Altered Gray Matter Structural Covariance Networks in Early Stages of Alzheimer's Disease
Clinical symptoms observed in Alzheimer's disease (AD) patients may reflect variations within specific large-scale brain networks, modeling AD as a disconnection syndrome. The present magnetic resonance imaging study aims to compare the organization of gray matter structural covariance networks between 109 cognitively unimpaired controls (CTRL) and 109 AD patients positive to beta-amyloid at the early stages of the disease, using voxel-based morphometry. The default-mode network (DMN; medial temporal lobe subsystem) was less extended in AD patients in comparison with CTRL, with a significant decrease in the structural asso...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Montembeault, M., Rouleau, I., Provost, J.-S., Brambati, S. M., for the Alzheimer's Disease Neuroimaging Initiative Tags: Articles Source Type: research
Rapid Activation of Glucocorticoid Receptors in the Prefrontal Cortex Mediates the Expression of Contextual Conditioned Fear in Rats
The aim of the present study was to investigate the role of glucocorticoids in medial prefrontal cortex (mPFC) activity and the expression of contextual conditioned fear (freezing). Rats were pretreated with vehicle or metyrapone, a corticosterone synthesis blocker, and exposed to a context previously paired with footshocks. Freezing and Fos-protein expression in different mPFC regions were assessed. Exposure to the aversive context led to increased freezing and Fos expression in the prelimbic (PrL), anterior cingulate areas 1 and 2 (Cg1/Cg2). Pretreatment with metyrapone decreased freezing and Fos expression in these area...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Reis, F. M. C. V., Almada, R. C., Fogaca, M. V., Brandao, M. L. Tags: Articles Source Type: research
Modulation of Beta-Band Activity in the Subgenual Anterior Cingulate Cortex during Emotional Empathy in Treatment-Resistant Depression
Deep brain stimulation (DBS) is a promising approach in treatment-resistant depression (TRD). TRD is associated with problems in interpersonal relationships, which might be linked to impaired empathy. Here, we investigate the influence of DBS in the subgenual anterior cingulate cortex (sgACC) on empathy in patients with TRD and explore the pattern of oscillatory sgACC activity during performance of the multifaceted empathy test. We recorded local field potential activity directly from sgACC via DBS electrodes in patients. Based on previous behavioral findings, we expected disrupted empathy networks. Patients showed increas...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Merkl, A., Neumann, W.-J., Huebl, J., Aust, S., Horn, A., Krauss, J. K., Dziobek, I., Kuhn, J., Schneider, G.-H., Bajbouj, M., Kühn, A. A. Tags: Articles Source Type: research
Thalamocortical Innervation Pattern in Mouse Auditory and Visual Cortex: Laminar and Cell-Type Specificity
Despite many previous studies, the functional innervation pattern of thalamic axons and their target specificity remains to be investigated thoroughly. Here, in primary auditory cortical slices, we examined thalamic innervation patterns for excitatory and different types of inhibitory neurons across laminae, by optogenetically stimulating axons from the medial geniculate body. We found that excitatory cells and parvalbumin (PV)-expressing inhibitory neurons across layer 2/3 (L2/3) to L6 are directly innervated by thalamic projections, with the strongest innervation occurring in L4. The innervation of PV neurons is stronger...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Ji, X.-y., Zingg, B., Mesik, L., Xiao, Z., Zhang, L. I., Tao, H. W. Tags: Articles Source Type: research
Individual Differences in Reward and Somatosensory-Motor Brain Regions Correlate with Adiposity in Adolescents
The prevalence of adolescent obesity has increased dramatically over the past three decades, and research has documented that the number of television shows viewed during childhood is associated with greater risk for obesity. In particular, considerable evidence suggests that exposure to food marketing promotes eating habits that contribute to obesity. The present study examines neural responses to dynamic food commercials in overweight and healthy-weight adolescents using functional magnetic resonance imaging (fMRI). Compared with non-food commercials, food commercials more strongly engaged regions involved in attention a...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Rapuano, K. M., Huckins, J. F., Sargent, J. D., Heatherton, T. F., Kelley, W. M. Tags: Articles Source Type: research
