Term
| what is the basic function of the basal ganglia (3 components)? |
|
Definition
| intiation, maintenance, and termination of voluntary movements = supervising motor control |
|
|
Term
| does the basal ganglia project directly to LMNs? |
|
Definition
|
|
Term
| if the basal ganglia doesn't interact directly with LMNs, how does it influence movements? |
|
Definition
| by regulating the activity of UMNs |
|
|
Term
| what is a subcortical loop |
|
Definition
| a loop that's below the cortex |
|
|
Term
| what does the basal ganglia's subcortical loop do? |
|
Definition
| links the cortex with the basal ganglia and then to other areas of the brain and back up to the cortex again |
|
|
Term
| what is the function of neurons in the basal ganglia's subcortical loop |
|
Definition
| normal initiation and maintenance of voluntary movements |
|
|
Term
| what are the 3 major nuclei of the basal ganglia |
|
Definition
| caudate, putamen, globus pallidus |
|
|
Term
| what 2 additional structures are closely associated with the motor functions of the basal ganglia |
|
Definition
| substantia nigra, subthalamic nuclei |
|
|
Term
| what is the immediate family of the basal ganglia family unit? |
|
Definition
| caudate, putamen, globus pallidus |
|
|
Term
| what is the extended family of the globus pallidus family unit |
|
Definition
| substantia nigra, subthalamic nuclei |
|
|
Term
| what happens when anyone in the globus pallidus extended or immediate family is troubled? |
|
Definition
| the family unit doesn't work properly |
|
|
Term
| where is the subthalamic nuclei? |
|
Definition
|
|
Term
| what are the 2 parts of the substantia nigra? |
|
Definition
| pars compacta, pars reticulata |
|
|
Term
| what are the 2 circuits within the basal ganglia |
|
Definition
| direct pathway, indirect pathway |
|
|
Term
| what is the main function of the direct pathway of the basal ganglia |
|
Definition
| releases UMNs from tonic inhibition |
|
|
Term
| what is the main function of the indirect pathway of the basal ganglia |
|
Definition
| increases tonic inhibition of UMNs |
|
|
Term
| using the car at the top of the hill metaphor, what does the direct pathway do? |
|
Definition
| allows the car to go down the hill |
|
|
Term
| using the car at the top of the hill metaphor, what does the indirect pathway do? |
|
Definition
| controls the car as it goes slowly down the hill |
|
|
Term
| do the pathways work at different times? |
|
Definition
| the pathways work concurrently |
|
|
Term
| of the direct and indirect pathways, which is the dominant pathway |
|
Definition
|
|
Term
| what is the input zone of the basal ganglia |
|
Definition
|
|
Term
| what is the corpus striatum |
|
Definition
|
|
Term
| what regions of the cortex project to the corpus striatum |
|
Definition
| nearly all regions of the cortex project to the corpus striatum |
|
|
Term
| what are the 2 types of pathways that bring infromatin to the corpus striatum? |
|
Definition
| corticostriatal pathway, nigrostriatal fibers (pathway?) |
|
|
Term
| through what pathway does the cortex project to the corpus striatum |
|
Definition
|
|
Term
| through what pathway do neurons from the substantia nigra pars compacta project to the striatum |
|
Definition
|
|
Term
| where are medium spiny neurons located |
|
Definition
| in the striatum (caudate and putamen) |
|
|
Term
| what synapses on the medium spiny neurons |
|
Definition
| corticostriatal and nigrostriatal fibers |
|
|
Term
| after being synapsed on by corticostriatal and nigrostriatal fibers, what do medium spiny neurons do |
|
Definition
| project to the globus pallidus and the substantia nigra pars reticulata |
|
|
Term
| what are the 2 parts of the globus pallidus |
|
Definition
| internal and external segments |
|
|
Term
| in the direct pathway, what do axons from the striatum mostly project to? |
|
Definition
| internal segment globus pallidus and substantia nigra pars reticulata |
|
|
Term
| in the indirect pathway, what do axons from the striatum mostly project to? |
|
Definition
| globus pallidus external segment |
|
|
Term
| what are the major output sources from the basal ganglia |
|
Definition
| globus pallidus and substantia nigra pars reticulata |
|
|
Term
| where do efferent neurons from the internal segment of the globus pallidus project to |
|
Definition
| VA and VL nuclei of the thalamus |
|
|
Term
| what are the pathways of projections from the VA and VL nuclei of the thalamus? |
|
Definition
| to the primary motor and premotor cortices, completing the loop! |
