Impaired and preserved aspects of feedback learning in aMCI: contributions of structural connectivity.

Distinct lines of research demonstrated that patients with amnestic mild cognitive impairment (aMCI), a potential precursor of Alzheimer disease (AD), are particularly impaired in remembering relations between items and that the use of emotional targets can facilitate memory in patients with AD. We link these findings by examining learning through positive and negative feedback in patients with aMCI, and explore its anatomic underpinnings with diffusion tensor imaging and tractography. Compared to healthy controls, patients with single-domain aMCI were impaired in learning from positive feedback, while learning from negative outcomes was preserved.

A combined electrophysiological and morphological examination of episodic memory decline in amnestic mild cognitive impairment.

Early stages of Alzheimer's disease (AD) are characterized by neuropathological changes within the medial temporal lobe cortex (MTLC), which lead to characteristic impairments in episodic memory, i.e., amnestic mild cognitive impairment (aMCI).

Using Voxel-Based Morphometry to Examine the Relationship between Regional Brain Volumes and Memory Performance in Amnestic Mild Cognitive Impairment.

Alzheimer's disease (AD) is a slowly progressive neurodegenerative disorder, in which morphological alterations of brain tissue develop many years before the first neuropsychological and clinical changes occur. Among the first and most prominent symptoms are deficiencies of declarative memory functions. This stage of precursory symptoms to AD has been described as amnestic mild cognitive impairment (aMCI) and is discussed as a potential AD prodrome.

Impaired anatomical connectivity and related executive functions: differentiating vulnerability and disease marker in bipolar disorder.

Background: Bipolar 1 disorder (BD1) has been associated with impaired set shifting, increased risk taking, and impaired integrity of frontolimbic white matter. However, it remains unknown to what extent these findings are related to each other and whether these abnormalities represent risk factors or consequences of the illness.

Methods: We addressed the first question by comparing 19 patients with BD1 and 19 healthy control subjects (sample 1) with diffusion tensor imaging, the Intra-Extra Dimensional Set Shift Task, and the Cambridge Gambling Task.

Increased medial orbitofrontal and amygdala activation: evidence for a systems-level endophenotype of bipolar I disorder.

Objective: Bipolar I disorder is highly heritable, but endophenotypes of the disorder mediating genetic risk are only beginning to be defined. The authors investigate state- and trait-related neural mechanisms related to motivation in euthymic bipolar patients and unaffected first-degree relatives of bipolar patients to define the status of motivational processing as a neural systems-level endophenotype.

Method: Our study comprised two samples; the first consisted of 19 euthymic bipolar patients and 19 matched comparison subjects, and the second included 22 relatives and 22 matched comparison subjects.

Genome-wide supported risk variant for bipolar disorder alters anatomical connectivity in the human brain.

Bipolar disorder is a devastating, highly heritable mental disorder related to disturbed connectivity between limbic and frontal brain areas. A meta-analysis of genome-wide association studies as well as independent replications showed ankyrin 3 (ANK3) to be one of the best-supported risk genes for bipolar disorder. Using an imaging genetics approach employing diffusion tensor imaging in 88 healthy volunteers, we show decreased white matter integrity, indicated by lower fractional anisotropy and longitudinal diffusivity, in healthy carriers of the ANK3 rs10994336 risk genotype in the anterior limb of the internal capsule.

Microstructure of a three-way anatomical network predicts individual differences in response inhibition: a tractography study.

Response inhibition is thought to depend critically on the inferior frontal gyrus, pars opercularis (IFGoper), presupplementary motor area (preSMA) and basal ganglia, including the subthalamic nucleus (STN), but the differential contribution of structural connections within this network to response inhibition remains unclear. Using diffusion tensor imaging and probabilistic fiber tractography, we investigated the relative associations between local white matter microstructure and stop-signal response inhibition in fronto-basal ganglia tracts delineated by probabilistic tractography. In a tract-of-interest approach, we identify significant associations with fractional anisotropy (FA) in fibers connecting the right STN region to both preSMA/SMA and IFGoper and in bilateral tracts connecting preSMA/SMA to IFGoper and the striatum.

Loss of callosal fibre integrity in healthy elderly with age-related white matter changes.

Age-related white matter changes (ARWMC) appear to correspond to a continuum from normal functioning to clinically overt neurological syndromes. Disturbance of the structural integrity of cerebral fibre tracts-the so-called cerebral network-by ARWMC might be one explanation for this development. From 3 T magnetic resonance imaging (MRI) data of 34 healthy elderly subjects (60-82 years) we calculated the lesion volume of ARWMC and the area of the corpus callosum (CC).

Motivational orientation modulates the neural response to reward.

Motivational orientation defines the source of motivation for an individual to perform a particular action and can either originate from internal desires (e.g., interest) or external compensation (e.