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Pruszynski, J. Andrew
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Publications (10 of 13) Show all publications
Pruszynski, J. A., Flanagan, J. R. & Johansson, R. S. (2018). Fast and accurate edge orientation processing during object manipulation. eLIFE, 7, Article ID e31200.
Open this publication in new window or tab >>Fast and accurate edge orientation processing during object manipulation
2018 (English)In: eLIFE, E-ISSN 2050-084X, Vol. 7, article id e31200Article in journal (Refereed) Published
Abstract [en]

Quickly and accurately extracting information about a touched object’s orientation is a critical aspect of dexterous object manipulation. However, the speed and acuity of tactile edge orientation processing with respect to the fingertips as reported in previous perceptual studies appear inadequate in these respects. Here we directly establish the tactile system’s capacity to process edge-orientation information during dexterous manipulation. Participants extracted tactile information about edge orientation very quickly, using it within 200 ms of first touching the object. Participants were also strikingly accurate. With edges spanning the entire fingertip, edge-orientation resolution was better than 3° in our object manipulation task, which is several times better than reported in previous perceptual studies. Performance remained impressive even with edges as short as 2 mm, consistent with our ability to precisely manipulate very small objects. Taken together, our results radically redefine the spatial processing capacity of the tactile system.

Place, publisher, year, edition, pages
ELIFE SCIENCES PUBLICATIONS LTD, 2018
National Category
Physiology
Identifiers
urn:nbn:se:umu:diva-151176 (URN)10.7554/eLife.31200 (DOI)000431038000001 ()29611804 (PubMedID)2-s2.0-85051947543 (Scopus ID)
Available from: 2018-09-05 Created: 2018-09-05 Last updated: 2018-09-05Bibliographically approved
Zhao, C. W., Daley, M. J. & Pruszynski, J. A. (2018). Neural network models of the tactile system develop first-order units with spatially complex receptive fields. PLoS ONE, 13(6), Article ID e0199196.
Open this publication in new window or tab >>Neural network models of the tactile system develop first-order units with spatially complex receptive fields
2018 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, no 6, article id e0199196Article in journal (Refereed) Published
Abstract [en]

First-order tactile neurons have spatially complex receptive fields. Here we use machine-learning tools to show that such complexity arises for a wide range of training sets and network architectures. Moreover, we demonstrate that this complexity benefits network performance, especially on more difficult tasks and in the presence of noise. Our work suggests that spatially complex receptive fields are normatively good given the biological constraints of the tactile periphery.

Place, publisher, year, edition, pages
Public Library Science, 2018
National Category
Neurology Neurosciences
Identifiers
urn:nbn:se:umu:diva-150783 (URN)10.1371/journal.pone.0199196 (DOI)000435424900098 ()29902277 (PubMedID)
Available from: 2018-08-23 Created: 2018-08-23 Last updated: 2018-08-23Bibliographically approved
Maeda, R. S., Cluff, T., Gribble, P. L. & Pruszynski, J. A. (2017). Compensating for intersegmental dynamics across the shoulder, elbow, and wrist joints during feedforward and feedback control. Journal of Neurophysiology, 118(4), 1984-1997
Open this publication in new window or tab >>Compensating for intersegmental dynamics across the shoulder, elbow, and wrist joints during feedforward and feedback control
2017 (English)In: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598, Vol. 118, no 4, p. 1984-1997Article in journal (Refereed) Published
Abstract [en]

Moving the arm is complicated by mechanical interactions that arise between limb segments. Such intersegmental dynamics cause torques applied at one joint to produce movement at multiple joints, and in turn, the only way to create single joint movement is by applying torques at multiple joints. We investigated whether the nervous system accounts for intersegmental limb dynamics across the shoulder, elbow, and wrist joints during self-initiated planar reaching and when countering external mechanical perturbations. Our first experiment tested whether the timing and amplitude of shoulder muscle activity account for interaction torques produced during single-joint elbow movements from different elbow initial orientations and over a range of movement speeds. We found that shoulder muscle activity reliably preceded movement onset and elbow agonist activity, and was scaled to compensate for the magnitude of interaction torques arising because of forearm rotation. Our second experiment tested whether elbow muscles compensate for interaction torques introduced by single-joint wrist movements. We found that elbow muscle activity preceded movement onset and wrist agonist muscle activity, and thus the nervous system predicted interaction torques arising because of hand rotation. Our third and fourth experiments tested whether shoulder muscles compensate for interaction torques introduced by different hand orientations during self-initiated elbow movements and to counter mechanical perturbations that caused pure elbow motion. We found that the nervous system predicted the amplitude and direction of interaction torques, appropriately scaling the amplitude of shoulder muscle activity during self-initiated elbow movements and rapid feedback control. Taken together, our results demonstrate that the nervous system robustly accounts for intersegmental dynamics and that the process is similar across the proximal to distal musculature of the arm as well as between feedforward (i.e., self- initiated) and feedback (i.e., reflexive) control. NEW & NOTEWORTHY Intersegmental dynamics complicate the mapping between applied joint torques and the resulting joint motions. We provide evidence that the nervous system robustly predicts these intersegmental limb dynamics across the shoulder, elbow, and wrist joints during reaching and when countering external perturbations.

