Corpus Striatum Flashcards
What 2 structures comprise the corpus striatum?
- Striatum
- Pallidum
What are the 3 components of the basal ganglia?
- Corpus striatum
- subthalamic nucleus
- substantia nigra
Where in the brain (generally) is the corpus striatum
Deep grey, in the forebrain
Sort of around the thalamus
What is the striatum comprised of?
- caudate nucleus
- Putamen
- nucleus accumbens (where they meet)
What is the lentiform nucleus comprised of?
- Putamen
- Globus pallidus
What is the main general function of the basal ganglia?
production of movement
What are the 3 inputs to the Striatum, and describe their role?
- Cerebral cortex (excitatory, glutamatergic)
- Thalamus (excitatory, glutamatergic)
- substantia nigra (excitatory & inhibitory, dopaminergic)
What are the 2 outputs from the striatum & describe their role)
- Globus pallidus (inhibitory, GABAergic)
- Substantia Nigra (inhibitory, GABA-ergic)
What are the 2 inputs to the pallidum?
- From striatum (inhibitory)]
- Frmo subthalamic nucleus (excitatory)
What are the outputs from the pallidum?
- Thalamus (from interna, to ventral lateral, ventral anterior & mediodorsal nuclei. From externa to subthalamic nuclei)
- Pedunculopontine nucleus
- Habenula
- superior colliculus
Describe the Direct Loop of the basal ganglia
- excitatory input from cortex
- excites inhibitory neuron from striatum
- disinhibits internal pallidum
- turns off inhibition to motor thalamus
- results in increased movement
Describe the Indirect Loop of the basal ganglia
- excitatory input from cortex
- excites inhibitory neuron from striatum
- disinhibits external pallidum
- removes inhibition from subthalamic nucleus
- excites internal pallidum
- maintains inhibition of motor thalamus
- results in decreased movement
How do the direct and indirect loops contribute to the facilitation of movement?
- Direct pathway stimulates facilitation of movement (necessary movements are made)
- Indirect pathway reduces activity & suppresses movement (unnecessary movements are prevented)
How do the direct and indirect loops contribute to the facilitation of movement?
- Direct pathway stimulates facilitation of movement (necessary movements are made)
- Indirect pathway reduces activity & suppresses movement (unnecessary movements are prevented)
What is the role of dopamine in the basal ganglia?
- Dopamine excites the direct pathway & inhibits the indirect pathway
- helps make necessary movement happen
- reduces the suppression of movement to further facilitate movement
Name the 4 parallel circuits of the corpus striatum
- Motor
- Oculomotor
- Prefrontal
- Limbic
Describe the motor parallel circuit of the corpus striatum
- From primary somatosensory, motor & premotor cortex
- to Putamen
- to globus pallidus
- to thalamus (ventral lateral & ventral anterior)
- to motor & premotor cortex
Describe the oculomotore parallel circuit of the corpus striatum
- From prefrontal & posterior parietal cortex
- to caudate nucleus (tail)
- to globus pallidus & substantia nigra pars reticulata
- to thalamus (ventral anterior and mediodorsal)
- to frontal eye fields
Describe the prefrontal parallel circuit of the corpus striatum
- from prefrontal & posterior parietal cortex
- to caudate nucleus (head)
- to globus pallidus
- to thalamus (ventral anterior & mediodorsal)
- to prefrontal cortex
Describe the limbic parallel circuit of the corpus striatum
- From temporal lobe, hippocampus, amygdala
- to nucleus accumbens
- to ventral apllidum
- to thalamus (mediodorsal)
- to cingulate gyrus & orbital prefrontal cortex