Dissociating Parieto-Frontal Networks for Phonological and Semantic Word Decisions: A Condition-and-Perturb TMS Study
Left posterior inferior frontal gyrus (pIFG) and supramarginal gyrus (SMG) are key regions for phonological decisions, whereas angular gyrus (ANG) and anterior IFG (aIFG) are associated with semantics. However, it is less clear whether the functional contribution of one area changes in the presence of a dysfunctional area within the network. Using repetitive transcranial magnetic stimulation (rTMS), we first tested whether perturbing one area would disrupt behavior. Second, we applied a condition-and-perturb approach, combining parietal offline rTMS with frontal online rTMS to investigate how the functional contribution of...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Hartwigsen, G., Weigel, A., Schuschan, P., Siebner, H. R., Weise, D., Classen, J., Saur, D. Tags: Articles Source Type: research
Enlargement of Axo-Somatic Contacts Formed by GAD-Immunoreactive Axon Terminals onto Layer V Pyramidal Neurons in the Medial Prefrontal Cortex of Adolescent Female Mice Is Associated with Suppression of Food Restriction-Evoked Hyperactivity and Resilience to Activity-Based Anorexia
Many, but not all, adolescent female mice that are exposed to a running wheel while food restricted (FR) become excessive wheel runners, choosing to run even during the hours of food availability, to the point of death. This phenomenon is called activity-based anorexia (ABA). We used electron microscopic immunocytochemistry to ask whether individual differences in ABA resilience may correlate with the lengths of axo-somatic contacts made by GABAergic axon terminals onto layer 5 pyramidal neurons (L5P) in the prefrontal cortex. Contact lengths were, on average, 40% greater for the ABA-induced mice, relative to controls. Cor...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Chen, Y.-W., Wable, G. S., Chowdhury, T. G., Aoki, C. Tags: Articles Source Type: research
Discrete Neural Signatures of Basic Emotions
Categorical models of emotions posit neurally and physiologically distinct human basic emotions. We tested this assumption by using multivariate pattern analysis (MVPA) to classify brain activity patterns of 6 basic emotions (disgust, fear, happiness, sadness, anger, and surprise) in 3 experiments. Emotions were induced with short movies or mental imagery during functional magnetic resonance imaging. MVPA accurately classified emotions induced by both methods, and the classification generalized from one induction condition to another and across individuals. Brain regions contributing most to the classification accuracy inc...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Saarimäki, H., Gotsopoulos, A., Jääskeläinen, I. P., Lampinen, J., Vuilleumier, P., Hari, R., Sams, M., Nummenmaa, L. Tags: Articles Source Type: research
Nicotinic Transmission onto Layer 6 Cortical Neurons Relies on Synaptic Activation of Non-{alpha}7 Receptors
Nicotinic excitation in neocortex is mediated by low-affinity α7 receptors and by high-affinity α4β2 receptors. There is evidence that α7 receptors are synaptic, but it is unclear whether high-affinity receptors are activated by volume transmission or synaptic transmission. To address this issue, we characterized responses of excitatory layer 6 (L6) neurons to optogenetic release of acetylcholine (ACh) in cortical slices. L6 responses consisted in a slowly decaying α4β2 current and were devoid of α7 component. Evidence that these responses were mediated by synapses was 4-fold. 1) Cha...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Hay, Y. A., Lambolez, B., Tricoire, L. Tags: Articles Source Type: research
Ubiquitin-Proteasome System Inhibition Promotes Long-Term Depression and Synaptic Tagging/Capture
In this study, we probed the possibility of regulating the UPS by inhibiting the proteasome function during the induction of protein synthesis-independent form of hippocampal long-term depression (early-LTD), an important component of synaptic plasticity. Here, we show that protein degradation is involved in early-LTD induction and interfering with this process facilitates early-LTD to late-LTD. We provide evidence here that under the circumstances of proteasome inhibition brain-derived neurotrophic factor is accumulated as plasticity-related protein and it drives the weakly depressed or potentiated synapses to associativi...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Li, Q., Korte, M., Sajikumar, S. Tags: Articles Source Type: research
