High-Side Digitally Current Controlled Biphasic Bipolar Microstimulator

Hanson, Timothy L.; Omarsson, B.; O’Doherty, Joseph E.; Peikon, Ian D.; Lebedev, Mikhail А.; Nicolelis, Miguel A. L.

doi:10.1109/tnsre.2012.2187219

Cited by 16 publications

(12 citation statements)

References 26 publications

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“…Low-current microstimulation (biphasic pulses at 100 Hz; 100-ms pulse width; 75 μA current) applied to M1 evoked clear motor responses and EMG bursts (36), whereas such low currents did not evoke motor responses when applied to S1.…”

Section: Methodsmentioning

confidence: 97%

Expanding the primate body schema in sensorimotor cortex by virtual touches of an avatar

Shokur

O’Doherty

Winans³

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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The brain representation of the body, called the body schema, is susceptible to plasticity. For instance, subjects experiencing a rubber hand illusion develop a sense of ownership of a mannequin hand when they view it being touched while tactile stimuli are simultaneously applied to their own hand. Here, the cortical basis of such an embodiment was investigated through concurrent recordings from primary somatosensory (i.e., S1) and motor (i.e., M1) cortical neuronal ensembles while two monkeys observed an avatar arm being touched by a virtual ball. Following a period when virtual touches occurred synchronously with physical brushes of the monkeys' arms, neurons in S1 and M1 started to respond to virtual touches applied alone. Responses to virtual touch occurred 50 to 70 ms later than to physical touch, consistent with the involvement of polysynaptic pathways linking the visual cortex to S1 and M1. We propose that S1 and M1 contribute to the rubber hand illusion and that, by taking advantage of plasticity in these areas, patients may assimilate neuroprosthetic limbs as parts of their body schema.multielectrode recordings | cortical plasticity I n the early 1900s, Head and Holmes coined the concept of the "body schema" to describe the spatial model of the body that the brain builds based on sensory inputs from the skin, joints, and muscles, as well as visual and auditory signals (1). Numerous studies since then have explored different aspects of the body schema (2-6), particularly the role of cortical areas (7,8). The accumulated literature indicates that the body schema is plastic and can even incorporate artificial tools (5, 9, 10). A striking example of body schema plasticity is provided by the rubber hand illusion (RHI), in which subjects start to perceive a mannequin hand as their own after their real hand, hidden from sight, and the mannequin hand are repeatedly touched simultaneously (11-13). Subjects do not perceive a third limb, but report a shift in position sense from the real arm to the fake one (11-14), and there is even a decrease in skin temperature of the real arm (15). Incorporation of artificial limbs into the body schema began to be further explored with the advancement of brain machine interfaces (BMIs), hybrid systems that connect the brain with external devices (16)(17)(18)(19). Here, we recorded cortical ensemble activity in monkeys exposed to the paradigm that elicits RHI in humans (11)(12)(13)(14)20). ResultsMonkeys M and N were chronically implanted with microwire arrays in the primary motor (i.e., M1) and somatosensory (i.e., S1) cortical neuronal ensembles. They observed a 3D image of a virtual arm (i.e., an avatar arm) being touched by a virtual ball on an LCD screen while a robot slid a physical brush through the skin of their real arms ( Fig. 1 A and B). The virtual touch (V) and physical touch (P) were synchronous or asynchronous (Fig. 1C). In a subset of trials, virtual brushing occurred alone (i.e., Vonly).Excitatory and Inhibitory Responses to Physical Touch. Experiments with mon...

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Section: Methodsmentioning

confidence: 97%

Expanding the primate body schema in sensorimotor cortex by virtual touches of an avatar

Shokur

O’Doherty

Winans³

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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“…We used four electrodes of the S1 implants for ICMS delivery. Stimulation was applied to the right hemisphere arm area of S1 in monkey M and the right hemisphere leg area of S1 in monkey N, using a custom built 4-channels current-controlled stimulator (Hanson et al, 2012). The monkeys were trained to move an image of the forearm and the hand (animated using MOTIONBUILDER, Autodesk) on a computer screen with a joystick (Fig.…”

