The Experts below are selected from a list of 94512 Experts worldwide ranked by ideXlab platform
Matthew F S Rushworth - One of the best experts on this subject based on the ideXlab platform.
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identification and disruption of a Neural Mechanism for accumulating prospective metacognitive information prior to decision making
Neuron, 2021Co-Authors: Kentaro Miyamoto, Lennart Verhagen, Nadescha Trudel, Kevin Kamermans, Michele C Lim, Alberto Lazari, Marco K Wittmann, Matthew F S RushworthAbstract:More than one type of probability must be considered when making decisions. It is as necessary to know one's chance of performing choices correctly as it is to know the chances that desired outcomes will follow choices. We refer to these two choice contingencies as internal and external probability. Neural activity across many frontal and parietal areas reflected internal and external probabilities in a similar manner during decision-making. However, Neural recording and manipulation approaches suggest that one area, the anterior lateral prefrontal cortex (alPFC), is highly specialized for making prospective, metacognitive judgments on the basis of internal probability; it is essential for knowing which decisions to tackle, given its assessment of how well they will be performed. Its activity predicted prospective metacognitive judgments, and individual variation in activity predicted individual variation in metacognitive judgments. Its disruption altered metacognitive judgments, leading participants to tackle perceptual decisions they were likely to fail.
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Activation and disruption of a Neural Mechanism for novel choice in monkeys
Nature, 2021Co-Authors: Alessandro Bongioanni, Davide Folloni, Lennart Verhagen, Jérôme Sallet, Miriam C. Klein-flügge, Matthew F S RushworthAbstract:Neural Mechanisms that mediate the ability to make value-guided decisions have received substantial attention in humans and animals^ 1 – 6 . Experiments in animals typically involve long training periods. By contrast, choices in the real world often need to be made between new options spontaneously. It is therefore possible that the Neural Mechanisms targeted in animal studies differ from those required for new decisions, which are typical of human imaging studies. Here we show that the primate medial frontal cortex (MFC)^ 7 is involved in making new inferential choices when the options have not been previously experienced. Macaques spontaneously inferred the values of new options via similarities with the component parts of previously encountered options. Functional magnetic resonance imaging (fMRI) suggested that this ability was mediated by the MFC, which is rarely investigated in monkeys^ 3 ; MFC activity reflected different processes of comparison for unfamiliar and familiar options. Multidimensional representations of options in the MFC used a coding scheme resembling that of grid cells, which is well known in spatial navigation^ 8 , 9 , to integrate dimensions in this non-physical space^ 10 during novel decision-making. By contrast, the orbitofrontal cortex held specific object-based value representations^ 1 , 11 . In addition, minimally invasive ultrasonic disruption^ 12 of MFC, but not adjacent tissue, altered the estimation of novel choice values. The primate medial frontal cortex has a key role in mediating the ability to choose between new options based on little or no direct experience.
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a Neural Mechanism underlying failure of optimal choice with multiple alternatives
Nature Neuroscience, 2014Co-Authors: Bolton K H Chau, Nils Kolling, Laurence T Hunt, Mark E Walton, Matthew F S RushworthAbstract:Despite widespread interest in Neural Mechanisms of decision-making, most investigations focus on decisions between just two options. Here we adapt a biophysically plausible model of decision-making to predict how a key decision variable, the value difference signal-encoding how much better one choice is than another-changes with the value of a third, but unavailable, alternative. The model predicts a surprising failure of optimal decision-making: greater difficulty choosing between two options in the presence of a third very poor, as opposed to very good, alternative. Both investigation of human decision-making and functional magnetic resonance imaging-based measurements of value difference signals in ventromedial prefrontal cortex (vmPFC) bore out this prediction. The vmPFC signal decreased in the presence of low-value third alternatives, and vmPFC effect sizes predicted individual variation in suboptimal decision-making in the presence of multiple alternatives. The effect contrasts with that of divisive normalization in parietal cortex.
Mehrdad Jazayeri - One of the best experts on this subject based on the ideXlab platform.
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a precise and adaptive Neural Mechanism for predictive temporal processing in the frontal cortex
Neuron, 2021Co-Authors: Nicolas Meirhaeghe, Mehrdad Jazayeri, Hansem SohnAbstract:Summary The theory of predictive processing posits that the brain computes expectations to process information predictively. Empirical evidence in support of this theory, however, is scarce and largely limited to sensory areas. Here, we report a precise and adaptive Mechanism in the frontal cortex of non-human primates consistent with predictive processing of temporal events. We found that the speed of Neural dynamics is precisely adjusted according to the average time of an expected stimulus. This speed adjustment, in turn, enables neurons to encode stimuli in terms of deviations from expectation. This lawful relationship was evident across multiple experiments and held true during learning: when temporal statistics underwent covert changes, Neural responses underwent predictable changes that reflected the new mean. Together, these results highlight a precise mathematical relationship between temporal statistics in the environment and Neural activity in the frontal cortex that may serve as a Mechanism for predictive temporal processing.
