Topic 11: Cutaneous Senses Flashcards
proprioception
cutaneous senses
perception of position, movement and effort from muscles, joints and tendons
-perception of touch and pain from stimulation of skin
skin
heaviest organ in body (12-15% of body weight)
-1.5-2 m2 of SA
protects body from external environment
hairy or glabrous (thicker)
epidermis
dermis
- outer layer made up of dead skin cells
- lower layer containing mechanoreceptors responsive to pressure, stretching, vibration etc
merkel receptors
meissner corpuscles
both on epidermis
- fire continuously while stim is present, percieve fine details (shape and texture), SA1 - slow adapting
- fire only when stim is applied/removed, precieves hand/grip control and motion, RA1 - rapid adapting
Ruffini cylinders
pacinian corpuscles
fire continuously to stim, perceive stretching of skin, SA2 - slowly adapting
-fire when stim is applied/removed, perceive vibrations and fine texture, RA2 - rapid adapting
medial lmniscal pathway
spinothalamic pathway
-large fibers, carries proprioception and touch into mechanoreceptors (decussates at brain)
-smaller fibers, carries temp and pain, deccusates at spinal cord
both arrive at ventrolateral nucleus of thalamus
tactile acuity
two point threshold
- raised pattern ID, used to determine smallest size that can be recognized (braille)
- min separation between 2 points to perceive them as 2 units
duplex theory of texture perception
spatial and temporal cues
- rough surfaces, determined by size, shape and distribution of larger surface elements (SA1)
- fine surfaces, determined by rate of vibration as skin is moved across finely textured surfaces (RA2)
adaptation experiment - Hollins 2001
p’s skin was adapted for meissner or pacinian
tested on ability to ID fine texture surfaces
losing ra1 - didnt effect ID ability but RA2 dod
need RA2 for texture ID
haptic perception
experiment - Lederman 1987
humans use active touch to interact with environment
- sensory, motor and cognitive systems
- we can ID in 1-2 sec, use exploratory procedures
motion sensitive neurons
orientation sensitive neurons
direction sensitive neurons
- respond to any motion in receptive field
- respond to motion along particular axis
- respond to motion in single direction
pain
inflammatory
neuropathic
nociceptive
unpleasant sensory and emotional experiences associated with actual or potential tissue damage
-pain from arthimitic joints
-carpal tunnel
chemical burn
nociceptors
sensory component
affective component
- receptors in skin for different types of painful stimuli, separate from other receptors
- refers to intensity (sharp, dull)
- refers to unpleasantness of pain
direct pathway model of pain
issues with direct pathway
phantom-limb phenomenon
- pain is due to nociceptive activation (skin to brain direct)
- soldiers and athletes experience no pain despite serious injuries (stim doesnt led to perception)
- loss of limb but retention of sensation, pain in area where limb is missing
placebo effect
nocebo effect
- decrease in perceived pain due to treatment with no physiological effect
- increase in perceived pain due to treatment with no physiological effect
gate control model of pain
nociceptor - spinal cord - brainstem (primary path)
-additional pathways control a gate between nociceptor and perception of pain
nociceptors - activate excitatory synapses (open)
mechanoreceptors - activate inhibitory (close)
central control - top-down cognitive input (open/close)
moderators of pain perception
expectations - placebo/nocebo
attention - distraction and mindfulness
emotions - pleasant music and/or images
attention and pain
pain can be moderated by attention, not in awareness it wont be as much of a problem
- VR games in hospitals to distract patients
- toys used for kids getting vaccines
emotion and pain
looking at positive pictures can reduce experience of pain
how long can p’s hold hand in water, longest when looking at positive pics
lower pain ratings to heat stim when listening to pleasant music
pain processing in the brain
s1, anterior cingulate cortex, PFC, amygdala and hypothalamus, insula
sensory: s1 and s2
affective: dorsal ACC and Insula
observing pain in others : singer 2004
p was shocked or watch partner get shocked
s1 acc and insula activated when you were shocked
acc and insula activated when partner was shocked
empathy = acc activation
