Science posts

See science posts on page 35 below.

    • 2009
    • Ryan K. Jessup et al.
    • Error Effects in Anterior Cingulate Cortex Reverse when Error Likelihood Is High
    • Strong error-related activity in medial prefrontal cortex (mPFC) has been shown repeatedly with neuroimaging and event-related potential studies for the last several decades. Multiple theories have been proposed to account for error effects, including comparator models and conflict detection models, but the neural mechanisms that generate error signals remain in dispute. Typical studies use relatively low error rates, confounding the expectedness and the desirability of an error. Here we show with a gambling task and functional magnetic resonance imaging that when losses are more frequent than wins, the mPFC error effect disappears, and moreover, exhibits the opposite pattern by responding more strongly to unexpected wins than losses. These findings provide perspective on recent ERP studies and suggest that mPFC error effects result from a comparison between actual and expected outcomes.
    • 2008
    • Mandana Modirrousta & Lesley K. Fellows
    • Dorsal Medial Prefrontal Cortex Plays a Necessary Role in Rapid Error Prediction in Humans
    • Activity in human dorsal anterior cingulate cortex (dACC) is correlated with errors, near-misses, and response conflict. Based on these observations, this region has been cast as playing a central role in models of error processing, conflict monitoring, and cognitive control. However, clear evidence that this region of the brain is necessary for these processes has been elusive. We studied the effects of damage to this region on four different error-related measures in five patients, and 19 healthy participants. Most error-related indices were not affected by such damage: patients had intact post-error slowing, and were able to report and to correct errors after they were made with accuracies comparable with the control group. However, all five patients were notably slow to correct errors, suggesting a deficit in on-line error prediction. This slowing was associated with impairment in the conscious prediction of error likelihood before a response. This finding constitutes important c..
    • 2011
    • William H Alexander & Joshua W Brown
    • Medial prefrontal cortex as an action-outcome predictor
    • The medial prefrontal cortex (mPFC) and especially anterior cingulate cortex is central to higher cognitive function and many clinical disorders, yet its basic function remains in dispute. Various competing theories of mPFC have treated effects of errors, conflict, error likelihood, volatility and reward, using findings from neuroimaging and neurophysiology in humans and monkeys. No single theory has been able to reconcile and account for the variety of findings. Here we show that a simple model based on standard learning rules can simulate and unify an unprecedented range of known effects in mPFC. The model reinterprets many known effects and suggests a new view of mPFC, as a region concerned with learning and predicting the likely outcomes of actions, whether good or bad. Cognitive control at the neural level is then seen as a result of evaluating the probable and actual outcomes of one's actions.
    • 2011
    • Derek Evan Nee et al.
    • Functional heterogeneity of conflict, error, task-switching, and unexpectedness effects within medial prefrontal cortex
    • The last decade has seen considerable discussion regarding a theoretical account of medial prefrontal cortex (mPFC) function with particular focus on the anterior cingulate cortex. The proposed theories have included conflict detection, error likelihood prediction, volatility monitoring, and several distinct theories of error detection. Arguments for and against particular theories often treat mPFC as functionally homogeneous, or at least nearly so, despite some evidence for distinct functional subregions. Here we used functional magnetic resonance imaging (fMRI) to simultaneously contrast multiple effects of error, conflict, and task-switching that have been individually construed in support of various theories. We found overlapping yet functionally distinct subregions of mPFC, with activations related to dominant error, conflict, and task-switching effects successively found along a rostral–ventral to caudal–dorsal gradient within medial prefrontal cortex. Activ..
    • 2004
    • Ugur Sak
    • A Synthesis of Research on Psychological Types of Gifted Adolescents
    • In this study, the author synthesizes results of studies about personality types of gifted adolescents. Fourteen studies were coded with 19 independent samples. The total number of identified participants in original studies was 5,723. The most common personality types among gifted adolescents were “intuitive” and “perceiving.” They were higher on the Introversion, Intuition, Thinking, and Perceiving dimensions of the personality scales of the Myers-Briggs Type Indicator (MBTI) when compared to general high school students. Also, gifted adolescents differed within the group by gender and by ability. Based on the findings, the author discusses teaching practices for gifted students according to their personality preferences.
    • 2014
    • Adam E. Green et al.
    • Frontopolar activity and connectivity support dynamic conscious augmentation of creative state
