Science posts

See science posts on page 48 below.

    • 2005
    • B. Calvo-Merino et al
    • Action Observation and Acquired Motor Skills: An fMRI Study with Expert Dancers
    • When we observe someone performing an action, do our brains simulate making that action? Acquired motor skills offer a unique way to test this question, since people differ widely in the actions they have learned to perform. We used functional magnetic resonance imaging to study differences in brain activity between watching an action that one has learned to do and an action that one has not, in order to assess whether the brain processes of action observation are modulated by the expertise and motor repertoire of the observer. Experts in classical ballet, experts in capoeira and inexpert control subjects viewed videos of ballet or capoeira actions. Comparing the brain activity when dancers watched their own dance style versus the other style therefore reveals the influence of motor expertise on action observation. We found greater bilateral activations in premotor cortex and intraparietal sulcus, right superior parietal lobe and left posterior superior temporal sulcus when expert da..
    • 2009
    • Frank Krueger et al
    • The frontopolar cortex mediates event knowledge complexity: a parametric functional MRI study
    • Event knowledge is organized on the basis of goals that enable the selection of specific event sequences to organize everyday life activities. Although the medial prefrontal cortex represents event knowledge, little is known about its role in mediating event knowledge complexity. We used functional MRI to investigate the patterns of brain activation while healthy volunteers were engaged in the task of evaluating the complexity (i.e. numbers of events) of daily life activities selected on the basis of normative data. Within a left frontoparietal network, we isolated the medial frontopolar cortex as the only region that showed a linear relationship between changes in the blood oxygen level-dependent signal and changes in event knowledge complexity. Our results specify the importance of the medial frontopolar cortex in subserving event knowledge that is required to build and execute complex behavior.
    • 2009
    • Elizabeth A. Kensinger
    • Remembering the Details: Effects of Emotion
    • Though emotion conveys memory benefits, it does not enhance memory equally for all aspects of an experience, nor for all types of emotional events. In this review, I outline the behavioral evidence for arousal's focal enhancements of memory and describe the neural processes that may support those focal enhancements. I also present behavioral evidence to suggest that these focal enhancements occur more often for negative experiences than for positive ones. This result appears to arise because of valence-dependent effects on the neural processes recruited during episodic encoding and retrieval, with negative affect associated with increased engagement of sensory processes, and positive affect leading to enhanced recruitment of conceptual processes.
    • 2014
    • Brendan Behan et al
    • Right prefrontal and ventral striatum interactions underlying impulsive choice and impulsive responding
    • Although a multifaceted concept, many forms of impulsivity may originate from interactions between prefrontally-mediated cognitive control mechanisms and limbic, reward or incentive salience approach processes. We describe a novel task that combines reward and control processes to probe this putative interaction. The task involves elements of the monetary incentive delay task (Knutson et al., [2000]: Neuroimage 12:20–27) and the Go/No-Go task (Garavan et al., [1999]: Neuroimage 17:1820–1829) and requires human subjects to make fast responses to targets for financial reward but to occasionally inhibit responding when a NoGo signal rather than a target is presented. In elucidating the dynamic between reward anticipation and control we observed that successful inhibitions on monetary trials, relative to unsuccessful inhibitions, were associated, during the anticipation phase, with increased activation in the right inferior frontal gyrus (rIFG), decreased activity in the ventral striatum..
    • 2005
    • Adam Gazzaley et al
    • Top-down Enhancement and Suppression of the Magnitude and Speed of Neural Activity
    • Top-down modulation underlies our ability to selectively attend to relevant stimuli and to ignore irrelevant stimuli. Theories addressing neural mechanisms of top-down modulation are driven by studies that reveal increased magnitude of neural activity in response to directed attention, but are limited by a lack of data reporting modulation of neural processing speed, as well as comparisons with a perceptual (passive view) baseline necessary to evaluate the presence of enhancement and suppression. Utilizing functional MRI (fMRI) and event-related potential recordings (ERPs), we provide converging evidence that both themagnitude of neural activity and thespeed of neural processing are modulated by top-down influences. Furthermore, bothenhancement andsuppression occur relative to a perceptual baseline depending on task instruction. These findings reveal the fine degree of influence that goal-directed attention exerts upon activity within the visual association cortex. We further documen..
