The basal ganglia Flashcards
What are the functions of the basal ganglia?
Are involved in the regulation of goal directed voluntary movements (selection,initiation, ending) –> motor learning and motor pattern behaviour
Which brainstructures belong to the basal ganglia?
Neostriatum, Paleostriatum, substantia nigra, subthalamic nucleus
Part of the basal ganglia:
Which brain structures are part of the neostriatum?
Caudate nucleus, putamen, ventral striatum (nucleus accumbens)
Part of the basal ganglia:
Which brainstructures are part of the paleostriatum?
Globus pallidus external and internal segment (GPe/GPi)
Part of the basal ganglia:
Which brainstructures belong to the substantia nigra?
Pars compacta and reticula (SNc/SNr)
Which cortices give input to the basal ganglia?
Frontal, parietal and temporal cortex
Where in the brain is dopamine synthesis?
Substantia nigra compacta, ventral tegmental area
What are the projections of dopamine from the VTA and SN?
SN:
- Nigro-striatal : to Caudate/putamen, nucleus accumbens (neostriatum)
VTA:
- Meso-cortical: PFc and other cortex
- Meso-limbic: amygdala, hippocampus
What does cocaine do to dopamine?
Causes accumulation of DA by binding to DAT and blocking reuptake
What is the function of the medial forebrain bundle?
Motivation, reward, reinforcement
Which neuron of the basal ganglia gets input from other basal ganglia neurons?
Medium spiny neurons:
input from cortical pyramidal neurons, dopaminergic neurons, globulus pallidus/substantia nigra pars reticulata neurons
What are the medium spiny neuron projections?
Putamen, caudate nucleus, globus pallidus, SNr
What is the pathway of the body movement loop?
- INPUT: Motor/premotor/somatosensory cortex
- Putamen
- Lateral GPi
- OUTPUT: VL/VA (complex) nuclei of the thalamus
–> M1/premotor/suplemmentary motor cortex
VL/VA = Ventral lateral & ventral anterior
What is the pathway of the oculomotor loop?
- INPUT: posterior parietal/prefrontal cortex
- Caudate
- GPi;SNr
- OUTPUT: mediodorsal & ventral anterior nuclei of thalamus
–> Frontal eye field, supplementary eye field
Through which structure goes the direct and indirect pathway of the basal ganglia? And what does it cause?
Direct via putamen and caudate –> facilitates movement
Indirect via subthalamic nucleus –> inhibits movement
Which brain structures are tonically active of the basal ganglia?
From GPe to subthalamic nucleus and from GPi to VA/VL complex of the thalamus
Also the SNr
VA/VL= ventral anterior/ventral lateral
Which DA pathway is primarily targeted in Parkinsons
Nigro-striatal pathway
What are the projections of the VTA?
- NaCC: medial and lateral shell, core
- Prefrontal cortex: prelimbic and infralimbic area
- Basolateral amygdala
Name 1 motor and 1 non-motor symptom of Parkinsons
Motor: tremor
Non-motor: sleep disturbance
What is a hypokinetic disorder? Give 1 example.
- Insufficient direct pathway output
- Excess indirect pathway output
–> Parkinsons: connection between SNc and caudate/putamen is degenerated
What is a hyperkinetic disorder? Give 1 example.
- Excess direct pathway output
- Insufficient indirect pathway output
–> Huntingtons: connection between caudate/putamen and GPe is degenerated
What are choreatic syndromes?
They are hyperkinetic disorders.
A movement disorder in which muscles contract involuntarily, causing repetitive or twisting movements
Match the choreatic (hyperkinetic) syndrome with the cause:
- Huntingtons chorea
- Dystonia
- Tardive dyskinesia
- DOPA-induced dyskinesia
- Hemiballismus
- Tourette’s syndrome
+
Chronic neuroleptic use, Genetic, Excessive D2-subtype, Genetic or idiopathic, Parkinsons therapy, unilateral vascular accident (subthalamic nucleus)
- Huntington & genetic (Autosomal dominant)
- Dystonia & genetic or idiopathic
- Tardive dyskinesia & chronic neuroleptic use
- DOPA-induced dyskinesia & Parkinsons therapy
- Hemiballismus & unilateral vascular accident
- Tourettes & Excessive D2-subtype
Why does specifically DBS of the subthalamic nucleus help Parkinson
Modulates overactivity of the subthalamic nucleus. Loss of dopamine increases STN activity, causing excessive inhibition of the thalamus and reduced motor cortex activity. High-frequency stimulation from DBS disrupts the abnormal firing patterns in the STN, restores balance in the basal ganglia circuits, and enhances motor control.
- Reduces symptomps
X Parkinsons: stimulated nuclei extra which balance out the loss of degenerated D1 and 2
