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perirhinal cortex

Rufin Vogels
New research published in Neuron describes assignment of cortical layer to single neurons recorded in awake monkeys. Applying the procedure to perirhinal cortex, Koyano et al. (2016) found marked and unsuspected differences among layers in the coding of associative memory signals.
October 19, 2016: Neuron
Wei Cheng, Edmund T Rolls, Jiang Qiu, Wei Liu, Yanqing Tang, Chu-Chung Huang, XinFa Wang, Jie Zhang, Wei Lin, Lirong Zheng, JunCai Pu, Shih-Jen Tsai, Albert C Yang, Ching-Po Lin, Fei Wang, Peng Xie, Jianfeng Feng
The first brain-wide voxel-level resting state functional connectivity neuroimaging analysis of depression is reported, with 421 patients with major depressive disorder and 488 control subjects. Resting state functional connectivity between different voxels reflects correlations of activity between those voxels and is a fundamental tool in helping to understand the brain regions with altered connectivity and function in depression. One major circuit with altered functional connectivity involved the medial orbitofrontal cortex Brodmann area 13, which is implicated in reward, and which had reduced functional connectivity in depression with memory systems in the parahippocampal gyrus and medial temporal lobe, especially involving the perirhinal cortex Brodmann area 36 and entorhinal cortex Brodmann area 28...
October 14, 2016: Brain: a Journal of Neurology
Long Xie, John B Pluta, Sandhitsu R Das, Laura E M Wisse, Hongzhi Wang, Lauren Mancuso, Dasha Kliot, Brian B Avants, Song-Lin Ding, José V Manjón, David A Wolk, Paul A Yushkevich
RATIONALE: The human perirhinal cortex (PRC) plays critical roles in episodic and semantic memory and visual perception. The PRC consists of Brodmann areas 35 and 36 (BA35, BA36). In Alzheimer's disease (AD), BA35 is the first cortical site affected by neurofibrillary tangle pathology, which is closely linked to neural injury in AD. Large anatomical variability, manifested in the form of different cortical folding and branching patterns, makes it difficult to segment the PRC in MRI scans...
October 1, 2016: NeuroImage
Celia O Fidalgo, Alana T Changoor, Elizabeth Page-Gould, Andy C H Lee, Morgan D Barense
There is an ongoing debate regarding the nature of memory deficits that occur in the early stages of mild cognitive impairment (MCI). MCI has been associated with atrophy to regions that process objects, namely perirhinal and lateral entorhinal cortices. However, it is currently unclear whether older adults with early MCI will show memory deficits that are specific to objects, or whether they will also show memory deficits for other stimulus classes, such as scenes. We tested 75 older adults using an object and scene recognition task with stimulus-specific interference (i...
September 20, 2016: Hippocampus
Eske Christiane Gertje, John Pluta, Sandhitsu Das, Lauren Mancuso, Dasha Kliot, Paul Yushkevich, David Wolk
BACKGROUND: Volumetry of medial temporal lobe (MTL) structures to diagnose Alzheimer's disease (AD) in its earliest symptomatic stage could be of great importance for interventions or disease modifying pharmacotherapy. OBJECTIVE: This study aimed to demonstrate the first application of an automatic segmentation method of MTL subregions in a clinical population. Automatic segmentation of magnetic resonance images (MRIs) in a research population has previously been shown to detect evidence of neurodegeneration in MTL subregions and to help discriminate AD and mild cognitive impairment (MCI) from a healthy comparison group...
October 4, 2016: Journal of Alzheimer's Disease: JAD
Sen Wang, Xu-Feng Huang, Peng Zhang, Hongqin Wang, Qingsheng Zhang, Shijia Yu, Yinghua Yu
High-fat (HF) diet modulates gut microbiota and increases plasma concentration of lipopolysaccharide (LPS) which is associated with obesity and its related low-grade inflammation and cognitive decline. Rhein is the main ingredient of the rhubarb plant which has been used as an anti-inflammatory agent for several millennia. However, the potential effects of rhein against HF diet-induced obesity and its associated alteration of gut microbiota, inflammation and cognitive decline have not been studied. In this study, C57BL/6J male mice were fed an HF diet for 8 weeks to induce obesity, and then treated with oral rhein (120 mg/kg body weight/day in HF diet) for a further 6 weeks...
