Podcast Beta
Questions and Answers
What initiates the withdrawal reflex?
What happens to the motor neurons of extensor muscles during the withdrawal reflex?
How do crossed extensor reflexes differ from withdrawal reflexes?
What is the role of the sensorimotor cortex in transcortical stretch reflexes?
Signup and view all the answers
Which type of reflex involves more complex circuits than simple withdrawal responses?
Signup and view all the answers
What might happen to voluntary actions in the presence of reflex abnormalities?
Signup and view all the answers
What influences reflex sensitivity in relation to postural stability?
Signup and view all the answers
What is the role of 'preparatory set' in postural control?
Signup and view all the answers
In the experiments assessing reflexes, how did reflex amplitude change?
Signup and view all the answers
What experimental setup was used to examine reflex responses to instability?
Signup and view all the answers
What type of reflexes are believed to contribute to postural stability in complex 3D situations?
Signup and view all the answers
How do reflexes respond to non-symmetric stability situations?
Signup and view all the answers
What early changes occur in response to postural errors?
Signup and view all the answers
Which variable does NOT influence the modulating of reflex responses?
Signup and view all the answers
What distinguishes transcortical reflexes from their spinal equivalents?
Signup and view all the answers
Which strategy is least suitable for correcting standing posture during small perturbations on stable surfaces?
Signup and view all the answers
What is a key feature of anticipatory postural adjustments (APAs)?
Signup and view all the answers
Which of the following best describes automatic reactions in postural control?
Signup and view all the answers
What role does the brainstem play in reactive postural control strategies?
Signup and view all the answers
How does the cortex influence the stretch reflex circuit during voluntary actions?
Signup and view all the answers
What has been demonstrated regarding pre-movement changes in neural activity?
Signup and view all the answers
In the context of postural stability, what role does preparatory set play?
Signup and view all the answers
What was concluded regarding the impact of motor cortex inhibition on reflex modulation?
Signup and view all the answers
What happens to stretch reflex sensitivity when stability is reduced?
Signup and view all the answers
How does co-contraction relate to environmental stability?
Signup and view all the answers
Which region showed larger long latency stretch reflexes without TMS in an unstable situation?
Signup and view all the answers
What did the hypothesis regarding co-contraction suggest?
Signup and view all the answers
What effect does TMS have on reflex responses in relation to postural stability?
Signup and view all the answers
What is suggested about reflex role in stability with regards to upper limbs?
Signup and view all the answers
Which hypothesis concerning motor cortex inhibition and reflex modulation is proposed?
Signup and view all the answers
Study Notes
Reflexes
- Reflexes are automatic responses to stimuli, involving neural circuits within the spinal cord.
- Examples include the withdrawal reflex and the crossed extensor reflex.
- The withdrawal reflex is initiated by pain receptors (nociceptors) and causes the withdrawal of a limb from a painful stimulus.
- The crossed extensor reflex is a simultaneous response where the opposite limb extends to provide stability during the withdrawal reflex.
Reflex Modulation
- Reflexes can be modulated by various factors, including the context of movement and the level of voluntary control.
- Transcortical stretch reflexes involve signals from stretch receptors reaching the sensorimotor cortex and modifying the reflex response.
- Preparatory set refers to the readiness of the motor system to generate a desired action or response, potentially influencing reflex expression.
- Changes in co-contraction, or the simultaneous activation of opposing muscle groups, are important for postural stability, with levels increasing as environmental stability decreases.
Automatic Postural Reactions
- Automatic postural reactions are complex responses to postural perturbations, involving multiple muscles and occurring too late to be reflexes.
- These reactions are generated in the brainstem and are likely driven by feedback or feedforward mechanisms.
- Anticipatory postural adjustments (APAs) are feed-forward responses to expected perturbations, occurring before a movement to enhance stability.
Reflex & Voluntary Interactions
- The cortex can regulate lower motor circuits and modulate reflexes.
- Voluntary muscle activation can inhibit reflexes, demonstrating cortical-spinal interactions.
- Muscle synergies, the coordinated activation of muscle groups, may simplify the complex control of movement.
Reflex Abnormalities
- Spasticity, an involuntary increase in muscle tone, often results from reduced inhibition of stretch reflexes due to reduced cortical input.
- This hyper-reactive stretch reflex leads to velocity-dependent resistance to movement and can cause pain.
- Abnormal reflexes are often the result of damage to the central nervous system, disrupting the normal regulation of reflex pathways.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz covers the automatic responses known as reflexes, including key examples like the withdrawal reflex and crossed extensor reflex. It also explores how reflexes can be influenced by factors such as context, voluntary control, and co-contraction. Test your understanding of these fundamental neurological concepts!