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| Author | Zopf, Regine; Truong, Sandra; Finkbeiner, Matthew; Friedman, Jason; Williams, Mark A | ||||
Title  |
Viewing and feeling touch modulates hand position for reaching | Type | Journal Article | ||
| Year | 2011 | Publication | Neuropsychologia | Abbreviated Journal | |
| Volume | 49 | Issue | 5 | Pages | 1287–1293 |
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| Abstract | Action requires knowledge of our body location in space. Here we asked if interactions with the external world prior to a reaching action influence how visual location information is used. We investigated if the temporal synchrony between viewing and feeling touch modulates the integration of visual and proprioceptive body location information for action. We manipulated the synchrony between viewing and feeling touch in the Rubber Hand Illusion paradigm prior to participants performing a ballistic reaching task to a visually specified target. When synchronous touch was given, reaching trajectories were significantly shifted compared to asynchronous touch. The direction of this shift suggests that touch influences the encoding of hand position for action. On the basis of this data and previous findings, we propose that the brain uses correlated cues from passive touch and vision to update its own position for action and experience of self-location. | ||||
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| Notes | Approved | no | |||
| Call Number | Penn State @ write.to.jason @ | Serial | 23 | ||
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| Author | Friedman, Jason; Flash, Tamar | ||||
| Title |
Trajectory of the index finger during grasping | Type | Journal Article | ||
| Year | 2009 | Publication | Experimental Brain Research | Abbreviated Journal | Exp Brain Res |
| Volume | 196 | Issue | 4 | Pages | 497-509 |
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| Abstract | The trajectory of the index finger during grasping movements was compared to the trajectories predicted by three optimization-based models. The three models consisted of minimizing the integral of the weighted squared joint derivatives along the path (inertia-like cost), minimizing torque change, and minimizing angular jerk. Of the three models, it was observed that the path of the fingertip and the joint trajectories, were best described by the minimum angular jerk model. This model, which does not take into account the dynamics of the finger, performed equally well when the inertia of the finger was altered by adding a 20 g weight to the medial phalange. Thus, for the finger, it appears that trajectories are planned based primarily on kinematic considerations at a joint level. | ||||
| Address | Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel, write.to.jason@gmail.com | ||||
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| Language | English | Summary Language | Original Title | ||
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| Series Volume | Series Issue | Edition | |||
| ISSN | 1432-1106 | ISBN | Medium | ||
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| Notes | PMID:19521692 | Approved | no | ||
| Call Number | Penn State @ write.to.jason @ | Serial | 17 | ||
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| Author | Friedman, Jason; SKM, Varadhan; Zatsiorsky, Vladimir M.; Latash, Mark L. | ||||
| Title |
The sources of two components of variance: an example of multifinger cyclic force production tasks at different frequencies | Type | Journal Article | ||
| Year | 2009 | Publication | Experimental Brain Research | Abbreviated Journal | Exp Brain Res |
| Volume | 196 | Issue | 2 | Pages | 263-277 |
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| Abstract | In a multifinger cyclic force production task, the finger force variance measured across trials can be decomposed into two components, one that affects the combined force output (“bad variance”) and one that does not (“good variance”). Previous studies have found similar time patterns of “bad variance” and force rate leading to an approximately linear relationship between them. Based on this finding and a recently developed model of multifinger force production, we expected the “bad variance” during cyclic force production to increase monotonically with the rate of force change, both within a cycle and across trials at different frequencies. Alternatively, “bad variance” could show a dependence on task frequency, not on actual force derivative values. Healthy subjects were required to produce cyclic force patterns to prescribed targets by pressing on unidimensional force sensors, at a frequency set by a metronome. The task was performed with only the index finger, and with all four fingers. In the task with all four fingers, the “good variance” increased approximately linearly with an increase in the force magnitude. The “bad variance” showed within-a-cycle modulation similar to that of the force rate. However, an increase in the frequency did not lead to an increase in the “bad variance” that could be expected based on the natural relationships between action frequency and the rate of force change modulation. The results have been interpreted in the framework of an earlier model of multifinger force production where “bad variance” is a result of variance of the timing parameter. The unexpected lack of modulation of the “bad variance” with frequency suggests a drop in variance of the timing parameter with increased frequency. This mechanism may serve to maintain a constant acceptable level of variance under different conditions. | ||||
