Task- and intensity-dependent modulation of arm-trunk neural interactions in the corticospinal pathway in humans

Depletion of estrogens and progesterone at menopause has been linked to an increased risk for the development of Alzheimer’s disease (AD) in women. A currently controversial literature indicates that although treatment of postmenopausal women with hormone therapy (HT) may reduce the risk of AD, several parameters of HT may limit its potential efficacy and perhaps, even exacerbate AD risk. One such parameter is continuous vs. cyclic delivery of the progestogen component of HT. Recent experimental evidence suggests that continuous progesterone can attenuate neural actions of estradiol (E2). In the present study, we compared the effects of continuous and cyclic progesterone treatment in the presence and absence of E2 in ovariectomized 3×Tg-AD mice, a transgenic mouse model of AD. We found that ovariectomy-induced hormone depletion increases AD-like pathology in female 3×Tg-AD mice, including accumulation of β-amyloid, tau hyperphosphorylation, and impaired hippocampal-dependent behavior. E2 treatment alone prevents the increases in pathology. Continuous progesterone did not affect β-amyloid levels when delivered alone but blocked the Aβ-lowering action of E2. In contrast, cyclic progesterone significantly reduced β-amyloid levels by itself and enhanced rather than inhibited the E2 effects. These results provide new insight into the neural interactions between E2 and progesterone that may prove valuable in optimizing HT regimens in postmenopausal women.

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Somatotopic analysis of fibre and terminal distribution in the primate corticospinal pathway

Developmental Brain Research ◽

10.1016/0165-3806(86)90013-1 ◽

1986 ◽

Vol 26 (1) ◽

pp. 115-123 ◽

Cited By ~ 20

Author(s):

N.A.H. Dawnay ◽

P. Glees

Keyword(s):

Corticospinal Pathway

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Effects of Local Nicotinic Activation of the Superior Colliculus on Saccades in Monkeys

Journal of Neurophysiology ◽

10.1152/jn.00558.2004 ◽

2005 ◽

Vol 93 (1) ◽

pp. 519-534 ◽

Cited By ~ 21

Author(s):

Masayuki Watanabe ◽

Yasushi Kobayashi ◽

Yuka Inoue ◽

Tadashi Isa

Keyword(s):

Superior Colliculus ◽

Reaction Times ◽

Low Frequency ◽

Visually Guided ◽

Population Activity ◽

Affected Area ◽

Movement Field ◽

Neural Interactions ◽

Restricted Region

To examine the role of competitive and cooperative neural interactions within the intermediate layer of superior colliculus (SC), we elevated the basal SC neuronal activity by locally injecting a cholinergic agonist nicotine and analyzed its effects on saccade performance. After microinjection, spontaneous saccades were directed toward the movement field of neurons at the injection site (affected area). For visually guided saccades, reaction times were decreased when targets were presented close to the affected area. However, when visual targets were presented remote from the affected area, reaction times were not increased regardless of the rostrocaudal level of the injection sites. The endpoints of visually guided saccades were biased toward the affected area when targets were presented close to the affected area. After this endpoint effect diminished, the trajectories of visually guided saccades remained modestly curved toward the affected area. Compared with the effects on endpoints, the effects on reaction times were more localized to the targets close to the affected area. These results are consistent with a model that saccades are triggered by the activities of neurons within a restricted region, and the endpoints and trajectories of the saccades are determined by the widespread population activity in the SC. However, because increased reaction times were not observed for saccades toward targets remote from the affected area, inhibitory interactions in the SC may not be strong enough to shape the spatial distribution of the low-frequency preparatory activities in the SC.

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BOLD Coherence Reveals Segregated Functional Neural Interactions When Adapting to Distinct Torque Perturbations

Journal of Neurophysiology ◽

10.1152/jn.00405.2006 ◽

2007 ◽

Vol 97 (3) ◽

pp. 2107-2120 ◽

Cited By ~ 16

Author(s):

Eugene Tunik ◽

Paul J. Schmitt ◽

Scott T. Grafton

Keyword(s):

Basal Ganglia ◽

Contextual Information ◽

Natural World ◽

Adaptive Responses ◽

Response Preparation ◽

Target Capture ◽

Neural Processes ◽

Neural Interactions ◽

The Right ◽

Level Analysis

In the natural world, we experience and adapt to multiple extrinsic perturbations. This poses a challenge to neural circuits in discriminating between different context-appropriate responses. Using event-related fMRI, we characterized the neural dynamics involved in this process by randomly delivering a position- or velocity-dependent torque perturbation to subjects’ arms during a target-capture task. Each perturbation was color-cued during movement preparation to provide contextual information. Although trajectories differed between perturbations, subjects significantly reduced error under both conditions. This was paralleled by reduced BOLD signal in the right dentate nucleus, the left sensorimotor cortex, and the left intraparietal sulcus. Trials included “NoGo” conditions to dissociate activity related to preparation from execution and adaptation. Subsequent analysis identified perturbation-specific neural processes underlying preparation (“NoGo”) and adaptation (“Go”) early and late into learning. Between-perturbation comparisons of BOLD magnitude revealed negligible differences for both preparation and adaptation trials. However, a network-level analysis of BOLD coherence revealed that by late learning, response preparation (“NoGo”) was attributed to a relative focusing of coherence within cortical and basal ganglia networks in both perturbation conditions, demonstrating a common network interaction for establishing arbitrary visuomotor associations. Conversely, late-learning adaptation (“Go”) was attributed to a focusing of BOLD coherence between a cortical–basal ganglia network in the viscous condition and between a cortical–cerebellar network in the positional condition. Our findings demonstrate that trial-to-trial acquisition of two distinct adaptive responses is attributed not to anatomically segregated regions, but to differential functional interactions within common sensorimotor circuits.

