scholarly journals A Neural Model of Intrinsic and Extrinsic Hippocampal Theta Rhythms: Anatomy, Neurophysiology, and Function

2021 ◽  
Vol 15 ◽  
Author(s):  
Stephen Grossberg
Keyword(s):  
Entorhinal Cortex ◽  
Category Learning ◽  
Neural Model ◽  
Brain Regions ◽  
Beta Oscillations ◽  
Emotional Processes ◽  
Theoretical Synthesis ◽  
Multiple Species ◽  
And Function ◽  
Hippocampal Theta

This article describes a neural model of the anatomy, neurophysiology, and functions of intrinsic and extrinsic theta rhythms in the brains of multiple species. Topics include how theta rhythms were discovered; how theta rhythms organize brain information processing into temporal series of spatial patterns; how distinct theta rhythms occur within area CA1 of the hippocampus and between the septum and area CA3 of the hippocampus; what functions theta rhythms carry out in different brain regions, notably CA1-supported functions like learning, recognition, and memory that involve visual, cognitive, and emotional processes; how spatial navigation, adaptively timed learning, and category learning interact with hippocampal theta rhythms; how parallel cortical streams through the lateral entorhinal cortex (LEC) and the medial entorhinal cortex (MEC) represent the end-points of the What cortical stream for perception and cognition and the Where cortical stream for spatial representation and action; how the neuromodulator acetylcholine interacts with the septo-hippocampal theta rhythm and modulates category learning; what functions are carried out by other brain rhythms, such as gamma and beta oscillations; and how gamma and beta oscillations interact with theta rhythms. Multiple experimental facts about theta rhythms are unified and functionally explained by this theoretical synthesis.

scholarly journals Spine impairment in mice high-expressing neuregulin 1 due to LIMK1 activation

2021 ◽  
Vol 12 (4) ◽  
Author(s):  
Peng Chen ◽  
Hongyang Jing ◽  
Mingtao Xiong ◽  
Qian Zhang ◽  
Dong Lin ◽  
...  
Keyword(s):  
Neural Development ◽  
Protein Level ◽  
Brain Regions ◽  
Postmortem Brain ◽  
Pathophysiological Mechanism ◽  
Brain Disorders ◽  
Spine Density ◽  
Genes Encoding ◽  
High Level ◽  
And Function

AbstractThe genes encoding for neuregulin1 (NRG1), a growth factor, and its receptor ErbB4 are both risk factors of major depression disorder and schizophrenia (SZ). They have been implicated in neural development and synaptic plasticity. However, exactly how NRG1 variations lead to SZ remains unclear. Indeed, NRG1 levels are increased in postmortem brain tissues of patients with brain disorders. Here, we studied the effects of high-level NRG1 on dendritic spine development and function. We showed that spine density in the prefrontal cortex and hippocampus was reduced in mice (ctoNrg1) that overexpressed NRG1 in neurons. The frequency of miniature excitatory postsynaptic currents (mEPSCs) was reduced in both brain regions of ctoNrg1 mice. High expression of NRG1 activated LIMK1 and increased cofilin phosphorylation in postsynaptic densities. Spine reduction was attenuated by inhibiting LIMK1 or blocking the NRG1–LIMK1 interaction, or by restoring NRG1 protein level. These results indicate that a normal NRG1 protein level is necessary for spine homeostasis and suggest a pathophysiological mechanism of abnormal spines in relevant brain disorders.

scholarly journals Differential Promotion of Glutamate Transporter Expression and Function by Glucocorticoids in Astrocytes from Various Brain Regions

2005 ◽  
Vol 280 (41) ◽  
pp. 34924-34932 ◽  
Author(s):  
Jürgen Zschocke ◽  
Nadhim Bayatti ◽  
Albrecht M. Clement ◽  
Heidrun Witan ◽  
Maciej Figiel ◽  
...  
Keyword(s):  
Glutamate Transporter ◽  
Brain Regions ◽  
And Function ◽  
Transporter Expression

Animal Models of Down Syndrome

2021 ◽  
Author(s):  
Anna J. Moyer ◽  
Roger H. Reeves
Keyword(s):  
Down Syndrome ◽  
Cognitive Impairment ◽  
Intellectual Disability ◽  
Animal Models ◽  
Brain Regions ◽  
Laboratory Mice ◽  
Tremendous Progress ◽  
New Treatments ◽  
And Function ◽  
Early Developmental

Is intellectual disability a treatable feature of persons with Down syndrome? Researchers have made tremendous progress in the last 30 years, from creating the first mouse model of Down syndrome to completing the first major clinical trial for cognitive impairment in people with Down syndrome. Until recently, normalizing brain development and function seemed too lofty a goal, and indeed, even proposing a candidate therapy requires answering a number of difficult questions. How does trisomy 21, a molecular diagnosis, cause the clinical phenotypes of Down syndrome? When, where, and how do trisomic genes act to disrupt normal development and which genes are involved with which outcomes? Which brain regions and behaviors are most impaired? Is there an early developmental window of time during which treatments are most effective? This article discusses how animal models such as laboratory mice can be used to understand intellectual disability and to develop new treatments for cognitive impairment.

