Modul 3 Lecture 3 Flashcards
___________ is a muscle movement
regulatory component of the central nervous
system
The basal ganglia
muscle can do
one thing at a time
Basal Ganglia
Has two core missions:
_________
__________
– Operational learning
– Action selection
________________
• All movements except for eye movement
• Basal ganglia receives information from other
areas in the cortex
Skeletal Motor Loop
• Basal ganglia receives information from _________
other
areas in the cortex
Basal ganglia facilitates movement by
focusing activity
Inputs to the Basal Ganglia
• Inputs from_________ shows somatotopy that
correlates with the cortex
• The medium spiny neurons project to the
___________________
the cortex
globus pallidus and substantia nigra
The striatum receives glutamatergic inputs from ____________________
most of cortex.
The Striatum receives all inputs.
Functionally related cortical areas
project to _________________
overlapping area of the
Striatum.
_____________ that are not functionally linked project to
different regions of the Striatum.
Cortical areas
Individual cortical cells project to more than one \_\_\_\_\_\_\_\_\_\_\_\_\_\_ This divergence may occur because single cortical neuron can be involved in more than one motor function.
Striatal area.
Cortical areas that are not
functionally linked project to
different regions of the Striatum.
Inputs to Caudate, Receives cortical projections from multimodal association area and from ________
frontal lobe eye movement area
Putamen
• Receives inputs from _________________ ___________________ in the
parietal lobe,
_____________ in the
occipital and temporal lobe,
_____________ from the frontal lobe, and
________________from the temporal lobes
the primary and
secondary somatic sensory cortices
the visual cortices
the premotor and
motor cortices
the premotor and
motor cortices
Three Major Pathways to Basal
Ganglia
- Direct pathway
- Indirect pathway
- Hyperdirect pathway
Direct pathway
• Inputs from the cortical areas excite cells in the
putamen which makes inhibitory synapse _________________ which in turn makes inhibitory
______________
to the
globus pallidus,
synapses with the VLo
• The VLo connections to the SMA cortex _________________
are
excitatory
• This allows the basal ganglia to enhance _______________
• Cortical activation of the putamen leads to
___________________
the initiation of desired movements
excitation of the SMA
Hyperdirect Pathway
____________
• The STN receives excitatory inputs from the
cortex, which in turn excites the GPi, leading
to________________
• Myelinated
thalamus inhibition
Whereas activation of the direct pathway by
the cortex tends________the thalamus,
activation of the indirect pathway by the
cortex tends to__________t the thalamus
to facilitate
inhibit
• The direct pathway may help to _________________while
the indirect pathway
simultaneously ____________
select certain motor actions
suppresses competing and inappropriate motor programs
Cells of the SN form dopaminergic synapses
• Though small pool of neurons, it exerts a
profound effect over the integration of the
cortical inputs in_________________
the corpus striatum
• SNc sends dopaminergic projections to the
______________________
medium spiny neurons
________ increases the
direct pathway, leading to
more movement.
DA (D1)
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ decreases the indirect pathway that normally inhibits movement, leading to more movement.
DA (D2)
Neurons of the SNc
- Some neurons are tonic
* Some neurons are phasic
Dopamine
• DA is a __________ NOT transmitter
modulator,
– It doesn’t directly allow ions to enter through it
but, rather, _______________
modulates other ion channels that do
• DA has many metabotropic receptors with
two important ones expressed on___________________
striatal
medium spiny neurons
The effect of dopamine is complex
– DA acts differently, depending on the type of
_________________
receptors on the postsynaptic neurons
• DA is excitatory on the striatum that synapse
on GPi in ____________
• DA is inhibitory on the striatum that synapse
on GPe in ________________________
the direct pathway (D1)
the indirect pathway (D2
DA receptors are G Protein coupled receptor
• D1 increases cAMP and therefore
increases the excitatory inputs from the cortex
• D2 decreases cAMP and therefore
decreases
the excitatory inputs from the cortex
Increased inhibition to the thalamus leads to
___________
• Decreased inhibition to the thalamus leads to
_____________
hypokinesia
hyperkinesia
\_\_\_\_\_\_\_\_\_\_\_\_\_\_ • Affects 1% of all people over the age of 60 • No known single cause • Characterized by slowness in movements (bradykinesia) – Festinating gait – Masked face – Change in voice pitch – Resting tremors • Difficulty in initiating movement (akinesia) • Increased muscle tone (rigidity) • Difficulty in cognition • Loss of movement “grouping”
Due to degeneration of neurons in the SN
– Symptoms arise when 80% of the dopaminergic neurons in
the SN have degenerated
• In 1976 and 1982, drug abusers developed Parkinson’s
symptoms due to to usage of synthetic opioid that
contained MPTP
• MPTP kills dopaminergic neurons
• Converted to MPP, it is taken inside the cells via the DA
transporters
• MPP affects the mitochondria function
• Depleted of ATP, the neurons die
Parkinson’s Disease
Parkinson’s Disease
• The action of DA is complex
– DA released from the SN excites the putamen
neurons of the direct pathway, releasing _____________
the
inhibition of the thalamus
The depletion of DA will have the opposite effect of the
VLo
– DA released from the SN inhibits the neurons of
the indirect pathway that send ________________
• The depletion of the DA will have the opposite effects
inhibitory inputs to
the GPe
Parkinson’s Disease Treatment
• Tyrosine hydroxylase (rate limiting enzyme) to
convert ________________________ __________________________
– L Dopa treatment (can cross the BBB)
• Honeymoon stage
tyrosine to Dopa which is then
converted to dopamine
Parkinson’s Disease Treatment
• Deep Brain Stimulation of STN or deep
pallidum
– Side effects
• Done with giving L Dopa
\_\_\_\_\_\_\_\_\_\_\_\_ • Hereditary, progressive, and fatal • Characterized by hyperkinesia and dyskinesia (abnormal movements), dementia, and a disorder of personality • Rare (5-10 people in 100,000)
Due to loss of neurons in the striatum that
inhibit the GPe
– GPe is always active, STN is always inhibited, Gpi is
always inhibited
– As a results there is a loss of inhibition to the
thalamus
– thalamus is active
Huntington’s Disease
________
• The disease is particularly insidious because its
symptoms usually do not appear until well into
adulthood
• In the past, patients often unwittingly passed the
gene on to their children before they knew they
had the disease
• It is now possible to perform a genetic test that
reveals whether a person carries the Huntington
gene
• People with Huntington’s disease exhibit changes
in mood, personality, and memory
Huntington’s Disease
