Download Control circuits PEDRO 2017 LS

THE BRAIN, SPEECH AND LANGUAGE:
CONTROL CIRCUITS
Pedro Amarante Andrade, PhD
LCSC06
BIOSCIENCES
FOR SPEECH AND LANGUAGE THERAPY
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CONTROL CIRCUITS
Integrate and control the activities
of the structures and pathways
involved in motor performance
Key point: Neither the basal
ganglia not the cerebellum project
directly onto lower motor neurons.
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CONTROL CIRCUITS
CEREBELLUM AND BASAL GANGLIA
• The cerebellum: coordinates motor and
sensory information
– Gets info from the cortex about what muscles
SHOULD be doing, and compares this with what is
ACTUALLY happening
• The basal ganglia: involved in control of
background movement, and initiation of
movement patterns
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THE CEREBELLUM
‘little brain’ in Latin
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FUNCTIONS OF THE CEREBELLUM
• Stores learned sequences of movements
• Participates in fine tuning and co-ordination
of movements produced elsewhere in the
brain
• Integrates all of these things to produce fluid
and harmonious movements.
So prime task is to ensure smooth
coordination of muscles
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CEREBELLUM
• Highly folded
surface
• Accounts for about a
tenth of the brain
mass yet contains
half of its total
amount of neurons
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CEREBELLUM
Tortora and Derrickson 2012. Principles of anatomy
and physiology. Pp 509
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CEREBELLUM
Tortora and Derrickson 2012. Principles of anatomy
and physiology. Pp 509
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ANTERIOR CEREBELLUM
Spinocerebellum
• projection area for the
spinocerebellar proprioceptive
information
• Receives input from muscle and
joint receptors (Golgi tendon
organs & muscle spindles) via
spinocerebellar tracts
• Regulates posture, gait and
truncal tone.;
• It is connected to the spinal cord
and controls postural muscle
activity by influencing muscle
tone.
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POSTERIOR CEREBELLUM
Cerebrocerebellum
• Connected to the contralateral
cortex and thalamus
• Lateral portions of the
cerebellar hemispheres have a
role in coordinating skilled,
sequential voluntary muscle
activity
• Ensures that when one set of
muscles initiates a movement,
the opposing set acts as a
brake, so that the body part in
question arrives at its target
precisely.
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FLOCCULONODULAR LOBE
Vestibulocerebellum
• The oldest part
phylogenetically so aka the
archicerebellum;
• Connects with the vestibule of
the inner ear and is involved in
balance.
• Contains the fastigial nucleus
which connects with the 4
vestibular
nuclei in the
vestibular nuclei
brainstem
• Modulates equilibrium
(balance) and orientation of
head and eyes
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FLOCCULONODULAR LOBE
Vestibulocerebellum
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PROJECTION TO THE CORTEX
Cortex sends information to
cerebellum via pontine nuclei
cerebellum send information
back to the cortex via the
thalamus
Cerebellum also receives
sensory information from the
brainstem and spinal cord (e.g.
proprioceptive stimuli via
spinocerebellar tracts)
The basal ganglia form a complex collection
of nuclei also involved in a loop from cortex
to basal ganglia to thalamus and back to
the cortex
http://www.sofiatopia.org/equiaeon/ibrain12.jpg
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CEREBELLAR PEDUNCLES
Superior
Middle
Inferior
Fibre tracts enter/leave
through the inferior, middle
and superior cerebellar
peduncles
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CEREBELLUM
• Superior cerebellar peduncles: red nuclei
(midbrain)
• Middle cerebellar peduncles: pontine nuclei
into cerebellum (largest)
• Inferior cerebellar peduncles:
a) Form spinocerebellar tract (sensory)
b) From vestibular apparatus (inner ear) and
vestibular nuclei of the medulla and pons
c) From Inferior olivary nucleus
d) To vestibular nuclei of the medulla and pons
e) To reticular formation
Tortora and Derrickson 2012. Principles of anatomy
and physiology. Pp 508
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CEREBELLAR ANATOMY
http://humanphysiology.academy/Neu
rosciences%202015/Chapter%205/A.5
p%20Cerebellar%20Pathways.html
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CEREBELLAR CONTROL CIRCUITS 1
loop important in planning and programming learned movements
Primary motor
& premotor
regions
Ventral
thalamus
Deep
cerebellar
nuclei
Pontine nuclei
Lateral
cerebellar
hemispheres
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CEREBELLAR CONTROL CIRCUITS 2
Primary motor
cortex
Ventral thalamic
nuclei
Deep cerebellar
nuclei
Corticospinal/
Corticobulbar
fibres
Intermediate
cerebellar
hemispheres
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CEREBELLAR CONTROL CIRCUITS
Primary motor
cortex
Corticospinal/
Corticobulbar
fibres
Ventral
thalamus
Deep
Intermediate
cerebellar
hemispheres
& premotor
regions
cerebellar
nuclei
Pontine nuclei
Lateral
cerebellar
hemispheres
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FUNCTIONS OF
CEREBELLAR CONTROL CIRCUITS
• Coordinate the timing between the single
components of a movement
• Scale the size of muscular actions
• Coordinate the sequence of agonists and
antagonist
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CEREBELLAR SPEECH MOTOR CONTROL
SUMMARY:
1. Cortex sends preliminary advance information
referring intended speech goals to cerebellum
2. These preliminary speech commands are provisional,
imprecise and in excess of those needed to
accomplish speech goal
3. Cerebellum is thus ‘primed’ to check the adequacy of
the outcome, based on sensory information coming in
from the periphery (i.e. muscle spindles, joint and
tendon sensors)
4. Cerebellum updates the motor output from the
cortex to help smooth the actions of
agonist/antagonist muscle contractions
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BASAL GANGLIA CIRCUITS
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ANATOMY OF THE BASAL GANGLIA
http://antranik.org/cerebral-white-matter-and-gray-matter-andbasal-ganglia/
https://kin450neurophysiology.wikispaces.com/Basal+Ganglia+II
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ANATOMY OF THE BASAL GANGLIA
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BASAL GANGLIA CIRCUITS
• Important in generating components of motor
programmes for speech
• Cortex initiates impulses in excess of
requirements to produce the motor act
• Basal ganglia is modulate through inhibition
these impulses
• Important in regulating muscle tone, goal
directed activities, automatic activities
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BASAL GANGLIA
http://7e.biopsychology.com/vs11.html
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BASAL GANGLIA CONTROL CIRCUITS
Selectively activates
and inhibits
movements. Provides
internal cues for
planning and refining
slow continuous
movement
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BASAL GANGLIA CONTROL CIRCUITS
Caudate nucleus and
putamen (the striatum): act
together as a functional unit INPUT
Globus pallidus interna and
substantia nigra pars
reticulata - main OUTPUT
Globus pallidus externa, Sub
thalamic nucleus, and
substantia nigra pars
compacta - intermediate
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BASAL GANGLIA CONTROL CIRCUITS
Two Loops
Direct = responsible for
activating movement
overall excitatory
Indirect = stopping
unwanted movement
overall inhibitory
The two pathways operate
together to provide balanced
control of descending
pathways.
