The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Douglas A Nitz - One of the best experts on this subject based on the ideXlab platform.
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secondary motor cortex transforms spatial information into planned Action during navigation
Current Biology, 2020Co-Authors: Jacob M Olson, Sarah Montgomery, Douglas A NitzAbstract:Summary Fluid navigation requires constant updating of planned movements to adapt to evolving obstacles and goals. For that reason, a neural substrate for navigation demands spatial and environmental information and the ability to effect Actions through efferents. The secondary motor cortex (M2) is a prime candidate for this role given its interconnectivity with association cortices that encode spatial relationships and its projection to the primary motor cortex. Here, we report that M2 neurons robustly encode both planned and current left/right turning Actions across multiple turn locations in a multi-route navigational task. Comparisons within a common statistical framework reveal that M2 neurons differentiate contextual factors, including environmental position, route, Action Sequence, orientation, and choice availability. Despite significant modulation by environmental factors, Action planning, and execution are the dominant output signals of M2 neurons. These results identify the M2 as a structure integrating spatial information toward the updating of planned movements.
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secondary motor cortex transforms spatial information into planned Action during navigation
bioRxiv, 2019Co-Authors: Jacob M Olson, Sarah Montgomery, Douglas A NitzAbstract:Fluid navigation requires constant updating of planned movements to adapt to evolving obstacles and goals. A neural substrate for navigation demands spatial and environmental information and the ability to effect Actions through efferents. Secondary motor cortex is a prime candidate for this role given its interconnectivity with association cortices that encode spatial relationships and its projection to primary motor cortex. Here we report that secondary motor cortex neurons robustly encode both planned and current left/right turning Actions across multiple turn locations in a multi-route navigational task. Comparisons within a common statistical framework reveal that secondary motor cortex neurons differentiate contextual factors including environmental position, route, Action Sequence, orientation, and choice availability. Despite significant modulation by context, Action planning and execution is the dominant output signal of secondary motor cortex neurons. These results identify secondary motor cortex as a structure integrating environmental context toward the updating of planned movements.
Clay B Holroyd - One of the best experts on this subject based on the ideXlab platform.
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neural representations of task context and temporal order during Action Sequence execution
Topics in Cognitive Science, 2021Co-Authors: Danesh Shahnazian, Mehdi Senoussi, Ruth M Krebs, Tom Verguts, Clay B HolroydAbstract:Routine Action Sequences can share a great deal of similarity in terms of their stimulus response mappings. As a conSequence, their correct execution relies crucially on the ability to preserve contextual and temporal information. However, there are few empirical studies on the neural mechanism and the brain areas maintaining such information. To address this gap in the literature, we recently recorded the blood-oxygen level dependent (BOLD) response in a newly developed coffee-tea making task. The task involves the execution of four Action Sequences that each comprise six consecutive decision states, which allows for examining the maintenance of contextual and temporal information. Here, we report a reanalysis of this dataset using a data-driven approach, namely multivariate pattern analysis, that examines context-dependent neural activity across several predefined regions of interest. Results highlight involvement of the inferior-temporal gyrus and lateral prefrontal cortex in maintaining temporal and contextual information for the execution of hierarchically organized Action Sequences. Furthermore, temporal information seems to be more strongly encoded in areas over the left hemisphere.
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neural representations of task context and temporal order during Action Sequence execution
bioRxiv, 2020Co-Authors: Danesh Shahnazian, Mehdi Senoussi, Ruth M Krebs, Tom Verguts, Clay B HolroydAbstract:Abstract Since routine Action Sequences can share a great deal of similarity in terms of their stimulus response mappings, their correct execution relies crucially on the ability to preserve contextual and temporal information (Lashley, 1951). However, there are few empirical studies on the neural mechanism and the brain areas maintaining such information. To address this gap in the literature, we recently recorded the blood-oxygen level dependent (BOLD) response in a newly developed coffee-tea making task (Holroyd et al., 2018). The task involves the execution of 4 Action Sequences that each feature 6 decision states. Here we report a reanalysis of this dataset using a data-driven approach, namely multivariate pattern analysis (MVPA), that examines context-dependent neural activity across several predefined regions of interest. Results highlight involvement of the inferior-temporal gyrus and lateral prefrontal cortex in maintaining temporal and contextual information for the execution of hierarchically-organized Action Sequences. Furthermore, temporal information seems to be more strongly encoded in areas over the left hemisphere.
Jacob M Olson - One of the best experts on this subject based on the ideXlab platform.
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secondary motor cortex transforms spatial information into planned Action during navigation
Current Biology, 2020Co-Authors: Jacob M Olson, Sarah Montgomery, Douglas A NitzAbstract:Summary Fluid navigation requires constant updating of planned movements to adapt to evolving obstacles and goals. For that reason, a neural substrate for navigation demands spatial and environmental information and the ability to effect Actions through efferents. The secondary motor cortex (M2) is a prime candidate for this role given its interconnectivity with association cortices that encode spatial relationships and its projection to the primary motor cortex. Here, we report that M2 neurons robustly encode both planned and current left/right turning Actions across multiple turn locations in a multi-route navigational task. Comparisons within a common statistical framework reveal that M2 neurons differentiate contextual factors, including environmental position, route, Action Sequence, orientation, and choice availability. Despite significant modulation by environmental factors, Action planning, and execution are the dominant output signals of M2 neurons. These results identify the M2 as a structure integrating spatial information toward the updating of planned movements.
