Midterm 2 - Unit 5 Lecture 2 Flashcards
function of Basal Ganglia
Used in the planning and control of complex movements
Organizes sequencing of movements
does the Basal Ganglia act directly or indirectly to lower motor neurons
indirectly
is the Basal ganglia involved with the SMA or PMA
SMA
Programs self-initiated movements
Self-initiated movement rather than stimulus triggered movement
Control of habitual, skill-based behaviours
The basal ganglia selectively activates some movements while suppressing others. true or false
True
the basal ganglia inhibits unwanted movements and releases this inhibition to trigger movement. True or false
true
what are the Group of nuclei at ‘base’ of cerebral cortex:
Caudate
Putamen
Globus Pallidus
Substantia Nigra
Subthalamic Nucleus
what makes up the striatum
Caudate and Putamen
what makes up the lenticular nucleus
Globus pallidus and putamen
what is the shape/structure of the caudate
C shaped structure
how is the caudate divided
Divided into three parts:
Head, body and tail
What part of the brain is the putamen in?
The putamen is a round structure located at the base of the forebrain (telencephalon)
how are the putamen and caudate connected
Cellular bridges to caudate nucleus
what are the two segments of the Globus Pallidus
Internal, medial component; GPi
External, lateral component; GPe
GPi is one of the major outputs of the basal ganglia. true or false
true
the Subthalamic Nucleus is inferior to which structure
thalamus
what is the shape of the Subthalamic Nucleus
‘Spindle’ or ‘lens’ shaped
the Subthalamic Nucleus communicates with the
Globus Pallidus
what are the two segments of the Substantia Nigra
Pars compacta: more dorsal, contains darkly pigmented dopaminergic neurons
Pars reticulata: more ventral, involved in output, inhibits thalamus
what is the input nuclei associated with the Basal ganglia
Striatum: Putamen and Caudate
the basal ganglia receive Inputs from widespread areas of Cerebral Cortex including
Sensory areas
Motor areas
Association areas
thalamus
what is the output nuclei associated with the Basal ganglia
Globus pallidus internal segment
Substantia nigra pars reticulata
does the Basal Ganglia Output have an inhibitory or an excitatory effect
inhibitory, GABA
where does the Basal Ganglia output to
Thalamus
Superior colliculus
The basal ganglia output nuclei have inhibitory projections to ______________
thalamus
BG modulates this tonic inhibitory output through two main pathways:
Direct and Indirect
At rest we know the Globus Pallidus internal has an _____________output and it talks to the ____________
inhibitory, thalamus
what happens at rest in the Basal Ganglia Pathways
At rest GPi and SNpr they are ticking away at some resting discharge rate
And this inhibition is causing the thalamus which has an excitatory connection with the cortex, its being inhibited = less excitatory effect
what is the direct pathway of Basal Ganglia
circuit best known for its hypothesized role in movement
The direct pathway, its net outcome is to
increase that thalamus output
how does the direct pathway increase that thalamus output
by reducing the Globus Pallidus internal segment
doing so reduces its inhibitory effect
The direct pathway starts with the ______________ and produces an ____________ output
cortex, excitatory
(Direct pathway) From the cortex, the ______________which is the main input nuclei, has an _______________effect on the ____________________
striatum, inhibitory effect, GPi
how does the striatum inhibiting the GPi reduce the inhibitory effects on the thalamus
because we know the GPi inhibits the thalamus, so because we’re inhibiting the GPi, we’re having less inhibitory effect on the thalamus
what is disinhibition
removing the inhibition on the thalamus
what happens when you take away that inhibition on the thalamus
you can increase the excitatory effect on the cortex, which will increase the descending drive
does the basal ganglia have indirect or direct effect on lower motor neurons
indirect
the direct pathway is all about ______________the lower motor neuron activity
increasing
The indirect pathway is all about ____________
decreasing thalamus output
how does the indirect pathway decrease thalamus output
when we increase that GPi, this effect is stronger, there is more inhibition on that thalamus
1.cortex excites striatum
2.striatum inhibits the GPe
3. GPe has an inhibitory effect on the STN(subthalamic nucleus)
4. the STN has an excitatory connection on the GPi,
6. GPi and has an inhibitory connection on the thalamus which is being strengthened
what does a greater inhibition on the Thalamus do
means we can’t excite the cortex as much
It eventually leads to a decreased descending drive
what are the Effect of Dopamine on these pathways
Dopamine allows you to produce the movement that’s desired, turning down the brake and turning up the gas
name a Basal Ganglia Dysfunction
Parkinson disease
what causes parkinson disease
Caused by neuron death in substantia nigra
loss of dopamine
What happens to the basal ganglia in Parkinson’s?
Disrupts normal modulation of BG output
So all of a sudden you can’t turn off the gas and theres too much break
what are the Classic Symptoms of Parkinson’s Disease
Akinesia and Bradykinesia
Difficulty initiating movement and slow small movements
Resting tremor
Rhythmic oscillation in distal limbs (usually hand or upper extremity)
Rigidity
Increased muscle tone and stiffness: “Lead pipe” or “cog-wheel” rigidity
Postural instability
Leading to unsteady gait
Other Symptoms of Parkinson’s Disease (Posture and gait related)
Stooped posture
Shuffling gait with freezing and difficulty turning
Diminished arm swing while walking
Other Symptoms of Parkinson’s Disease
Micrographia and Hypophonia
Diminished facial expressions
what is another Basal Ganglia Disorder that we learned
Huntington’s Disease
what is Huntington’s Disease
Hyperkinestic movement disorder
Degeneration of striatal neurons in caudate and putamen
Neurons of indirect pathway more severely affected
Not enough inhibition (for the unwanted movements)
symptoms of Huntington’s Disease
Hyperkinetic movements: Chorea and dystonia
