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Brain Structure & Function

Andrea Aguilar-Arredondo, Angélica Zepeda
The dentate gyrus (DG) is a neurogenic structure that exhibits functional and structural reorganization after injury. Neurogenesis and functional recovery occur after brain damage, and the possible relation between both processes is a matter of study. We explored whether neurogenesis and the activation of new neurons correlated with DG recovery over time. We induced a DG lesion in young adult rats through the intrahippocampal injection of kainic acid and analyzed functional recovery and the activation of new neurons after animals performed a contextual fear memory task (CFM) or a control spatial exploratory task...
April 16, 2018: Brain Structure & Function
Dogu Baran Aydogan, Russell Jacobs, Stephanie Dulawa, Summer L Thompson, Maite Christi Francois, Arthur W Toga, Hongwei Dong, James A Knowles, Yonggang Shi
Tractography is a powerful technique capable of non-invasively reconstructing the structural connections in the brain using diffusion MRI images, but the validation of tractograms is challenging due to lack of ground truth. Owing to recent developments in mapping the mouse brain connectome, high-resolution tracer injection-based axonal projection maps have been created and quickly adopted for the validation of tractography. Previous studies using tracer injections mainly focused on investigating the match in projections and optimal tractography protocols...
April 16, 2018: Brain Structure & Function
Javier Lázaro, Moritz Hertel, Chet C Sherwood, Marion Muturi, Dina K N Dechmann
The seasonal changes in brain size of some shrews represent the most drastic reversible transformation in the mammalian central nervous system known to date. Brain mass decreases 10-26% from summer to winter and regrows 9-16% in spring, but the underlying structural changes at the cellular level are not yet understood. Here, we describe the volumetric differences in brain structures between seasons and sexes of the common shrew (Sorex araneus) in detail, confirming that changes in different brain regions vary in the magnitude of change...
April 16, 2018: Brain Structure & Function
Sarah R Heilbronner, Mariah A A Meyer, Eun Young Choi, Suzanne N Haber
The frontal cortico-basal ganglia network plays a central role in action selection, associative learning, and motivation, processes requiring the integration of information from functionally distinct cortical regions. The cortico-striatal projection is a likely substrate of information integration, as terminal fields from different cortical regions converge in the striatum. These intersecting projections form complex zones of unique cortical inputs. Here, our goal was to follow these projection zones downstream in the basal ganglia to the globus pallidus...
April 13, 2018: Brain Structure & Function
Randa Kassab, Frédéric Alexandre
Pattern separation is a fundamental hippocampal process thought to be critical for distinguishing similar episodic memories, and has long been recognized as a natural function of the dentate gyrus (DG), supporting autoassociative learning in CA3. Understanding how neural circuits within the DG-CA3 network mediate this process has received much interest, yet the exact mechanisms behind remain elusive. Here, we argue for the case that sparse coding is necessary but not sufficient to ensure efficient separation and, alternatively, propose a possible interaction of distinct circuits which, nevertheless, act in synergy to produce a unitary function of pattern separation...
April 11, 2018: Brain Structure & Function
Estibaliz González de San Román, Hans-Jürgen Bidmon, Milena Malisic, Iuliana Susnea, Astrid Küppers, Rene Hübbers, Andreas Wree, Volker Nischwitz, Katrin Amunts, Pitter F Huesgen
The primary visual cortex (area V1) is an extensively studied part of the cerebral cortex with well-characterized connectivity, cellular and molecular architecture and functions (for recent reviews see Amunts and Zilles, Neuron 88:1086-1107, 2015; Casagrande and Xu, Parallel visual pathways: a comparative perspective. The visual neurosciences, MIT Press, Cambridge, pp 494-506, 2004). In humans, V1 is defined by heavily myelinated fibers arriving from the radiatio optica that form the Gennari stripe in cortical layer IV, which is further subdivided into laminae IVa, IVb, IVcα and IVcβ...
April 10, 2018: Brain Structure & Function
Michael G White, Brian N Mathur
The claustrum is a telencephalic gray matter nucleus that is richly interconnected with the neocortex. This structure subserves top-down executive functions that require frontal cortical control of posterior cortical regions. However, functional anatomical support for the claustrum allowing for long-range intercortical communication is lacking. To test this, we performed a channelrhodopsin-assisted long-circuit mapping strategy in mouse brain slices. We find that anterior cingulate cortex input to the claustrum is transiently amplified by claustrum neurons that, in turn, project to parietal association cortex or to primary and secondary visual cortices...
