Basal Ganglia
what is the name of the pathway that travels form the cortex to the striatum
corticostriatal pathway
how can the SN par compact have differing affects on the substantia nigra
depending on the receptor if D1 receptor then this causes excitation of cholinergic interneuron if D2 receptor then this causes inhibition of excitatory cholinergic neuron
what types of symptoms help to distinguish diseases of the cerebellum vs diseases of the basal ganglia
disease of the basal ganglia tend to also cause alterations in cognitive and psychological function
the putamen portion of the striatum mainly receives afferents from which cortex
parietal/temporal cortex
what is the function of the association circuit
participates in planning of a complex motor activity that has not been learned yet
the caudate portion of the striatum mainly receives afferents from which cortex
prefrontal/premotor cortex
where does the initial input for the limbic circuit come from
projections from 1) limbic cortex 2) paralimbic cortex 3) hippocampus 4) amygdala
where does the initial input for the associate circuit come from
projections from the dorsolateral prefrontal and lateral orbitofrontal cortex
what is the function of the limbic circuit
regulation of emotional, motivational, and affective aspects of behavior
where does the initial input for the motor circuit come from
sensorimotor and premotor cortex sends projections to the putamen
what are the mix function nuclei of the basal ganglia
substantia nigra pars compacta
what is the mix function nucleus of the basal ganglia
substantia nigra pars compacta (SNpc)
what is the name of the pathway that travels from the subthalamic nucleus to the globus pallidus
subthalamic fasiculus
describe the indirect pathway
1) cortex send excitatory signal to the striatum and SNc sends inhibitory signal via D2 receptor to the striatum 2) a GABAergic projection from the striatum to the GPe fires to inhibit the GABAergic projection from the GPe to the STN 3) because of the reduced inhibition to the STN there STN can fire its excitatory glutamatergic neuron to the GPi and SNr 4) increases excitation to the GPi and SNr leads to increased firing of their GABAergic projection to the thalamus 5) this inhibits the thalamus leading to decreased excitatory glutamatergic projection to the motor cortex
diseases of the basal ganglia will lead to impairments of what actions
1) decision to move 2) amplitude of movement 3) direction of movement 4) emotional body language
describe the path of the executive loop (associative circuit)
1) dorsolateral prefrontal/lateral orbitofrontal cortex 2) to caudate and putamen 3) to GPi/GPe 4) to thalamus 5) to cortex
what are the side effects of dopamine agonists
1) euphoria 2) hallucinations 3) compulsive behaviors (eating, shopping, gambling etc...)
outputs from the basal ganglia come from which nuclei
1) globus pallidus internal (GPi) 2) substantia nigra par reticulata (SNr)
what are typical motor clinical sings of basal ganglia lesions
1) hypokinesia 2) hyperkinesia 3) rigidity 4) tremors at rest 5) abnormal posture
what are the major functions of the basal ganglia
1) initiation of movement 2) amplitude of the moment 3) direction of the movement 4) emotional body language
describe the path of the motivational loop (limbic circuit)
1) limbic/paralimbic cortex/hippocampus/amygdala 2) to caudate and putamen 3) to GPi 4) to thalamus 5) to cortex
clinical signs of basal ganglia lesion can be devided into what two major subsection
1) motor 2) non-motor
what is the very general motor loop that the basal ganglia is involved in
1) motor cortex sends information to basal ganglia 2) basal ganglia relays information to the thalamus 3) thalamus sends info back to the motor cortex to modulate the cortical outputs to the reticular formation
what are the two subdivision of the substantia nigra
1) pars compacta (dorsally) 2) pars reticulata (ventrally)
describe the reward/limbic circuit
1) prefrontal cortex, hippocmapus, ventral tegmental area, and amygdala all send projections to the nucleus accumbens and the ventral aspects of caudate and putamen (collectively called ventral striatum) 2) outputs are then sent to the thalamus (VP and DM) and the STN to influence thalamic output
the striatum (neostriatum) is made up of what structures
1) putamen 2) caudate nucleus
describe the path of the motor loop (motor circuit)
1) sensorimotor/premotor cortex 2) to putamen 3) to GPi (or GPe->ST->GPi) 4) to thalamus 5) to cortex
the globus pallidus internal contains what types of neurons
GABAergic neurons
what is the major output nucleus of the basal ganglia
GPi
projections from layer 5 of the medial motor cortex and lateral motor cortex will go to which portions of the striatum respectively
Medial (foot) will project to the lateral putamen Lateral (face) will project to the medial putamen
what are the main NTs of the basal ganglia
1) GABA in striatum, GP, SNr 2) Glutamate in cortex, thalamus, and subthalamus 3) Acetylcholine for neurons within striatum 4) dopamine in SNc
what are the processing nuclei of the basal ganglia
1) GPe 2) subthalamic nucleus
what are the output nuclei of the basal ganglia
1) GPi 2) SNr
what are the subsections of the globus pallidus
1) Globus pallidus external 2) globus pallidus internal
the processing nuclei of the basal ganglia are what
1) Globus pallidus external (GPe) 2) subthalamic nucleus (STN)
