scholarly journals Modulation of motor behavior by the mesencephalic locomotor region

2020 ◽  
Author(s):  
Daniel Dautan ◽  
Adrienn Kovács ◽  
Tsogbadrakh Bayasgalan ◽  
Miguel A. Diaz-Acevedo ◽  
Balazs Pal ◽  
...  
Keyword(s):  
Motor Activity ◽  
Motor Neurons ◽  
Muscle Activation ◽  
Motor Behavior ◽  
Muscle Tone ◽  
Pedunculopontine Nucleus ◽  
Mesencephalic Locomotor Region ◽  
Glutamatergic Neurons ◽  
Axonal Projections ◽  
Physiological Properties

AbstractThe mesencephalic locomotor region (MLR) serves as an interface between higher-order motor systems and lower motor neurons. The excitatory module of the MLR is composed of the pedunculopontine nucleus (PPN) and the cuneiform nucleus (CnF), and their activation has been proposed to elicit different modalities of movement, but how the differences in connectivity and physiological properties explain their contributions to motor activity is not known. Here we report that CnF glutamatergic neurons are electrophysiologically homogeneous and have short-range axonal projections, whereas PPN glutamatergic neurons are heterogeneous and maintain long-range connections, most notably with the basal ganglia. Optogenetic activation of CnF neurons produced fast-onset, involuntary motor activity mediated by short-lasting muscle activation. In contrast, activation of PPN neurons produced long-lasting increases in muscle tone that reduced motor activity and disrupted gait. Our results thus reveal a differential contribution to motor behavior by the structures that compose the MLR.

DISTRIBUTIONS OF LOCAL MANDELBROT-HURST EXPONENTS: MOTOR ACTIVITY IN FETAL RATS OF COCAINIZED MOTHERS AND MANIC-DEPRESSIVE PATIENTS

Fractals ◽  
1995 ◽  
Vol 03 (04) ◽  
pp. 893-904 ◽  
Author(s):  
KAREN A. SELZ ◽  
ARNOLD J. MANDELL ◽  
CARL M. ANDERSON ◽  
WILLIAM P. SMOTHERMAN ◽  
MARTIN H. TEICHER
Keyword(s):  
Time Series ◽  
Motor Activity ◽  
Motor Behavior ◽  
Pregnant Rats ◽  
Behavioral Systems ◽  
Statistical Indices ◽  
Manic Depressive ◽  
The One ◽  
Depressive Patients ◽  
Hurst Exponents

Intermittency, in which the normalized weight of large fluctuations grows for increasingly longer statistical samples, is seen as irregular bursting activity in time and is characteristic of the behavior of many brain and behavioral systems. This pattern has been related to the brain-stabilizing interplay of the general mechanisms of silence-evoked sensitization and activity-evoked desensitization, which can be found at most levels of neurobiological function and which vary more smoothly and at much longer times than the phasic observables. We use both the global Mandelbrot-Hurst exponent and the distribution of local Mandelbrot-Hurst exponents, in combination with dynamical entropies, to quantitate the property of nonuniform persistence which we treat as both deterministically expansive and statistically diffusive. For example, varying the parameter of the one-dimensional, Manneville-Pomeau intermittency map generated time series which demonstrated systematic changes in these statistical indices of persistence. Relatively small doses of cocaine administered to pregnant rats increased statistical indices of expansiveness and persistence in fetal motor behavior. These techniques also model and characterize a breakdown of statistical scaling in 72-hour time series of the amount of motor activity in some hospitalized manic-depressive patients.

scholarly journals A genetic manipulation of motor neuron excitability does not alter locomotor output in Drosophila larvae

2014 ◽  
Author(s):  
Erin C. McKiernan
Keyword(s):  
Motor Neuron ◽  
Motor Neurons ◽  
Motor Behavior ◽  
Genetic Manipulation ◽  
Motor Output ◽  
Membrane Properties ◽  
Neuron Excitability ◽  
Motor Neuron Excitability ◽  
The Face

