Science posts

See science posts on page 42 below.

    • 2005
    • Trevor W. Robbins
    • Chemistry of the mind: Neurochemical modulation of prefrontal cortical function
    • The neurochemical modulation of prefrontal cortical function is reviewed with special reference to the ascending dopaminergic and serotoninergic projections. Evidence is surveyed from studies of rats, nonhuman primates, and humans to suggest that prefrontal dopamine has specific functions in attentional control and working memory, mediated mainly through the D1 receptor, whereas manipulations of serotonin are shown by contrast to affect reversal learning in monkeys and human volunteers and measures of impulsivity in rats. These findings are discussed in the context of these as well as other neurotransmitter systems (including noradrenaline and acetylcholine) having distinct roles in the neuromodulation of prefrontal cortical function. The capacity of the prefrontal cortex itself to exert top-down regulation of these ascending neurochemical systems is also discussed.
    • 2009
    • Dayan P et al
    • Serotonin in affective control.
    • Serotonin is a neuromodulator that is extensively entangled in fundamental aspects of brain function and behavior. We present a computational view of its involvement in the control of appetitively and aversively motivated actions. We first describe a range of its effects in invertebrates, endowing specific structurally fixed networks with plasticity at multiple spatial and temporal scales. We then consider its rather widespread distribution in the mammalian brain. We argue that this is associated with a more unified representational and functional role in aversive processing that is amenable to computational analyses with the kinds of reinforcement learning techniques that have helped elucidate dopamine's role in appetitive behavior. Finally, we suggest that it is only a partial reflection of dopamine because of essential asymmetries between the natural statistics of rewards and punishments.
    • 2001
    • Wright, Christopher I. et al
    • Differential prefrontal cortex and amygdala habituation to repeatedly presented emotional stimuli
    • Repeated presentations of emotional facial expressions were used to assess habituation in the human brain using fMRI. Significant fMRI signal decrement was present in the left dorsolateral prefrontal and premotor cortex, and right amygdala. Within the left prefrontal cortex greater habituation to happy vs fearful stimuli was evident, suggesting devotion of sustained neural resources for processing of threat vs safety signals. In the amygdala, significantly greater habituation was observed on the right compared to the left. In contrast, the left amygdala was significantly more activated than the right to the contrast of fear vs happy. We speculate that the right amygdala is part of a dynamic emotional stimulus detection system, while the left is specialized for sustained stimulus evaluations.
    • 2013
    • Li Yan McCurdy et al
    • Anatomical Coupling between Distinct Metacognitive Systems for Memory and Visual Perception
    • A recent study found that, across individuals, gray matter volume in the frontal polar region was correlated with visual metacognition capacity (i.e., how well one's confidence ratings distinguish between correct and incorrect judgments). A question arises as to whether the putative metacognitive mechanisms in this region are also used in other metacognitive tasks involving, for example, memory. A novel psychophysical measure allowed us to assess metacognitive efficiency separately in a visual and a memory task, while taking variations in basic task performance capacity into account. We found that, across individuals, metacognitive efficiencies positively correlated between the two tasks. However, voxel-based morphometry analysis revealed distinct brain structures for the two kinds of metacognition. Replicating a previous finding, variation in visual metacognitive efficiency was correlated with volume of frontal polar regions. However, variation in memory metacognitive efficiency was..
    • 2012
    • Chris D. Frith
    • The role of metacognition in human social interactions
    • Metacognition concerns the processes by which we monitor and control our own cognitive processes. It can also be applied to others, in which case it is known as mentalizing. Both kinds of metacognition have implicit and explicit forms, where implicit means automatic and without awareness. Implicit metacognition enables us to adopt a we-mode, through which we automatically take account of the knowledge and intentions of others. Adoption of this mode enhances joint action. Explicit metacognition enables us to reflect on and justify our behaviour to others. However, access to the underlying processes is very limited for both self and others and our reports on our own and others' intentions can be very inaccurate. On the other hand, recent experiments have shown that, through discussions of our perceptual experiences with others, we can detect sensory signals more accurately, even in the absence of objective feedback. Through our willingness to discuss with others the reasons for our act..