what are the three major basal ganglia loops
1) Motor circuit (motor loop) 2) association circuit (executive loop) 3) limbic circuit (motivational loop)
what are typical non motor signs of basal ganglia lesions
1) OCD 2) addictive behavior 3) attention deficit 4) depression 5) schizophrenia
the striatum receives information from where
1) Prefrontal/premotor cortex 2) parietal/temporal cortex 3) nigrostriatal pathway (from substantia nigra pars compacta) 4) limbic structures
the substantia nigra pars reticulata projects to which major structures
1) VA/VL of thalamus via ansa lenticularis 2) superior colliculus
what are the receiving nuclei of the basal ganglia
1) caudate 2) putamen
what are the 5 basal ganglia nuclei
1) caudate nucleus 2) putamen 3) globus pallidus 4) substantia nigra 5) subthalamic nuclei
describe the direct pathway
1) cortex send excitatory signal to the striatum and SNc sends excitatory signal via D1 receptor to the striatum 2) activates cholinergic interneurons which activate GABAergic output neurons to GPi and SNr 3) this inhibits the GPi and SNr decreasing their inhibitory GABAergic projections to the thalamus 4) because of the decreases inhibition to the thalamus (VA and VL specifically) there is increases excitatory glutamatergic output to the motor areas of the cortex
why is the substantia nigra pars compacta considered a mix function nucleus
because the dopaminergic neurons that project via the nigrostriatal pathway can have different functions depending on the receptor present in the striatum that will either cause an inhibitory and excitatory effect
are the projections from the motor cortex to the basal ganglia contralateral or ipsilateral
bilateral
what is the difference in inputs to the basal ganglia and cerebellum from the cortex
Basal ganglia: inputs from the entire cortex excluding the visual and a portion of the auditory Cerebellum: inputs from only the motor area
what is the difference in function between the basal ganglia and cerebellum
Basal ganglia: integrators of movement, cognition, and emotion cerebellum: chief coordinator and predictor of movement and cognition
which dopaminergic receptors are associated with the direct and indirect pathway
D1 is associated with the direct D2 is associated with the indirect
how will activation of the D1 and D2 receptors affect movement
D1: Activation of D1 leads to increase in direct pathway leading to less inhibition of the thalamus and more movement D2: Activation of D2 leads to decrease in indirect pathway leading to less inhibition of the thalamus and more movement
parkinson disease is associates with destruciton of the substantia nigra and thus loss of dopaminergic neurons of the nigrostriatal pathway. Why can we not just give patient L-DOPA to treat parkinsons
DA is also an important NT of ventral tegmental area projections in the limbic circuit. Increasing DA can also cause an increase in this circuit which can lead to psychogenic side affects in the patient
what type of neurons are fond in the substantia nigra
Par compacta: dopaminergic Reticulata: GABAergic
which nuclei of the thalamus is being acted on by the GPi
VA/VL
where is the sub thalamic nucleus located in relation to the internal capsule, lentiform nucleus, and thalamus
it is found superior to the internal capsule, medial to the lentiform nucleus, and inferior to the thalamus
how does the basal ganglia interact with the tonic inhibition of the thalamus
it will either increase this inhibition or decreasing it to modulate outputs of the thalamus to the cortex
what is the function of the motor circuit
motor performance and regulation of eye movement
what is the name of the pathway that travels form the substantia nigra to the striatum
nigrostriatal pathway
what is the name of the pathway that travels form the globus pallidus internal to the thalamus
thalamic fasiculus
what is the lentiform nucleus
the combination of the globes pallidus and putamen
what is the function of the direct pathway
the direct pathway functions to release the thalamus from tonic inhibition leading to increased cortical output
which nucleus of the basal ganglia is the major processing nucleus of the basal ganglia and why
the globus pallidus external is the major processing nucleus of the basal ganglia because it exerts control over the GPi via the subthalmus and thus control of the GPe will ultimately control the affects of the BG loop
what is the function of the indirect pathway
the indirect pathway functions to increases the tonic inhibition of the thalamus to decrease cortical outputs
the thalamic fasiculus is made up of what
the lenticular fasiculus and the ansa lenticularis
what is the nucleus accumbens
the most anterior portion of the striatum where the head of the caudate and putamen meet
the globus pallidus is also sometimes called what
the paleostriatum
input to the basal ganglia goes to which nuclei
the striatum (caudate nucleus and putamen)
what is the name of the projection of the GPi to the VA/VL nuclei of the thalmus
the thalamic fasciculus made of the ansa lenticularis and lenticular fasiculus
is the thalamus under inhibitory or excitatory control
the thalamus is under tonic inhibition
true or false: the basal ganglia have a somatotopic organization
true: with the face being more medial and the leg being more lateral in the putamen
the nucleus accumbens receives dopaminergic projections from which area
ventral tegmental area