Spencer Kellis
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View article: Control of a commercial vehicle by a tetraplegic human using a bimanual brain-computer interface
Control of a commercial vehicle by a tetraplegic human using a bimanual brain-computer interface Open
Brain-computer interfaces (BCIs) read neural signals directly from the brain to infer motor planning and execution. However, the implementation of this technology has been largely limited to laboratory settings, with few real-world applica…
View article: Beta-band desynchronization in the human hippocampus during movement preparation in a delayed reach task
Beta-band desynchronization in the human hippocampus during movement preparation in a delayed reach task Open
Though the hippocampus is known for its role in memory and navigation, growing evidence has suggested that it is involved in voluntary movement. By investigating whether the hippocampus is active during movement preparation, we can underst…
View article: Understanding and Addressing Variability Through Recalibration in a Brain–Computer Interface for Intelligent Vehicle Control Using Long-Term Implanted Human Neural Data: A Case Study
Understanding and Addressing Variability Through Recalibration in a Brain–Computer Interface for Intelligent Vehicle Control Using Long-Term Implanted Human Neural Data: A Case Study Open
This work involved human subject in its research. Approval of all ethical and experimental procedures and protocols was granted by the FDA and IRB (NCT01997125). Even when trained on sufficient neural data, the performance of a brain-compu…
View article: Quantifying physical degradation alongside recording and stimulation performance of 980 intracortical microelectrodes chronically implanted in three humans for 956-2246 days
Quantifying physical degradation alongside recording and stimulation performance of 980 intracortical microelectrodes chronically implanted in three humans for 956-2246 days Open
Motivation The clinical success of brain-machine interfaces depends on overcoming both biological and material challenges to ensure a long-term stable connection for neural recording and stimulation. Therefore, there is a need to quantify …
View article: Neural subspaces of imagined movements in parietal cortex remain stable over several years in humans
Neural subspaces of imagined movements in parietal cortex remain stable over several years in humans Open
Objective. A crucial goal in brain–machine interfacing is the long-term stability of neural decoding performance, ideally without regular retraining. Long-term stability has only been previously demonstrated in non-human primate experiment…
View article: Beta-band power modulation in the human amygdala differentiates between go/no-go responses in an arm-reaching task
Beta-band power modulation in the human amygdala differentiates between go/no-go responses in an arm-reaching task Open
Objective . Traditionally known for its involvement in emotional processing, the amygdala’s involvement in motor control remains relatively unexplored, with sparse investigations into the neural mechanisms governing amygdaloid motor moveme…
View article: Beta-band power classification of go/no-go arm-reaching responses in the human hippocampus
Beta-band power classification of go/no-go arm-reaching responses in the human hippocampus Open
Objective. Can we classify movement execution and inhibition from hippocampal oscillations during arm-reaching tasks? Traditionally associated with memory encoding, spatial navigation, and motor sequence consolidation, the hippocampus has …
View article: Understanding the human conflict processing network: A review of the literature on direct neural recordings during performance of a modified stroop task
Understanding the human conflict processing network: A review of the literature on direct neural recordings during performance of a modified stroop task Open
The Stroop Task is a well-known neuropsychological task developed to investigate conflict processing in the human brain. Our group has utilized direct intracranial neural recordings in various brain regions during performance of a modified…
View article: Primary somatosensory cortex organization for engineering artificial somatosensation
Primary somatosensory cortex organization for engineering artificial somatosensation Open
Somatosensory deficits from stroke, spinal cord injury, or other neurologic damage can lead to a significant degree of functional impairment. The primary (SI) and secondary (SII) somatosensory cortices encode information in a medial to lat…
View article: Suppression of cortical electrostimulation artifacts using pre-whitening and null projection
Suppression of cortical electrostimulation artifacts using pre-whitening and null projection Open
Objective. Invasive brain–computer interfaces (BCIs) have shown promise in restoring motor function to those paralyzed by neurological injuries. These systems also have the ability to restore sensation via cortical electrostimulation. Cort…
View article: Neural subspaces of imagined movements in parietal cortex remain stable over several years in humans
Neural subspaces of imagined movements in parietal cortex remain stable over several years in humans Open