| Address | Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, USA | ||||
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| Language | English | Summary Language | Original Title | ||
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| ISSN | 1432-1106 | ISBN | Medium | ||
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| Notes | PMID:19468721 | Approved | no | ||
| Call Number | Penn State @ write.to.jason @ | Serial | 15 | ||
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| Author | Nahab, Fatta; Kundu, Prantik; Gallea, Cecile; Kakareka, John; Pursley, Randy; Pohida, Tom; Miletta, Nathaniel; Friedman, Jason; Hallett, Mark | ||||
| Title |
The neural processes underlying self-agency | Type | Journal Article | ||
| Year | 2011 | Publication | Cerebral Cortex | Abbreviated Journal | |
| Volume | 21 | Issue | 1 | Pages | 48-55 |
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| Abstract | Self-agency (SA) is the individual’s perception that an action is the consequence of his/her own intention. The neural networks underlying SA are not well understood. We carried out a novel, ecologically valid, virtual-reality experiment using BOLD-fMRI where SA could be modulated in real-time while subjects performed voluntary finger movements. Behavioral testing was also performed to assess the explicit judgment of SA. Twenty healthy volunteers completed the experiment. Results of the behavioral testing demonstrated paradigm validity along with the identification of a bias that led subjects to over- or underestimate the amount of control they had. The fMRI experiment identified two discrete networks. These leading and lagging networks likely represent a spatial and temporal flow of information, with the leading network serving the role of mismatch detection and the lagging network receiving this information and mediating its elevation to conscious awareness, giving rise to SA. |
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| Notes | Approved | no | |||
| Call Number | Penn State @ write.to.jason @ | Serial | 21 | ||
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| Author | Finkbeiner, Matthew; Friedman, Jason | ||||
| Title |
The flexibility of nonconsciously deployed cognitive processes: Evidence from masked congruence priming | Type | Journal Article | ||
| Year | 2011 | Publication | PLoS ONE | Abbreviated Journal | |
| Volume | 6 | Issue | 2 | Pages | e17095 |
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| Abstract | Background It is well accepted in the subliminal priming literature that task-level properties modulate nonconscious processes. For example, in tasks with a limited number of targets, subliminal priming effects are limited to primes that are physically similar to the targets. In contrast, when a large number of targets are used, subliminal priming effects are observed for primes that share a semantic (but not necessarily physical) relationship with the target. Findings such as these have led researchers to conclude that task-level properties can direct nonconscious processes to be deployed exclusively over central (semantic) or peripheral (physically specified) representations. Principal Findings We find distinct patterns of masked priming for “novel” and “repeated” primes within a single task context. Novel primes never appear as targets and thus are not seen consciously in the experiment. Repeated primes do appear as targets, thereby lending themselves to the establishment of peripheral stimulus-response mappings. If the source of the masked priming effect were exclusively central or peripheral, then both novel and repeated primes should yield similar patterns of priming. In contrast, we find that both novel and repeated primes produce robust, yet distinct, patterns of priming. Conclusions Our findings indicate that nonconsciously elicited cognitive processes can be flexibly deployed over both central and peripheral representations within a single task context. While we agree that task level properties can influence nonconscious processes, our findings sharply constrain the extent of this influence. Specifically, our findings are inconsistent with extant accounts which hold that the influence of task-level properties is strong enough to restrict the deployment of nonconsciously elicited cognitive processes to a single type of representation (i.e. central or peripheral). |
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| Notes | Approved | no | |||
| Call Number | Penn State @ write.to.jason @ | Serial | 22 | ||
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