Place, publisher, year, edition, pages
American Physiological Society, 2017
Keywords
upper limb, intersegmental limb dynamics, voluntary movements, long-latency reflex, redundancy
National Category
Neurosciences Physiology
Identifiers
urn:nbn:se:umu:diva-142916 (URN)10.1152/jn.00178.2017 (DOI)000412642900007 ()28701534 (PubMedID)
Available from: 2017-12-13 Created: 2017-12-13 Last updated: 2018-06-09Bibliographically approved
Pruszynski, J. A., Johansson, R. S. & Flanagan, J. R. (2016). A Rapid Tactile-Motor Reflex Automatically Guides Reaching toward Handheld Objects. Current Biology, 26(6), 788-792
Open this publication in new window or tab >>A Rapid Tactile-Motor Reflex Automatically Guides Reaching toward Handheld Objects
2016 (English)In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 26, no 6, p. 788-792Article in journal (Refereed) Published
Abstract [en]

The ability to respond quickly and effectively when objects in the world suddenly change position is essential for skilled action, and previous work has documented how unexpected changes in the location of a visually presented target during reaching can elicit rapid reflexive (i.e., automatic) corrections of the hand's trajectory [1-12]. In object manipulation and tool use, the sense of touch can also provide information about changes in the location of reach targets. Consider the many tasks where we reach with one hand to part of an object grasped by the other hand: reaching to a berry while holding a branch, reaching for a cap while grasping a bottle, and reaching toward a dog's collar while holding the dog's leash. In such cases, changes in the position of the reach target, due to wind, slip, or an active agent, can be detected, in principle, through touch. Here, we show that when people reach with their right hand to a target attached to the far end of a rod contacted, at the near end, by their left hand, an unexpected change in target location caused by rod rotation rapidly evokes an effective reach correction. That is, spatial information about a change in target location provided by tactile inputs to one hand elicits a rapid correction of the other hand's trajectory. In addition to uncovering a tactile-motor reflex that can support manipulatory actions, our results demonstrate that automatic reach corrections to moving targets are not unique to visually registered changes in target location.

National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-119280 (URN)10.1016/j.cub.2016.01.027 (DOI)000372411600023 ()26898466 (PubMedID)
Available from: 2016-06-02 Created: 2016-04-15 Last updated: 2018-06-07Bibliographically approved
Weiler, J., Saravanamuttu, J., Gribble, P. L. & Pruszynski, J. A. (2016). Coordinating long-latency stretch responses across the shoulder, elbow, and wrist during goal-directed reaching. Journal of Neurophysiology, 116(5), 2236-2249
Open this publication in new window or tab >>Coordinating long-latency stretch responses across the shoulder, elbow, and wrist during goal-directed reaching
2016 (English)In: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598, Vol. 116, no 5, p. 2236-2249Article in journal (Refereed) Published
Abstract [en]

The long-latency stretch response (muscle activity 50-100 ms after a mechanical perturbation) can be coordinated across multiple joints to support goal-directed actions. Here we assessed the flexibility of such coordination and whether it serves to counteract intersegmental dynamics and exploit kinematic redundancy. In three experiments, participants made planar reaches to visual targets after elbow perturbations and we assessed the coordination of long-latency stretch responses across shoulder, elbow, and wrist muscles. Importantly, targets were placed such that elbow and wrist (but not shoulder) rotations could help transport the hand to the target-a simple form of kinematic redundancy. In experiment 1 we applied perturbations of different magnitudes to the elbow and found that long-latency stretch responses in shoulder, elbow, and wrist muscles scaled with perturbation magnitude. In experiment 2 we examined the trial-by-trial relationship between long-latency stretch responses at adjacent joints and found that the magnitudes of the responses in shoulder and elbow muscles, as well as elbow and wrist muscles, were positively correlated. In experiment 3 we explicitly instructed participants how to use their wrist to move their hand to the target after the perturbation. We found that long-latency stretch responses in wrist muscles were not sensitive to our instructions, despite the fact that participants incorporated these instructions into their voluntary behavior. Taken together, our results indicate that, during reaching, the coordination of long-latency stretch responses across multiple joints counteracts intersegmental dynamics but may not be able to exploit kinematic redundancy.

