MIMO channel estimation setup, the proposed deep task-bask quantizer is capable of approaching the optimal performance limits dictated by indirect rate-distortion theory, achievable using vector quantizers and requiring complete knowledge of the underlying statistical model. Furthermore, for a symbol detection scenario, it is demonstrated that the proposed approach can realize reliable bit-efficient hybrid MIMO receivers capable of setting their quantization rule in light of the task, e.g., to minimize the bit error rate.

This will sound familiar to anyone who has owned a smartphone in the last decade. I can't remember the last time I took the time to type out the entire query on Google Search. I simply ask the question – and Google lays out the entire weather pattern for me. It saves me a ton of time and I can quickly glance at my screen and get back to work. But how does Google understand what I'm saying?

Computing accurate estimates of the Fourier transform of analog signals from discrete data points is important in many fields of science and engineering. The conventional approach of performing the discrete Fourier transform of the data implicitly assumes periodicity and bandlimitedness of the signal. In this paper, we use Gaussian process regression to estimate the Fourier transform (or any other integral transform) without making these assumptions. This is possible because the posterior expectation of Gaussian process regression maps a finite set of samples to a function defined on the whole real line, expressed as a linear combination of covariance functions. We estimate the covariance function from the data using an appropriately designed gradient ascent method that constrains the solution to a linear combination of tractable kernel functions. This procedure results in a posterior expectation of the analog signal whose Fourier transform can be obtained analytically by exploiting linearity. Our simulations show that the new method leads to sharper and more precise estimation of the spectral density both in noise-free and noise-corrupted signals. We further validate the method in two real-world applications: the analysis of the yearly fluctuation in atmospheric CO2 level and the analysis of the spectral content of brain signals.

The brain's signals are analog, those in the computer are digital. Neural signals are noisy and unreliable, digital switches are designed to be absolutely reliable. It is of great irony that on a global level this relationship inverts: in unstructured natural environments the brain performs reliably whereas the computer fails. Is this a freak or is there something magic about analog signals? Digital systems rely on absolute reliability of signals.

For many people, the word "digital" is synonymous with modern, technologically advanced programs or devices capable of performing complex processes in a fraction of the time that it would take a manual or analog system to do the same thing. Analog, on the other hand, is generally thought of as old-fashioned and something that needs to be converted to digital in order to be in line with the modern technology, even though much of what we take for granted in terms of technology actually runs on analog components. In fact, one of the most transformative trends in technology today relies heavily on analog technology. When you think of artificial intelligence, you probably think of robots or at least high-powered computers like IBM's Watson-- the epitome of modern technology -- you probably don't think analog, with its reliance on capturing real-time data and measuring the changes in the signals put out by physical phenomena. The Executive Office of the President recently said that advances in AI will make it easier than ever to search public records and streamline healthcare.

We explore the hypothesis that the neuronal spike generation mechanism is an analog-to-digital converter, which rectifies low-pass filtered summed synaptic currents and encodes them into spike trains linearly decodable in post-synaptic neurons. To digitally encode an analog current waveform, the sampling rate of the spike generation mechanism must exceed its Nyquist rate. Such oversampling is consistent with the experimental observation that the precision of the spike-generation mechanism is an order of magnitude greater than the cut-off frequency of dendritic low-pass filtering. To achieve additional reduction in the error of analog-to-digital conversion, electrical engineers rely on noise-shaping. If noise-shaping were used in neurons, it would introduce correlations in spike timing to reduce low-frequency (up to Nyquist) transmission error at the cost of high-frequency one (from Nyquist to sampling rate). Using experimental data from three different classes of neurons, we demonstrate that biological neurons utilize noise-shaping. We also argue that rectification by the spike-generation mechanism may improve energy efficiency and carry out de-noising. Finally, the zoo of ion channels in neurons may be viewed as a set of predictors, various subsets of which are activated depending on the statistics of the input current.

In this paper we examine the practical use of hardware neural networks in an autonomous mobile robot. We have developed a hardware neural system based around a custom VLSI chip, EP SILON III, designed specifically for embedded hardware neural applications. We present here a demonstration application of an autonomous mobile robot that highlights the flexibility of this system.