Champalimaud Institute for the Unknown

Lisbon, Portugal

Champalimaud Institute for the Unknown

Lisbon, Portugal
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Machado I.P.,New University of Lisbon | Machado I.P.,Champalimaud Institute for the Unknown | Luisa Gomes A.,New University of Lisbon | Gamboa H.,New University of Lisbon | And 3 more authors.
Information Processing and Management | Year: 2015

Background: Our methodology describes a human activity recognition framework based on feature extraction and feature selection techniques where a set of time, statistical and frequency domain features taken from 3-dimensional accelerometer sensors are extracted. This framework specifically focuses on activity recognition using on-body accelerometer sensors. We present a novel interactive knowledge discovery tool for accelerometry in human activity recognition and study the sensitivity to the feature extraction parametrization. Results: The implemented framework achieved encouraging results in human activity recognition. We have implemented a new set of features extracted from wearable sensors that are ambitious from a computational point of view and able to ensure high classification results comparable with the state of the art wearable systems (Mannini et al. 2013). A feature selection framework is developed in order to improve the clustering accuracy and reduce computational complexity.1 Several clustering methods such as K-Means, Affinity Propagation, Mean Shift and Spectral Clustering were applied. The K-means methodology presented promising accuracy results for person-dependent and independent cases, with 99.29% and 88.57%, respectively. Conclusions: The presented study performs two different tests in intra and inter subject context and a set of 180 features is implemented which are easily selected to classify different activities. The implemented algorithm does not stipulate, a priori, any value for time window or its overlap percentage of the signal but performs a search to find the best parameters that define the specific data. A clustering metric based on the construction of the data confusion matrix is also proposed. The main contribution of this work is the design of a novel gesture recognition system based solely on data from a single 3-dimensional accelerometer. © 2015 Published by Elsevier Ltd.

PubMed | University of California at San Diego, Stanford University, Champalimaud Institute for the Unknown, U.S. National Institutes of Health and Massachusetts Institute of Technology
Type: Journal Article | Journal: Neuron | Year: 2016

Everyday function demands efficient and flexible decision-making that allows for habitual and goal-directed action control. An inability to shift has been implicated in disorders with impaired decision-making, including obsessive-compulsive disorder and addiction. Despite this, our understanding of the specific molecular mechanisms and circuitry involved in shifting action control remains limited. Here we identify an endogenous molecular mechanism in a specific cortical-striatal pathway that mediates the transition between goal-directed and habitual action strategies. Deletion of cannabinoid type 1 (CB1) receptors from cortical projections originating in the orbital frontal cortex (OFC) prevents mice from shifting from goal-directed to habitual instrumental lever pressing. Activity of OFC neurons projecting to dorsal striatum (OFC-DS) and, specifically, activity of OFC-DS terminals is necessary for goal-directed action control. Lastly, CB1 deletion from OFC-DS neurons prevents the shift from goal-directed to habitual action control. These data suggest that the emergence of habits depends on endocannabinoid-mediated attenuation of a competing circuit controlling goal-directed behaviors.

Gremel C.M.,U.S. National Institutes of Health | Costa R.M.,U.S. National Institutes of Health | Costa R.M.,Champalimaud Institute for the Unknown
Frontiers in Computational Neuroscience | Year: 2013

Shifting between motor plans is often necessary for adaptive behavior. When faced with changing consequences of one's actions, it is often imperative to switch from automatic actions to deliberative and controlled actions. The pre-supplementary motor area (pre-SMA) in primates, akin to the premotor cortex (M2) in mice, has been implicated in motor learning and planning, and action switching. We hypothesized that M2 would be differentially involved in goal-directed actions, which are controlled by their consequences vs. habits, which are more dependent on their past reinforcement history and less on their consequences. To investigate this, we performed M2 lesions in mice and then concurrently trained them to press the same lever for the same food reward using two different schedules of reinforcement that differentially bias towards the use of goal-directed versus habitual action strategies. We then probed whether actions were dependent on their expected consequence through outcome revaluation testing. We uncovered that M2 lesions did not affect the acquisition of lever-pressing. However, in mice with M2 lesions, lever-pressing was insensitive to changes in expected outcome value following goal-directed training. However, habitual actions were intact. We confirmed a role for M2 in goal-directed but not habitual actions in separate groups of mice trained on the individual schedules biasing towards goal-directed versus habitual actions. These data indicate that M2 is critical for actions to be updated based on their consequences, and suggest that habitual action strategies may not require processing by M2 and the updating of motor plans. © 2013 Gremel and Costa.

Gremel C.M.,U.S. National Institutes of Health | Costa R.M.,Champalimaud Institute for the Unknown
Nature Communications | Year: 2013

Shifting between goal-directed and habitual actions allows for efficient and flexible decision making. Here we demonstrate a novel, within-subject instrumental lever-pressing paradigm, in which mice shift between goal-directed and habitual actions. We identify a role for orbitofrontal cortex (OFC) in actions following outcome revaluation, and confirm that dorsal medial (DMS) and lateral striatum (DLS) mediate different action strategies. Simultaneous in vivo recordings of OFC, DMS and DLS neuronal ensembles during shifting reveal that the same neurons display different activities depending on whether presses are goal-directed or habitual, with DMS and OFC becoming more and DLS less engaged during goal-directed actions. Importantly, the magnitude of neural activity changes in OFC following changes in outcome value positively correlates with the level of goal-directed behavior. Chemogenetic inhibition of OFC disrupts goal-directed actions, whereas optogenetic activation of OFC specifically increases goal-directed pressing. These results also reveal a role for OFC in action revaluation, which has implications for understanding compulsive behavior.

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