Keywords
coordination, EMG, feedback, goal-dependent activity, long-latency stretch response, reflex, movement, upper limb, intersegmental dynamics
National Category
Physiology
Identifiers
urn:nbn:se:umu:diva-129881 (URN)10.1152/jn.00524.2016 (DOI)000387983300020 ()27535378 (PubMedID)
Available from: 2017-01-17 Created: 2017-01-10 Last updated: 2018-06-09Bibliographically approved
Johansson, A. S., Pruszynski, J. A., Edin, B. B. & Westberg, K.-G. (2014). Biting intentions modulate digastric reflex responses to sudden unloading of the jaw. Journal of Neurophysiology, 112(5), 1067-1073
Open this publication in new window or tab >>Biting intentions modulate digastric reflex responses to sudden unloading of the jaw
2014 (English)In: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598, Vol. 112, no 5, p. 1067-1073Article in journal (Refereed) Published
Abstract [en]

Reflex responses in jaw opening muscles can be evoked when a brittle object cracks between the teeth and suddenly unloads the jaw. We hypothesized that this reflex response is flexible and, as such, is modulated according to the instructed goal of biting through an object. Study participants performed two different biting tasks when holding a peanut-half stacked on a chocolate piece between their incisors. In one task, they were asked to split the peanut-half only (single-split task) and, in the other task, they were asked to split both the peanut and the chocolate in one action (double-split task). In both tasks, the peanut split evoked a jaw opening muscle response, quantified from EMG recordings of the digastric muscle in a window 20-60 ms following peanut split. Consistent with our hypothesis, we found that the jaw opening muscle response in the single-split trials was about twice the size of the jaw opening muscle response in the double-split trials. A linear model that predicted the jaw opening muscle response on a single trial basis indicated that task settings played a significant role in this modulation but also that the pre-split digastric muscle activity contributed to the modulation. These findings demonstrate that, like reflex responses to mechanical perturbations in limb muscles, reflex responses in jaw muscles not only show gain-scaling but also are modulated by subject intent.

Keywords
EMG, jaw-opening reflex, motor control, reflex modulation, trigeminal
National Category
Physiology
Identifiers
urn:nbn:se:umu:diva-89697 (URN)10.1152/jn.00133.2014 (DOI)000341687200005 ()24899675 (PubMedID)
Available from: 2014-06-10 Created: 2014-06-10 Last updated: 2018-06-07Bibliographically approved
Pruszynski, J. A. & Johansson, R. S. (2014). Edge-orientation processing in first-order tactile neurons. Nature Neuroscience, 17(10), 1404-1409
Open this publication in new window or tab >>Edge-orientation processing in first-order tactile neurons
2014 (English)In: Nature Neuroscience, ISSN 1097-6256, E-ISSN 1546-1726, Vol. 17, no 10, p. 1404-1409Article in journal (Refereed) Published
Abstract [en]

A fundamental feature of first-order neurons in the tactile system is that their distal axon branches in the skin and forms many transduction sites, yielding complex receptive fields with many highly sensitive zones. We found that this arrangement constitutes a peripheral neural mechanism that allows individual neurons to signal geometric features of touched objects. Specifically, we observed that two types of first-order tactile neurons that densely innervate the glabrous skin of the human fingertips signaled edge orientation via both the intensity and the temporal structure of their responses. Moreover, we found that the spatial layout of a neuron's highly sensitive zones predicted its sensitivity to particular edge orientations. We submit that peripheral neurons in the touch-processing pathway, as with peripheral neurons in the visual-processing pathway, perform feature extraction computations that are typically attributed to neurons in the cerebral cortex.

Place, publisher, year, edition, pages
Nature Publishing Group, 2014
National Category
Physiology Neurosciences
Identifiers
urn:nbn:se:umu:diva-92698 (URN)10.1038/nn.3804 (DOI)000342327000021 ()25174006 (PubMedID)
Available from: 2014-09-01 Created: 2014-09-01 Last updated: 2018-06-07Bibliographically approved
Pruszynski, J. A., Omrani, M. & Scott, S. H. (2014). Goal-dependent modulation of fast feedback responses in primary motor cortex. Journal of Neuroscience, 34(13), 4608-4617
Open this publication in new window or tab >>Goal-dependent modulation of fast feedback responses in primary motor cortex
2014 (English)In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 34, no 13, p. 4608-4617Article in journal (Refereed) Published
Abstract [en]

Many human studies have demonstrated that rapid motor responses (i.e., muscle-stretch reflexes) to mechanical perturbations can be modified by a participant's intended response. Here, we used a novel experimental paradigm to investigate the neural mechanisms that underlie such goal-dependent modulation. Two monkeys positioned their hand in a central area against a constant load and responded to mechanical perturbations by quickly placing their hand into visually defined spatial targets. The perturbation was chosen to excite a particular proximal arm muscle or isolated neuron in primary motor cortex and two targets were placed so that the hand was pushed away from one target (OUT target) and toward the other (IN target). We chose these targets because they produced behavioral responses analogous to the classical verbal instructions used in human studies. A third centrally located target was used to examine responses with a constant goal. Arm muscles and neurons robustly responded to the perturbation and showed clear goal-dependent responses ∼35 and 70 ms after perturbation onset, respectively. Most M1 neurons and all muscles displayed larger perturbation-related responses for the OUT target than the IN target. However, a substantial number of M1 neurons showed more complex patterns of target-dependent modulation not seen in muscles, including greater activity for the IN target than the OUT target, and changes in target preference over time. Together, our results reveal complex goal-dependent modulation of fast feedback responses in M1 that are present early enough to account for goal-dependent stretch responses in arm muscles.