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Dynamical Latent State Computation in the Posterior Parietal Cortex

10.1101/2022.01.12.476065 ◽

2022 ◽

Author(s):

Kaushik J Lakshminarasimhan ◽

Eric Avila ◽

Xaq Pitkow ◽

Dora E Angelaki

Keyword(s):

Parietal Cortex ◽

Posterior Parietal Cortex ◽

Target Location ◽

Neural Representation ◽

World Model ◽

Population Activity ◽

The World ◽

Neural Interactions ◽

Posterior Parietal ◽

Hidden States

Success in many real-world tasks depends on our ability to dynamically track hidden states of the world. To understand the underlying neural computations, we recorded brain activity in posterior parietal cortex (PPC) of monkeys navigating by optic flow to a hidden target location within a virtual environment, without explicit position cues. In addition to sequential neural dynamics and strong interneuronal interactions, we found that the hidden state -- monkey's displacement from the goal -- was encoded in single neurons, and could be dynamically decoded from population activity. The decoded estimates predicted navigation performance on individual trials. Task manipulations that perturbed the world model induced substantial changes in neural interactions, and modified the neural representation of the hidden state, while representations of sensory and motor variables remained stable. The findings were recapitulated by a task-optimized recurrent neural network model, suggesting that neural interactions in PPC embody the world model to consolidate information and track task-relevant hidden states.

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Refinement of the primate corticospinal pathway during prenatal development

10.1101/575936 ◽

2019 ◽

Author(s):

Ana Rita Ribeiro Gomes ◽

Etienne Olivier ◽

Herbert P. Killackey ◽

Pascale Giroud ◽

Michel Berland ◽

...

Keyword(s):

Occipital Cortex ◽

Prenatal Development ◽

Zona Incerta ◽

Central Nucleus ◽

Projection Neurons ◽

Subcortical Structures ◽

Corticospinal Pathway ◽

Contralateral Projection ◽

Order Of Magnitude ◽

Ipsilateral Projection

AbstractPerturbation of the developmental refinement of the corticospinal pathway leads to motor disorders. In non-primates developmental refinement is well documented, however in primates invasive investigations of the developing corticospinal pathway have been confined to neonatal and postnatal stages when refinement is relatively modest.Here, we investigated the developmental changes in the distribution of corticospinal projection neurons in cynomolgus monkey. Injections of retrograde tracer at the cervical levels of the spinal cord at embryonic day (E) 95 and E105 show that (i) areal distribution of back-labeled neurons is more extensive than in the neonate and dense labeling is found in prefrontal, limbic, temporal and occipital cortex; (ii) distributions of contra- and ipsilateral projecting corticospinal neurons are comparable in terms of location and numbers of labeled neurons, in contrast to the adult where the contralateral projection is an order of magnitude higher than the ipsilateral projection. Findings from one largely restricted injection suggest a hitherto unsuspected early innervation of the gray matter.In the fetus there was in addition dense labeling in the central nucleus of the amygdala, the hypothalamus, the subthalamic nucleus and the adjacent region of the zona incerta, subcortical structures with only minor projections in the adult control.

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Dynamical differential covariance recovers directional network structure in multiscale neural systems

10.1101/2021.06.18.448901 ◽

2021 ◽

Author(s):

Yusi Chen ◽

Burke Q Rosen ◽

Terrence J Sejnowski

Keyword(s):

Structural Connectivity ◽

Network Models ◽

Ground Truth ◽

Neural Systems ◽

Noise Tolerance ◽

Functional Magnetic Resonance ◽

Resonance Imaging ◽

Dynamical Models ◽

Wide Range ◽

Neural Interactions

Investigating causal neural interactions are essential to understanding sub- sequent behaviors. Many statistical methods have been used for analyzing neural activity, but efficiently and correctly estimating the direction of net- work interactions remains difficult. Here, we derive dynamical differential covariance (DDC), a new method based on dynamical network models that detects directional interactions with low bias and high noise tolerance with- out the stationary assumption. The method is first validated on networks with false positive motifs and multiscale neural simulations where the ground truth connectivity is known. Then, applying DDC to recordings of resting-state functional magnetic resonance imaging (rs-fMRI) from over 1,000 individual subjects, DDC consistently detected regional interactions with strong structural connectivity. DDC can be generalized to a wide range of dynamical models and recording techniques.

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Interlimb neural interactions in the corticospinal pathways

The Journal of Physical Fitness and Sports Medicine ◽

10.7600/jpfsm.3.181 ◽

2014 ◽

Vol 3 (2) ◽

pp. 181-190 ◽

Cited By ~ 7

Author(s):

Toshiki Tazoe ◽

Tomoyoshi Komiyama

Keyword(s):

Neural Interactions

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