Download Chapter 12

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project

Document related concepts

Synaptogenesis wikipedia , lookup

Long-term depression wikipedia , lookup

Stimulus (physiology) wikipedia , lookup

Cortical cooling wikipedia , lookup

Neuromuscular junction wikipedia , lookup

Neuroplasticity wikipedia , lookup

Neurocomputational speech processing wikipedia , lookup

Neuroscience in space wikipedia , lookup

Time perception wikipedia , lookup

Human brain wikipedia , lookup

Environmental enrichment wikipedia , lookup

Rheobase wikipedia , lookup

Allochiria wikipedia , lookup

Feature detection (nervous system) wikipedia , lookup

Aging brain wikipedia , lookup

Clinical neurochemistry wikipedia , lookup

Neuropsychopharmacology wikipedia , lookup

Evoked potential wikipedia , lookup

Proprioception wikipedia , lookup

Embodied language processing wikipedia , lookup

Central pattern generator wikipedia , lookup

Muscle memory wikipedia , lookup

Hypothalamus wikipedia , lookup

Circumventricular organs wikipedia , lookup

Synaptic gating wikipedia , lookup

Microneurography wikipedia , lookup

Cognitive neuroscience of music wikipedia , lookup

Neuroanatomy of memory wikipedia , lookup

Premovement neuronal activity wikipedia , lookup

Cerebral cortex wikipedia , lookup

Superior colliculus wikipedia , lookup

Motor cortex wikipedia , lookup

Cerebellum wikipedia , lookup

Eyeblink conditioning wikipedia , lookup

Transcript
Chapters 12 Motor System – Cerebellum
 Chris Rorden
University of South Carolina
Norman J. Arnold School of Public Health
Department of Communication Sciences and Disorders
University of South Carolina
1
Function of Cerebellum
Error Control Device - Monitor, Quality Control
– Monitors outputs to muscles from motor cortex and
sensory signals from receptors
– Compares the efferent project plan with execution
at motor action site
– Considers related factors and makes adjustments
2
Cerebellum
50% of brain’s neurons, 10% of volume
Can change movements as necessary
– E.G. Walking or talking
Does not reach conscious awareness
Muscle synergy or coordination monitored
Important in running, speaking - all fluid
movements
3
tentorium cerebelli
 "tent of the cerebellum"
dura mater that
separates the cerebellum
from the inferior portion
of the occipital lobes.
4
Posterior Cranial Fossa
Fossa is a depression or
cavity in the bone
Cerebellum, pons, and
medulla oblongata sit in
the Posterior cranial fossa
5
Cerebellar Anatomy
Seen from feet
Located dorsal to pons
and medulla
In posterior fossa under
tentorium cerebelli
Lobes
– Floccular Nodular(small
fluffy mass)
– Anterior
– Posterior
Anterior lobe (H)
Posterior lobe (I) 6
Flattened Cerebellum
Longitudinally
separated into
hemispheres and
cortices
– Median (Vermal)
Vermis=worm
– Paramedian
(Paravermal)
– Lateral
7
Cerebellum
Median
Prepyramidal Fissure
Posterolateral Fissure
Paramedian
Primary
Fissure
Posterior
Superior
Fissure
Horizontal
Fissure
8
Cerebellar Nuclei (Nuclei = deep cluster of neurons)
 Dentate nucleus
– Largest, communicates through cerebellar peduncle
– Carries information important for coordination of limb
movements (along with the motor cortex and basal
ganglia)
 Emboliform nucleus (medial side of the nucleus
dentatus)
– Regulates movements of ipsilateral extremity
 Globose nucleus
– Regulates movements of ipsilateral extremity
 Fastigial nucleus
– Regulates body posture
– Is related to the flocculo nodular lobe
9
Dentate Nucleus
Pontine
Projections
Pons
Dentate
Nucleus
Superior
Cerebellar
Peduncle
10
Somatotopic Organization
Tactile information
– Ipsilateral anterior lobule
– Bilateral paramedian lobules
– Cerebral Cortex and
Cerebellum have similar
representations
Motor representation
– Same area as sensory
mapping
– May have auditory and visual
processing
11
Transverse Cerebellar Regions
1. Floccular nodular lobe (Archicerebellum )
– Oldest, related to vestibular part of CN VIII
– Regulates equilibrium through vestibulospinal tract
