Dopamine modulation of neuronal activity during memory tasks identifies a nonlinear inverted-U shaped function. Both the dopamine transporter (DAT) and dopamine D2 receptors (encoded by DRD 2) critically regulate dopamine signaling in the striatum and in prefrontal cortex during memory. Moreover, in vitro studies have demonstrated that DAT and D2 proteins reciprocally regulate each other presynaptically. Therefore, we have evaluated the genetic interaction between a DRD 2 polymorphism (rs1076560) causing reduced presynaptic D2 receptor expression and the DAT 3′-VNTR variant (affecting DAT expression) in a large sample of healthy subjects undergoing blood oxygenation level-dependent (BOLD)-functional magnetic resonance imaging (MRI) during memory tasks and structural MRI. Results indicated a significant DRD 2/ DAT interaction in prefrontal cortex and striatum BOLD activity during both working memory and encoding of recognition memory. The differential effect on BOLD activity of the DAT variant was mostly ma...

Binocular disparity provides a strong, unambiguous cue for depth perception in primates. Several cortical areas in both the dorsal and the ventral visual pathways are involved in the processing of depth from binocular disparity. Previous functional magn...

Functional brain imaging studies - including position emission tomography (Fias, Lammertyn, Reynvoet, Dupont, & Orban, 2003; Pesenti, Thioux, Seron, & De Volder, 2000), functional magnetic resonance imaging (Bugden, Price, McLean, & Ansari, 2012; Dehaen...

NMO (or Devic syndrome) is a demyelinating disease characterized by the concomitant presence of optic neuritis and myelitis. Since its first characterization, it has been controversial whether NMO should be considered as a subtype of multiple sclerosis (MS) or for its clinical and topographical characterization it should be regarded as a distinct nosological entity. NMO affects specifically the optic nerve and the spinal cord without involvement of the brain. MRI scans of the spinal cord usually show extensive lesions (extending over 3 segments), while brain MRI are generally normal. We report a case of NMO with atypical clinical and neuroimaging findings. Initial clinical presentation, neuroimaging studies, CSF analysis, and presence of NMO IgG autoantibodies confirmed the diagnosis of NMO. However, our patient also demonstrated clinical involvement of brain stem. Magnetic Resonance imaging demonstrated extensive lesions within the medulla, pons and optic radiations. The spectrum of clinical and radiologi...

Cerebral amyloid angiopathy (CAA) is a common feature of Alzheimer's disease (AD). More advanced stages are accompanied by microhemorrhages and vasculitis. Peripheral blood-borne macrophages are intimately linked to cerebrovascular pathology coincident with AD. Magnetic resonance imaging (MRI) was used to noninvasively study microvascular lesions in amyloid precursor protein transgenic mouse AD models. Foci of signal attenuation were detected in cortical and thalamic brain regions of aged APP23 mice. Their strength and number was considerably enhanced by intravenous administration of iron oxide nanoparticles, which are taken up by macrophages through absorptive endocytosis, 24 h before image acquisition. The number of cortical sites displaying signal attenuation increased with age. Histology at these sites demonstrated the presence of iron-containing macrophages in the vicinity of CAA-affected blood vessels. A fraction of the sites additionally showed thickened vessel walls and vasculitis. Consistent with ...

Language and music exhibit similar acoustic and structural properties, and both appear to be uniquely human. Several recent studies suggest that speech and music perception recruit shared computational systems, and a common substrate in Broca's area for hierarchical processing has recently been proposed. However, this claim has not been tested by directly comparing the spatial distribution of activations to speech and music processing within subjects. In the present study, participants listened to sentences, scrambled sentences, and novel melodies. As expected, large swaths of activation for both sentences and melodies were found bilaterally in the superior temporal lobe, overlapping in portions of auditory cortex. However, substantial nonoverlap was also found: sentences elicited more ventrolateral activation, whereas the melodies elicited a more dorsomedial pattern, extending into the parietal lobe. Multivariate pattern classification analyses indicate that even within the regions of blood oxygenation le...

The primary sensory cortices have been shown in recent years to undergo experience- and learning-related plasticity under a variety of experimental circumstances. In this study, we used functional magnetic resonance imaging (fMRI) in parallel with both delay and trace eyeblink conditioning to image the learning-related functional activation within the primary visual cortex (V1) of awake, behaving rabbits. We expected that the differing level of forebrain dependence between these two conditioning paradigms should produce a differential blood oxygenation level-dependent (BOLD) functional response in V1. Our results showed a significant expansion of activated volume within V1, particularly early in learning, after training with the more cognitively demanding trace paradigm. In contrast, the simpler delay paradigm produced an increase in the magnitude of the BOLD response in activated voxels, but no significant change in activated volume. No accompanying learning-related changes were observed in the primary so...

Cannabis is one of the most frequently used illicit drugs worldwide, and has been banned in the United States and Canada since the early 1900s. A recent United Nations report places cannabis at the top of the 2010 illicit drug use list, at an estimated ...

B. Andersson1, Z. Chen1,3, E. Syková2, K. Bjelke1*, B. Bjelke1 1MR-Center, Dept. of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden. 2Dept. of Neuroscience, 2nd Medical Faculty, Charles University, Prague, Czech Republic. 3Dept. of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Science, Beijing 100730, P.R.China. We mimic late phase of stroke in an experimental rat model using a photochemically induced lesion which results in pan-necrotic brain tissue. By combining behavioural tests and magnetic resonance imaging (MRI) with morphological examination of the tissue under electron microscope (EM), we define the temporal profile of the cellular changes in the lesion and in the contralateral hemisphere. Male Spraque-Dawley rats are used. After behavioural tests and MRI the brains are prepared for EM examination according to standard procedure. At the ultrastructural level the neurons show changes such as nuclear chromatin clumping and condensation, membrane rupture ...

The study establishes the empirical approach and the methodologies to classify predictive imaging markers for progressive neurological disease, specifically focusing on changes that occur in the brain as a consequence of Human Immunodeficiency Virus (HI...