Test 2: lecture 15 somatosensory Flashcards
___ are sensitive to bending, stretching, pressure or vibration
mechanoreceptors
Specialized nerve endings: Merkel’s Disk, Meissner’s corpuscle, Pacinian Corpuscle, Ruffini ending
___ are receptors specialized for proprioception
muscle spindles
golgi tendon organ
4 qualities of a stimulus
modality (vision, hearing, touch taste, smell and their submodalities)
location
intensity
duration
rapidly adapting neurons
fire at the onset and stop of a stimulus
vibration sensors
slow adapting receptors will ___
fire continuously
(touch, light touch, deep touch, pressure)
Awareness of spatial aspects depends on ____ of activated receptors
spatial distribution
____ the space within the receptive sheet in which the sensory receptor is located and in which it transduces stimuli
receptive field of a receptor
____ certain area of skin where it can transduce pressure or vibration
receptive field of mechanoreceptor
There is a gradient of ____ within the receptive field
sensitivity
-highest in the center and progressively lower toward the periphery
receptive field has a gradient of sensitivity meaning ____
there will be more AP created when you touch the center of a receptive field then when you touch the edge
The frequency of Action Potentials is proportional to the ____ of the stimulus
intensity
press harder = more AP
light touch= less AP
what does it mean when neuron will adapt to a prolonged stimulus
at first a stimulus will trigger a bunch of AP
but over time the AP will decrease
it will take the neuron some time to return to normal
___ receptors small field size and rapid adapation
meissner’s corpuscle
___ receptors have large receptive field size and rapid adaptation
pacinian corpuscle$
____ receptors have slow adaptation and small receptive field size
merkel’s disk
___ receptors have large receptive field size and slow adaptation
ruffini’s ending
Most 2nd order neurons have ____ in their RFs which enhances spatial resolution
surround inhibition
will turn off neighbor
a high innervation density mean ____
you can detect two points at a smaller range
(more detail)
hands have a higher innervation density then the back
what is it important for 2nd order neurons to have surround inhibition
makes detecting two points easier
improves two point discrimination
two point discrimination is best for body regions with the ___ innervation density and amount of cortical area devoted to them
highest
fingers have many nerves in a small area and can detect the difference between two points at a smaller distance then somewhere with less density like the back
•Each___ provides sensory innervation to a particular region of the ski
spinal segment
____: the area of skin and deeper tissues innervated by a single dorsal root
dematome
dorsal column medial lemniscal tract
3 neuron path for touch, pressure and proprioception for the limbs
1st neuron is large myelinated axon will come through the dorsal root, synapse on the dorsal root ganglion and will split and contribute to reflexes in the ventral horn and branch up the spinal cord up the dorsal funiculus (FC or FG)to the dorsal column nuclei (NC or NG) in the medulla, cross sides and up by the medial lemniscus to the VPL of the thalamus , then up to the S1, primary somatosensory cortex of the cerebral cortex
Dorsal Trigeminothalamic tract
touch and vibration for the head
receptor in the face and head in through the trigeminal nerve, synapse on the main sensory nucleus of CN 5, cross sides up to the VPM of the thalamus, then up to S1 -primary somatosensory cortex
nociceptors
mediate transduction of Pain
activated by stimuli that could cause tissue damage
free nerve endings
TRP receptors (Activate _T_ransient _R_eceptor _P_otential ion channels)
___ are pain and thermal receptors
_T_ransient _R_eceptor _P_otential ion channels (TRP)
free nerve endings
thermal receptors
Mediate transduction of cold, cool, warm and hot
free nerve endings → _T_ransient _R_eceptor _P_otential ion channels (TRP)
spinothalamic tracts
pain and temp from body
get info from TRP receptors (nociceptors for pain and thermal receptors for temperature), come in through the dorsal root on small lightly myelinated axons and synapse in the substantia gelatinosa of the dorsal horn, cross sides and travel up the lateral ventral column as the lateral spinothalamic tract all the way up to the VPL of the thalamus, synapse and then up to the S1- somatosensory cortex
where does the 1st neuron of the spinothalamic tract synapse
substantia gelatinosa of the dorsal horn
pain and temp from body
ventral/spinal trigeminothalamic tract
(ventral trigeminal tract)
pain and temp for the head
in through the trigeminal ganglion at mid pons, down the spinal trigeminal tract to the caudal medulla, synapse at the spinal trigeminal nucleus, back up to the VPM in the thalamus, then up to the S1 somatosensory cortex
lesions in the S1 leads to losses on what side of the body?
opposite side
Sensory signals from each vibrissa follicle go to one cluster of SI neurons called a ____
barrel
S1 primary somatosensory cortex are divided into what brodmann’s area?
2 and 3a: proprioceptive stimuli from muscles and joints
1 and 3b: cutaneous stimuli
area 1 and 3a :
cutaneous stimuli
carries info to the secondary somatosensory cortex → amygdala and hippocampus
Area 3a and 2
carriers proprioceptive stimuli from muscle and joints
3a → secondary somatosensory cortex → amygdala and hippocampus
3a→2
2→ parietal areas 5 and 7 → to motor and premotor cortical area
2→secondary somatosensory cortex → amygdala and hippocampus
functional columns in the neocortex
neurons from the same modality line up with each other within the somatopic map
slowly adapting vs rapidly adapting neurons
cortical map plasticity
if an area of cells no longer receive input/are dead, the cells around them will take over that territory
maps are dynamic
adjust depending on the amount of sensory experience
posterior parietal cortex
involved in somatic sensation
analysis of “where” things are from visual inputs
inability to recognize objects
agnosia
loss of stereognosis: the ability to perceive the form of an object by using the sense of touch.
- Can you tell a quarter from a nickel by just feeling it in your pocket?
astereognosia
asterognosia
loss of stereognosis: the ability to perceive the form of an object by using the sense of touch.
- Can you tell a quarter from a nickel by just feeling it in your pocket?
issue with the posterior parietal cortex
neglect syndrome
part of body or part of world is ignored
caused by issues with the posterior parietal cortex
three issues from posterior parietal cortex lesions
Agnosia – inability to recognize objects
Astereognosia
– loss of stereognosis: the ability to perceive the form of an object by using the sense of touch.
- Can you tell a quarter from a nickel by just feeling it in your pocket?
Neglect syndrome – part of body or part of world is ignored
