Karteikarten
NEUR2530 - Weeks 7-9
Karten in diesem Stapel (55)
- 1What are the key characteristics of voluntary movements?-Greater flexibility than reflexes or rhythmic movements
-Goal directed
-Begin non-specific intent to more specific signals to muscles
-higher order (decisions making) to lower order (specific commands) - 2What is the spinal cord made of?-White matter: ascending & descending tracts
-Gray matter: cell bodies (motorneurons & interneurons) - 3What are the components & features of the brain stem?-Midbrain
-Pons
-Medulla oblongata
Contains groups of cell bodies: nuclei (gray matter) & relay processing centres
-Contains fibre tracts: spinal cord (white matter) - 4What are the components of the cerebrum?-Cerebral cortex
-Diencephalon (thalamus & hypothalamus)
- - 5What are the areas of the brain?Brainstem, cerebrum, basal ganglia & cerebellum
- 6Name the features of the cerebrum.-Cortex has thin sheet of cell bodies (2-4mm)
-Folded to increase area, higher processing
-Divided into lobes: frontal, parietal, temporal, occipital
-Primary & secondary motor cortex - 7What is within the thalamus?-Group of nuclei
-Relay and processing information
-Basal Ganglia & cerebellum - 8What is the function of the ascending pathways?-Pass info from spinal cord (sensory receptors) to brain
-Sensory perception
-Integrate with movement control: planning & feedback - 9What are the general characteristics of ascending pathways?-Topographic organisation: based on location of receptors (maintained throughout CNS)
-Segregation of ascending tracts
-Relay nuclei: process & pass on info
-Reach somatosensory cortex where somatotopic organisation maintained - 10What is the function of decending pathways?-Pass info from brain to spinal cord
-Muscle activation though direct (monosynaptic) & indirect (di-synaptic) action on mn's
-Create info about movement commands (efference copy): intended vs. actual outcome - 11How does a spinal cord injury occur?-Severity of dysfunction determined by "completeness" of lesion
-Interupts transmission of afferent & efferent signals below lesion - 12What are the different outcome of SCI?-Paresis (weakness) & paralysis (no activation)
-Spacticity (rigidity & jerky mvm't): hyperactive velocity dependent stretch reflexes - 13What are the general characteristics of decending pathways?-Tracts organised somatotopically
-Axial muscles ventro-medial
-Distal musces dorso-lateral - 14What is the corticospinal pathway?-Decending pathway
-1M fibres
-Originates in Primary motor cortex, premotor areas & somatosensory cortex
-Divides into lateral (distal) & ventral (axial) corticospinal tracts - 15What is the purpose of the lateral corticospinal pathway?-Projects to alpha & gamma mn's & in's of distal muscles
-Some direct connections w/ mn's
- monosynaptic connection to hand > more proximal muscles
-Greater flexibility & fine control of digits - 16What is the function of ventral corticospinal tracts?-Fibres don't cross midline at pyramidal decussation
-Fibres project bilaterally to ventro-medial spinal cord (axial muscles)
-Innervate similar targets to ventro-medial brainstem tracts - 17Explain the vestibulo-spinal pathway-Oldest decending pathway
-Large input from vestibular apparatus and cerebellum
-Terminate in ventro-medial grey matter (mostly interneurons)
-Axial muscles - 18What happens in the pathways between the cortical & subcortical motor areas?-Cortical motor-areas receive input directly or indirectly (via thalamic relay)
-Send info about expected sensory outcome (cerebellum)
-Determine how to modify commands based on movements progression etc. (sensory receptors, cerebellum etc)
-Refine & initiate movement patterns (basal ganglia) - 19What does the primary motor cortex (m1) control?-Involvement in executive control of movement in M1
- 20What does codes for mean?-Cells in nervous system fire based on particular characteristic of mvm't
-E.g. cell fire fastest when elbow flexors activated and slowest when extensors activated, codes 4 activation flexor musles
-Can find what type of info cells are responsible for in mvm't planning - 21How is M1 organised?-Homonculus: loosely accurate
-M1 cells that fire fastest for activation of different muscles overlap considerably
- - 22What exactly does M1 do?-Projects to mn's of many muscles in spinal cord
-Makes indirect & direct connections with mn's
-Inputs from M1 are integrated with inputs from other decending tracts & spinal circuits - 23What is the relationship of motor unit firing frequency and force?-Sigmoidal
-Slow twitch less force than fast twitch - 24Results of monkey wrist extension/flexion experiment.-CTN (corticospinal tract neurons) fires prior to active wrist flexion
-CTN fires faster when ^ Force required 4 Fl
-CTN quiet when wrist passively moved E>F
-M1 neurons code active movement as well as body position - 25What is force coding?-M1 cells increase firing rate w/ ^ing force
-Not linear relationship
-4 pattern types: phasic tonic (59%), tonic (28%), phasic ramp (8%), ramp (5%)
-Produce constant force but M1 cells switching on & off or changing frequency - 26How does M1 code for direction of movement/force?-Monkey moved to 8 targets
-Cells fire at higher rates for "preferred" movement direction
-M1 cells directionally tuned: still fire when movement is near preferred direction
-Movement direction can be predicted by vector sum: "population coding" - 27Do M1 cells shift preferred direction with posture change?-50% cells did not shift preferred direction
-These cells code for direction of movement in space
-32% M1 cells shifted preferred direction in the same way as muscles
-These cells code "muscle activation" - 28What are the characteristics of the secondary motor area?-Supplementary motor area (SMA) & Premotor cortex (PMC) project to both M1 & spinal cord
-Higher order processing & diret movement control
-Stimulation of PMC > mvm't @ >1 joints