    • 2014
    • Hee Seung Lee et al
    • An fMRI investigation of instructional guidance in mathematical problem solving
    • In this fMRI study, students learned to solve algebra-like problems in one of the four instructional conditions during behavioral session and solved transfer problems during imaging session. During learning, subjects were given explanatory or non-explanatory verbal instruction, and examples that illustrated the problem structure or the solution procedure. During transfer, participants solved problems that required complex graphical parsing and problems that required algebraic transformations. Explanatory instruction helped in the initial phase of learning, but this benefit disappeared in transfer. The example type had little effect on learning, but interacted with problem type in the transfer. Only for algebraic problems, the structural example led to better transfer than the procedural example. The imaging data revealed no effect of verbal instruction, but found that participants who had studied structural examples showed higher engagement in the prefrontal cortex and angular gyrus...
    • 2014
    • Micah Allen e al
    • Balancing internal and external attention: mind-wandering variability predicts error awareness
    • Spontaneous, endogenously driven fluctuations in attention are common occurrences, impacting both cognition and well-being. Such fluctuations, known as 'mind-wandering', are often treated as executive failures and recruit the default mode network (DMN). However, recent evidence suggests that task-unrelated thoughts (TUTS) can also facilitate memory, creativity, and meta-cognition. To clarify the costs and benefits of mind-wandering, we investigated TUTs during the error-awareness fMRI task (EAT). 42 participants (27 females) completed the EAT during fMRI scanning. The EAT is a visuomotor response inhibition task with color-word "Go" (e.g. the word red colored green) and "Stop" targets (the word red colored red). Participant's TUT intensity (1-7) was assessed at pseudo-random intervals. For each participant, mean stop accuracy (SA), error-awareness (EA), TUT intensity (TUTMean), and TUT variability (TUTSD) were calculated. Blood-oxygenation level dependent responses to stop accuracy, ..
    • 2010
    • Reginald B. Adams, Jr. et al
    • Cross-cultural Reading the Mind in the Eyes: An fMRI Investigation
    • The ability to infer others' thoughts, intentions, and feelings is regarded as uniquely human. Over the last few decades, this remarkable ability has captivated the attention of philosophers, primatologists, clinical and developmental psychologists, anthropologists, social psychologists, and cognitive neuroscientists. Most would agree that the capacity to reason about others' mental states is innately prepared, essential for successful human social interaction. Whether this ability is culturally tuned, however, remains entirely uncharted on both the behavioral and neural levels. Here we provide the first behavioral and neural evidence for an intracultural advantage (better performance for same- vs. other-culture) in mental state decoding in a sample of native Japanese and white American participants. We examined the neural correlates of this intracultural advantage using fMRI, revealing greater bilateral posterior superior temporal sulci recruitment during same- versus other-culture ..
    • 2010
    • John R. Anderson et al
    • Cognitive and metacognitive activity in mathematical problem solving: prefrontal and parietal patterns
    • Students were taught an algorithm for solving a new class of mathematical problems. Occasionally in the sequence of problems, they encountered exception problems that required that they extend the algorithm. Regular and exception problems were associated with different patterns of brain activation. Some regions showed a Cognitive pattern of being active only until the problem was solved and no difference between regular or exception problems. Other regions showed a Metacognitive pattern of greater activity for exception problems and activity that extended into the post-solution period, particularly when an error was made. The Cognitive regions included some of parietal and prefrontal regions associated with the triple-code theory of (Dehaene, S., Piazza, M., Pinel, P., & Cohen, L. (2003). Three parietal circuits for number processing. Cognitive Neuropsychology, 20, 487–506) and associated with algebra equation solving in the ACT-R theory (Anderson, J. R. (2005). Human symbol manipula..
    • 2009
    • Ken Yaoi et al
    • Is the self special in the dorsomedial prefrontal cortex? An fMRI study
    • In recent years, several neuroimaging studies have suggested that the neural basis of the self-referential process1 is special, especially in the medial prefrontal cortex (MPFC). However, it remains controversial whether activity of the MPFC (and other related brain regions) appears only during the self-referential process. We investigated the neural correlates during the processing of references to the self, close other (friend), and distant other (prime minister) using fMRI. In comparison with baseline findings, referential processing to the three kinds of persons defined above showed common activation patterns in the dorsomedial prefrontal cortex (DMPFC), left middle temporal gyrus, left angular gyrus, posterior cingulate cortex and right cerebellum. Additionally, percent changes in BOLD signal in five regions of interest demonstrated the same findings. The result indicated that DMPFC was not special for the self-referential process, while there are common neural bases for evaluat..