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Intracortical microstimulation of human somatosensory cortex as a source of cutaneous feedback

Flesher, Sharlene N (2018) Intracortical microstimulation of human somatosensory cortex as a source of cutaneous feedback. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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The field of brain computer interfaces (BCI) has been making rapid advances in decoding brain activity into control signals capable of operating neural prosthetic devices, such as dexterous robotic arms and computer cursors. Potential users of neural prostheses, including people with amputations or spinal cord injuries, retain intact brain function that can be decoded using BCIs. Recent work has demonstrated simultaneous control over up to 10 degrees-of-freedom, but the current paradigms lack a component crucial to normal motor control: somatosensory feedback. Currently, BCIs are controlled using visual feedback alone, which is important for many reaching movement and identifying target locations. However, as the actuators controlled by BCIs become more complex and include devices approximating the performance of human limbs, visual feedback becomes especially limiting, as it cannot convey information used during object manipulation, such as grip force.
The objective of this work is to provide real-time, cutaneous, somatosensory feedback to users of dexterous prosthetic limbs under BCI control by applying intracortical microstimulation (ICMS) to primary somatosensory cortex (S1). Long-term microstimulation of the cortex with microelectrode arrays had never been attempted in a human prior to this work, and while this work is ultimately motivated by efforts to improve BCIs, this general approach also enables
Sharlene Nicole Flesher, PhD
University of Pittsburgh, 2017
unprecedented access to the human cortex enabling investigations of more basic scientific issues surrounding cutaneous perception, its conscious components, and its role in motor planning and control.
To this end, two microelectrode arrays were placed in human somatosensory cortex of a human participant. I first characterized qualities of sensations evoked via ICMS, such as percept location, modality, intensity and size, over a two-year study period. The sensations were found to be focal to a single digit, and increased in intensity linearly with pulse train amplitude, which suggests that ICMS will be a suitable means of relaying locations of object contact with single-digit precision, and a range of grasp forces can be relayed for each location. Additionally, I found these qualities to be stable over a two-year period, suggesting that delivering ICMS was not damaging the electrode-tissue interface. ICMS was then used as a real-time feedback source during BCI control of a robotic limb during tasks ranging from simple force-matching tasks to functional reach, grasp and carry tasks. Finally, we examined the relationship between pulse train parameters and conscious perception of sensations, an endeavor that until now could not have been undertaken.
These results demonstrate that ICMS is a suitable means of relaying somatosensory feedback to BCI users. Adding somatosensory feedback to BCI users has the potential to improve embodiment and control of the devices, bringing this technology closer to restoring upper limb function.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Flesher, Sharlene Nsnf12@pitt.edusnf120000-0003-0740-0018
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairGaunt, Robertrag53@pitt.edurag530000-0001-6202-5818
Committee MemberBatista, Aaronaaron.batista@pitt.eduaaron.batista0000-0002-1719-0061
Committee MemberBensmaia, Slimansliman@uchicago.edu0000-0003-4039-9135
Committee MemberCollinger, Jennifercollinger@pitt.educollinger0000-0002-4517-5395
Committee MemberAndrew, Schwartzabs21@pitt.eduabs21
Date: 24 January 2018
Date Type: Publication
Defense Date: 6 July 2017
Approval Date: 24 January 2018
Submission Date: 26 July 2017
Access Restriction: 2 year -- Restrict access to University of Pittsburgh for a period of 2 years.
Number of Pages: 153
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Bioengineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: somatosensory feedback, brain-computer interface, somatosensory cortex, microstimulation, neural prosthesis
Date Deposited: 24 Jan 2018 20:56
Last Modified: 24 Jan 2020 06:15


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