|
|
Term
| where do efferent neurons from the substantia nigra pars reticulata project to |
|
Definition
| UMNs in the superior colliculus that command eye movements |
|
|
Term
| can the basal ganglia influence eye movement? |
|
Definition
|
|
Term
| what are the steps of the direct pathway |
|
Definition
| Input from the cortical areas and the substantia nigra pars compacta project to the striatum. The striatum projects to the internal globus pallidus. The internal globus pallidus projects to the VA/VL complex of the thalamus. The VA/VL complex of the thalamus projects to the motor cortex. |
|
|
Term
| what types of synapses do all corticostriatal fibers make on the medium spiny neurons within the striatum? |
|
Definition
| excitatory glutamatergic synapses |
|
|
Term
| what types of synapses do nigrastriatal fibers make on the medium spiny neurons within the striatum in the direct pathway? |
|
Definition
| excitatory dopaminergic synapses |
|
|
Term
| area all glutamtergic synapses excitatory |
|
Definition
|
|
Term
| are all dopaminergic synapses exciatory |
|
Definition
| no, but they can be. It depends on the dopamine receptor whether it's excitatory or not |
|
|
Term
| what types of synapses do fibers from the medium spiny neurons of the striatum make on the globus pallidus internal segment |
|
Definition
|
|
Term
| is GABA an inhibitory or excitatory neurotransmitter |
|
Definition
|
|
Term
| when are medium spiny neurons silent (not firing)? |
|
Definition
| always, unless we initate movement or are moving |
|
|
Term
| when is the globus pallidus active? |
|
Definition
| always, unless they are silenced by movement |
|
|
Term
| to where does the globus pallidus internus constantly fire action potentials |
|
Definition
| VA and VL nuclei of the thalamus |
|
|
Term
| what type of neurons project to the VA and VL nuclei of the thalamus from the GP internal segment? |
|
Definition
|
|
Term
| is the output of the basal ganglia inhibitory or excitatory |
|
Definition
|
|
Term
| what do the neurons from the globus pallidus interal segment do? |
|
Definition
| project to the VA/VL of the thalamus and prevent movement by inhibiting the neurons that project from the VA/VL to the motor cortex |
|
|
Term
| when you're at rest and the car is parked at the top of thehill, what affect does the globus pallidus have on the car? |
|
Definition
| keeps the car parked at the top of the hill, preventing the thalamus from exciting the motor cortex and letting the car go down the hill |
|
|
Term
| are the basal ganglia important in initating movement? |
|
Definition
|
|
Term
| what are the steps of the direct pathway including excitation/inhibition at rest/with no movement |
|
Definition
| 1. There is no excitation of stritatal neurons from the cortex or substantia nigra; 2. without excitation, the striatal neurons are silent; 3. without inhibition from striatum, globus pallidus is tonically inhibitory; 4. the globus palldus inhibits the VA/VL complex of the thalamus; 5. inhibited thalamic neurons can't excite motor cortex neurons so no movement occurs |
|
|
Term
| what are striatal neurons doing at rest |
|
Definition
|
|
Term
| what is the globus pallidus doing at rest |
|
Definition
| tonically inhiiting the thalamus |
|
|
Term
| what are the steps of the direct pathway including excitation/inhibition at with movement |
|
Definition
| 1. striatal neurons are excited by the cortex and the substantia nigra pars compacta; 2. striatal neurons inhibit the globus pallidus; 3. the globus pallidus stops inhibiting the VA/VL nuclei of the thalamus; 4. the VA/VL nuclei of the thalamus excite the motor cortex neurons; 5. motor cortex excitement leads to movement |
|
|
Term
| which neurotransmitter inhibits the globus pallidus from the striatum during movement? |
|
Definition
|
|
Term
| what do we call the circuit that allows UMNs to send commands that initiate movement |
|
Definition
| disinhibitory circuit/direct pathway |
|
|
Term
| what has its foot on the brake in allowing movement |
|
Definition
|
|
Term
| how is the direct pathway a disinhibition circuit? |
|
Definition
| activation of the direct pathway serves to release the UMNs from tonic inhibition |
|
|
Term
| what is the indirect pathway |
|
Definition
| the pathway that increases the level of tonic inhibition to UMNs, increasing control of movement |
|
|
Term
| what is the car metaphor of the indirect pathway |
|
Definition
| we let the car go down the hill, but we control it |