October 2016: Journal of Nutritional Biochemistry
David R Roalf, Megan Quarmley, Monica E Calkins, Theodore D Satterthwaite, Kosha Ruparel, Mark A Elliott, Tyler M Moore, Ruben C Gur, Raquel E Gur, Paul J Moberg, Bruce I Turetsky
Structural brain abnormalities have been amply demonstrated in schizophrenia. These include volume decrements in the perirhinal/entorhinal regions of the ventromedial temporal lobe, which comprise the primary olfactory cortex. Olfactory impairments, which are a hallmark of schizophrenia, precede the onset of illness, distinguish adolescents experiencing prodromal symptoms from healthy youths, and may predict the transition from the prodrome to frank psychosis. We therefore examined temporal lobe regional volumes in a large adolescent sample to determine if structural deficits in ventromedial temporal lobe areas were associated, not only with schizophrenia, but also with a heightened risk for psychosis...
August 24, 2016: Schizophrenia Bulletin
Dagmar Zeithamova, Christine Manthuruthil, Alison R Preston
Repeated encounters with the same event typically lead to decreased activation in the medial temporal lobe (MTL) and dopaminergic midbrain, a phenomenon known as repetition suppression. In contrast, encountering an event that overlaps with prior experience leads to increased response in the same regions. Such increased responding is thought to reflect an associative novelty signal that promotes memory updating to resolve differences between current events and stored memories. Here, we married these ideas to test whether event overlap significantly modulates MTL and midbrain responses-even when events are repeated and expected-to promote memory updating through integration...
August 1, 2016: Hippocampus
Gaby Pfeifer, Jamie Ward, Dennis Chan, Natasha Sigala
The representational account of memory envisages perception and memory to be on a continuum rather than in discretely divided brain systems [Bussey, T. J., & Saksida, L. M. Memory, perception, and the ventral visual-perirhinal-hippocampal stream: Thinking outside of the boxes. Hippocampus, 17, 898-908, 2007]. We tested this account using a novel between-group design with young grapheme-color synesthetes, older adults, and young controls. We investigated how the disparate sensory-perceptual abilities between these groups translated into associative memory performance for visual stimuli that do not induce synesthesia...
July 26, 2016: Journal of Cognitive Neuroscience
Andrew J D Nelson, Cristian M Olarte-Sánchez, Eman Amin, John P Aggleton
Rats with lesions in the perirhinal cortex and their control group learnt to discriminate between mirror-imaged visual landmarks to find a submerged platform in a watermaze. Rats initially learnt this discrimination passively, in that they were repeatedly placed on the platform in one corner of a square watermaze with walls of different appearance, prior to swimming to that same location for the first time in a subsequent probe trial. Perirhinal cortex lesions spared this passively learnt ability, despite the common visual elements shared by the guiding landmarks...
October 15, 2016: Behavioural Brain Research
Yuji Naya
Declarative memories are our so-called daily language memories, which we are able to describe or explicitly experience through the act of remembering. This conscious recollection makes it possible for us to think about the future based on our previous experience (episodic memory) and knowledge (semantic memory). This cognitive function is substantiated by the medial temporal lobe (MTL), a hierarchically organized complex in which the perirhinal cortex and parahippocampal cortex provide item and context information to the hippocampus via the entorhinal cortex, and the hippocampus plays the main role in association and recollection...
July 11, 2016: Neuroscience Research
Lisa Kinnavane, Eman Amin, Cristian M Olarte-Sánchez, John P Aggleton
Perirhinal cortex provides object-based information and novelty/familiarity information for the hippocampus. The necessity of these inputs was tested by comparing hippocampal c-fos expression in rats with or without perirhinal lesions. These rats either discriminated novel from familiar objects (Novel-Familiar) or explored pairs of novel objects (Novel-Novel). Despite impairing Novel-Familiar discriminations, the perirhinal lesions did not affect novelty detection, as measured by overall object exploration levels (Novel-Novel condition)...
July 11, 2016: Hippocampus
Kun Xie, Grace E Fox, Jun Liu, Joe Z Tsien
The development of technologies capable of recording both single-unit activity and local field potentials (LFPs) over a wide range of brain circuits in freely behaving animals is the key to constructing brain activity maps. Although mice are the most popular mammalian genetic model, in vivo neural recording has been traditionally limited to smaller channel count and fewer brain structures because of the mouse's small size and thin skull. Here, we describe a 512-channel tetrode system that allows us to record simultaneously over a dozen cortical and subcortical structures in behaving mice...