-Stimulation SMA cause bilateral mvm'ts - 29How do lesions interfere?-Lesions interfere with performance of complex rather than simple movements
- 30What was the role of SMA thought to be historically?-Primary involved in planning & control of sequential movements, that are internally initiated
-SMA active during active & mental rehearsal - 31What is the recent idea of SMA?-SMA contributes to control of "difficult" coordination tasks
-Same area of M1 activated in synergist & non-synergist tasks
-^ activation SMA for non-synergistic tasks - 32How are cells of PMC involved in various situations?-All cells in PMC involved in control of external direction
-Changes in PMC activity earlier than changes for M1
-Time for corticospinal transmission and electro-mehanical delay around 60-100ms - 33Is the PMC anatomically defined?-PM cortex active during both toe & finger signing
-So organisation not strictly anatomically defined
-Toe areas in M1 can access circuits in PMC that usually project to fingers
-Can produce similar movement patterns in different body parts - 34What invariants are evident?1) Invariant sequence of kinematic events e.g. maxima & minima in speed profile
2) Invariant relative timin in occurence of these events (irrespective of speed or size of movement) - 35Name the 5 nuclei of the basal ganglia1) caudate, 2) putamen, 3) subthalamic nucleus (STN) - input
4) globus pallidus, 5) substantia nigra (output) - 36Where do the nuclei input & output?-Input from cortex & thalamus
-Output to cortex and brainstem - 37What are the two pathways of the Basal ganglia & what is their role?Direct routh to GPi
Indirect routh: GPe to STN to GPi
-Modulate inhibitory output of basal ganglia - 38What is the direct route?-Activating inhibits the GPi
-Reduces normal inhibitory effect of Gpi
-Results in LESS inhibition of thalamus & MORE excitation of cortex
-Facilitation of movement "releasing brakes" - 39What is the indirect route?-Activating (by inhibition of STN) causes excitation of GPi
-Increases inhibitory effect of GPi
-MORE inhibition LESS excitation of cortex
-Inhibits movement: "slamming brakes" - 40Why are there 2 pathways for basal ganglia?1. Balance of pathways helps scale the magnitude of cortical & muscle activity. "finetuning"
2. Direct could reinforce activation of required muscles & Indirect could ensure unwanted muscles not activated - FOCUS activation of appropriate cortical areas - 41How does dopamine affect the direct & indirect pathways of the basal ganglila?-Facilitates movement
-Excitatory to striatal neurons that project to direct route
-Inhibitory to striatal neurons that project to indirect route - 42What are the symptoms of Parkinson's disease?TRAP (tremor, rigidity, akinesea/bradykinesia, postural instability)
Akinesea = lack of movement
Bradykinesia = slow movement - 43What causes parkinson's disease?-Degeneration of dopaminergic neurons in the substantia nigra
-Drug induced: botched amphetamine
-Highly toxic to dopaminergic neurons in the substanttia nigra pars compacta - 44How can parkinson's be treated with drugs?-Levodopa, cable to cross blood brain barrier, dopamine receptor agonists
-Effects decline with use (less improvement over years)
-Can't offset the death of dopaminergic neurons on striatum - 45Surgical treatments for parkinsons-Lesion of globus pallidus internal segment or subthalamic nucleus (reduced thalamic inhibition), irreversible
-Deep brain stimulation:
-High frequency stimulation of STN to GPi, causing interference, stops unwanted excessive inhibition - 46What is huntingtons disease?-Hyperkinetic disease: inherited
-Symptoms: abnormal movements, cognitive decline
-Cause: specific death of indirect pathway neurons in striatum (atrophy of caudate & putamen)
-Decrease in inhibition from indirect route, NO TREATMENT - 47Describe some anatomical features of the cerebellum-Arranged in folia & 2 hemispheres
-Cerebellar cortex - gray matter outside
-Internal white matter: tracts & 3 pairs of deep nuclei
-Connected to brainstem by inferior, superior & middle peduncles - 48What is the role of the cerebellum?-Compares intended movement with the actual movement & helps adjust motor output accordingly
-Removal disrupts spatial & temporal accuracy, balance, muscle tone & motor learning. - 49What is the input for the cerebellum?-Massive input from cortex (intention info)
-20M cortico-ponto-cerebellar axon
-Input from sensory receptors provide info about execution - 50What is the output of the cerebellum?-Through cerebellar nuclei to motor and premotor brain regions (via thalamus) which ontrol spinal interneurons & motoneurons
- 51Name and describe the functional divisions of the cerebellum-Vestibulocerebellum: most primitive, balance, eye movements
-Spinocerebellum: ongoing control of voluntary movement, posture & locomotion
-Cerebrocerebellum: most recent, planning & conscious assessment of mvm't - 52What are the input and outputs of vestibulocerebellar?I: Vestibular apparatus, vision
O: Vestibular nuclei, alters vestibulospinal & corticospinal tracts
Damage: disturbances of equilibrium
Nystagmus at same side lesion - 53What are the input & outputs for the spinocerebellum?I: cortex & spinal interneurons
O: Deep cerebellar nuclei controls proximal & distal musculature
-Alters activity in rubrospinal & corticospinal pathways
Damage: Unaccurate reaching, uncoordinated movement, hypotonia - 54Cerebrocerebellum input & outputsI: cerebral cortex via nuclei in pons
O: Deep cerebellar nucleus to cortico motor & premotor regions & red nucleus
Damage: timing movements, perceptual aspects timing - 55List the cerebellar movement disorders?1. Impaired balance & gait
2. Impaired coordination (Ataxia)
3. Decreased muscle tone (hypotonia)
4. slow corrective movements
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- NEUR2530 Karteikarten am NEUR2530 - Weeks 7-9, erstellt von Mikaela Sullivan am 07/11/2017.
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- Mikaela Sullivan
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