scholarly journals The neural pathway midline crossing theory: a historical analysis of Santiago Rámon y Cajal’s contribution on cerebral localization and on contralateral forebrain organization

2019 ◽  
Vol 47 (3) ◽  
pp. E10
Author(s):  
Carla Mora ◽  
Carlos Velásquez ◽  
Juan Martino
Keyword(s):  
Brain Plasticity ◽  
Great Influence ◽  
Optic Chiasm ◽  
Compensatory Mechanism ◽  
Neural Pathways ◽  
Neural Pathway ◽  
Cortical Function ◽  
Cerebral Lateralization ◽  
Midline Crossing ◽  
Crossing Theory

Throughout history, many scientists have wondered about the reason for neural pathway decussation in the CNS resulting in contralateral forebrain organization. Hitherto, one of the most accepted theories is the one described by the renowned Spanish physician, Santiago Rámon y Cajal at the end of the 19th century. This Nobel Prize winner, among his many contributions to science, gave us the answer to this question: the key lies in the optic chiasm. Based on the fact that the ocular lenses invert the image formed in the retina, Cajal explained how the decussation of the fibers in the optic chiasm is necessary to obtain a continuous image of the outside in the brain. The crossing of the tactile and motor pathways occurred posteriorly as a compensatory mechanism to allow the cortical integration of the sensory, motor, and visual functions. This theory had a great influence on the scientific community of his time, and maintains its importance today, in which none of the theories formulated to date has managed to entirely refute Cajal’s. In addition, the decussation of neural pathways plays a significant role in different diseases, especially in the recovery process after a hemispheric lesion and in several congenital pathologies. The advantages of cerebral lateralization have also recently been published, although the evolutionary connection between fiber decussation and cortical function lateralization remains a mystery to be solved. A better understanding of the molecular and genetic substrates of the midline crossing processes might result in significant clinical advances in brain plasticity and repair.

scholarly journals Optic Chiasm Presentation of Semaphorin6D in the Context of Plexin-A1 and Nr-CAM Promotes Retinal Axon Midline Crossing

Neuron ◽  
2012 ◽  
Vol 74 (4) ◽  
pp. 676-690 ◽  
Author(s):  
Takaaki Kuwajima ◽  
Yutaka Yoshida ◽  
Noriko Takegahara ◽  
Timothy J. Petros ◽  
Atsushi Kumanogoh ◽  
...  
Keyword(s):  
Optic Chiasm ◽  
Midline Crossing ◽  
Retinal Axon

scholarly journals Eyes Open on Sleep and Wake: In Vivo to In Silico Neural Networks

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Amaury Vanvinckenroye ◽  
Gilles Vandewalle ◽  
Christophe Phillips ◽  
Sarah L. Chellappa
Keyword(s):  
In Silico ◽  
Brain Function ◽  
Computational Models ◽  
Temporal Dynamics ◽  
Brain Plasticity ◽  
Effective Connectivity ◽  
Normal Brain ◽  
Cortical Function ◽  
Eyes Open

Functional and effective connectivity of cortical areas are essential for normal brain function under different behavioral states. Appropriate cortical activity during sleep and wakefulness is ensured by the balanced activity of excitatory and inhibitory circuits. Ultimately, fast, millisecond cortical rhythmic oscillations shape cortical function in time and space. On a much longer time scale, brain function also depends on prior sleep-wake history and circadian processes. However, much remains to be established on how the brain operates at the neuronal level in humans during sleep and wakefulness. A key limitation of human neuroscience is the difficulty in isolating neuronal excitation/inhibition drive in vivo. Therefore, computational models are noninvasive approaches of choice to indirectly access hidden neuronal states. In this review, we present a physiologically driven in silico approach, Dynamic Causal Modelling (DCM), as a means to comprehend brain function under different experimental paradigms. Importantly, DCM has allowed for the understanding of how brain dynamics underscore brain plasticity, cognition, and different states of consciousness. In a broader perspective, noninvasive computational approaches, such as DCM, may help to puzzle out the spatial and temporal dynamics of human brain function at different behavioural states.