Section: Methodsmentioning

confidence: 99%

Stochastic Facilitation of Artificial Tactile Sensation in Primates

Medina

Lebedev

O’Doherty³

et al. 2012

J. Neurosci.

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Artificial sensation via electrical or optical stimulation of brain sensory areas offers a promising treatment for sensory deficits. For a brain-machine-brain interface (BMBI), such artificial sensation conveys feedback signals from a sensorized prosthetic limb. The ways neural tissue can be stimulated to evoke artificial sensation and the parameter space of such stimulation, however, remain largely unexplored. Here we investigated whether stochastic facilitation (SF) could enhance an artificial tactile sensation produced by intracortical microstimulation (ICMS). Two rhesus monkeys learned to use a virtual hand, which they moved with a joystick, to explore virtual objects on a computer screen. They sought an object associated with a particular artificial texture (AT) signaled by a periodic ICMS pattern delivered to the primary somatosensory cortex (S1) through a pair of implanted electrodes. During each behavioral trial, aperiodic ICMS (i.e., noise) of randomly chosen amplitude was delivered to S1 through another electrode pair implanted 1 mm away from the site of AT delivery. Whereas high-amplitude noise worsened AT detection, moderate noise clearly improved the detection of weak signals, significantly raising the proportion of correct trials. These findings suggest that SF could be utilized to enhance prosthetic sensation.

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“…One limitation of this approach is that it does not directly address the problem of amplifier saturation and hence is less effective with prolonged amplifier saturation, unless care is taken in the design of the recording and stimulating circuitry to prevent or minimize amplifier saturation by decreasing the duration and amplitude of the artifacts [7]–[9]. On the other hand, the major advantage of this approach as compared to blanking (i.e., disconnecting the recording amplifier input during stimulation) is that it has the potential to retain signal information during stimulation, while fully eliminating large stimulus artifacts from the contaminated data record in real time, as demonstrated in this work.…”

Section: Discussionmentioning

confidence: 99%

“…Using active feedback circuitry to provide a low-impedance discharge path for the stimulating electrode [7], [8], and careful stimulator design related to the isolation of stimulation channels and parasitic current injection [9] have also been shown to decrease the duration and amplitude of the artifacts. However, these approaches cannot fully eliminate them, often leaving behind considerable residual artifacts.…”

Section: Introductionmentioning

confidence: 99%

VLSI implementation of a template subtraction algorithm for real-time stimulus artifact rejection

Limnuson

Chiel

et al. 2010

2010 Annual International Conference of the IEEE Engineering in Medicine and Biology

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This paper presents very-large-scale integrated (VLSI) implementation of an infinite impulse response (IIR) temporal filtering technique for real-time stimulus artifact rejection (SAR) in bidirectional interfacing with the nervous system. The template subtraction-based, IIR-SAR algorithm is implemented on a μW-level digital signal processing (DSP) unit that initializes its embedded 16b, 4K SRAM with the first recorded stimulus artifact to reduce the operation time in generating an accurate artifact template signal for subtraction. The DSP unit is integrated with spike-recording and microstimulation circuitry to create a functional, standalone, prototype system-on-chip (SoC) fabricated in AMS 0.35μm 2P/4M CMOS. The DSP unit functionality has been validated in benchtop tests using a prerecorded neural dataset from a laboratory rat, as well as in neurobiological experiments with isolated buccal ganglia of an Aplysia californica (a marine mollusk). The SoC can successfully remove mV-range stimulus artifacts with duration of <114.7ms from the contaminated neural data in real time and recover μV-range extracellular neural spikes that occur on the tail end of the artifacts. The root-mean-square (rms) value of the pre-processed stimulus artifact is reduced on average by a factor of ~24–30 post-processing, with DSP unit power consumption of <25μW from 1.5V.

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High-Side Digitally Current Controlled Biphasic Bipolar Microstimulator

Cited by 16 publications

References 26 publications

Expanding the primate body schema in sensorimotor cortex by virtual touches of an avatar

Expanding the primate body schema in sensorimotor cortex by virtual touches of an avatar

Stochastic Facilitation of Artificial Tactile Sensation in Primates

VLSI implementation of a template subtraction algorithm for real-time stimulus artifact rejection

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