Week 9 Flashcards
What do our skins and touch sensations do?
- Protect inner organ systems
- Maintain homeostasis
- Provide strong social feedback
- Enable planned motion
- Detect objects and textures
The ability to sense the ** position** of the body and limbs.
Proprioception
The ability to sense ** movement ** of the body and limb.
Kinethesis
Perception of touch and pain from stimulation of the skin.
Cutaneous senses
Proprioception
Our (static) perception of our bodies, caused by feedback rom the skin, muscles, and joints.
Kinethesis
Tracking our body as it moves
- information is sent to the spinal cord and brain from Corgi tendon organs (monitor tension) and muscle spindles (monitor stretch and speed). These are proprioceptors.
- motor signals return to the muscle to execute both planned and automatic movements.
Mechanoreceptors
Provide detail about items we touch and hold.
The receptors that establish our ** cutaneous receptive fields ** include:
- Merkel receptors
- Meissen corpuscles
- Ruffini cylinders
- Pacinian corpuses
Merkel receptors
Fire continuously while stimulus is present.
Slow adapting - DETAIL
Have small cutaneous and high acuity. Located close to surface of skin.
Meissen corpuscles
Fires only when a stimulus is first applied and when it is removed.
Rapid Adapting - responsible fro controlling HANDGRIP.
Have small cutaneous and high acuity. Located close to surface of skin.
Ruffini cylinders
Fires continuously to stimulation
Slow adapting - associated with STRETCHING of the skin around objects and gross movements.
Larger cutaneous receptive fields and low acuity. Located deeper in the skin.
Pacinian corpuscles
Fires only when a stimulus is first applied and when it is removed.
Rapid Adapting - associated with sensing FAST VIBRATIONS and FINE TEXTURE.
Larger cutaneous receptive fields and low acuity. Located deeper in the skin.
SA
Slow Adapting
RA
Rapid Adapting
Which mechanoreceptors seems most useful for kinethesis?
A. Golgi tendon organ
B. Merkel
C. Meissner corpuscles
D. Ruffini cylinders
E. Pacinian corpuscles
D
Tactile Acuity
Sensitivity to details on the skin
Two-point threshold
Minimum separation needed between two points to perceive them as two points.
Grating acuity
Place a grooved stimulus on the skin and the participants to indicate the orientation of the grating.
Raised pattern indentification
Using letters or simple shapes to determine the smallest size that can be identified
Which mechanoreceptors do you expect to have the greatest acuity in the somatosensory system?
A. Merkel
B. Meissner corpuscles
C. Ruffini cylinders
D. Pacinian corpuscles
A
What does the high density of Merkel disk receptors in the fingerprints (glamorous skin) mean?
That its sensitive to small differences in the grating space.
What does the firing of the Merkel disk reflect?
The pattern in the grooves on a grating acuity test
Pacinian does not
Cortical Magnification
Strong correlation between areas of the hand and tactile acuity.
Finger tip > Base of finger > Palm
The Pacinian corpuscle CP is primarily responsible for
Sensing vibration
Nerve fibers associated with PCs respond best to
High rates of vibration
They are rapid adopting cells.
The structure of the PC is responsible for the
Response to vibration.
Fibers with the PC covering removed will respond to continuous pressure.
Spatial cues
Are determined by the size shape and distribution of surface elements like bump and grooves.
SA
Merkel
Temporal cues
Are determined by the rate of vibration his skin is moved across, finally texture surface like sandpaper.
RA
Pacinian
Duplex theory of texture perception
Perception of texture need to have special cues and temporal cues acting together.
What can you use to determine which rapid adapting cell is involved in texture?
Selective adaptation
Result of the adaptation experiment to determine which rapid adapting cell involved in texture
Only the adaptation to the 250Hz stimulus affected the perception of fine texture.
Movement is necessary for fine texture detection, and this involves Merkel cells and Pacinian corpuscles.
Signals travel in bundles of nerve fibers, and enter the spinal cord via the ___
Dorsal root
Spinothalamic pathway
Consists of smaller fibers that carry temperature and pain information
Medial lemniscal pathway
Consists of large fibers that carry proprioceptive and touch information
Spinothalamic pathway and medial lemniscal pathway, both (mostly) pass through the _____ in the thalamus.
Ventral Posterolateral nucleus.
Signals travel from the thalamus to the primary somatosensory receiving area (S1), and the secondary receiving area (S2) in the ____ lobe.
Parietal
Homunculus
Cortical representation of the body
True or false: sensory and motor maps are static, and would not change.
False, the Maps can change in response to sensory input
Focal dystonia
A neurological disorder that causes involuntary muscle movement or contractions in one part of your body.
Haptic perception
The use of active touch in the exploration of 3-D objects with the hands
Three systems of haptic perception
- Sensory system
- Motor system
- Cognitive system
exploratory procedures
Lateral motion
Pressure
Enclosure
Contour following
True or false people can identify objects haptically in 1 to 2 seconds
True
In somatosensory cortex, single cell recordings indicate
Some cells respond, maxima lead to orientations of stimuli and others to direction of the movement.
What can also increase the firing rate of somatosensory cells?
Paying attention
Pain
Multi modal phenomenon, containing a sensory component (from the area of pain) and an affective component (emotional).
Skin uses pain receptors as a____
Threat detection system
Congenital insensitivity to pain CIP
People with CIP don’t experience pain and can unintentionally injure themselves while performing normal activities.
Sensory processing disorder SPD
Can result when an individual is too sensitive to common sensations
Nociceptive pain
These signal impending damage to the skin
- Specific nociceptors respond to heat, chemicals, severe pressure and cold.
- These typically trigger a protective (withdrawal) response.
Inflammatory pain
Caused by damage or irritation, within tissues and joints
- Infections or injury associated with immune responses make nociceptors more responsive (hyperalgesia)
- tumor cells (release toxins in the tissue causing immune response)
Neuropathic pain
Caused by damage to the nervous system, including:
- Brain damage caused by stroke
- Repetitive movement which causes conditions like carpal tunnel syndrome.
Social pain
This perceived pain resulting from interactions with other people (or lack thereof)
- Sometimes called, psychological or mental pain
- Typically cases involving depression and social rejection
- No tissue damage with strong affective element
Direct pathway model
Suggested that nociceptors are stimulated by the appropriate stimuli, and immediately send signals to the brain.
Problems with this model :
- Pain can be affected by a persons mental state
- Pain can occur when there is no stimulation of the skin (phantom limbs)
- Pain can be affected by a person’s attention.
Gate control model
the gate consists of substantia gelatinosa cells in the dorsal horn of the signal cord. (SG- and SG+)
Gate input
- S small diameter fibers: information from nociceptors.
- L large diameter fibers: information from tactile stimuli (Mechanoreceptors)
-Central control: information from top down cognitive factors from the cortex.
Gate output
Gate output is transmission cell activity. More T cells activity means more intense pain.
Pain ____ when the gate is closed by stimulation of SG- by central control or L-fibers.
Decreases
Pain ______ when stimulation of the S-fibers activate S+ to open the gate.
Increases
What can we do with the gate control model?
We can regulate amount of pain sensed through other tactile input (rub or scratch), or cognitive factors, (mood or attention)
