Week 2: Sensory Proprioception and Stages of Skill Acquisition Learning Flashcards
(39 cards)
What is afferent (sensory) neural activity?
The process by which sensory information is transmitted from sensory receptors, through the spinal column, and back to the CNS
What is efferent neural activity?
Involves signals originating from the CNS that are sent to muscles to produce movement
Describe sensory poly-neuropathy
degeneration of large afferent fibers carrying proprioceptive and tactile inputs
What are the (5) common properties of the afferent (sensory) system?
- Modalities
- Location
- Intensity
- Timing
- Transduction
Explain what a person with sensory poly-neuropathy experiences
No internal understanding of what is happening to limbs and body position during movement; starting and changes in movement are unknown
What (4) sensors are involved with touch modality?
- Meissner’s corpuscle
- Merkel cells
- Pacinian corpuscle
- Ruffini endings
How do Meissner’s corpuscles contribute to touch modality?
Meissner’s corpuscles are fast-adapting type 1 receptors that respond to dynamic changes in mechanical indentation, providing sensitivity to light touch and detecting changes in texture during movement across a surface.
What role do Ruffini endings play in touch modality?
Ruffini endings are slow-adapting type 2 receptors that sense skin stretch and contribute to the detection of sustained pressure and the positioning of body parts in space, important for proprioception.
What is the function of Merkel cells in touch modality?
Merkel cells are slow-adapting type 1 receptors that detect static pressure and fine spatial details, providing information about the precise location and texture of objects touching the skin.
Out of the (4) touch receptors, which lie in the dermis (2) and epidermis (2)?
Dermis
1. Pacinian corpuscle (deep pressure)
2. Ruffini corpuscle (warmth)
Epidermis
1. Meissner’s corpuscle (light touch)
2. Merkel cells (touch)
What is the primary function of Pacinian corpuscles in touch modality?
Pacinian corpuscles are fast-adapting type 2 receptors that detect rapid vibrations and deep pressure, providing information about mechanical changes in the environment over a larger area.
What determines the sensitivity of touch perception in different areas of the body?
The spatial distribution and density of cutaneous receptors determine sensitivity. Areas with a higher density of receptors, like the fingers, toes, and mouth, have greater touch sensitivity.
How is the location of a stimulus on the body determined through touch?
The precise location of a stimulus is conveyed by the spatial arrangement of cutaneous receptors, which send information about where contact is made on the skin.
What test is commonly used to assess the sensitivity of touch (location) on the body?
The two-point discrimination test is used to determine how sensitive a specific body area is by measuring the minimum distance at which two points can be distinguished as separate.
How does receptor density affect the resolution of touch location?
Areas with densely packed receptors, like the fingertips, can resolve finer details, while areas with fewer receptors, like the back, have lower touch resolution.
What is meant by the “intensity” of a stimulus in sensory systems?
Intensity refers to how strong or weak a stimulus is, which is conveyed by the rate of neural firing. A stronger stimulus leads to a higher rate of afferent nerve firing.
How is the “timing” of a sensory stimulus detected by the nervous system?
Timing is detected by when a stimulus starts, how long it lasts, and how quickly it changes. Different receptors respond at different rates to give precise information about the onset and duration of a stimulus.
What role does “transduction” play in sensory perception?
Transduction is the process by which physical stimuli (e.g., pressure, heat) are converted into neural signals that can be interpreted by the central nervous system.
How do fast-adapting receptors differ from slow-adapting receptors in timing?
Fast-adapting receptors respond quickly to changes in stimuli but cease firing when the stimulus is constant, while slow-adapting receptors continue to fire as long as the stimulus persists.
How is stimulus intensity encoded by sensory receptors?
The intensity of a stimulus is encoded by the frequency of action potentials (neural firing). Stronger stimuli produce more frequent neural signals, giving the CNS information about the force of the stimulus.
It is detected in a 1:1 ratio of detection and perception of increasing signal
What is static pressure in the context of touch proprioception?
Static pressure refers to the continuous or unchanging pressure applied to the skin, detected by slow-adapting receptors like Merkel cells and Ruffini endings, which provide information about constant touch or pressure.
What is dynamic pressure in the context of touch proprioception?
Dynamic pressure refers to the changes in pressure or movement across the skin, detected by fast-adapting receptors like Meissner’s and Pacinian corpuscles, which respond to quick or varying stimuli like vibrations or brief touches.
What are muscle spindles? (modality)
Muscle receptors that are responsive to stretch (lengthening and partial shortening) detecting the rate of change, and absolute muscle fiber length
How is the sensitivity of muscle spindles adjusted according to the task being performed?
The sensitivity of muscle spindles is adjusted by fusimotor drive (GAMMA efferent neural signals), which changes the length of the muscle fibers to ensure that static or dynamic spindles are appropriately sensitive for the task, such as holding a position or reacting to rapid movements.