Place, publisher, year, edition, pages
Society for neuroscience, 2014
Keywords
feedback, instruction, primary motor cortex, reflex, single-unit recording, task-goal
National Category
Neurosciences Physiology
Identifiers
urn:nbn:se:umu:diva-87438 (URN)10.1523/JNEUROSCI.4520-13.2014 (DOI)000333674200017 ()24672006 (PubMedID)
Available from: 2014-04-01 Created: 2014-04-01 Last updated: 2018-06-08Bibliographically approved
Omrani, M., Pruszynski, J. A., Murnaghan, C. D. & Scott, S. H. (2014). Perturbation-evoked responses in primary motor cortex are modulated by behavioral context. Journal of Neurophysiology, 112(11), 2985-3000
Open this publication in new window or tab >>Perturbation-evoked responses in primary motor cortex are modulated by behavioral context
2014 (English)In: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598, Vol. 112, no 11, p. 2985-3000Article in journal (Refereed) Published
Abstract [en]

Corrective responses to external perturbations are sensitive to the behavioral task being performed. It is believed that primary motor cortex (M1) forms part of a transcortical pathway that contributes to this sensitivity. Previous work has identified two distinct phases in the perturbation response of M1 neurons, an initial response starting similar to 20 ms after perturbation onset that does not depend on the intended motor action and a task- dependent response that begins similar to 40 ms after perturbation onset. However, this invariant initial response may reflect ongoing postural control or a task- independent response to the perturbation. The present study tested these two possibilities by examining if being engaged in an ongoing postural task before perturbation onset modulated the initial perturbation response in M1. Specifically, mechanical perturbations were applied to the shoulder and/ or elbow while the monkey maintained its hand at a central target or when it was watching a movie and not required to respond to the perturbation. As expected, corrective movements, muscle stretch responses, and M1 population activity in the late perturbation epoch were all significantly diminished in the movie task. Strikingly, initial perturbation responses (<40 ms postperturbation) remained the same across tasks, suggesting that the initial phase of M1 activity constitutes a task- independent response that is sensitive to the properties of the mechanical perturbation but not the goal of the ongoing motor task.

Place, publisher, year, edition, pages
American Physiological Society, 2014
Keywords
feedback control, task dependency, transcortical feedback pathway, reflex, task-independent sponse, neural activity, primary motor cortex
National Category
Neurosciences Neurology Physiology
Identifiers
urn:nbn:se:umu:diva-97891 (URN)10.1152/jn.00270.2014 (DOI)000346023000024 ()
Available from: 2015-01-13 Created: 2015-01-08 Last updated: 2018-06-07Bibliographically approved
Pruszynski, J. A. (2014). Primary motor cortex and fast feedback responses to mechanical perturbations: a primer on what we know now and some suggestions on what we should find out next.. Frontiers in Integrative Neuroscience, 8
Open this publication in new window or tab >>Primary motor cortex and fast feedback responses to mechanical perturbations: a primer on what we know now and some suggestions on what we should find out next.
2014 (English)In: Frontiers in Integrative Neuroscience, ISSN 1662-5145, E-ISSN 1662-5145, Vol. 8Article in journal (Refereed) Published
Abstract [en]

Many researchers have drawn a clear distinction between fast feedback responses to mechanical perturbations (e.g., stretch responses) and voluntary control processes. But this simple distinction is difficult to reconcile with growing evidence that long-latency stretch responses share most of the defining capabilities of voluntary control. My general view-and I believe a growing consensus-is that the functional similarities between long-latency stretch responses and voluntary control processes can be readily understood based on their shared neural circuitry, especially a transcortical pathway through primary motor cortex. Here I provide a very brief and selective account of the human and monkey studies linking a transcortical pathway through primary motor cortex to the generation and functional sophistication of the long-latency stretch response. I then lay out some of the notable issues that are ready to be answered.

National Category
Basic Medicine
Identifiers
urn:nbn:se:umu:diva-117593 (URN)10.3389/fnint.2014.00072 (DOI)25309359 (PubMedID)
Available from: 2016-03-02 Created: 2016-03-02 Last updated: 2018-06-07
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