Motor activity, like that producing locomotion, is generated by networks of neurons. At the last output level of these networks are the motor neurons, which send signals to the muscles, causing them to contract. Current research in motor control is focused on finding out how motor neurons contribute to shaping the timing of motor behaviors. Are motor neurons just passive relayers of the signals they receive? Or, do motor neurons shape the signals before passing them on to the muscles, thereby influencing the timing of the behavior? It is now well accepted that motor neurons have active, intrinsic membrane properties - there are ion channels in the cell membrane that allow motor neurons to respond to input in non-linear and diverse ways. However, few direct tests of the role of motor neuron intrinsic properties in shaping motor behavior have been carried out, and many questions remain about the role of specific ion channel genes in motor neuron function. In this study, two potassium channel transgenes were expressed in Drosophila larvae, causing motor neurons to fire at lower levels of current stimulation and at higher frequencies, thereby increasing excitability. Mosaic animals were created in which some identified motor neurons expressed the transgenes while others did not. Motor output underlying crawling was compared in muscles innervated by control and experimental neurons in the same animals. Counterintuitively, no effect of the transgenic manipulation on motor output was seen. Future experiments are outlined to determine how the larval nervous system produces normal motor output in the face of altered motor neuron excitability.

scholarly journals New perspectives on cytoskeletal dysregulation and mitochondrial mislocalization in amyotrophic lateral sclerosis

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Frances Theunissen ◽  
Phillip K. West ◽  
Samuel Brennan ◽  
Bojan Petrović ◽  
Kosar Hooshmand ◽  
...  
Keyword(s):  
Amyotrophic Lateral Sclerosis ◽  
Motor Neurons ◽  
Retrograde Transport ◽  
Cytoskeletal Proteins ◽  
Charcot Marie Tooth Disease ◽  
Mitochondrial Homeostasis ◽  
Axonal Projections ◽  
Cytoskeletal Network ◽  
Brain And Spinal Cord ◽  
Lateral Sclerosis

AbstractAmyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by selective, early degeneration of motor neurons in the brain and spinal cord. Motor neurons have long axonal projections, which rely on the integrity of neuronal cytoskeleton and mitochondria to regulate energy requirements for maintaining axonal stability, anterograde and retrograde transport, and signaling between neurons. The formation of protein aggregates which contain cytoskeletal proteins, and mitochondrial dysfunction both have devastating effects on the function of neurons and are shared pathological features across several neurodegenerative conditions, including ALS, Alzheimer's disease, Parkinson's disease, Huntington’s disease and Charcot-Marie-Tooth disease. Furthermore, it is becoming increasingly clear that cytoskeletal integrity and mitochondrial function are intricately linked. Therefore, dysregulations of the cytoskeletal network and mitochondrial homeostasis and localization, may be common pathways in the initial steps of neurodegeneration. Here we review and discuss known contributors, including variants in genetic loci and aberrant protein activities, which modify cytoskeletal integrity, axonal transport and mitochondrial localization in ALS and have overlapping features with other neurodegenerative diseases. Additionally, we explore some emerging pathways that may contribute to this disruption in ALS.

scholarly journals Toxicity associated with ingestion of a polyacrylic acid hydrogel dog pad

2018 ◽  
Vol 30 (5) ◽  
pp. 708-714 ◽  
Author(s):  
David C. Dorman ◽  
Melanie L. Foster ◽  
Brooke Olesnevich ◽  
Brad Bolon ◽  
Aude Castel ◽  
...  
Keyword(s):  
Motor Activity ◽  
Polyacrylic Acid ◽  
Muscle Tone ◽  
Clinical Signs ◽  
High Dose ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Before And After ◽  
Acute Neurotoxicity ◽  
Disposable Diapers