NB Do not confuse these
loops with the direct/indirect
activation pathway
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TWO LOOPS
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NEUROTRANSMITTERS
• GABA (gamma
aminobutyric acid) =
inhibitory • Glutamate = excitatory +
• Ach (acetylcholine) synapse in the striatum –
excitatory +
• Dopamine (substantia
nigra) neuromodulatory
The balance of these is crucial
to normal functioning of the
loops and therefore motor
output
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DIRECT/INDIRECT PATHWAY OF BASAL
GANGLIA
Direct = Making
movement
(excitatory)
Indirect = not
moving
(inhibitory)
http://neurolove.tumblr.com/post/2745681497/lets-breakdown-thebasal-ganglia-pathways-there
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DIRECT/INDIRECT PATHWAY OF BASAL
GANGLIA
CORTEX
Direct =
Promoting
movement
(excitatory)
Striatum
Thalamus
Globus Pallidus
Subthalamus
Substantia nigra
Glutamate (+)
GABA (-)
Dopamina
Aim = Reduce the
natural inhibited
state of the
Thalamus :o(
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DIRECT/INDIRECT PATHWAY OF BASAL
GANGLIA
CORTEX
Indirect = not
moving
(inhibitory)
Striatum
Thalamus
Globus Pallidus
Subthalamus
Substantia nigra
Glutamate (+)
GABA (-)
Dopamina
Aim = Avoid
unwanted
movement
(Thalamus and
Subthalamus) :O(
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DIRECT/INDIRECT LOOPS OF BASAL
GANGLIA
Premotor/motor cortex
Striatum
External globus
pallidus
Subthalamic
nucleus
Indirect
loop
Substantia
nigra
Internal globus
pallidus
Direct
loop
Thalamus
PATHWAYS
GREEN = EXCITATORY
RED = INHIBITORY
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NEUROMODULATORY EFFECT OF
DOPAMINE
•Direct Pathway: Stimulates
•Indirect Pathway: Inhibits
•Overall Excitatory
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OTHER FUNCTIONS/LOOPS OF THE BASAL
GANGLIA
An executive loop may regulate the initiation and
termination of cognitive processes such as planning,
working memory, and attention.
The limbic loop may regulate emotional behaviour.
The deterioration of cognitive and emotional
function in both Huntington's disease and
Parkinson's disease could be the result of disruption
of these non-motor loops.
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SAME TYPICAL EXAMS QUESTIONS
1. Which of the two following components of
the basal ganglia form a functional unit?
I. putamen and globus pallidus
II. Substantia nigra and putamen
III. Putamen and caudate nucleus
2. Complete the following: the lentiform nucleus
is composed
of……………………………………………….
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3. Which of the following statements is NOT
true of the functions of the cerebellum?
I.Stores learned sequences of movements
II.Ensures smooth coordination of muscles
III.Regulates postural adjustments during skilled
movements
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4. In addition to its role in movement control,
list 2 other posited functions of the basal ganglia
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WHAT TO DO NOW
• Read the scanned chapter by Ellison (2012),
chapter 6, Moving On. This should consolidate
your understanding of movement, and the
complex pathways involved.
• Chapter 10 in Atkinson and McHanwell
provides a more comprehensive summary.
• Chapter 2 in Duffy (2007), a text you will use
next year also has a good summary
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THE CEREBELLUM
‘little brain’ in Latin
Vestibulocerebellum = flocculonodular lobe
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CEREBELLAR CONTROL CIRCUITS 2
Primary motor
cortex
Ventral thalamic
nuclei
Deep cerebellar
nuclei
Corticospinal/
Corticobulbar
fibres
Intermediate
cerebellar
hemispheres
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DIRECT/INDIRECT PATHWAY OF BASAL
GANGLIA
Direct = Making
movement
(excitatory)
Indirect = not
moving
(inhibitory)
http://neurolove.tumblr.com/post/2745681497/lets-breakdown-thebasal-ganglia-pathways-there
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ANATOMY OF THE BASAL GANGLIA
https://kin450neurophysiology.wikispaces.com/Basal+Ganglia+II
LCSC06 | Biosciences for SLT