|
|
Term
| does the indirect route go through the basal ganglia |
|
Definition
|
|
Term
| what population of medium spiny neurons is involved in the indirect pathway |
|
Definition
| population of medium spiny neurons in the striatum that projects to the globus pallidus externus. |
|
|
Term
| in the indirect pathway, where do dopamine neurons come from |
|
Definition
| substantia nigra pars compacta |
|
|
Term
| are dopamine neurons in the indirect pathway excitatory or inhibitory |
|
Definition
|
|
Term
| what type of dopamine receptors are inhibitory |
|
Definition
|
|
Term
| do the indirect and direct pathways occur simultenously |
|
Definition
| yes, but the direct pathway is a little stronger |
|
|
Term
| what happens when any component of the basal ganglia is compromised? |
|
Definition
|
|
Term
| what are 3 examples of basal ganglia dysfunction |
|
Definition
| hemiballismus, parkinson's, huntington's |
|
|
Term
| symptoms of hemiballismus |
|
Definition
| violent, uncontrolled movements of the limbs confined to one side of the body |
|
|
Term
| what part of the brain is damaged with hemiballismus |
|
Definition
| subthalamic nucleus on opposite sideof the body |
|
|
Term
| a stroke of which artery would cause hemiballismus |
|
Definition
| middle cerebral artery that vascularizes the thalamus |
|
|
Term
| what causes the violent, uncontrolled movements in hemiballismus? |
|
Definition
| movements are initiated by abnormal discharges of UMNs that are receiving less tonic inhibition from the basal ganglia (the globus pallidus internal is not excited by subthalamus to increase its tonic inhibition to the thalamus) |
|
|
Term
| what is parkinson's disease |
|
Definition
| neurodegenerative disease characterized by loss of nigrostriatal dopamine neurons from the substantia nigra pars compacta |
|
|
Term
| what is the common age range of onset of parkinson's? |
|
Definition
|
|
Term
| can younger people (than 50) get parkinson's? |
|
Definition
|
|
Term
| if you have parkinson's what will you have difficult with |
|
Definition
|
|
Term
| what are the 4 cardinal features of Parkinson's disease? |
|
Definition
| Tremor (resting); Rigidity; Akinesia (minimal facial expression) or bradykinesia; Postural changes - flexed or stooped over position |
|
|
Term
| describe the posture of someone with Parkinson's |
|
Definition
| stooped over, arms flexed. No arm swing during gait |
|
|
Term
| describe the gait of someone with Parkinson's |
|
Definition
| shuffle gait: short steps, unable to sstop |
|
|
Term
| describe rigidity of someone with parkinson's |
|
Definition
| affects all somatic muscles, but greater in flexors - causes stopped osture |
|
|
Term
| what is cogwheel rigidity |
|
Definition
| some parkinson's patients experience muscle resistance that is overcome in a series of jerks |
|
|
Term
| what causes resting tremors in people with PD |
|
Definition
| result of alternating contraction of agonists and antagonists caused by cerebellum |
|
|
Term
| why do some parkinson's patients have uncontrollable dyskinesia-like motor symptoms? |
|
Definition
| some are medication induced; some may be from imbalance of excitatory and inhibitory signals in both the direct and indirect pathways, leading to the diminished ability of the basal ganglia to properly control motor function. |
|
|
Term
| what are the effects on direct pathwaysdue to parkinson's |
|
Definition
| inputs from the substantia nigra pars compacta are diminished. This makes it more difficult to generate transient inhibition from the striatum. The result is to sustain the tonic inhibition from the globus pallidus to the thalamus, decreasing the excitiation of the motor cortex |
|
|
Term
| what is hypokinetic movement |
|
Definition
|
|
Term
| what happens if you don't have dopamine |
|
Definition
| you can't inhibit the globus pallidus so it tonically inhibits the thalamus |
|
|
Term
| what are fetal tissue grafts |
|
Definition
| implant fetal midbrain tissue into caudate and putamen for PD treatment |
|
|
Term
| how is gene therapy used in PD treatment |
|
Definition
| implant cells that are genetically modified to produce high levels of tyrosine hydroxylase, which converts tyrosine to L-DOPA, increasing dopamine in th ebasal ganglia |
|
|
Term
| how are neural stem cells used in PD treatment |
|
Definition
| implant progenitor cells that have been engineered to differentiate into dopamine neurons |
|
|
Term
| is deep brain stimulation an effective treatment for PD? |
|