Superabsorbent sodium polyacrylate polymeric hydrogels that retain large amounts of liquids are used in disposable diapers, sanitary napkins, and other applications. These polymers are generally considered “nontoxic” with acute oral median lethal doses (LD50) >5 g/kg. Despite this favorable toxicity profile, we identified a novel toxic syndrome in dogs and rats following the ingestion of a commercial dog pad composed primarily of a polyacrylic acid hydrogel. Inappropriate mentation, cerebellar ataxia, vomiting, and intention tremors were observed within 24 h after the ingestion of up to 15.7 g/kg of the hydrogel by an adult, castrated male Australian Shepherd mix. These observations prompted an experimental study in rats to further characterize the toxicity of the hydrogel. Adult, female Sprague Dawley rats ( n = 9) were assessed before and after hydrogel ingestion (2.6–19.2 g/kg over 4 h) using a functional observation battery and spontaneous motor activity. Clinical signs consistent with neurotoxicity emerged in rats as early as 2 h after the end of hydrogel exposure, including decreased activity in an open field, hunched posture, gait changes, reduced reaction to handling, decreased muscle tone, and abnormal surface righting. Hydrogel-exposed rats also had reduced motor activity when compared with pre-exposure baseline data. Rats that ingested the hydrogel did not develop nervous system lesions. These findings support the conclusion that some pet pad hydrogel products can induce acute neurotoxicity in animals under high-dose exposure conditions.

The control of rostrocaudal pattern in the developing spinal cord: specification of motor neuron subtype identity is initiated by signals from paraxial mesoderm

Development ◽  
1998 ◽  
Vol 125 (6) ◽  
pp. 969-982 ◽  
Author(s):  
M. Ensini ◽  
T.N. Tsuchida ◽  
H.G. Belting ◽  
T.M. Jessell
Keyword(s):  
Spinal Cord ◽  
Motor Neuron ◽  
Motor Neurons ◽  
Neural Tube ◽  
Motor Behavior ◽  
Neural Tube Closure ◽  
Paraxial Mesoderm ◽  
Homeodomain Protein ◽  
Mesodermal Cell ◽  
Developing Spinal Cord

The generation of distinct classes of motor neurons is an early step in the control of vertebrate motor behavior. To study the interactions that control the generation of motor neuron subclasses in the developing avian spinal cord we performed in vivo grafting studies in which either the neural tube or flanking mesoderm were displaced between thoracic and brachial levels. The positional identity of neural tube cells and motor neuron subtype identity was assessed by Hox and LIM homeodomain protein expression. Our results show that the rostrocaudal identity of neural cells is plastic at the time of neural tube closure and is sensitive to positionally restricted signals from the paraxial mesoderm. Such paraxial mesodermal signals appear to control the rostrocaudal identity of neural tube cells and the columnar subtype identity of motor neurons. These results suggest that the generation of motor neuron subtypes in the developing spinal cord involves the integration of distinct rostrocaudal and dorsoventral patterning signals that derive, respectively, from paraxial and axial mesodermal cell groups.

Temporal Sparseness of the Premotor Drive Is Important for Rapid Learning in a Neural Network Model of Birdsong

2004 ◽  
Vol 92 (4) ◽  
pp. 2274-2282 ◽  
Author(s):  
Ila R. Fiete ◽  
Richard H.R. Hahnloser ◽  
Michale S. Fee ◽  
H. Sebastian Seung
Keyword(s):  
Neural Network ◽  
Network Model ◽  
Motor Neurons ◽  
Neural Network Model ◽  
Motor Behavior ◽  
Analytical Techniques ◽  
Temporal Coding ◽  
Neural Codes ◽  
Learning Time ◽  
Complex Motor