    • No ability is more valued in the modern innovation-fueled economy than thinking creatively on demand, and the “thinking cap” capacity to augment state creativity (i.e., to try and succeed at thinking more creatively) is of broad importance for education and a rich mental life. Although brain-based creativity research has focused on static individual differences in trait creativity, less is known about changes in creative state within an individual. How does the brain augment state creativity when creative thinking is required? Can augmented creative state be consciously engaged and disengaged dynamically across time? Using a novel “thin slice” creativity paradigm in 55 fMRI participants performing verb-generation, we successfully cued large, conscious, short-duration increases in state creativity, indexed quantitatively by a measure of semantic distance derived via latent semantic analysis. A region of left frontopolar cortex, previously associated with creati..
    • 2015
    • Anthony J. Ryals et al.
    • Associative Recognition Memory Awareness Improved by Theta-Burst Stimulation of Frontopolar Cortex
    • Neuroimaging and lesion studies have implicated specific prefrontal cortex locations in subjective memory awareness. Based on this evidence, a rostrocaudal organization has been proposed whereby increasingly anterior prefrontal regions are increasingly involved in memory awareness. We used theta-burst transcranial magnetic stimulation (TBS) to temporarily modulate dorsolateral versus frontopolar prefrontal cortex to test for distinct causal roles in memory awareness. In three sessions, participants received TBS bilaterally to frontopolar cortex, dorsolateral prefrontal cortex, or a control location prior to performing an associative-recognition task involving judgments of memory awareness. Objective memory performance (i.e., accuracy) did not differ based on stimulation location. In contrast, frontopolar stimulation significantly influenced several measures of memory awareness. During study, judgments of learning were more accurate such that lower ratings were given to items that wer..
    • 2008
    • Ahmed A. Moustafa et al
    • A dopaminergic basis for working memory, learning and attentional shifting in Parkinsonism
    • Parkinson's disease (PD) patients exhibit cognitive deficits, including reinforcement learning, working memory (WM) and set shifting. Computational models of the basal ganglia–frontal system posit similar mechanisms for these deficits in terms of reduced dynamic range of striatal dopamine (DA) signals in both medicated and non-medicated states. Here, we report results from the first study that tests PD patients on and off dopaminergic medications in a modified version of the AX continuous performance (AX-CPT) working memory task, consisting of three performance phases and one phase requiring WM associations to be learned via reinforcement feedback. Patients generally showed impairments relative to controls. Medicated patients showed deficits specifically when having to ignore distracting stimuli during the delay. Our models suggest that this impairment is due to medication causing excessive WM updating by enhancing striatal “Go” signals that facilitate such updating..
    • 2010
    • Okihide Hikosaka et al.
    • Switching from automatic to controlled behavior: cortico-basal ganglia mechanisms
    • Most daily tasks are performed almost automatically, but occasionally it is necessary to alter a routine if something changes in the environment and the routine behavior becomes inappropriate. Such behavioral switching can occur either retroactively based on error feedback or proactively by detecting a contextual cue. Recent imaging and electrophysiological data in humans and monkeys support the view that the frontal cortical areas play executive roles in behavioral switching. The anterior cingulate cortex acts retroactively and the pre-supplementary motor area acts proactively to enable behavioral switching. The lateral prefrontal cortex reconfigures cognitive processes constituting the switched behavior. The subthalamic nucleus and the striatum in the basal ganglia mediate these cortical signals to achieve behavioral switching. We discuss how breaking a routine to allow more adaptive behavior requires a fine-tuned recruitment of the frontal cortical-basal ganglia neural network.
    • 2008
    • Hannah S. Locke et al.
    • Motivational influences on cognitive control: Behavior, brain activation, and individual differences
    • What changes in brain activity are associated with changes in motivational state? The present study addressed this question by having participants perform a cognitive task (AX variant of the Continuous Performance Test; AX-CPT) under three different blocked motivational conditions (reward-incentive, penalty-incentive, and baseline). Behavioral data showed that the incentive conditions modulated task performance, potentially by altering participants’ cognitive control strategy. Neuroimaging data indicated that the reward condition was associated with a sustained increase in a primarily right-lateralized network that included parietal and prefrontal cortex. Additionally, individual differences were observed, such that activation in both reward-related brain regions and frontopolar cortex was linked to the degree of motivation-induced performance enhancement and to motivation-related personality variables. These results suggest that changes in motivational state may modulate perfo..

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