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