Behavioral/Systems/Cognitive Distinct Representations of a Perceptual Decision and the Associated Oculomotor Plan in the Monkey Lateral Intraparietal Area

Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6074, USA.
The Journal of Neuroscience : The Official Journal of the Society for Neuroscience (Impact Factor: 6.34). 01/2011; 31(3):913-21. DOI: 10.1523/JNEUROSCI.4417-10.2011
Source: PubMed


Perceptual decisions that are used to select particular actions can appear to be formed in an intentional framework, in which sensory evidence is converted directly into a plan to act. However, because the relationship between perceptual decision-making and action selection has been tested primarily under conditions in which the two could not be dissociated, it is not known whether this intentional framework plays a general role in forming perceptual decisions or only reflects certain task conditions. To dissociate decision and motor processing in the brain, we recorded from individual neurons in the lateral intraparietal area of monkeys performing a task that included a flexible association between a decision about the direction of random-dot motion and the direction of the appropriate eye-movement response. We targeted neurons that responded selectively in anticipation of a particular eye-movement response. We found that these neurons encoded the perceptual decision in a manner that was distinct from how they encoded the associated response. These decision-related signals were evident regardless of whether the appropriate decision-response association was indicated before, during, or after decision formation. The results suggest that perceptual decision-making and action selection are different brain processes that only appear to be inseparable under particular behavioral contexts.

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    • "monitoring signal keeping track of the accumulated evidence. Different or additional brain regions may be involved in encoding this DVs when choices are not by design decoupled from motor plans as in the present study (Bennur and Gold, 2011; Hebart et al, 2012; O'Connell et al, 2012; de Lange et al, 2013; Filimon et al, 2013). "
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    ABSTRACT: Perceptual confidence refers to the degree to which we believe in the accuracy of our percepts. Signal detection theory suggests that perceptual confidence is computed from an internal "decision variable," which reflects the amount of available information in favor of one or another perceptual interpretation of the sensory input. The neural processes underlying these computations have, however, remained elusive. Here, we used fMRI and multivariate decoding techniques to identify regions of the human brain that encode this decision variable and confidence during a visual motion discrimination task. We used observers' binary perceptual choices and confidence ratings to reconstruct the internal decision variable that governed the subjects' behavior. A number of areas in prefrontal and posterior parietal association cortex encoded this decision variable, and activity in the ventral striatum reflected the degree of perceptual confidence. Using a multivariate connectivity analysis, we demonstrate that patterns of brain activity in the right ventrolateral prefrontal cortex reflecting the decision variable were linked to brain signals in the ventral striatum reflecting confidence. Our results suggest that the representation of perceptual confidence in the ventral striatum is derived from a transformation of the continuous decision variable encoded in the cerebral cortex.
    Cerebral Cortex 08/2014; DOI:10.1093/cercor/bhu181 · 8.67 Impact Factor
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    • "The generality of the intentional/action-based framework, however , has recently been challenged by new findings showing that signals reflecting evidence accumulation can be dissociated from signals reflecting action planning even within the same oculo-motor neurons of the LIP (Bennur & Gold, 2011). In particular, when decisions are not linked to a specific action, as part of a task set, representations for perceptual decisions appear to be independent of representations for action selection. "
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    ABSTRACT: During simple perceptual decisions, sensorimotor neurons in monkey fronto-parietal cortex represent a decision variable that guides the transformation of sensory evidence into a motor response, supporting the view that mechanisms for decision-making are closely embedded within sensorimotor structures. Within these structures, however, decision signals can be dissociated from motor signals, thus indicating that sensorimotor neurons can play multiple and independent roles in decision-making and action selection/planning. Here we used functional magnetic resonance imaging to examine whether response-selective human brain areas encode signals for decision-making or action planning during a task requiring an arbitrary association between face pictures (male vs. female) and specific actions (saccadic eye vs. hand pointing movements). The stimuli were gradually unmasked to stretch the time necessary for decision, thus maximising the temporal separation between decision and action planning. Decision-related signals were measured in parietal and motor/premotor regions showing a preference for the planning/execution of saccadic or pointing movements. In a parietal reach region, decision-related signals were specific for the stimulus category associated with its preferred pointing response. By contrast, a saccade-selective posterior intraparietal sulcus region carried decision-related signals even when the task required a pointing response. Consistent signals were observed in the motor/premotor cortex. Whole-brain analyses indicated that, in our task, the most reliable decision signals were found in the same neural regions involved in response selection. However, decision- and action-related signals within these regions can be dissociated. Differences between the parietal reach region and posterior intraparietal sulcus plausibly depend on their functional specificity rather than on the task structure.
    European Journal of Neuroscience 03/2014; 39(8). DOI:10.1111/ejn.12511 · 3.18 Impact Factor
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    • "The involvement of multiple brain regions in the oculomotor network reflects the behavioral context in which these perceptual decisions were studied (but may also be more general; see Bennur and Gold, 2011; Freedman and Assad, 2006; Rishel et al., 2013). Specifically, the monkeys were trained to indicate their direction decisions with saccadic eye movements to visual targets located along the axis of coherent motion. "
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    ABSTRACT: Perceptual decision making is a computationally demanding process that requires the brain to interpret incoming sensory information in the context of goals, expectations, preferences, and other factors. These integrative processes engage much of cortex but also require contributions from subcortical structures to affect behavior. Here we summarize recent evidence supporting specific computational roles of the basal ganglia in perceptual decision making. These roles probably share common mechanisms with the basal ganglia's other, more well-established functions in motor control, learning, and other aspects of cognition and thus can provide insights into the general roles of this important subcortical network in higher brain function.
    Neuron 08/2013; 79(4):640-9. DOI:10.1016/j.neuron.2013.07.042 · 15.05 Impact Factor
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