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secondary motor cortex transforms spatial information into planned Action during navigation
bioRxiv, 2019Co-Authors: Jacob M Olson, Sarah Montgomery, Douglas A NitzAbstract:Fluid navigation requires constant updating of planned movements to adapt to evolving obstacles and goals. A neural substrate for navigation demands spatial and environmental information and the ability to effect Actions through efferents. Secondary motor cortex is a prime candidate for this role given its interconnectivity with association cortices that encode spatial relationships and its projection to primary motor cortex. Here we report that secondary motor cortex neurons robustly encode both planned and current left/right turning Actions across multiple turn locations in a multi-route navigational task. Comparisons within a common statistical framework reveal that secondary motor cortex neurons differentiate contextual factors including environmental position, route, Action Sequence, orientation, and choice availability. Despite significant modulation by context, Action planning and execution is the dominant output signal of secondary motor cortex neurons. These results identify secondary motor cortex as a structure integrating environmental context toward the updating of planned movements.
Kate M Wassum - One of the best experts on this subject based on the ideXlab platform.
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dynamic mesolimbic dopamine signaling during Action Sequence learning and expectation violation
Scientific Reports, 2016Co-Authors: Anne L Collins, Venuz Y Greenfield, Jeffrey K Bye, Kay E Linker, Alice S Wang, Kate M WassumAbstract:Prolonged mesolimbic dopamine concentration changes have been detected during spatial navigation, but little is known about the conditions that engender this signaling profile or how it develops with learning. To address this, we monitored dopamine concentration changes in the nucleus accumbens core of rats throughout acquisition and performance of an instrumental Action Sequence task. Prolonged dopamine concentration changes were detected that ramped up as rats executed each Action Sequence and declined after earned reward collection. With learning, dopamine concentration began to rise increasingly earlier in the execution of the Sequence and ultimately backpropagated away from stereotyped Sequence Actions, becoming only transiently elevated by the most distal and unexpected reward predictor. Action Sequence-related dopamine signaling was reactivated in well-trained rats if they became disengaged in the task and in response to an unexpected change in the value, but not identity of the earned reward. Throughout training and test, dopamine signaling correlated with Sequence performance. These results suggest that Action Sequences can engender a prolonged mode of dopamine signaling in the nucleus accumbens core and that such signaling relates to elements of the motivation underlying Sequence execution and is dynamic with learning, overtraining and violations in reward expectation.
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phasic mesolimbic dopamine signaling precedes and predicts performance of a self initiated Action Sequence task
Biological Psychiatry, 2012Co-Authors: Kate M Wassum, Sean B Ostlund, Nigel T MaidmentAbstract:Background Sequential reward-seeking Actions are readily learned despite the temporal gap between the earliest (distal) Action in the Sequence and the reward delivery. Fast dopamine signaling is hypothesized to mediate this form of learning by reporting errors in reward prediction. However, such a role for dopamine release in voluntarily initiated Action Sequences remains to be demonstrated. Methods Using fast-scan cyclic voltammetry, we monitored phasic mesolimbic dopamine release, in real time, as rats performed a self-initiated Sequence of lever presses to earn sucrose rewards. Before testing, rats received either 0 ( n = 11), 5 ( n = 11), or 10 ( n = 8) days of Action Sequence training. Results For rats acquiring the Action Sequence task at test, dopamine release was strongly elicited by response-contingent (but unexpected) rewards. With learning, a significant elevation in dopamine release preceded performance of the proximal Action and subsequently came to precede the distal Action. This predistal dopamine release response was also observed in rats previously trained on the Action Sequence task, and the amplitude of this signal predicted the latency with which rats completed the Action Sequence. Importantly, the dopamine response to contingent reward delivery was not observed in rats given extensive pretraining. Pharmacological analysis confirmed that task performance was dopamine-dependent. Conclusions These data suggest that phasic mesolimbic dopamine release mediates the influence that rewards exert over the performance of self-paced, sequentially-organized behavior and sheds light on how dopamine signaling abnormalities may contribute to disorders of behavioral control.
Patrick Perez - One of the best experts on this subject based on the ideXlab platform.
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cross view Action recognition from temporal self similarities
European Conference on Computer Vision, 2008Co-Authors: Imran N Junejo, Emilie Dexter, Ivan Laptev, Patrick PerezAbstract:This paper concerns recognition of human Actions under view changes. We explore self-similarities of Action Sequences over time and observe the striking stability of such measures across views. Building upon this key observation we develop an Action descriptor that captures the structure of temporal similarities and dissimilarities within an Action Sequence. Despite this descriptor not being strictly view-invariant, we provide intuition and experimental validation demonstrating the high stability of self-similarities under view changes. Self-similarity descriptors are also shown stable under Action variations within a class as well as discriminative for Action recognition. Interestingly, self-similarities computed from different image features possess similar properties and can be used in a complementary fashion. Our method is simple and requires neither structure recovery nor multi-view correspondence estimation. Instead, it relies on weak geometric properties and combines them with machine learning for efficient cross-view Action recognition. The method is validated on three public datasets, it has similar or superior performance compared to related methods and it performs well even in extreme conditions such as when recognizing Actions from top views while using side views for training only.