April 6, 2018: Brain Structure & Function
Sila Genc, Charles B Malpas, Gareth Ball, Timothy J Silk, Marc L Seal
The corpus callosum is integral to the central nervous system, and continually develops with age by virtue of increasing axon diameter and ongoing myelination. Magnetic resonance imaging (MRI) techniques offer a means to disentangle these two aspects of white matter development. We investigate the profile of microstructural metrics across the corpus callosum, and assess the impact of age, sex and pubertal development on these processes. This study made use of two independent paediatric populations. Multi-shell diffusion MRI data were analysed to produce a suite of diffusion tensor imaging, neurite orientation dispersion and density imaging, and apparent fibre density (AFD) metrics...
April 5, 2018: Brain Structure & Function
Sebastian Hormigo, Dolores E López, Antonio Cardoso, Gladys Zapata, Jacqueline Sepúlveda, Orlando Castellano
The acoustic startle reflex (ASR) is a short and intense defensive reaction in response to a loud and unexpected acoustic stimulus. In the rat, a primary startle pathway encompasses three serially connected central structures: the cochlear root neurons, the giant neurons of the nucleus reticularis pontis caudalis (PnC), and the spinal motoneurons. As a sensorimotor interface, the PnC has a central role in the ASR circuitry, especially the integration of different sensory stimuli and brain states into initiation of motor responses...
March 24, 2018: Brain Structure & Function
Bart L van de Bank, Marnix C Maas, Lauren J Bains, Arend Heerschap, Tom W J Scheenen
Phosphorus magnetic resonance spectroscopy (31 P MRS) has been employed before to assess phosphocreatine (PCr) and other high-energy phosphates in the visual cortex during visual stimulation with inconsistent results. We performed functional31 P MRS imaging in the visual cortex and control regions during a visual stimulation paradigm at an unprecedented sensitivity, exploiting a dedicated RF coil design at a 7 T MR system. Visual stimulation in a 3 min 24 s on-off paradigm in eight young healthy adults generated a clear BOLD effect with traditional1 H functional MRI in the visual cortex (average z score 9...
March 23, 2018: Brain Structure & Function
Alessandra D Nostro, Veronika I Müller, Deepthi P Varikuti, Rachel N Pläschke, Felix Hoffstaedter, Robert Langner, Kaustubh R Patil, Simon B Eickhoff
Personality is associated with variation in all kinds of mental faculties, including affective, social, executive, and memory functioning. The intrinsic dynamics of neural networks underlying these mental functions are reflected in their functional connectivity at rest (RSFC). We, therefore, aimed to probe whether connectivity in functional networks allows predicting individual scores of the five-factor personality model and potential gender differences thereof. We assessed nine meta-analytically derived functional networks, representing social, affective, executive, and mnemonic systems...
March 23, 2018: Brain Structure & Function
Albert J Hunt, Rajan Dasgupta, Shivakumar Rajamanickam, Zhiying Jiang, Michael Beierlein, C Savio Chan, Nicholas J Justice
Stress evokes directed movement to escape or hide from potential danger. Corticotropin-releasing factor (CRF) neurons are highly activated by stress; however, it remains unclear how this activity participates in stress-evoked movement. The external globus pallidus (GPe) expresses high levels of the primary receptor for CRF, CRFR1, suggesting the GPe may serve as an entry point for stress-relevant information to reach basal ganglia circuits, which ultimately gate motor output. Indeed, projections from CRF neurons are present within the GPe, making direct contact with CRFR1-positive neurons...
March 23, 2018: Brain Structure & Function
Hagar Lavian, Yocheved Loewenstern, Ravit Madar, Mara Almog, Izhar Bar-Gad, Eitan Okun, Alon Korngreen
Dopamine is critical for the normal functioning of the basal ganglia, modulating both input and output nuclei of this system. The distribution and function of each of the five dopamine receptor subtypes have been studied extensively in the striatum. However, the role of extrastriatal dopamine receptors in basal ganglia information processing is less clear. Here, we studied the anatomical distribution of dopamine receptors in one of the output nuclei of the rodent basal ganglia, the entopeduncular nucleus (EP)...
March 22, 2018: Brain Structure & Function
Michael Willis, Irmgard Leitner, Klaus Seppi, Maria Trieb, Georg Wietzorrek, Josef Marksteiner, Hans-Günther Knaus
In this study, we investigated the tissue expression levels, alpha subunit composition and distribution of Shaker-related voltage-dependent potassium Kv1 channels in human hippocampus by combining western blotting experiments, toxin autoradiography, in vivo radioligand binding studies, immunoprecipitation and immunohistochemistry. Tissue expression of Kv1.1 and Kv1.2 α-subunits in human post-mortem brain tissue was confirmed in immunoblot analysis using a panel of specific monoclonal and polyclonal antibodies...
