Science posts

See science posts on page 58 below.

    • 2011
    • Takashi J. Ozaki
    • Frontal-to-Parietal Top-Down Causal Streams along the Dorsal Attention Network Exclusively Mediate Voluntary Orienting of Attention
    • Previous effective connectivity analyses of functional magnetic resonance imaging (fMRI) have revealed dynamic causal streams along the dorsal attention network (DAN) during voluntary attentional control in the human brain. During resting state, however, fMRI has shown that the DAN is also intrinsically configured by functional connectivity, even in the absence of explicit task demands, and that may conflict with effective connectivity studies. To resolve this contradiction, we performed an effective connectivity analysis based on partial Granger causality (pGC) on event-related fMRI data during Posner's cueing paradigm while optimizing experimental and imaging parameters for pGC analysis. Analysis by pGC can factor out exogenous or latent influences due to unmeasured variables. Typical regions along the DAN with greater activation during orienting than withholding of attention were selected as regions of interest (ROIs). pGC analysis on fMRI data from the ROIs showed that frontal-to..
    • 2013
    • Simone Vossel et al
    • Dorsal and Ventral Attention Systems Distinct Neural Circuits but Collaborative Roles
    • The idea of two separate attention networks in the human brain for the voluntary deployment of attention and the reorientation to unexpected events, respectively, has inspired an enormous amount of research over the past years. In this review, we will reconcile these theoretical ideas on the dorsal and ventral attentional system with recent empirical findings from human neuroimaging experiments and studies in stroke patients. We will highlight how novel methods—such as the analysis of effective connectivity or the combination of neurostimulation with functional magnetic resonance imaging—have contributed to our understanding of the functionality and interaction of the two systems. We conclude that neither of the two networks controls attentional processes in isolation and that the flexible interaction between both systems enables the dynamic control of attention in relation to top-down goals and bottom-up sensory stimulation. We discuss which brain regions potentially govern this int..
    • 2013
    • R. Nathan Spreng et al
    • Intrinsic Architecture Underlying the Relations among the Default, Dorsal Attention, and Frontoparietal Control Networks of the Human Brain
    • Human cognition is increasingly characterized as an emergent property of interactions among distributed, functionally specialized brain networks. We recently demonstrated that the antagonistic “default” and “dorsal attention” networks—subserving internally and externally directed cognition, respectively—are modulated by a third “frontoparietal control” network that flexibly couples with either network depending on task domain. However, little is known about the intrinsic functional architecture underlying this relationship. We used graph theory to analyze network properties of intrinsic functional connectivity within and between these three large-scale networks. Task-based activation from three independent studies were used to identify reliable brain regions (“nodes”) of each network. We then examined pairwise connections (“edges”) between nodes, as defined by resting-state functional connectivity MRI. Importantly, we used a novel bootstrap resampling procedure to determine the relia..
    • 2012
    • Wei Gao et al
    • The Synchronization within and Interaction between the Default and Dorsal Attention Networks in Early Infancy
    • An anticorrelated interaction between the dorsal attention and the default-mode networks has been observed, although how these 2 networks establish such relationship remains elusive. Behavioral studies have reported the emergence of attention and default network–related functions and a preliminary competing relationship between them at early infancy. This study attempted to test the hypothesis—resting-state functional magnetic resonance imaging will demonstrate not only improved network synchronization of the dorsal attention and the default networks, respectively, during the first 2 years of life but also an anticorrelated network interaction pattern between the 2 networks at 1 year which will be further enhanced at 2 years old. Our results demonstrate that both networks start from an isolated region in neonates but evolve to highly synchronized networks at 1 year old. Paralleling the individual network maturation process, the anticorrelated behaviors are absent at birth but become ..
    • 1999
    • Richard A. Depue et al
    • Neurobiology of the structure of personality: Dopamine, facilitation of incentive motivation, and extraversion
    • Extraversion has two central characteristics: (1) interpersonal engagement, which consists of affiliation (enjoying and valuing close interpersonal bonds, being warm and affectionate) and agency (being socially dominant, enjoying leadership roles, being assertive, being exhibitionistic, and having a sense of potency in accomplishing goals) and (2) impulsivity, which emerges from the interaction of extraversion and a second, independent trait (constraint). Agency is a more general motivational disposition that includes dominance, ambition, mastery, efficacy, and achievement. Positive affect (a combination of positive feelings and motivation) is closely associated with extraversion. Extraversion is accordingly based on positive incentive motivation. Parallels between extraversion (particularly its agency component) and a mammalian behavioral approach system based on positive incentive motivation implicate a neuroanatomical network and modulatory neurotransmitters in the processing o..
