Basal Ganglia Part 1 Flashcards
What 6 structures make up the basal ganglia system of gray matter?
caudate, putamen, nucleus acumbens, globus pallidus, subthalamic nucleus, substantia nigra, ventral tegmentum
The corpus striatum is made of what?
the caudate and the putamen
The globus pallidus is (medial/lateral?) to the putamen?
medial, just underneath it
Where is the subthalamus?
at midbrain, just under the globus pallidus, it interconnects the globus pallidus
The substantia nigra, Pars compacta and SNpc communicate with the ________with ________neurotransmitter.
communicate with the striatum with DA
Starting from the cortex, what is the basal ganglia feedback loop?
cortex–>caudate/putamen–>ex GP/int GP–>thalamus –>cortex
substantia nigra caudate and putamen
subthalamic nucleus int/ext GP
What is the direct pathway?
cortex –>+striatum –>inhibits GPi–>less inhibitory signal to thalamus–>greater + from thalamus to cortex–>motor output
What is the indirect pathway?
striatum inhibits GPe–> less inhibitory signal to SubTh–>large excit of GPi–>inhibition of thalamus–>less signal to cortex –>decreased motor output
How does the striatum inhibit unintended movements?
by increasing GPi activity via the indirect path
DA from the SN to the striatum activates the ______ pathway via ____________receptors and inhibits the _______pathway via _________receptors
activates the direct pathway via D1 type DA receptors
inhibits the indirects pathway via D2 type DA receptors
What are the four cortico-striate loops?
visual, motivational, executive, motor/premotor (somatosensory)
What cortex is involved in the motivational/limbic loop? What part of the basal ganglia does that cortex project to?
the anterior cingulate, OFC project to the nucleus accumbens/ventral striatum
What cortex is involved in the executive/cognitive loop?What part of the basal ganglia does that cortex project to?
dlPFC projects to the caudate
What cortex is involved in the motor loop? What part of the basal ganglia does that cortex project to?
primary motor, premotor, supplementary motor cortex project to putamen
What cortex is involved in the visual loop? What part of the basal ganglia does that cortex project to?
extrastriate cortex (inferotemporal and fusiform gyrus) project to the tail of the caudate
Which corticostriate loop projects to the caudate?
the executive/cognitive loop
Which corticostriate loop projects to the putamen?
the motor loop
Which corticostriate loop projects to the tail of the caudate?
the visual loop
Which corticostriate loop projects to the nucleus accumbens?
the motivational loop
Where is declarative (episodic/semantic) memory generated?
hippocampus/limbic
Where is emotional memory generated?
amygdala (fear conditioning)
Where is procedural (non-declarative) memory associated?
cerebellum (motor-skill) and basal ganglia (habit formation)
Parallel loops of procedural memory help facilitate what 3 things?
category representation, action selection, insturmental/reward learning
Procedural memory is an emergent property of _______
parallel cortico-striate loops
Which corticostriate loop is most active in category representation?
the visual loop
What structures do declarative visual categories depend on? What kind of memory is this?
depend on hippocampus and prefrontal regions involved in working memory and executive attention (vmPFC, dlPFC). compositional, made of separable elements
Describe procedural visual categories
visual cortco-striate loop branches to executive and premotor loops to integrate with executive control. blended, less flexible categories often associated with behavioral responses
Describe the mosaic of broken mirrors model of action selection.
overlapping representation of body part with a seen visual object and with an encoded type of movement. utilizes polymodal neurons
What is insturmental/procedural learning?
behavioral reinforcement of habit formation. requires extinction of inappropriate learned responses and associated of a stimulus (eg. ball moving towards foot) with a response (eg. kick the ball)
What does instrumental and reward learning depend on?
repetitive reinforcement with DA
What are the three dopamine pathways from the midbrain to the striatum for reward learning reinforcement?
nigrostriatal: SN to striatum
mesolimbic: ventral tegmentum to nucleus accumbens
mesocortical: ventral tegmentum to PFC
Performance of well established behaviors is/is not outcome mediated and is more/less DA dependent.
IS NOT outcome mediated
LESS DA dependent
What are the two types of learning?
instrumental (procedural) and reward learning
Reward learning is mediated by what loop and what cortical areas?
the motivational loop,
vmPFC, OFC, nucleus accumbens
how does DA reinforce reward learning and what DA pathway is involved?
mesolimbic DA innervates the nucleus accumens to strengthen links between behavior and reward
Learning occurs in which anatomical direction?
rostral –>caudal
What is the sequence of corticostriate loops in reward learning?
motivational loop–>executive loop–>motor loop
external triggers activate which loop mainly?
sensorimotor (willfull behavior)
internal triggers activate which loops mainly?
motivational and executive
