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Related Concept Videos

Disorders of the Skeletal Muscle01:28

Disorders of the Skeletal Muscle

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The clinical conditions affecting the skeletal muscle tissue are broadly categorized as musculoskeletal and neuromuscular disorders.
Musculoskeletal disorders
Musculoskeletal disorders involve injuries and conditions affecting the skeletal muscles and associated connective tissues. These disorders can arise from acute biomechanical stresses or chronic overuse and can occur across different age groups. Common injuries include sprains, fractures, and muscular strains, often resulting from...
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Directly Acting Muscle Relaxants: Dantrolene and Botulinum Toxin01:26

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Directly acting muscle relaxants like dantrolene and botulinum toxin (BoNT) have distinct mechanisms and applications. Dantrolene, a hydantoin derivative, acts on the ryanodine receptor (RYR1) in skeletal muscle cells. RYR1 are calcium channels present at the sarcoplasmic reticulum membrane. In response to excitation, they release calcium ions from the sarcoplasmic reticulum to the cytosol. Calcium promotes actin-myosin-mediated contraction of muscles.
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Motor Unit Stimulation01:20

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When the neuron of a motor unit fires an action potential, it triggers a series of events, leading to a twitch contraction in the muscle fibers. The process of excitation-contraction coupling is crucial in relaying the action potential to the muscle fibers.
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The contraction strength of muscles is regulated by motor neurons, which modulate the frequency of action potentials dispatched to the motor units based on the body's requirements. This process of varying the muscle stimulation frequency allows muscles to contract with a force that is precisely tailored to the needs of the moment, whether lifting a feather or a heavy box.
Wave summation
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Satellite Stem Cells and Muscular Dystrophy01:21

Satellite Stem Cells and Muscular Dystrophy

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Satellite stem cells or myosatellite cells are quiescent stem cells that Alexander Mauro first identified in 1961. These cells are located between the sarcolemma, the plasma membrane of muscle fibers, and the basal lamina, the connective tissue sheath covering it. These mononucleated cells are activated in response to muscle injury, can transform into myoblasts, and may form or repair muscle fibers. Myosatellite cells can provide additional myonuclei for muscle regeneration or return to a...
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Neurodegenerative disorders are progressive diseases that cause irreversible damage and loss to neurons in specific brain areas. Examples of these disorders include Parkinson's disease, Alzheimer's disease, Multiple Sclerosis (MS), and Amyotrophic Lateral Sclerosis (ALS). These disorders share characteristics such as proteinopathies, selective neuronal vulnerability, and a complex interplay between genetic and environmental factors. The primary therapeutic goal for these conditions is...
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Related Experiment Video

Updated: Feb 26, 2026

Implantation of Osmotic Pumps and Induction of Stress to Establish a Symptomatic, Pharmacological Mouse Model for DYT/PARK-ATP1A3 Dystonia
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Implantation of Osmotic Pumps and Induction of Stress to Establish a Symptomatic, Pharmacological Mouse Model for DYT/PARK-ATP1A3 Dystonia

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Dystonia as a patterned motor malflow.

Takahiro Mezaki1

  • 1Department of Neurology, Sakakibara Hakuho Hospital, 5630 Sakakibara-cho, Tsu-City, Mie 514-1251, Japan.

Medical Hypotheses
|July 25, 2017
PubMed
Summary

Dystonia involves both excessive muscle contractions ("overflow") and the inability to activate necessary muscles ("negative dystonia"). Both phenomena stem from disrupted central motor control, suggesting they are two aspects of the same motor control disorder.

Area of Science:

  • Neurology
  • Movement Disorders

Background:

  • Dystonia is traditionally defined by excessive muscle activity causing abnormal postures or movements.
  • This definition overlooks cases where patients struggle to activate muscles for intended actions, despite normal strength.

Purpose of the Study:

  • To propose a unified concept of dystonia encompassing both excessive muscle activation and impaired muscle activation.
  • To introduce the term "negative dystonia" for the latter phenomenon.

Main Methods:

  • Conceptual analysis of dystonia symptoms and underlying motor control mechanisms.
  • Review of clinical presentations, including "overflow phenomenon" and apraxia of eyelid opening.

Main Results:

  • Dystonia encompasses two distinct but related phenomena: "overflow" (excessive muscle contraction) and "flow failure" (inability to activate muscles).

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Handwriting Analysis Indicates Spontaneous Dyskinesias in Neuroleptic Naïve Adolescents at High Risk for Psychosis
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  • "Negative dystonia" describes the "flow failure" aspect, characterized by fixed patterns and potential amelioration with sensory tricks.
  • Both overflow and flow failure are hypothesized to result from a loss of central motor control.

    • Conclusions:

    • Dystonia is redefined as a disorder of patterned motor malflow (abnormal flow) due to impaired central motor control.
    • Overflow and negative dystonia are presented as two sides of the same coin, reflecting different manifestations of motor control loss.