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Timecorrelated single-photon counting based method for submillimeter transillumination imaging of objects embedded in tissue-phantoms.
No full textA Multi-Channel Low-Power System-on-Chip for in vivo NeuralSpike Recording
Full text linkThis paper reports a multi-channel neural spike
recording system-on-chip (SoC) with digital data compression
and wireless telemetry. The circuit consists of a 64-channel
low-power low-noise analog front-end, a single 8-bit analog-todigital
converter (ADC), followed by digital signal compression
and transmission units. The 400-MHz transmitter employs a
Manchester-Coded Frequency Shift Keying (MC-FSK) modulator
with low modulation index. In this way a 1.25-Mbit/s data
rate is delivered within a band of about 3 MHz. Compression of
the raw data is implemented by detecting the action potentials
(APs) and storing 20 samples for each spike waveform. The choice
greatly improves data quality and allows single neuron identification.
A larger than 10-m transmission range is reached with
an overall power consumption of 17.2 mW. This figure translates
into a power budget of 269 μW per channel, which is in line
with the results in literature but allowing a larger transmission
distance and more efficient wireless link bandwidth occupation.
The implemented IC was mounted on a small and light printed
circuit board to be used during neuroscience experiments with
freely-behaving rats. Powered by 2 AAA batteries the system can
work continuously for more than 100 hours allowing long-lasting
neural spike recordings
Fully Integrated Systems for Neural Signal Recording: Technology Perspective and Low-Noise Front-End Design
No full textSince the dawn of microelectronic industry integrated technologies have been fuelling tremendous advances in science,
engineering and applications leading to an increasing inclusion of intelligence in infrastructures, equipments and
products. This trend, leveraging on silicon device miniaturization, is still on-going and is having a profound impact
in all fields, medical science and therapeutics included. In the forthcoming years, availability of decananometer
silicon technologies, advances in micro-mechanical and packaging manufacturing, energy-conversion techniques and
material engineering are expected to provide the solutions needed to develop fully miniaturized, low-power, energy-
autonomous smart systems. These systems will promote a more intimate smart link between humans, from a high level
interaction down to cellular level, things and environment.
Implantable recording systems are a challenging test field for deeply scaled technologies since demanding performance
required for the application and the tight constraints imposed by the surrounding environment, i.e. the body.
But big challenges translate in big opportunities: the potentials of this trend are already clearly visible,
neurotechnology being one of the leading examples. Technological advances are enabling innovative interfaces between
neurons and electronics, opening the way to new therapeutic devices for neurological diseases as well as to detailed
investigation tools of the cognitive processes.
The chapter reviewed the performance requirements and the perspectives of fully integrated neural recording systems,
pointing out the issues faced in the definition of optimal architectures and function partitioning. In this frame,
energy-efficiency and low noise design are key ingredients. The fundamental metrics to quantitatively judge the trade
off between noise, power consumption, and processing speed have been introduced and adopted to compare the most recent
system implementations. It has been shown that a 10uW power budget target per sensing channel is attainable by
using cutting edge technologies and careful design. Finally, we focused on the particular issue of neural amplifier
design: leveraging on a detailed break-down of the noise sources and by mean of an insightful design strategy we
addressed the problem of noise-power trade-off and we presented a neural amplifier that achieved the best performance
so far reported
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A Low-power Integrated Circuit for Analog Spike Detection and Sorting in Neural Prosthesis Systems
No full textCounting photoelectrons in the response of a photomultiplier tube to single picosecond light pulses
No full textOrigins of 1/f2 scaling in the power spectrum of intracortical local field potential.
No full textIt has been noted that the power spectrum of intracortical local field potential (LFP) often scales as 1/f(-2). It is thought that LFP mostly represents the spiking-related neuronal activity such as synaptic currents and spikes in the vicinity of the recording electrode, but no 1/f(2) scaling is detected in the spike power. Although tissue filtering or modulation of spiking activity by UP and DOWN states could account for the observed LFP scaling, there is no consensus as to how it arises. We addressed this question by recording simultaneously LFP and single neurons ("single units") from multiple sites in somatosensory cortex of anesthetized rats. Single-unit data revealed the presence of periods of high activity, presumably corresponding to the "UP" states when the neuronal membrane potential is depolarized, and periods of no activity, the putative "DOWN" states when the membrane potential is close to resting. As expected, the LFP power scaled as 1/f(2) but no such scaling was found in the power spectrum of spiking activity. Our analysis showed that 1/f(2) scaling in the LFP power spectrum was largely generated by the steplike transitions between UP and DOWN states. The shape of the LFP signal during these transitions, but not the transition timing, was crucial to obtain the observed scaling. These transitions were probably induced by synchronous changes in the membrane potential across neurons. We conclude that a 1/f(2) scaling in the LFP power indicates the presence of steplike transitions in the LFP trace and says little about the statistical properties of the associated neuronal firing
A power-efficient analog integrated circuit for amplification and detection of neural signals
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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