The neuroscience of translation

Target ◽  
2012 ◽  
Vol 24 (1) ◽  
pp. 83-102 ◽  
Author(s):  
Maria Tymoczko
Keyword(s):  
Language Processing ◽  
New Technologies ◽  
Brain Plasticity ◽  
Translation Studies ◽  
Neural Pathways ◽  
Quarter Century ◽  
Terra Incognita ◽  
Known Unknowns ◽  
The Individual ◽  
The Brain

The neurological mechanisms involved in translating and interpreting are one of the chief known unknowns in translation studies. Translation studies has explored many facets of the processes and products of translation and interpreting, ranging from the linguistic aspects to the textual aspects, from the politics of translation to implications from cognitive science, but little is known about the production and reception of translation at the level of the individual brain and the level of molecular biology.1 Much of this terra incognita will be explored and illuminated by neuroscience in the coming quarter century, and significant discoveries pertaining to language processing in translation will be made during the coming decade, linking observable behaviors at the macro level with knowledge of what happens in the production and reception of translation at the micro level of the neuron and the neuronal pathways of the brain. In the past two decades powerful new techniques for observing brain function in healthy living individuals have been devised. To a large extent neuroscience has become a rapidly developing field because of new technologies that make it possible to monitor the brain as it actually works, to document neural pathways, and even to track the activity of specific neurons. This article focuses on discoveries in neuroscience pertaining to perception, memory, and brain plasticity that have already achieved consensus in the field and that have durable implications for the ways we will think about translation in the future.

scholarly journals DRD2 Taq1A Polymorphism-Related Brain Volume Changes in Parkinson’s Disease: Voxel-Based Morphometry

2020 ◽  
Author(s):  
Kenji Ohira ◽  
Hajime Yokota ◽  
Shigeki Hirano ◽  
Motoi Nishimura ◽  
Hiroki Mukai ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Brain Volume ◽  
Clinical Performance ◽  
Morphological Changes ◽  
Compensatory Mechanism ◽  
Voxel Based Morphometry ◽  
Cortical Function ◽  
Increased Risk ◽  
The Relationship

Abstract Taq1A polymorphism is a DRD2 gene variant located in an exon of the ANKK1 gene and has an important role in the brain’s dopaminergic functions. Some studies have indicated that A1 carriers have an increased risk of developing Parkinson’s disease (PD) and show poorer clinical performance than A2 homo carriers. Previous studies have suggested that A1 carriers had fewer dopamine D2 receptors in the caudate and increased cortical activity as a compensatory mechanism. However, there is little information about morphological changes associated with this polymorphism in patients with PD. The study aim was to investigate the relationship between brain volume and Taq1A polymorphism in PD using voxel-based morphometry (VBM). Based on Taq1A polymorphism, 103 patients with PD were divided into two groups: A1 carriers (A1/A1, A1/A2) and A2 homo carriers (A2/A2). The volume of the left prefrontal cortex (PFC) was significantly decreased in A2 homo carriers compared to A1 carriers. This finding supports the association between Taq1A polymorphism and brain volume in PD and may explain the compensation of cortical function in A1 carriers with PD.

scholarly journals Musical practice and BDNF plasma levels as a potential marker of synaptic plasticity: an instrument of rehabilitative processes

2020 ◽  
Author(s):  
Alessandro Minutillo ◽  
Gabriele Panza ◽  
Massimo Carlo Mauri
Keyword(s):  
Synaptic Plasticity ◽  
Plasma Levels ◽  
Brain Plasticity ◽  
Autism Spectrum ◽  
Synaptic Function ◽  
Neural Pathways ◽  
Musical Practice ◽  
Potential Marker ◽  
The Difference ◽  
Attention To Detail

Abstract Background and objectives The aim of the study was to investigate the influence of musical practice on brain plasticity. BDNF (brain-derived neurotrophic factor) is a neurotrophin involved in neuroplasticity and synaptic function. Materials and methods We recruited 48 healthy subjects of equal age and sex (21 musicians and 27 non-musicians). All subjects were administered the AQ (Autism-Spectrum Questionnaire) and plasma levels (PLs) of BDNF, oxytocin (OT), and vasopressin (VP) were measured in the blood sample of every participant. Results. The difference between BDNF PLs in the two groups was found to be statistically significant (t = − 2.214, p = 0.03). Furthermore, oxytocin (OT) PLs and musical practice were found to be independent positive predictors of BDNF PLs (p < 0.04). We also found a negative correlation between BDNF PLs and AD (attention to detail) sub-scale score of AQ throughout the whole sample. Assuming BDNF PLs to be a marker of synaptic plasticity, higher PLs could be associated with the activation of alternative neural pathways: a lower score in the “attention to detail” sub-scale could imply greater flexibility of higher cerebral functions among musicians. Further researches should be conducted to assess the rehabilitative usefulness of these findings among patients affected by psychiatric disorders.

