Tien, Rex N
(2021)
Encoding of Object Presence and Manipulation Affordances in the Frontoparietal Grasp Network.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
The ability to grasp and manipulate objects is a fundamental human capacity. Loss of this function due to injury or disease can result in the inability to independently perform tasks of daily living. Brain computer interfaces (BCIs), which decode neural activity to control assistive devices, represent a new class of potential therapies to restore arm and hand function. Recent efforts to implement BCI control of a robotic hand for grasping have been hindered by unexpected neural modulations in primary motor cortex (M1) related to the contextual factor of whether movements were made with or without an object present. We designed and carried out three experiments in healthy rhesus macaque monkeys to characterize the influence of various object-related contextual factors on movement features (MFs — kinematics and muscle activity of the arm and hand) and on neural activity in three grasp-related brain areas: M1, ventral premotor cortex (PMV) and anterior intraparietal area (AIP). A novel method was devised to implant intracortical microelectrode arrays in PMV and AIP for these experiments. In Experiment 1, monkeys performed similar reaching movements with or without an object present. In Experiment 2, monkeys performed similar grasps on a set of objects with different grip affordances (objects could be grasped in multiple ways). In Experiment 3, monkeys performed similar grasps on two objects with different use affordances (one was stationary and one could be lifted). All object-related contextual factors were found to evoke small but significant differences in MFs despite task requirements remaining constant across contexts. These context-dependent behavioral differences were accompanied by proportionately larger neural differences in all three brain areas. The presence or absence of an object resulted in changes in neuronal firing rates that could not be accounted for by linear encoding of MFs. This object presence signal was found to interact with MF encoding in M1 in a way that was detrimental for BCI-style MF decoding. Object grip affordance differences resulted in similar but smaller neural modulations that did not impact MF decoding. Neural modulations related to object use affordance were prominent only in PMV.
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Details
| Item Type: |
University of Pittsburgh ETD
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| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| Date: |
13 June 2021 |
| Date Type: |
Publication |
| Defense Date: |
17 December 2020 |
| Approval Date: |
13 June 2021 |
| Submission Date: |
20 January 2021 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
490 |
| 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: |
Primary Motor Cortex, M1, Ventral Premotor Cortex, PMV, F5, Anterior Intraparietal Area, AIP, Grasping, Reach, Reaching, Context, Kinematics, Electromyography, EMG, Behavior, Microelectrode Array, Visuomotor, Learning, Decoding, Brain-Computer Interface, BCI, Brain-Machine Interface, BMI, Neuroprosthetics |
| Date Deposited: |
13 Jun 2021 17:21 |
| Last Modified: |
13 Jun 2021 17:21 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/40183 |
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