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The cutaneous rabbit illusion affects human primary sensory cortex somatotopically

We used functional magnetic resonance imaging (fMRI) to study neural correlates of a robust somatosensory illusion that can dissociate tactile perception from physical stimulation. Repeated rapid stimulation at the wrist, then near the elbow, can create the illusion of touches at intervening locations along the arm, as if a rabbit hopped along it. We examined brain activity in humans…

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English / 01/01/2006

Repetitive transcranial magnetic stimulation-induced changes in sensorimotor coupling parallel improvements of somatosensation in humans

Repetitive transcranial magnetic stimulation (rTMS) is an established technique for non-invasive stimulation of human cortex. Although studies have shown an influence of rTMS on single cortical regions and on simple behavioral response patterns, its influences on the dynamics of task-related activity in cortical networks have not been characterized. We provide such a characterization…

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English / 01/01/2006

Short- and long-term changes in anterior cingulate activation during resolution of task-set competition

Alternating between task sets involves detection that the current task set is unfavorable, initiation of a change in set, and application of the new task set while fine-tuning to optimally adjust to the demands of the environment. Functional magnetic resonance imaging (fMRI) studies of cognitive flexibility consistently report activation of the anterior cingulate cortex and/or…

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English / 01/01/2006

Functional connectivity reveals load dependent neural systems underlying encoding and maintenance in verbal working memory

One of the main challenges in working memory research has been to understand the degree of separation and overlap between the neural systems involved in encoding and maintenance. In the current study we used a variable load version of the Sternberg item recognition test (two, four, six, or eight letters) and a functional connectivity method based on constrained principal component…

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English / 01/01/2006

Human neural learning depends on reward prediction errors in the blocking paradigm

Learning occurs when an outcome deviates from expectation (prediction error). According to formal learning theory, the defining paradigm demonstrating the role of prediction errors in learning is the blocking test. Here, a novel stimulus is blocked from learning when it is associated with a fully predicted outcome, presumably because the occurrence of the outcome fails to produce a…

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English / 01/01/2006

Earlier development of the accumbens relative to orbitofrontal cortex might underlie risk-taking behavior in adolescents

Adolescence has been characterized by risk-taking behaviors that can lead to fatal outcomes. This study examined the neurobiological development of neural systems implicated in reward-seeking behaviors. Thirty-seven participants (7-29 years of age) were scanned using event-related functional magnetic resonance imaging and a paradigm that parametrically manipulated reward values. The…

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English / 01/01/2006

Anterior cingulate and posterior parietal cortices are sensitive to dissociable forms of conflict in a task-switching paradigm

The conflict-monitoring hypothesis posits that anterior cingulate cortex (ACC) monitors conflict in information processing and recruits dorsolateral prefrontal cortex (DLPFC) to resolve competition as needed. We used fMRI to test this prediction directly in the context of a task-switching paradigm, in which subjects responded to the color or the motion of a visual stimulus. Conflict…

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English / 01/01/2006

Anterolateral prefrontal cortex mediates the analgesic effect of expected and perceived control over pain

Perceived control attenuates pain and pain-directed anxiety, possibly because it changes the emotional appraisal of pain. We examined whether brain areas associated with voluntary reappraisal of emotional experiences also mediate the analgesic effect of perceived control over pain. Using functional magnetic resonance imaging, we compared self-controlled noxious stimuli with…

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English / 01/01/2006

Acute changes in frontoparietal activity after repetitive transcranial magnetic stimulation over the dorsolateral prefrontal cortex in a cued reaction time task

Lesion and functional imaging studies in humans have suggested that the dorsolateral prefrontal cortex (DLPFC), ventrolateral prefrontal cortex (VLPFC), and intraparietal sulcus (IPS) are involved in orienting attention. A functional magnetic resonance imaging study supplemented by a behavioral experiment examined the effects of 5 Hz repetitive transcranial magnetic stimulation (rTMS…

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English / 01/01/2006

Context-dependent human extinction memory is mediated by a ventromedial prefrontal and hippocampal network

In fear extinction, an animal learns that a conditioned stimulus (CS) no longer predicts a noxious stimulus [unconditioned stimulus (UCS)] to which it had previously been associated, leading to inhibition of the conditioned response (CR). Extinction creates a new CS-noUCS memory trace, competing with the initial fear (CS-UCS) memory. Recall of extinction memory and, hence, CR…

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English / 01/01/2006

The left parietal cortex and motor intention: an event-related functional magnetic resonance imaging study

Traditionally the posterior parietal cortex was believed to be a sensory structure. More recently, however, its important role in sensory-motor integration has been recognized. One of its functions suggested in this context is the forming of intentions, i.e. high-level cognitive plans for movements. The selection and planning of a specific movement defines motor intention. In this…

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English / 01/01/2006

Task and content modulate amygdala-hippocampal connectivity in emotional retrieval

The ability to remember emotional events is crucial for adapting to biologically and socially significant situations. Little is known, however, about the nature of the neural interactions supporting the integration of mnemonic and emotional information. Using fMRI and dynamic models of effective connectivity, we examined regional neural activity and specific interactions between…

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English / 01/01/2006

Models of functional neuroimaging data

Inferences about brain function, using functional neuroimaging data, require models of how the data were caused. A variety of models are used in practice that range from conceptual models of functional anatomy to nonlinear mathematical models of hemodynamic responses (e.g. as measured by functional magnetic resonance imaging, fMRI) and neuronal responses. In this review, we discuss…

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English / 01/01/2006

Synaptic plasticity and dysconnection in schizophrenia

Current pathophysiological theories of schizophrenia highlight the role of altered brain connectivity. This dysconnectivity could manifest 1) anatomically, through structural changes of association fibers at the cellular level, and/or 2) functionally, through aberrant control of synaptic plasticity at the synaptic level. In this article, we review the evidence for these theories,…

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English / 01/01/2006

Empathic neural responses are modulated by the perceived fairness of others

The neural processes underlying empathy are a subject of intense interest within the social neurosciences. However, very little is known about how brain empathic responses are modulated by the affective link between individuals. We show here that empathic responses are modulated by learned preferences, a result consistent with economic models of social preferences. We engaged male…

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English / 01/01/2006

Nicotinic modulation of human auditory sensory memory: Evidence from mismatch negativity potentials

Impairment in mismatch negativity (MMN) generation is a robust biological marker of schizophrenia. Understanding the physiological and pharmacological processes involved in its generation may therefore advance our understanding of this complex disorder. The present study tested if acute administration of nicotine modulates human auditory sensory memory as measured with MMN. ERP…

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English / 01/01/2006

A role for Broca's area beyond language processing: Evidence from neuropsychology and fMRI

Broca's area (or, more generally, the left inferior frontal region) is implicated in many language and language-related tasks. This chapter addresses the question of whether it is legitimate to move from this assertion (supported by very large numbers of lesion studies and functional neuroimaging experiments) to the theoretical claim that the exclusive (or even the core)…

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English / 01/01/2006

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