Exam I Flashcards
Hierarchical processing
higher level of CNS are concerned with abstract processing of information and lower levels bring in/send information
Parallel processing
the same signal might reach different brain structures simultaneously for processing (divergent), but different purposes.
Spinal cord connections
Hierarchically ‘lowest level employees’ – responding to sensory inputs and following ‘orders’ from action systems
Involved in initial signal reception and final execution of voluntary/involuntary movements (final common pathway)
Basic/simple signal processing – spinal reflexes
Brain Stem connections
‘Middle management’ - contain important control centers (sensory and motor) for postural control and locomotion, Receives inputs from head/neck, vestibular and visual systems, sends somewhat processed signals to sensory/perceptual centers, contain motor nuclei for descending pathways to neck/face/eyes, and extra pyramidal pathways
Cerebellar connections
‘back-channel employee’ needed for comparing and calibrating movements, contains feedback and feedforward mechanisms. it has Indirect influence on motor outputs to generate smooth coordinated movements, important center for coordination and postural control during movements.
Thalamus connections
The ‘doorkeeper to the boardroom’
Acts as a junction, a relay center for signal processing
Basal Ganglia connections
Involved in higher order motor planning for coordinated movements
Receives inputs from many areas of cerebral cortex
Sends output back to motor cortex via thalamus
Cerebral Cortex connections
Highest executive level of motor control hierarchy, Has direct control on voluntary movements by activating/controlling motor neurons via corticospinal/corticobrainstem pathways
Interacts with other high level association cortical areas (premotor/SMA) to form motor plan/strategy
cross-modal processing
Information from muscle spindles, joints receptors, cutaneous receptors, etc., are integrated to give accurate information about movements in a limb
Primary motor cortex connections
Primary motor cortex have one-to-one connection (somatotopy) to the level of single motor neuron in spinal cord.
However, convergent and divergent parallel pathways are possible– one cortical site can be connect to a bunch of motor neurons (hence muscles) and one muscle can also potentially be connected to many neurons in a cortical site.
Important for recovery after injuries
Supplemental Motor Area
controls internally generated movements, also controls learned motor programs, but can transfer those programs to primary motor cortex after extensive training, also involved in planning complex motor programs
Premotor (PM) area
controls movements activated by external stimuli, like visual cues, e.g., ‘go’ when signal changes to green
Necrosis
severe injury - cellular swelling (osmosis), fragmentation of structure and cell disintegration, inflammatory response
Apoptosis
programmed cell death, no inflammatory reaction
Excitotoxicity
when neurotransmitters rise above normal levels – opens ion channels leads to excessive entry of Ca2+ ions – triggers all kinds of harmful cellular pathways – cell death
anesthesia
If all sensory modalities lost/absent
hypoesthesia
if partial loss of somatosensory
hyperesthesia
if somatosensory is hypersensitive
Parasthesia
unpleasant sensations like burning, tingling, pricking, numbness with/without sensory stimulus
Allodynia
painful sensation to a normal stimulus that should not be painful
Hyperalgesia
increased painful sensations to normally painful stimulus
Peripheral vestibular disorders
Nerve problems - vestibular neuritis (infection of nerve), perilymph fistula, Meniere’s disease
Canal problems - BPPV
Central vestibular disorders
Stroke in brainstem/cerebellum
Cerebellar degeneration
Arnold-Chiari malformation (cerebellum is coming out of foramen magnum
Nystagmus from peripheral lesions
Direction-fixed beating
Follows Alexander’s and Ewald’s laws
Beating increases as eyes are moved towards the fast phase
Beating occurs in the plane of impaired canals
Able to fixate with gaze stabilization
Habituates/compensates rapidly with time
Good outcomes with vestibular rehab
Examples of disorders – vestibular neuritis, BPPV
Nystagmus from central lesions
Pure vertical or pure torsional or direction-changing beating depending on gaze
Does not follow Alexander’s law
Unable to fixate with gaze stabilization
Takes longer to habituate/compensate
Worse (than peripheral) outcomes
Examples of disorders – Stroke in brainstem/cerebellum, medications
Patterns of motor deficits for UMN disorders
Paresis/paralysis
Abnormal tone - spasticity
Abnormal reflexes
Loss of fractionated movements/abnormal synergies
No atrophy
Abnormal co-contractions - CP
Patterns of motor deficits for LMN disorders
Paresis/paralysis
Decrease in muscle tone - flaccidity
Decrease in reflex activity
Neurogenic atrophy – due to lack of trophic support to muscles
Tone
resistance to passive stretch
Hypertonia results from…
results from increased baseline muscle sensitivity to stretch through mechanisms like loss of descending inhibitory control on motor neurons, loss of presynaptic inhibition, denervation hypersensitivity, etc.
Hypotonia results from…
results from decreased lower motor neuronal (LMN) activity on muscles due, damage to peripheral nerve, or due to other subcortical lesions, in cerebellum, or from developmental delays
Spastic paralysis caused by UMN lesions
velocity-dependent hypertonia
Flaccid paralysis can be caused by…
LMN lesions (due to decreased neuronal activity on muscles), or immediately after UMN lesions (as a result of shock).
Rigidity
caused by extrapyramidal lesions - velocity-independent hypertonia
UMN - Signs of spastic paralysis
weakness, increased tone, increased reflexes, spastic patterns/synergies (eg, flexors for UE and extensors for LE in stroke)
LMN - Signs of flaccid paralysis
weakness, decreased tone, decreased reflexes, muscle atrophy, fasciculations and fibrillations, eg, polio, peripheral nerve injuries
spastic pattern
Abnormal stereotypical patterns of movements that cannot be adapted – muscles are tightly linked, typically associated with stroke
spastic synergies
Typical flexion and extension synergies of UE and LE, person perform voluntary movements in these patterns, typically associated with stroke
Movement problems associated with cerebellum
delayed timing, dysmetria (errors in force, ROM, direction), dyesynergia (incorrect sequence of muscle activation), dysdiadokokinesia (difficulty with RAM), Intention tremors (involuntary rhythmic oscillations), and rebound phenomenon (inability to terminate movements), all of these make up ataxic gait, more include dysarthria and asthenia
Movement problems associated with basal ganglia
hypokinesias, hyperkinesias such as chorea (twitching, jerking movements), athetosis (writhing, twisting movements), Ballismus (violent, flinging movements), resting tremors
Resting tremor
When body is supported and relaxed, hallmark of PD
Intention Tremor
Target related movements
Hallmark of cerebellar dysfunction
Ataxic gait
cerebellar lesions – wide-based staggering gait, excessive trunk movements, arms wide out, lack of arm swing, LOBs towards ipsilateral side, difficulty in maintaining a line.
Parkinsons gait
short shuffling gait with festinations, freezing, difficulty turning, tremor in arms at times
Scissoring gait
in spastic CP due to adductor spasticity
Hemiplegic gait
circumducting or hip hiking due to LE extensor spastic synergies, arm in flexor synergy
Neuropathic gait
high steppage gait due to DF weakness and diminished sensation from feet, eg, diabetic neuropathy
Right hemisphere deficits
Spatial deficits – hemineglect, tactile extinction (more common with right-side lesions)
Non-spatial deficits – reduced levels of arousal, attention, orientation to stimuli, emotional disturbances