Descending Control, M1, Spine Flashcards
Lectures 14/15/16
Area M1
Primary motor cortex
Area S1
Somatosensory cortex
Is M1 rostral/caudal to the premotor cortex?
caudal (posterior)
Betz cells
-large layer 5 neurons that send AP down descending spinal tract
If you were to cut M1 in the frontal plane, describe the areas of processing from medial to lateral…
(Medial) lower extremity, trunk, upper extremity, face (lateral)
Which areas of the body have the most innervations in M1?
Face, hands = fine motor control, dexterity (less force)
A pulse is sent into a monkey for 50ms, then 500ms, what pattern was noticed?
The longer the stimulus, the more complex movements occurred
By viewing EMG readings what did we notice about the order of M1 activation and muscle contraction?
M1 is activated before movement
What happens when we move outside of a neurons optimal movement?
The neuron decreases firing (goes silent)
Explain the concept of optimal movement
Each neuron is tuned to a particular direction of movement
Population vector
average vector from individual M1 neurons
What does the population predict (proceed)?
The observed movement vector (M1 fires first!)
How is the M1 population vector being used in technology?
-spinal cord injury implants
-can respond w/ mechanical exoskeleton/robots
What info is relayed by the ventral posterior medial nucleus (VPM)?
Info about neck/face (think: medial as central as “headquarters)
What info is relayed by the ventral posterior lateral nucleus (VPL)?
Info from below neck, body (think: lateral like peripheral and limbs)
The motor homunculus of the somatosensory cortex (S1) is a…
somatotopic map of the body
What does it mean that S1 is plastic?
Subject to change depending on use (“use it or lose it”)
Do phantom limb sensations originate from M1 or S1
S1
When do patients experience phantom pain?
-when the S1 is in the process of remapping
-includes shrinking sensations
Descending tracts
-send motor commands
-include lateral corticospinal tract (LCT), and ventral corticospinal tract (VCT)
Ascending tracts
-send sensory info
-include dorsal column medial lemniscus tract (DCML), ventral spinothalamic tract (VST)
Which nerves innervate the face?
cranial (not spinal)
Which areas are innervated by the cervical spine region?
neck, arms
Which areas are innervated by the thoracic spine?
back, chest, gut
Which areas are innervated by the lumbar spine?
Butt, lower back, anterior legs
Which areas are innervated by the sacral spine?
Reproductive organs, posterior legs
What is the dorsal root of the spinal cord responsible for?
Transmitting sensory info (body to brain)
contralateral
opposite side
ispilateral
same side
In general, the left side of the brain interprets the _______ side of the body
right
decussate
switching sides (crossing the midline)
Which tract do pain and temperature info travel along?
spinothalamic tract
When does the ventral spinothalamic tract (VST) decussate?
-immediately at the level it enters
When does the dorsal column medial lemniscus (DCML) decussate?
-at caudal medulla
When does the lateral corticospinal (LCST) tract decussate?
-at the caudal medulla
-contralateral
When does the ventral corticospinal (VCST) tract decussate?
-N/A
-bilaterally innervates (ipsilateral)
What is the LCST for?
distal muscles
What is the VCST for?
proximal muscles
What is the VST for?
pain/temperature
What is the DCML for?
mechanoreceptors
Paraplegia
paralysis of lower body
Hemiplegia
paralysis of one side of the body
Tetraplegia (quadriplegia)
paralysis of all four limbs
Incomplete lesion: central cord syndrome
-tumor
-torsion injuries
-high fevers
Incomplete lesion: anterior cord syndrome
-car accidents
Incomplete lesion: Brown-Sequard syndrome (right/left)
-blunt force trauma (or tumor)
-stabbing
-shot
-ischemia (obstruction of blood vessel)
-infectious/inflammatory diseases
Symptoms of Brown-Sequard syndrome
-contralateral: loss of pain, temp, light touch sense
-ipsilateral: loss of motor function, vibration, position, and deep touch
Babinski’s sign
normal: toes curl
abnormal: toes up, and fan
febrile
seizures due to high body temps
hypesthesia
diminished sense of touch
Diagnosing a spinal cord injury (SCI)
-light touch score (cutaneous receptors)
-pin prick score (pain/temp)
-strength testing
Incomplete lesions have not lost total control, what does this mean for rehab?
Is possible for improvement of coordination and limb function