Definition
|
|
Term
| what is the set up for deep brain stimulation |
|
Definition
| battery packs are placed near clavicles and electrodes are inserted bilaterally into the globus pallidus or subthalamus. |
|
|
Term
| how does deep brain stimulation work |
|
Definition
| deep brain stimulation signals override pathologic circuitry with properly structured neural patterns to coordinate voluntary movements |
|
|
Term
| when a patient with PD receives deep brain stimulation and it is turned off, what happens? |
|
Definition
|
|
Term
| what is huntington's disease |
|
Definition
| neurodegenerative disease characterized by inappropriate motor activity |
|
|
Term
| what are choreiform movements |
|
Definition
|
|
Term
| which basal ganglia disease is an inherited autosomal dominant disease |
|
Definition
|
|
Term
| at what age range does huntington's disease usually occur |
|
Definition
|
|
Term
| what is the final result of huntington's disease |
|
Definition
|
|
Term
| what is the hallmark of huntington's |
|
Definition
|
|
Term
| what gene is responsible for huntington's disease |
|
Definition
|
|
Term
| what are the physical effects of huntington disease on the brain |
|
Definition
| caudate and putamen atrophy |
|
|
Term
| how does huntington's affect medium spiny neurons that project to the extneral GP? |
|
Definition
|
|
Term
| what is the result of huntington's disease on the indirect pathway |
|
Definition
| the absence of inhibitory input from the medium spiny neurons to the external GP causes the external GP to become overactive. The overactive external GP provides more inhibition to the subthalamic nucleus. The inhibited subthalamic nucleus provides less excitation to the internal GP. The internal GP provides less tonic inhibition to the thalamus. The result is over-activated UMNs and hyperkinetic movements |
|
|
Term
| aside from motor loops, what are basal ganglia involved with |
|
Definition
| other cognitive functions |
|
|
Term
| what are 2 non-motor subcortical loops that include the basal ganglia |
|
Definition
| limbic loop, prefrontal loop |
|
|
Term
| what is the function of the limbic loop |
|
Definition
| regulate emotional and motivational aspects of behavior |
|
|
Term
| what is the prefrontal loop important for? |
|
Definition
| important in initiating cognitive processes like planning and attention |
|
|
Term
| does parkinson's affect cognition |
|
Definition
|
|
Term
| in the indirect pathway, where do the medium spiny neurons from the striatum project? |
|
Definition
|
|
Term
| in the indirect pathway, are the dopamine neurons from the substantia nigra pars compact inhibitory or excitatory |
|
Definition
|
|
Term
| in the indirect pathway, what makes the dopamine from the substantia nigra pars compacta inhibitory |
|
Definition
| D2 receptors of the striatum are inhibitory dopamine receptors |
|
|
Term
| how does the inhibitory dopamine in the striatum affect the excitatory input from the cortex to the striatum |
|
Definition
|
|
Term
| what 2 places does the GPE project to |
|
Definition
|
|
Term
| what does the subthalamus project to |
|
Definition
|
|
Term
| is the GPE tonically/transiently excitatory/inhibitory to the subthalamus |
|
Definition
|
|
Term
| why do the GPE's projections to the GPI not matter when we activate the indirect pathway |
|
Definition
| the GPE is shut off in the indirect pathway, so it doesn't have control over the GPI. The subthalamus will then be able to have the control of the GPI |
|
|
Term
| what does the subthalamus want to do to the GPI that the GPE tonically inhibits it from doing |
|
Definition
|
|
Term
| what is the indirect pathway including all excitations and inhibitions when activated because of movement |
|
Definition
| excitatory signals from the cortex and inhibitory dopaminergic signals from the substantia nigra enter the striatum simultaneously. Excitation from the cortex is dampened by the inhibition from the substantia nigra, but the cortical excitation wins, and the striatum sends transient inhibition to the GPE via medium spiny neurons. The GPE is inhibited, so its tonic inhibition of the subthalamus is temporarily stopped. The subthalamus is also receiving excitatory input from the cortex, and without its inhibition form the GPE, it's able to excite the GPI. The excited GPI inhibitis the thalamus, reducing excitation to the cortex and reducing/preventing movement |
|
|
Term
| does the indirect pathway increase or release tonic inhibition of UMNs |
|
Definition
|
|