2. Anterior lobe (Paleocerebellum)
– Rostral to Primary Fissure
– General Sensory Receptors
– Concerned with muscle tone and walking
3. Posterior lobe (Neocerebellum)
– Newest and Largest, Receives afferent projections from
contralateral sensorimotor cortex
– Projects to contralateral motor cortex
– Functions in coordination of fine and skilled movements
12
Longitudinal Cerebellar Regions
Vermis
– Contributes to body posture
Paravermal region
– Regulates movements of ipsilateral extremities
(e.g. walking)
Lateral Zone
– Regulates skilled movements of ipsilateral
extremity (e.g. tying your shoe)
13
Cerebellar Connection
 Three Peduncles
1. Inferior – afferent: mediate sensorimotor input to the
cerebellum
2. Middle – afferent: same as above
3. Superior – efferent: transmit output from the cerebellum to
the brainstem and on to the thalamus, motor cortex, and
spinal cord
 Varied afferents to Cerebellum :
– spinal cord
– brainstem
– motor cortex
 Afferenet:Efferent Ratio = 40:1
– For each going from cerebellum to body, 40 coming in
14
Afferent Pathways (Inferior)
Vestibulocerebellar Tract
– Info From Semicircular Canals Through Inferior
Peduncle
– Maintains Upright Posture
Dorsal Spinocerebellar Tract
– Info From Reticular Nuclei (involved in regulation
of sleep, respiration, heartbeat, etc.)
– Unconscious Proprioception From Muscle
Spindles, Golgi Tendons and Tactile Receptors
15
Afferent Pathways (Inferior 2)
 Reticulocerebellar Tract
– Info From Cerebral Cortices, Spinal Cord, Vestibular
Complex, and Red Nucleus
 Olivocerebellar Tract
– Info From Spinal Cord Through Olivary N to Contralateral
Cerebellar Hemisphere
– Source of Climbing Fibers for Direct Input to Cerebellum
 Cuneocerebellar Tract
– Mediate Proprioception From Upper Limbs and Neck
16
Afferent and Efferent Projections
Thalamus
Red nucleus
Superior Cerebellar
Peduncle
Middle Cerebellar
Peduncle (pontocerebellar
fibers)
Inferior Cerebellar Nucleus
(olivocerebellar fibers)
17
Afferent Pathways (Middle)
Info From Pontine Nuclei From Opposite
Cerebral Cortex, Visual and Auditory Inputs
To Opposite Cerebellar Hemisphere
18
Efferent Pathways
Arise From Cerebellar Nuclei
– Dentate nucleus
– Emboliform nucleus
– Globose Nucleus
Through Superior Cerebellar Peduncle to
– Red Nucleus (Brainstem)
– Thalamus
– Motor Cortex
19
Cerebellar Cortex
 Structured in Three Parallel
Layers
– Molecular
– Purkinje
 Connecting Surface and Deep
Cerebellar Nuclei
 Source of All Efferent Fibers
 Cerebellar Cortex
– Granular
 Have Mossy Fiber Axons to
Purkinje Axons
20
Clinical Considerations
 Signs of Dysfunction
–
–
–
–
Impaired Muscle Synergy
Reduced Muscle Tone
Evident in Skilled Tasks
Ataxia
 Lack of Order and Coordination in Activities
 Slow Movement (Bradykinesia)
 Mild Muscular Weakness (Asthenia)
 Asynergia (Poor coordination of muscles: Dysdiadochokinesia)
 Speech difficulties (Ataxic Dysarthria)
– affects respiration, phonation, resonance and articulation, but most
pronounced in articulation and prosody.
21
Clinical Considerations 2
 Dysdiadochokinesia
– Clumsiness in Alternating Movements
 Switching between supination and pronation – e.g. screwing in a
light buld
– Tapping, Speech Sound
 Dysarthria
– Ataxic Dysarthria
– Poor articulation: Slurred and Disjointed Speech
 Dysmetria
– Error in Judgment of Range and Distance of Target
– Undershooting or Overshooting
22
Clinical Considerations 3
 Intentional Tremor
– Accessory Movement During Volitional Task
– vs. Parkinson’s Disease Where Tremor Lessens During
Volitional Movement
 Hypotonia
– Reduced Resistance to Passive Stretch
 Rebounding
– Inability to Predict Movement
– Cannot Hold Back Movement
 Disequilibrium
– Unsteady Gait, Body Wavering
23
Cerebellar Pathologies
 Cerebrovascular Accident (CVA)
– Thrombotic, embolic or hemorrhagic
– Vertebrobasilar Artery
 Toxicity
– Chronic Alcoholism
 Progressive Cerebellar Degeneration
– Friedrich's Ataxia: Autosomal Recessive Heredity
Degenerative Condition
– Combined Sensory and Motor Dysfunctions
 Poor coordination of Gait and speech
24