scholarly journals FOXP2 exhibits projection neuron class specific expression, but is not required for multiple aspects of cortical histogenesis

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Ryan J Kast ◽  
Alexandra L Lanjewar ◽  
Colton D Smith ◽  
Pat Levitt
Keyword(s):  
Expression Patterns ◽  
Projection Neuron ◽  
Specific Expression ◽  
Neuron Populations ◽  
Mouse Cortex ◽  
Molecular Studies ◽  
Multiple Species ◽  
Molecular Phenotypes ◽  
And Function

The expression patterns of the transcription factor FOXP2 in the developing mammalian forebrain have been described, and some studies have tested the role of this protein in the development and function of specific forebrain circuits by diverse methods and in multiple species. Clinically, mutations in FOXP2 are associated with severe developmental speech disturbances, and molecular studies indicate that impairment of Foxp2 may lead to dysregulation of genes involved in forebrain histogenesis. Here, anatomical and molecular phenotypes of the cortical neuron populations that express FOXP2 were characterized in mice. Additionally, Foxp2 was removed from the developing mouse cortex at different prenatal ages using two Cre-recombinase driver lines. Detailed molecular and circuit analyses were undertaken to identify potential disruptions of development. Surprisingly, the results demonstrate that Foxp2 function is not required for many functions that it has been proposed to regulate, and therefore plays a more limited role in cortical development than previously thought.

scholarly journals Novel Inferences in a Multidimensional Social Network Use a Grid-like Code

2020 ◽  
Author(s):  
Seongmin A. Park ◽  
Douglas S. Miller ◽  
Erie D. Boorman
Keyword(s):  
Decision Making ◽  
Prefrontal Cortex ◽  
Medial Prefrontal Cortex ◽  
Entorhinal Cortex ◽  
Brain Regions ◽  
Cognitive Map ◽  
General Mechanism ◽  
Temporoparietal Junction ◽  
Flexible Behavior ◽  
Discrete Problems

ABSTRACTGeneralizing experiences to guide decision making in novel situations is a hallmark of flexible behavior. It has been hypothesized such flexibility depends on a cognitive map of an environment or task, but directly linking the two has proven elusive. Here, we find that discretely sampled abstract relationships between entities in an unseen two-dimensional (2-D) social hierarchy are reconstructed into a unitary 2-D cognitive map in the hippocampus and entorhinal cortex. We further show that humans utilize a grid-like code in several brain regions, including entorhinal cortex and medial prefrontal cortex, for inferred direct trajectories between entities in the reconstructed abstract space during discrete decisions. Moreover, these neural grid-like codes in the entorhinal cortex predict neural decision value computations in the medial prefrontal cortex and temporoparietal junction area during choice. Collectively, these findings show that grid-like codes are used by the human brain to infer novel solutions, even in abstract and discrete problems, and suggest a general mechanism underpinning flexible decision making and generalization.

Thallium Induced Changes in Behavioral Patterns: Correlation With Altered Lipid Peroxidation and Lysosomal Enzyme Activity in Brain Regions of Male Rats

1985 ◽  
Vol 1 (1) ◽  
pp. 81-98 ◽  
Author(s):  
David R. Brown ◽  
Barbara G. Callahan ◽  
Mark A. Cleaves ◽  
Robert A. Schatz
Keyword(s):  
Lipid Peroxidation ◽  
Lysosomal Enzyme ◽  
Brain Regions ◽  
Male Rats ◽  
Patterns Of Behavior ◽  
Low Levels ◽  
Behavioral Sequelae ◽  
Human Poisoning ◽  
And Function ◽  
Induced Changes

The effects of exposures to low levels of heavy metals is a complex and serious problem. Thallium is a metal which produces behavioral sequelae in human poisoning and is potentially hazardous with low level exposures. A test battery is presented which utilizes biochemical and behavioral testing to assess the effects of low levels of thallium on central nervous system chemistry and function in rats. The doses of thallium used (4 and 8 mg/kg) produced no overt signs of behavioral toxicity but did produce dose-related increases in lipid peroxidation and activation of the lysosomal enzyme beta-galactosidase in selected brain regions. At these dose levels, thallium also selectively altered the patterns of behavior. The study suggests that the target regions of thallium in the brain include the cortex, the cerebellum and the brainstem. The dose-response relationships, found for certain pairs of behavioral acts, were correlated with biochemical changes in one or more brain regions.

scholarly journals Silence, Solitude, and Serotonin: Neural Mechanisms Linking Hearing Loss and Social Isolation

2020 ◽  
Vol 10 (6) ◽  
pp. 367
Author(s):  
Sarah M. Keesom ◽  
Laura M. Hurley
Keyword(s):  
Hearing Loss ◽  
Social Isolation ◽  
Human Subjects ◽  
Brain Regions ◽  
Neural Systems ◽  
Depression And Anxiety ◽  
Auditory Cognition ◽  
Regulatory Systems ◽  
Two Factors ◽  
And Function