    • 2005
    • David Badre et al
    • Frontal Lobe Mechanisms that Resolve Proactive Interference
    • Memory of a past experience can interfere with processing during a subsequent experience, a phenomenon termed proactive interference (PI). Neuroimaging and neuropsychological evidence implicate the left mid-ventrolateral prefrontal cortex (mid-VLPFC) in PI resolution during short-term item recognition, though the precise mechanisms await specification. The present functional magnetic resonance imaging (fMRI) experiment sought to further constrain theorizing regarding PI resolution. On each trial, subjects maintained a target set of words, and then decided if a subsequent probe was contained in the target set (positive) or not (negative). Importantly, for half of the negative and half of the positive trials, the probe had been contained in the previous target set (recent). Relative to non-recent trials, negative–recent trials produced an increase in response times and error rates, behavioral markers of PI. In fMRI measures, negative recency was associated with increased activation in ..
    • 1999
    • Mark D’Esposito et al
    • The neural substrate and temporal dynamics of interference effects in working memory as revealed by event-related functional MRI
    • Research on the prefrontal cortex (PFC) of monkeys and humans indicates that this region supports a heterogeneous repertoire of mental processes that contribute to many complex behaviors, such as working memory. Anatomical evidence for some of these processes derives from functional neuroimaging experiments using blocked experimental designs, which average signal across all components of many trials and therefore cannot dissociate distinct processes with different time courses. Using event-related functional MRI, we were able to isolate temporally the neural correlates of processes contributing to the target presentation, delay, and probe portions of an item-recognition task. Two types of trials were of greatest interest: those with Recent Negative probes that matched an item from the target set of the previous, but not the present, two trials, and those with Nonrecent Negative probes that did not match a target item from either the present or the two previous trials. There was no di..
    • 2007
    • C. Brock Kirwan et al
    • Overcoming interference: An fMRI investigation of pattern separation in the medial temporal lobe
    • The medial temporal lobe (MTL) supports the formation and retrieval of long-term declarative memories, or memories for facts and everyday events. One challenge posed for this type of memory stems from the highly overlapping nature of common episodes. Within cognitive psychology, it is widely accepted that interference between information learned at different times is a major limitation on memory. In spite of several decades of intense research in the fields of interference theory and the neurobiological underpinnings of declarative memory, there is little direct evidence bearing on how the MTL resolves this interference to form accurate memories of everyday facts and events. Computational models of MTL function have proposed a mechanism in which the MTL, specifically the hippocampus, performs pattern separation, whereby overlapping representations are made less similar. However, there is little evidence bearing on how this process is carried out in the intact human MTL. Using high-re..
    • 2014
    • Leonie Koban et al
    • Brain systems underlying the affective and social monitoring of actions: An integrative review
    • Action monitoring allows the swift detection of conflicts, errors, and the rapid evaluation of outcomes. These processes are crucial for learning, adaptive behavior, and for the regulation of cognitive control. Our review discusses neuroimaging and electrophysiological studies that have explored the contribution of emotional and social factors during action monitoring. Meta-analytic brain activation maps demonstrate reliable overlap of error monitoring, emotional, and social processes in the dorsal mediofrontal cortex (dMFC), lateral prefrontal areas, and anterior insula (AI). Cumulating evidence suggests that action monitoring is modulated by trait anxiety and negative affect, and that activity of the dMFC and the amygdala during action monitoring might contribute to the ‘affective tagging’ of actions along a valence dimension. The role of AI in action monitoring may be the integration of outcome information with self-agency and social context factors, thereby generating more comple..
    • 2014
    • Rasa Gulbinaite et al
    • Fronto-parietal network oscillations reveal relationship between working memory capacity and cognitive control
    • Executive-attention theory proposes a close relationship between working memory capacity (WMC) and cognitive control abilities. However, conflicting results are documented in the literature, with some studies reporting that individual variations in WMC predict differences in cognitive control and trial-to-trial control adjustments (operationalized as the size of the congruency effect and congruency sequence effects, respectively), while others report no WMC-related differences. We hypothesized that brain network dynamics might be a more sensitive measure of WMC-related differences in cognitive control abilities. Thus, in the present study, we measured human EEG during the Simon task to characterize WMC-related differences in the neural dynamics of conflict processing and adaptation to conflict. Although high- and low-WMC individuals did not differ behaviorally, there were substantial WMC-related differences in theta (4–8 Hz) and delta (1–3 Hz) connectivity in fronto-parietal networks..