The Focus of Spatial Attention Determines the Number and Precision of Face Representations in Working Memory
The capacity of visual working memory for faces is extremely limited, but the reasons for these limitations remain unknown. We employed event-related brain potential measures to demonstrate that individual faces have to be focally attended in order to be maintained in working memory, and that attention is allocated to only a single face at a time. When 2 faces have to be memorized simultaneously in a face identity-matching task, the focus of spatial attention during encoding predicts which of these faces can be successfully maintained in working memory and matched to a subsequent test face. We also show that memory represe...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Towler, J., Kelly, M., Eimer, M. Tags: Articles Source Type: research
Defects During Mecp2 Null Embryonic Cortex Development Precede the Onset of Overt Neurological Symptoms
We describe the pattern and timing of Mecp2 expression in the embryonic neocortex highlighting its low but consistent expression in virtually all cells and show the unexpected occurrence of transcriptional defects in the Mecp2 null samples at a stage largely preceding the onset of overt symptoms. Through the deregulated expression of ionic channels and glutamatergic receptors, the lack of Mecp2 during early neuronal maturation leads to the reduction in the neuronal responsiveness to stimuli. We suggest that such features concur to morphological alterations that begin affecting Mecp2 null neurons around the perinatal age an...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Bedogni, F., Cobolli Gigli, C., Pozzi, D., Rossi, R. L., Scaramuzza, L., Rossetti, G., Pagani, M., Kilstrup-Nielsen, C., Matteoli, M., Landsberger, N. Tags: Articles Source Type: research
Prediction During Natural Language Comprehension
The notion of prediction is studied in cognitive neuroscience with increasing intensity. We investigated the neural basis of 2 distinct aspects of word prediction, derived from information theory, during story comprehension. We assessed the effect of entropy of next-word probability distributions as well as surprisal. A computational model determined entropy and surprisal for each word in 3 literary stories. Twenty-four healthy participants listened to the same 3 stories while their brain activation was measured using fMRI. Reversed speech fragments were presented as a control condition. Brain areas sensitive to entropy we...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Willems, R. M., Frank, S. L., Nijhof, A. D., Hagoort, P., van den Bosch, A. Tags: Articles Source Type: research
The Behavioral Relevance of Task Information in Human Prefrontal Cortex
Human lateral prefrontal cortex (LPFC) is thought to play a critical role in enabling cognitive flexibility, particularly when performing novel tasks. However, it remains to be established whether LPFC representation of task-relevant information in such situations actually contributes to successful performance. We utilized pattern classification analyses of functional MRI activity to identify novelty-sensitive brain regions as participants rapidly switched between performance of 64 complex tasks, 60 of which were novel. In three of these novelty-sensitive regions—located within distinct areas of left anterior LPFC&md...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Cole, M. W., Ito, T., Braver, T. S. Tags: Articles Source Type: research
A Neural Substrate for Rapid Timbre Recognition? Neural and Behavioral Discrimination of Very Brief Acoustic Vowels
The timbre of a sound plays an important role in our ability to discriminate between behaviorally relevant auditory categories, such as different vowels in speech. Here, we investigated, in the primary auditory cortex (A1) of anesthetized guinea pigs, the neural representation of vowels with impoverished timbre cues. Five different vowels were presented with durations ranging from 2 to 128 ms. A psychophysical experiment involving human listeners showed that identification performance was near ceiling for the longer durations and degraded close to chance level for the shortest durations. This was likely due to spectral spl...
Source: Cerebral Cortex - May 16, 2016 Category: Neurology Authors: Occelli, F., Suied, C., Pressnitzer, D., Edeline, J.- M., Gourevitch, B. Tags: Articles Source Type: research
