Related Experiment Video
Updated: Jun 18, 2026
08:38
Habituation and Prepulse Inhibition of Acoustic Startle in Rodents
Published on: September 1, 2011
Mechanical perturbations applied during impending movement evoke startle-like responses.
Vengateswaran J Ravichandran1, Jonathan B Shemmell, Eric J Perreault
1Biomedical Engineering Department, Northwestern University, Chicago, IL 60611, USA. vennjr@u.northwestern.edu
Summary
Stretch reflexes, typically simple, show complex behavior. Unexpected limb perturbations during movement preparation trigger early muscle activity, suggesting interaction with voluntary motor control.
Area of Science:
- Neuroscience
- Motor Control
- Human Physiology
Background:
- Stretch reflexes are fundamental neural circuits.
- Their role in voluntary movement is debated.
- Acoustic stimuli can elicit movement-direction dependent responses.
Purpose of the Study:
- To investigate if limb perturbations during movement preparation elicit early muscle activity.
- To determine if this early activity is dependent on perturbation direction.
- To explore the interaction between stretch reflexes and voluntary activity.
Main Methods:
- Participants prepared for a voluntary movement.
- Unexpected mechanical perturbations were applied to the limb during preparation.
- Electromyography recorded muscle activity.
Main Results:
- Perturbations during movement preparation triggered early-onset muscle activity.
- This early activity was dependent on the direction of the perturbation.
- Responses indicated a modulation of stretch reflex pathways.
Conclusions:
- Limb perturbations can initiate early motor responses, similar to acoustic stimuli.
- Stretch reflexes interact with voluntary motor commands during movement preparation.
- These findings challenge the view of stretch reflexes as purely stabilizing mechanisms.
Related Concept Videos
01:20Motor Unit Stimulation
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.
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
01:22Muscle Stimulation Frequency
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
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
01:08Reflex Activity
A reflex activity is an automatic, involuntary response to specific stimuli. It is a part of our survival mechanism, designed to protect us from potential harm. For example, when a bright light suddenly shines into our eyes, we instinctively close them or look away. This is a simple reflex activity orchestrated by the nervous system without conscious thought or effort.
A reflex exam is a diagnostic procedure performed by a healthcare professional to evaluate the functionality of a patient's...
A reflex exam is a diagnostic procedure performed by a healthcare professional to evaluate the functionality of a patient's...
01:22Somatic Spinal Reflexes
Somatic spinal reflexes are rapid, involuntary muscular responses to external stimuli that involve the somatic musculature and the spinal cord.
One of the most well-known somatic spinal reflexes is the stretch reflex, which is activated by the sudden stretching of a muscle. This reflex involves the activation of specialized sensory receptors called muscle spindles, which are located in the muscle tissue and detect changes in the length and speed of muscle contractions. When a muscle is suddenly...
One of the most well-known somatic spinal reflexes is the stretch reflex, which is activated by the sudden stretching of a muscle. This reflex involves the activation of specialized sensory receptors called muscle spindles, which are located in the muscle tissue and detect changes in the length and speed of muscle contractions. When a muscle is suddenly...
01:12Mechanically-gated Ion Channels
Mechanically-gated ion channels are proteins found in eukaryotic and prokaryotic cell membranes that open in response to mechanical stress. Tension, compression, swelling, and shear stress can alter the conformation of the protein, opening a transmembrane channel that allows the passage of ions for signal transmission. In eukaryotes, mechanically-gated channels are distributed in several regions like the neurons, lungs, skin, bladder, and heart, where they play critical roles in numerous...
01:16Sympathetic Activation
The sympathetic division can influence tissues and organs by releasing norepinephrine at peripheral synapses and distributing epinephrine and norepinephrine through the bloodstream. In times of crisis or stress, sympathetic activation occurs, which is regulated by sympathetic centers in the hypothalamus. As a result, sympathetic activation prepares the body for physical exertion, rapid ATP production, and heightened alertness, allowing individuals to respond effectively to challenging or...