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A Neural Mechanism for Sensing and Reproducing a Time Interval.
Current biology : CB, 2015Co-Authors: Mehrdad Jazayeri, Michael N. ShadlenAbstract:Timing plays a crucial role in sensorimotor function. However, the Neural Mechanisms that enable the brain to flexibly measure and reproduce time intervals are not known. We recorded Neural activity in parietal cortex of monkeys in a time reproduction task. Monkeys were trained to measure and immediately afterward reproduce different sample intervals. While measuring an interval, Neural responses had a nonlinear profile that increased with the duration of the sample interval. Activity was reset during the transition from measurement to production and was followed by a ramping activity whose slope encoded the previously measured sample interval. We found that firing rates at the end of the measurement epoch were correlated with both the slope of the ramp and the monkey's corresponding production interval on a trial-by-trial basis. Analysis of response dynamics further linked the rate of change of firing rates in the measurement epoch to the slope of the ramp in the production epoch. These observations suggest that, during time reproduction, an interval is measured prospectively in relation to the desired motor plan to reproduce that interval.
Yumie Ono - One of the best experts on this subject based on the ideXlab platform.
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a cross brain Neural Mechanism for human to human verbal communication
Social Cognitive and Affective Neuroscience, 2018Co-Authors: Joy Hirsch, Adam J Noah, Xian Zhang, Swethasri Dravida, Yumie OnoAbstract:Neural Mechanisms that mediate dynamic social interactions remain understudied despite their evolutionary significance. The interactive brain hypothesis proposes that interactive social cues are processed by dedicated brain substrates and provides a general theoretical framework for investigating the underlying Neural Mechanisms of social interaction. We test the specific case of this hypothesis proposing that canonical language areas are upregulated and dynamically coupled across brains during social interactions based on talking and listening. Functional near-infrared spectroscopy (fNIRS) was employed to acquire simultaneous deoxyhemoglobin (deOxyHb) signals of the brain on partners who alternated between speaking and listening while doing an Object Naming & Description task with and without interaction in a natural setting. Comparison of interactive and non-interactive conditions confirmed an increase in Neural activity associated with Wernicke’s area including the superior temporal gyrus (STG) during interaction (P = 0.04). However, the hypothesis was not supported for Broca’s area. Cross-brain coherence determined by wavelet analyses of signals originating from the STG and the subcentral area was greater during interaction than non-interaction (P < 0.01). In support of the interactive brain hypothesis these findings suggest a dynamically coupled cross-brain Neural Mechanism dedicated to pathways that share interpersonal information.
Mikko Sams - One of the best experts on this subject based on the ideXlab platform.
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short term plasticity as a Neural Mechanism supporting memory and attentional functions
Brain Research, 2011Co-Authors: Iiro P Jaaskelainen, Jyrki Ahveninen, Mark L Andermann, John W Belliveau, Tommi Raij, Mikko SamsAbstract:Based on behavioral studies, several relatively distinct perceptual and cognitive functions have been defined in cognitive psychology such as sensory memory, short-term memory, and selective attention. Here, we review evidence suggesting that some of these functions may be supported by shared underlying neuronal Mechanisms. Specifically, we present, based on an integrative review of the literature, a hypothetical model wherein short-term plasticity, in the form of transient center-excitatory and surround-inhibitory modulations, constitutes a generic processing principle that supports sensory memory, short-term memory, involuntary attention, selective attention, and perceptual learning. In our model, the size and complexity of receptive fields/level of abstraction of Neural representations, as well as the length of temporal receptive windows, increases as one steps up the cortical hierarchy. Consequently, the type of input (bottom-up vs. top down) and the level of cortical hierarchy that the inputs target, determine whether short-term plasticity supports purely sensory vs. semantic short-term memory or attentional functions. Furthermore, we suggest that rather than discrete memory systems, there are continuums of memory representations from short-lived sensory ones to more abstract longer-duration representations, such as those tapped by behavioral studies of short-term memory.
John A Assad - One of the best experts on this subject based on the ideXlab platform.
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a proposed common Neural Mechanism for categorization and perceptual decisions
Nature Neuroscience, 2011Co-Authors: David J Freedman, John A AssadAbstract:One of the most fascinating issues in neuroscience is how the brain makes decisions. Recent evidence points to the parietal cortex as an important locus for certain kinds of decisions. Because parietal neurons are also involved in movements, it has been proposed that decisions are encoded in an intentional, action-based framework based on the movements used to report decisions. An alternative or complementary view is that decisions represent more abstract information not linked to movements per se. Parallel experiments on categorization suggest that parietal neurons can indeed represent abstract categorical outcomes that are not linked to movements. This could provide a unified or complementary view of how the brain decides and categorizes.