Sparse neural codes have been widely observed in cortical sensory and motor areas. A striking example of sparse temporal coding is in the song-related premotor area high vocal center (HVC) of songbirds: The motor neurons innervating avian vocal muscles are driven by premotor nucleus robustus archistriatalis (RA), which is in turn driven by nucleus HVC. Recent experiments reveal that RA-projecting HVC neurons fire just one burst per song motif. However, the function of this remarkable temporal sparseness has remained unclear. Because birdsong is a clear example of a learned complex motor behavior, we explore in a neural network model with the help of numerical and analytical techniques the possible role of sparse premotor neural codes in song-related motor learning. In numerical simulations with nonlinear neurons, as HVC activity is made progressively less sparse, the minimum learning time increases significantly. Heuristically, this slowdown arises from increasing interference in the weight updates for different synapses. If activity in HVC is sparse, synaptic interference is reduced, and is minimized if each synapse from HVC to RA is used only once in the motif, which is the situation observed experimentally. Our numerical results are corroborated by a theoretical analysis of learning in linear networks, for which we derive a relationship between sparse activity, synaptic interference, and learning time. If songbirds acquire their songs under significant pressure to learn quickly, this study predicts that HVC activity, currently measured only in adults, should also be sparse during the sensorimotor phase in the juvenile bird. We discuss the relevance of these results, linking sparse codes and learning speed, to other multilayered sensory and motor systems.

Control Mechanisms in Oscillatory Motor Behavior

2013 ◽  
Author(s):  
Davide Piovesan ◽  
Felix C. Huang
Keyword(s):  
Muscle Activation ◽  
Motor Behavior ◽  
Rhythmic Movement ◽  
Control Mechanisms ◽  
Rhythmic Movements ◽  
Movement Trajectories ◽  
Reduced Frequency ◽  
The Central Nervous System ◽  
Human Motor ◽  
Inertial Loading

Studies on unimpaired humans have demonstrated that the central nervous system employs internal representations of limb dynamics and intended movement trajectories for planning muscle activation during pointing and reaching tasks. However, when performing rhythmic movements, it has been hypothesized that a control scheme employing an autonomous oscillator — a simple feedback circuit lacking exogenous input — can maintain stable control. Here we investigate whether such simple control architectures that can realize rhythmic movement that we observe in experimental data. We asked subjects to perform rhythmic movements of the forearm while a robotic interface simulated inertial loading. Our protocol included unexpected increases in loading (catch trials) as a probe to reveal any systematic changes in frequency and amplitude. Our primary findings were that increased inertial loading resulted in reduced frequency of oscillations, and in some cases multiple frequencies. These results exhibit some agreement with an autonomous oscillator model, though other features are more consistent with feedforward planning of force. This investigation provides a theoretical and experimental framework to reveal basic computational elements for how the human motor system achieves skilled rhythmic movement.

Measuring poststroke spasticity

2000 ◽  
Vol 10 (1) ◽  
pp. 69-74 ◽  
Author(s):  
J. M. Gregson ◽  
A. K. Sharma
Keyword(s):  
Normal State ◽  
Stretch Reflex ◽  
Muscle Activation ◽  
Muscle Tone ◽  
Clinical Syndrome ◽  
Motor Disorder ◽  
Muscle Forces ◽  
Joint Movement ◽  
Stretch Reflexes ◽  
Reflex Action

What is spasticity?Spasticity is a well-recognized and potentially important clinical syndrome comprising inappropriate and involuntary high muscle tone. It has been variably defined, with debate still ongoing. Currently, the most widely accepted definition is that of Lance, stating that spasticity is ‘a motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes (muscle tone) with exaggerated tendon jerks, resulting from hyper-excitability of the stretch reflex.’ Unfortunately, even this description does not fully encompass the multifactorial nature of spasticity, since resistance to movement, even in the normal state, is subject to varied contributors. These include patient volition, inertia, visco-elastic muscle forces and range of joint movement, as well as true muscle activation secondary to reflex action. In the real clinical world, it is often not possible to distinguish which of these features is/are dominant. Furthermore, spastic muscle undergoes physiopathological, rheologic change with stiffness, atrophy, fibrosis and finally contracture.

Sign in / Sign up

Export Citation Format

Share Document