Extensors respond faster than flexors for the MCP joints even under the loss of the corticospinal system

2021 ◽  
Author(s):  
Dongwon Kim ◽  
Raziyeh Baghi ◽  
Kyung Koh ◽  
Li-Qun Zhang ◽  
Jong-Moon Hwang
Keyword(s):  
Corticospinal Tract ◽  
Force Generation ◽  
Finger Movement ◽  
Neural Pathways ◽  
Neural Pathway ◽  
Paretic Side ◽  
Corticospinal System ◽  
Movement Smoothness ◽  
Measured Activation ◽  
Flexion And Extension

Damage in the corticospinal system following stroke produces imbalance between flexors and extensors in the upper extremity including the fingers, eventually leading to flexion-favored postures. The substitution of the reticospinal tract for the damaged corticospinal tract is known to excessively activate flexors of the fingers while the fingers are voluntarily being extended. Here, we questioned whether the cortical source or/and neural pathways of the flexors and extensors of the fingers are coupled and what factor of impairment influences finger movement. In this study, a total of 7 male participants with hemiplegic stroke conducted isometric flexion and extension at the MCP joints in response to auditory tones. We measured activation and de-activation delays of the flexor and extensor of the MCP joints on the paretic side, as well as, force generation and co-contraction between the flexor and extensor. All participants generated greater torque in the direction of flexion (p=0.017). Regarding co-contraction, coupled activation of the extensor is also made during flexion in the similar way to coupled activation of the flexor made during extension. As opposite to our expectation, we observed that during extension, the extensor showed marginally significantly faster activation (p=0.66) while it showed faster de-activation (p=0.038), in comparison to activation and de-activation of the flexor during flexion. But movement smoothness was not affected by those factors. Our results imply that the cortical source and neural pathway for the extensors of the MCP joints are not coupled with those for the flexors of the MCP joints and extensor weakness mainly contributes to the asymmetry between flexors and extensors.

scholarly journals Tracking the visual system—from the optic chiasm to primary visual cortex

2020 ◽  
Author(s):  
Robert J. Puzniak ◽  
Gokulraj T. Prabhakaran ◽  
Lars Buentjen ◽  
Friedhelm C. Schmitt ◽  
Michael B. Hoffmann
Keyword(s):  
Visual System ◽  
Brain Structures ◽  
Optic Chiasm ◽  
Visual Pathways ◽  
Visual Field Defects ◽  
Neural Pathways ◽  
Diffusion Modeling ◽  
Resonance Imaging ◽  
Established Method ◽  
Inherent Risk

AbstractEpilepsy surgery is a well-established method of treatment for pharmacoresistant focal epilepsies, but it carries an inherent risk of damaging eloquent brain structures. This holds true in particular for visual system pathways, where the damage to, for example, the optic radiation may result in postoperative visual field defects. Such risk can be minimized by the identification and localization of visual pathways using diffusion magnetic resonance imaging (dMRI). The aim of this article is to provide an overview of the step-by-step process of reconstructing the visual pathways applying dMRI analysis. This includes data acquisition, preprocessing, identification of key structures of the visual system necessary for reconstruction, as well as diffusion modeling and the ultimate reconstruction of neural pathways. As a result, the reader will become familiar both with the ideas and challenges of imaging the visual system using dMRI and their relevance for planning the intervention.

scholarly journals Reduced Interhemispheric Coherence after Cerebellar Vermis Output Perturbation

2020 ◽  
Vol 10 (9) ◽  
pp. 621 ◽  
Author(s):  
Elena Laura Georgescu Margarint ◽  
Ioana Antoaneta Georgescu ◽  
Carmen-Denise-Mihaela Zahiu ◽  
Alexandru Răzvan Șteopoaie ◽  
Stefan-Alexandru Tirlea ◽  
...  
Keyword(s):  
Motor Coordination ◽  
Motor Behavior ◽  
Cerebellar Vermis ◽  
Oscillatory Activity ◽  
Neck Muscle ◽  
Compensatory Mechanism ◽  
Neural Pathways ◽  
Interhemispheric Coherence ◽  
Wide Range ◽  
Left And Right

Motor coordination and motor learning are well-known roles of the cerebellum. Recent evidence also supports the contribution of the cerebellum to the oscillatory activity of brain networks involved in a wide range of disorders. Kainate, a potent analog of the excitatory neurotransmitter glutamate, can be used to induce dystonia, a neurological movement disorder syndrome consisting of sustained or repetitive involuntary muscle contractions, when applied on the surface of the cerebellum. This research aims to study the interhemispheric cortical communication between the primary motor cortices after repeated kainate application on cerebellar vermis for five consecutive days, in mice. We recorded left and right primary motor cortices electrocorticograms and neck muscle electromyograms, and quantified the motor behavior abnormalities. The results indicated a reduced coherence between left and right motor cortices in low-frequency bands. In addition, we observed a phenomenon of long-lasting adaptation with a modification of the baseline interhemispheric coherence. Our research provides evidence that the cerebellum can control the flow of information along the cerebello-thalamo-cortical neural pathways and can influence interhemispheric communication. This phenomenon could function as a compensatory mechanism for impaired regional networks.

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