Functional neuroanatomical substrates of altered reward processing in major depressive disorder revealed by a dopaminergic probe.

Context: The pathophysiology of major depressive disorder (MDD) includes disturbances in several neuroanatomical substrates and neurotransmitter systems. The challenge is to elucidate the brain mechanisms of MDD behavioral symptoms, chiefly those of anhedonia.

Objectives: To visualize the neuroanatomical substrates implicated in altered reward processing in MDD, using functional magnetic resonance imaging in combination with a dopaminergic probe (a 30-mg dose of oral dextroamphetamine sulfate) to stimulate the brain reward system; and to test the hypothesis that a hypersensitive response to dextroamphetamine in MDD involves the prefrontal cortex and the striatum.

The functional organization of auditory working memory as revealed by fMRI.

Spatial and nonspatial auditory tasks preferentially recruit dorsal and ventral brain areas, respectively. However, the extent to which these auditory differences reflect specific aspects of mental processing has not been directly studied. In the present functional magnetic resonance imaging experiment, participants encoded and maintained either the location or the identity of a sound for a delay period of several seconds and then subsequently compared that information with a second sound.

The functional neuroanatomy of episodic and semantic autobiographical remembering: a prospective functional MRI study.

Autobiographical memory comprises episodic and semantic components mediated by dissociable states of consciousness, one promoting the experience of the self at a specific moment in the past, and the other involving self-knowledge that does not require ''mental time travel.'' These components can be difficult to dissociate using retrospective autobiographical stimuli collection. In this study, we manipulated the episodic/semantic distinction within prospectively collected autobiographical stimuli.

Distributed self in episodic memory: neural correlates of successful retrieval of self-encoded positive and negative personality traits.

Words processed with reference to the self are generally better remembered than words processed in semantic terms. An account of this phenomenon, labeled the Self Reference Effect (SRE), is that the self promotes elaboration and organization of encoded information. Although a few neuroimaging studies associated self-referential encoding with activations of the medial prefrontal cortex, no previous study has investigated the neural correlates of remembering emotional words encoded in an SRE paradigm.

Remembering our past: functional neuroanatomy of recollection of recent and very remote personal events.

Functional magnetic resonance imaging was used to study brain regions implicated in retrieval of memories that are decades old. To probe autobiographical memory, family photographs were selected by confederates without the participant's involvement, thereby eliminating many of the variables that potentially confounded previous neuroimaging studies. We found that context-rich memories were associated with activity in lingual and precuneus gyri independently of their age.

Deep brain stimulation for Parkinson's disease dissociates mood and motor circuits: a functional MRI case study.

Behavioral disturbances have been reported with subthalamic (STN) deep brain stimulation (DBS) treatment in Parkinson's disease (PD). We report correlative functional imaging (fMRI) of mood and motor responses induced by successive right and left DBS. A 36-year-old woman with medically refractory PD and a history of clinically remitted depression underwent uncomplicated implantation of bilateral STN DBS.

In search of the emotional self: an fMRI study using positive and negative emotional words.

Objective: The authors used functional magnetic resonance imaging (fMRI) to define the neural regions mediating self-referential processing of emotional stimuli and to explore how these regions are influenced by the emotional valence of the stimulus.

Method: Ten healthy subjects were presented with words describing positive and negative personality traits during fMRI scanning in three different conditions. In the self-referential processing condition, subjects judged whether they thought each trait described them.

An fMRI study investigating cognitive modulation of brain regions associated with emotional processing of visual stimuli.

Brain regions modulated by cognitive tasks during emotional processing were investigated using fMRI. Participants performed indirect and direct emotional processing tasks on positive and negative faces and pictures. We used a multivariate technique, partial least squares (PLS) to determine spatially distributed patterns of brain activity associated with different tasks and stimulus conditions, as well as the interaction between the two.