2016: Frontiers in Systems Neuroscience
Janske G P Willems, Wytse J Wadman, Natalie L M Cappaert
The perirhinal (PER) and entorhinal cortex (EC) receive input from the agranular insular cortex (AiP) and the subcortical lateral amygdala (LA) and the main output area is the hippocampus. Information transfer through the PER/EC network however, is not always guaranteed. It is hypothesized that this network actively regulates the (sub)cortical activity transfer to the hippocampal network and that the inhibitory system is involved in this function. This study determined the recruitment by the AiP and LA afferents in PER/EC network with the use of voltage sensitive dye (VSD) imaging in horizontal mouse brain slices...
2016: Frontiers in Neural Circuits
Ben Bowles, Devin Duke, R Shayna Rosenbaum, Ken McRae, Stefan Köhler
The ability to recognize the prior occurrence of objects can operate effectively even in the absence of successful recollection of episodic contextual detail about a relevant past object encounter. The pertinent process, familiarity assessment, is typically probed in humans with recognition-memory tasks that include an experimentally controlled study phase for a list of items. When meaningful stimuli such as words or pictures of common objects are employed, participants must judge familiarity with reference to the recent experimental encounter rather than their lifetime of autobiographical experience, which may have involved hundreds or thousands of exposures across numerous episodic contexts...
September 2016: Neuropsychologia
Jason D Ozubko, Paul Seli
Memory can be divided into recollection and familiarity. Recollection is characterized as the ability to vividly re-experience past events, and is believed to be supported by the hippocampus, whereas familiarity is defined as an undifferentiated feeling of knowing or acquaintance, and is believed to be supported by extra-hippocampal regions, such as the perirhinal cortex. Recent evidence suggests that the neural architectures of the hippocampus and neocortex lead information in these regions being susceptible to different forgetting processes...
September 2016: Neuropsychologia
Cirong Liu, Yonghui Li, Timothy J Edwards, Nyoman D Kurniawan, Linda J Richards, Tianzi Jiang
Social experience is essential for adolescent development and plasticity of social animals. Deprivation of the experience by social isolation impairs white matter microstructures in the prefrontal cortex. However, the effect of social isolation may involve highly distributed brain networks, and therefore cannot be fully explained by a change of a single region. Here, we compared the connectomes of adolescent socially-isolated mice and normal-housed controls via diffusion magnetic resonance imaging. The isolated mice displayed an abnormal connectome, characterized by an increase in degree and reductions in measures such as modularity, small-worldness, and betweenness...
June 20, 2016: NeuroImage
Natalia I Córdova, Alexa Tompary, Nicholas B Turk-Browne
Attention prioritizes information that is most relevant to current behavioral goals. This prioritization can be accomplished by amplifying neural responses to goal-relevant information and by strengthening coupling between regions involved in processing this information. Such modulation occurs within and between areas of visual cortex, and relates to behavioral effects of attention on perception. However, attention also has powerful effects on learning and memory behavior, suggesting that similar modulation may occur for memory systems...
October 2016: Neurobiology of Learning and Memory
Nicole J Gervais, Laurie M Hamel, Wayne G Brake, Dave G Mumby
Intra-rhinal cortical infusion of 17-β estradiol (E2, 244.8pg/μl) enhances performance on the Novel-Object Preference (NOP) test and impairs accuracy on the delayed nonmatching-to-sample (DNMS) task in the same set of ovariectomized rats (Gervais, Jacob, Brake, & Mumby, 2013). These results appear paradoxical, as normal performance on both tests require intact object-recognition memory (ORM) ability. While demonstrating a preference for the novel object requires recognizing the sample object, rodents can recognize the sample object and still fail to demonstrate a preference...
September 2016: Neurobiology of Learning and Memory
Wendie N Marks, Stuart M Cain, Terrance P Snutch, John G Howland
Childhood absence epilepsy (CAE) is often comorbid with behavioral and cognitive symptoms, including impaired visual memory. Genetic Absence Epilepsy Rats from Strasbourg (GAERS) is an animal model closely resembling CAE; however, cognition in GAERS is poorly understood. Crossmodal object recognition (CMOR) is a recently developed memory task that examines not only purely visual and tactile memory, but also requires rodents to integrate sensory information about objects gained from tactile exploration to enable visual recognition...
October 2016: Neurobiology of Disease
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