March 21, 2018: Brain Structure & Function
Xin Li, Goran Papenberg, Grégoria Kalpouzos, Lars Bäckman, Jonas Persson
Dopaminergic neuromodulation is critically important for brain and cognitive integrity. The DRD2/ANKK1 Taq1A polymorphism is associated with striatal dopamine (DA) D2 receptor availability. Some previous studies have found that the A allele of the Taq1A polymorphism influences brain structure, but the results are inconsistent, likely due to population heterogeneity and small sample sizes. We investigated the genetic effect on caudate volume in a large sample of older adults without dementia. Results show that A-allele carriers have smaller caudate volume compared to non-carriers in relatively older adults (n = 167; Mage = 77...
March 21, 2018: Brain Structure & Function
Jacob Itzhacki, Daniel Clesse, Yannick Goumon, Eus J Van Someren, Jorge Mendoza
Seasonal affective disorder (SAD), beyond mood changes, is characterized by alterations in daily rhythms of behavior and physiology. The pathophysiological conditions of SAD involve changes in day length and its first-line treatment is bright light therapy. Animal models using nocturnal rodents have been studied to elucidate the neurobiological mechanisms of depression, but might be ill suited to study the therapeutic effects of light in SAD since they exhibit light-aversive responses. Here Arvicanthis ansorgei, a diurnal rodent, was used to determine behavioral, molecular and brain dopamine changes in response to exposure to a winter-like photoperiod consisting of a light-dark cycle with 8 h of light, under diminished light intensity, and 16 h of darkness...
March 20, 2018: Brain Structure & Function
Crystle J Kelly, Marco Martina
Functional deactivation of the prefrontal cortex (PFC) is a critical step in the neuropathic pain phenotype. We performed optogenetic circuit dissection to study the properties of ventral hippocampal (vHipp) and thalamic (MDTh) inputs to L5 pyramidal cells in acute mPFC slices and to test whether alterations in these inputs contribute to mPFC deactivation in neuropathic pain. We found that: (1) both the vHipp and MDTh inputs elicit monosynaptic excitatory and polysynaptic inhibitory currents. (2) The strength of the excitatory MDTh input is uniform, while the vHipp input becomes progressively stronger along the dorsal-ventral axis...
March 17, 2018: Brain Structure & Function
Francesca Zanderigo, Spiro Pantazatos, Harry Rubin-Falcone, R Todd Ogden, Binod Thapa Chhetry, Gregory Sullivan, Maria Oquendo, Jeffrey M Miller, J John Mann
Serotonin 1A (5-HT1A ) receptors mediate serotonin trophic role in brain neurogenesis. Gray matter volume (GMV) loss and 5-HT1A receptor binding alterations have been identified in major depressive disorder (MDD). Here we investigated the relationship between 5-HT1A receptor binding and GMV in 40 healthy controls (HCs) and, for the first time, 47 antidepressant-free MDD patients using Voxel-Based Morphometry and [11 C]WAY100635 Positron Emission Tomography. Values of GMV and 5-HT1A binding (expressed as BPF , one of the types of binding potentials that refer to displaceable or specific binding that can be quantified in vivo with PET) were obtained in 13 regions of interest, including raphe, and at the voxel level...
March 17, 2018: Brain Structure & Function
Frank E Garcea, Quanjing Chen, Roger Vargas, Darren A Narayan, Bradford Z Mahon
A whole-brain network of regions collectively supports the ability to recognize and use objects-the Tool Processing Network. Little is known about how functional interactions within the Tool Processing Network are modulated in a task-dependent manner. We designed an fMRI experiment in which participants were required to either generate object pantomimes or to carry out a picture matching task over the same images of tools, while holding all aspects of stimulus presentation constant across the tasks. The Tool Processing Network was defined with an independent functional localizer, and functional connectivity within the network was measured during the pantomime and picture matching tasks...
March 13, 2018: Brain Structure & Function
Mariko Nishibe, Yu Katsuyama, Toshihide Yamashita
The motor deficit of the reeler mutants has largely been considered cerebellum related, and the developmental consequences of the cortex on reeler motor behavior have not been examined. We herein showed that there is a behavioral consequence to reeler mutation in models examined at cortex-dependent bimanual tasks that require forepaw dexterity. Using intracortical microstimulation, we found the forelimb representation in the motor cortex was significantly reduced in the reeler. The reeler cortex required a significantly higher current to evoke skeletal muscle movements, suggesting the cortical trans-synaptic propagation is disrupted...
March 13, 2018: Brain Structure & Function
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