N39 Flashcards
Corpus striatum refers to
caudate + putamen + globus pallidus
Striatum refers to
caudate + putamen
Lenticular nucleus refers to
putamen + globus pallidus
nucleus accumbens
anterior area where caudate putamen are continuous centrally; related to limbic system and role in drug and alcohol addictions
Neurons in the striatum use what NTs
Ach or GABA
Globus pallidus neurons use what NT
GABA (inhibitory)
2 parts of globus pallidus
internal segment: projects to VA/VL thalamus (lenticular fasciculus and ansa lenticularis)
external segment: input from striatum and projects to internal segment and subthalamus
2 parts of substantia nigra
pars compacta and pars reticulata
Pars compacta of substantia nigra
Use dopamine and contain neruomelanin
Pars reticulata of substantia nigra
use GABA
Most inputs to basal ganglia are to
the striatum
Most outputs from basal ganglia are
from the GPi
Corticostriate
Cerebral cortex to ipsilateral striatum; excitatory and use glutamate
Within striatum there are 2 cell types
spiny neurons and cholinergic interneurons
Cholinergic interneurons
modulate local activity, activate neurons ACh-excitatory
Spiny neurons
require activation; GABA inhibition
Nigrostriatal
inputs use DOPAMINE via D1-D5 receptors (excitatory or inhibitory)
D1 and D5 when bound to dopamine exerts an
excitatory effect DIRECT PATHWAY
D2, D3, D4 when bound to dopamine exerts an
inhibitory effect INDIRECT PATHWAY
Straiatopallidal projections (GPe and GPi)
GABA pathways
Striatonigral projections
GABA pathways
Subthalamic projections to GPi and pars reticulata uses
Glutamate
GPi outputs to
ansa lenticularis –> VA –> premotor cortex
lenticular fasciculus –> VL –> primary motor cortex
GPi outputs use what NT
GABA = inhibitory
Direct pathway
D1 receptor, excitatory, increases thalamic and cortical activity
Indirect pathway
D2 receptor, inhibitory, decreases thalamic and cortical activity (through the subthalamic nucleus)
Direct pathway
Corticostriate (+) –> activates inhibitory spiny neurons Striatopalladal (-) –> Palladothalamic (-) –> Thalamocortical (+) = Activation of LMN
Indirect Pathway
Corticostriate (+) –> activates inhibitory spiny neurons Striatopalladal (GPe) (-) –> Subthalamic nucleus (-) –> Subthalamic nucleus to GPi (+) –> palladothalamic (GPi) (-) –> thalamocortical are inhibited = Inactivation of LMN
Dopamine and the Direct pathway
excites the direct pathway (D1) by inhibiting inhibitory cells of the substantia nigra
Dopamine and the indirect pathway
inhibition in the indirect pathway (D2) by activation of inhibitory cells of the substantia nigra
Parkinsonism
indirect system dominates due to loss of dopaminergic input to striatum (ACh dominates)
ACh excites the Indirect pathway
leading to further activation of indirect pathway and decreased movement
ACh inhibits the direct pathway
leading to further decreased movement
Chorea
loss of cholinergic neurons, direct system dominates and excessive, unwanted movements occur
Basal Ganglia function
planning of voluntary movement and influence motor movements without a direct connection to LMN
Basal ganglia are connected with the limbic system and orbitofrontal cortex
memory, behavior changes, drug and alcohol addiction