For social animals that communicate acoustically, hearing loss and social isolation are factors that independently influence social behavior. In human subjects, hearing loss may also contribute to objective and subjective measures of social isolation. Although the behavioral relationship between hearing loss and social isolation is evident, there is little understanding of their interdependence at the level of neural systems. Separate lines of research have shown that social isolation and hearing loss independently target the serotonergic system in the rodent brain. These two factors affect both presynaptic and postsynaptic measures of serotonergic anatomy and function, highlighting the sensitivity of serotonergic pathways to both types of insult. The effects of deficits in both acoustic and social inputs are seen not only within the auditory system, but also in other brain regions, suggesting relatively extensive effects of these deficits on serotonergic regulatory systems. Serotonin plays a much-studied role in depression and anxiety, and may also influence several aspects of auditory cognition, including auditory attention and understanding speech in challenging listening conditions. These commonalities suggest that serotonergic pathways are worthy of further exploration as potential intervening mechanisms between the related conditions of hearing loss and social isolation, and the affective and cognitive dysfunctions that follow.

scholarly journals Automatic Segmentation of the Dorsal Claustrum in Humans Using in vivo High-Resolution MRI

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Shai Berman ◽  
Roey Schurr ◽  
Gal Atlan ◽  
Ami Citri ◽  
Aviv A Mezer
Keyword(s):  
High Resolution ◽  
Automatic Segmentation ◽  
Thin Sheet ◽  
Brain Regions ◽  
Reproducible Research ◽  
Human Connectome Project ◽  
High Resolution Mri ◽  
Magnetic Resonance Imaging Mri ◽  
And Function

Abstract The claustrum is a thin sheet of neurons enclosed by white matter and situated between the insula and the putamen. It is highly interconnected with sensory, frontal, and subcortical regions. The deep location of the claustrum, with its fine structure, has limited the degree to which it could be studied in vivo. Particularly in humans, identifying the claustrum using magnetic resonance imaging (MRI) is extremely challenging, even manually. Therefore, automatic segmentation of the claustrum is an invaluable step toward enabling extensive and reproducible research of the anatomy and function of the human claustrum. In this study, we developed an automatic algorithm for segmenting the human dorsal claustrum in vivo using high-resolution MRI. Using this algorithm, we segmented the dorsal claustrum bilaterally in 1068 subjects of the Human Connectome Project Young Adult dataset, a publicly available high-resolution MRI dataset. We found good agreement between the automatic and manual segmentations performed by 2 observers in 10 subjects. We demonstrate the use of the segmentation in analyzing the covariation of the dorsal claustrum with other brain regions, in terms of macro- and microstructure. We identified several covariance networks associated with the dorsal claustrum. We provide an online repository of 1068 bilateral dorsal claustrum segmentations.

scholarly journals Cross-sectional associations of tau-PET signal with cognition in cognitively unimpaired adults

Neurology ◽  
2019 ◽  
Vol 93 (1) ◽  
pp. e29-e39 ◽  
Author(s):  
Val J. Lowe ◽  
Tyler J. Bruinsma ◽  
Heather J. Wiste ◽  
Hoon-Ki Min ◽  
Stephen D. Weigand ◽  
...  
Keyword(s):  
Entorhinal Cortex ◽  
Medial Temporal Lobe ◽  
Memory Performance ◽  
Standardized Uptake Value ◽  
Brain Regions ◽  
Population Based ◽  
Cognitive Test ◽  
Amyloid Pet ◽  
Cross Sectional ◽  
Tau Pet

ObjectiveTo assess cross-sectional associations of neurofibrillary tangles, measured by tau-PET, with cognitive performance in cognitively unimpaired (CU) adults.MethodsTau- and amyloid-PET were performed in 579 CU participants aged 50–98 from the population-based Mayo Clinic Study of Aging. Associations between tau-PET signal in 43 brain regions and cognitive test scores were assessed using penalized linear regression. In additional models, participants were classified by normal/abnormal global amyloid-PET (A+/A−) and normal/abnormal regional tau-PET (T+/T−). Regional tau-PET cutpoints were defined as standardized uptake value ratio (SUVR) greater than the 95th percentile of tau-PET SUVR in that region among 117 CU participants aged 30–49.ResultsHigher tau-PET signal was associated with poorer memory performance in all medial temporal lobe (MTL) regions and also in the middle temporal pole and frontal olfactory regions. The largest association with tau-PET and memory z scores was seen in the entorhinal cortex; this association was independent of tau-PET signal in other brain regions. Tau-PET in the entorhinal cortex was also associated with poorer global and language performance. In the entorhinal cortex, T+ was associated with lower memory performance among both A− and A+.ConclusionsTau deposition in MTL regions, as reflected by tau-PET signal, was associated with poorer performance on memory tests in CU participants. The association with entorhinal cortex tau-PET was independent of tau-PET signal in other brain regions. Longitudinal studies are needed to understand the fate of CU participants with elevated medial temporal tau-PET signal.

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