A crucial goal in brain-machine interfacing is long-term stability of neural decoding performance, ideally without regular retraining. Here we demonstrate stable neural decoding over several years in two human participants, achieved by lat…
View article: Neural representations of economic decision variables in human posterior parietal cortex
Neural representations of economic decision variables in human posterior parietal cortex Open
Decision making has been intensively studied in the posterior parietal cortex in non-human primates on a single neuron level. In humans decision making has mainly been studied with psychophysical tools or with fMRI. Here, we investigated h…
View article: Benchtop and bedside validation of a low-cost programmable cortical stimulator in a testbed for bi-directional brain-computer-interface research
Benchtop and bedside validation of a low-cost programmable cortical stimulator in a testbed for bi-directional brain-computer-interface research Open
Introduction Bi-directional brain-computer interfaces (BD-BCI) to restore movement and sensation must achieve concurrent operation of recording and decoding of motor commands from the brain and stimulating the brain with somatosensory feed…
View article: S1 represents multisensory contexts and somatotopic locations within and outside the bounds of the cortical homunculus
S1 represents multisensory contexts and somatotopic locations within and outside the bounds of the cortical homunculus Open
The responsiveness of primary somatosensory cortex (S1) to physical tactile stimuli is well documented but the extent to which it is modulated by vision is unresolved. Additionally, recent literature has suggested that tactile events are r…
View article: Baseline hippocampal beta band power is lower in the presence of movement uncertainty
Baseline hippocampal beta band power is lower in the presence of movement uncertainty Open
Objective. This study aimed to characterize hippocampal neural signatures of uncertainty by measuring beta band power in the period prior to movement cue. Approach . Participants with epilepsy were implanted with hippocampal depth electrod…
View article: Theta low-gamma phase amplitude coupling in the human orbitofrontal cortex increases during a conflict-processing task
Theta low-gamma phase amplitude coupling in the human orbitofrontal cortex increases during a conflict-processing task Open
Objective . The human orbitofrontal cortex (OFC) is involved in automatic response inhibition and conflict processing, but the mechanism of frequency-specific power changes that control these functions is unknown. Theta and gamma activity …
View article: Decoding grasp and speech signals from the cortical grasp circuit in a tetraplegic human
Decoding grasp and speech signals from the cortical grasp circuit in a tetraplegic human Open
Tetraplegia from spinal cord injury leaves many patients paralyzed below the neck, leaving them unable to perform most activities of daily living. Brain-machine interfaces (BMIs) could give tetraplegic patients more independence by directl…
View article: Neuropathological effects of chronically implanted, intracortical microelectrodes in a tetraplegic patient
Neuropathological effects of chronically implanted, intracortical microelectrodes in a tetraplegic patient Open
Objective. Intracortical microelectrode arrays (MEA) can be used as part of a brain–machine interface system to provide sensory feedback control of an artificial limb to assist persons with tetraplegia. Variability in functionality of elec…
View article: The Neurophysiological Representation of Imagined Somatosensory Percepts in Human Cortex
The Neurophysiological Representation of Imagined Somatosensory Percepts in Human Cortex Open
Intracortical microstimulation (ICMS) in human primary somatosensory cortex (S1) has been used to successfully evoke naturalistic sensations. However, the neurophysiological mechanisms underlying the evoked sensations remain unknown. To un…
View article: The human primary somatosensory cortex encodes imagined movement in the absence of sensory information
The human primary somatosensory cortex encodes imagined movement in the absence of sensory information Open
Classical systems neuroscience positions primary sensory areas as early feed-forward processing stations for refining incoming sensory information. This view may oversimplify their role given extensive bi-directional connectivity with mult…
View article: Gamma-band modulation in the human amygdala during reaching movements
Gamma-band modulation in the human amygdala during reaching movements Open
OBJECTIVE Motor brain-computer interface (BCI) represents a new frontier in neurological surgery that could provide significant benefits for patients living with motor deficits. Both the primary motor cortex and posterior parietal cortex h…
View article: Beta-band power modulation in the human hippocampus during a reaching task
Beta-band power modulation in the human hippocampus during a reaching task Open
This finding is consistent with previous literature suggesting that the hippocampus may be involved in the execution of movement, and it is the first time that changes in beta-band power have been demonstrated in the hippocampus using huma…