    • 2002
    • Nieoullon A. et al
    • Dopamine and the regulation of cognition and attention.
    • Dopamine (DA) acts as a key neurotransmitter in the brain. Numerous studies have shown its regulatory role for motor and limbic functions. However, in the early stages of Parkinson's disease (PD), alterations of executive functions also suggest a role for DA in regulating cognitive functions. Some other diseases, which can also involve DA dysfunction, such as schizophrenia or attention deficit hyperactivity disorder (ADHD) in children, as shown from the ameliorative action of dopaminergic antagonists and agonists, respectively, also show alteration of cognitive functions. Experimental studies showed that selective lesions of the dopaminergic neurons in rats or primates can actually provide cognitive deficits, especially when the mesocorticolimbic component of the dopaminergic systems is altered. Data from the experiments also showed significant alteration in attentional processes, thus raising the question of direct involvement of DA in regulating attention. Since the dopaminergic in..
    • 2001
    • Lucas, Richard E et al
    • Understanding extraverts' enjoyment of social situations: The importance of pleasantness.
    • Extraversion is a broad, multifaceted trait, yet researchers are still unsure of its defining characteristics. One possibility is that the essential feature of extraversion is the tendency to enjoy social situations. An alternative possibility is that extraversion represents sensitivity to rewards and the tendency to experience pleasant affect. In three studies, participants rated situations that varied on two dimensions: (a) whether they were social or nonsocial and (b) whether they were very pleasant, moderately pleasant, moderately unpleasant, or very unpleasant. Extraverts only rated social situations more positively than introverts did when the situations were pleasant, and extraverts also rated nonsocial situations more positively than introverts did if the situations were pleasant. Thus, the pleasantness of situations was more important than whether they were social or nonsocial in determining extraverts' and introverts' enjoyment.
    • 2007
    • Caroline Catmur et al
    • Sensorimotor Learning Configures the Human Mirror System
    • Cells in the “mirror system” fire not only when an individual performs an action but also when one observes the same action performed by another agent [1–4] . The mirror system, found in premotor and parietal cortices of human and monkey brains, is thought to provide the foundation for social understanding and to enable the development of theory of mind and language [5–9] . However, it is unclear how mirror neurons acquire their mirror properties—how they derive the information necessary to match observed with executed actions [10] . We address this by showing that it is possible to manipulate the selectivity of the human mirror system, and thereby make it operate as a countermirror system, by giving participants training to perform one action while observing another. Before this training, participants showed event-related muscle-specific responses to transcranial magnetic stimulation over motor cortex during observation of little- and index-finger movements [11–13] . After training,..
    • 2005
    • Alessio Avenanti et al
    • Transcranial magnetic stimulation highlights the sensorimotor side of empathy for pain
    • Pain is intimately linked with action systems that are involved in observational learning and imitation. Motor responses to one's own pain allow freezing or escape reactions and ultimately survival. Here we show that similar motor responses occur as a result of observation of painful events in others. We used transcranial magnetic stimulation to record changes in corticospinal motor representations of hand muscles of individuals observing needles penetrating hands or feet of a human model or noncorporeal objects. We found a reduction in amplitude of motor-evoked potentials that was specific to the muscle that subjects observed being pricked. This inhibition correlated with the observer's subjective rating of the sensory qualities of the pain attributed to the model and with sensory, but not emotional, state or trait empathy measures. The empathic inference about the sensory qualities of others' pain and their automatic embodiment in the observer's motor system may be crucial for the ..
    • 2014
    • Paola Sessa et al
    • Double dissociation of neural responses supporting perceptual and cognitive components of social cognition: Evidence from processing of others' pain
    • Models on how perceptual and cognitive information on others' mental states are treated by the cognitive architecture are often framed as duplex models considering two independent systems. In the context of the neuroscience of empathy analogous systems have been described. Using event-related potentials (i.e., ERPs) technique, we tested the hypothesis of temporal dissociation of two functional systems. We implemented a design in which perceptual (i.e., painful or neutral facial expressions) and contextual (i.e., painful or neutral related sentences) cues on others' mental states were orthogonally manipulated. Painful expressions selectively modulated the early activity at 110–360 ms over fronto-central and centro-parietal regions, whereas painful contexts selectively modulated the late activity at 400–840 ms over these same regions. Notably, the reactions to pain triggered by these cues added up when both were available, that is the joint reaction was characterized by additive effect..