Term
| The basal ganglia are intercalated in a side loop between what two pathways? |
|
Definition
| the direct & indirect descending motor pathways |
|
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Term
| 5 things that make up the "basal ganglia" (when defining it as a functionally related cell group & not strictly anatomically) |
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Definition
1. caudate nucleus
2. putamen
3. globus pallidus
4. substantia nigra
5. subthalamic nucleus |
|
|
Term
| 3 structures that make up the "basal ganglia" (when defining it strictly anatomically) |
|
Definition
1. caudate nucleus
2. putamen
3. globus pallidus |
|
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Term
| 2 things that make up the lentiform nucleus (name comes from their shape) |
|
Definition
1. the putamen
2. the globus pallidus |
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Term
| How does the globus pallidus (paleostriatum or pallidum) have a different internal structure than the striatum? |
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Definition
| it has larger, more "motoneuron"-like cells |
|
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Term
| 2 parts of the globus pallidus |
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Definition
1. internal segment (GPi)
2. external segment (GPe) |
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Term
| 2 things that make up the corpus striatum |
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Definition
1. the pallidum
2. the neostriatum |
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Term
| 2 things that make up the striatum (neostriatum) |
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Definition
1. caudate nucleus
2. putamen |
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Term
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Definition
| cell groups that join the corpus striatum ventrally without sharp transitions; included in the basal-ganglia concept; ex) the nucleus accumbens & the olfactory tubercle |
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Term
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Definition
| a ventral extension of the globus pallidus |
|
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Term
| What is the ventral stiratopallidum important for? |
|
Definition
| behavior governed by emotions |
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|
Term
| Where does the largest contingent of afferents to the striatum come from? |
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Definition
|
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Term
| 2 places where the putamen dominantly gets its somatotopically organized inputs from |
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Definition
|
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Term
| Where does the caudate nucleus receive fibers predominantly from? |
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Definition
| association areas (regions that are less directly concerned with motor control than with cognitive functions & emotions) |
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Term
| What information is brought to the striatum from the numerous intralaminar thalamic nuclei afferents? |
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Definition
| information about stimuli that need special attention |
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Term
| What type of afferents are brought to the dorsal striatum from the pars compacta of the substantia nigra & to the ventral striatum from the ventral tegmental area dorsal to the substantia nigra? |
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Definition
| dopaminergic striatal afferents |
|
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Term
| Do quantitatively major or minor afferent contingents to the striatum come from the serotonergic raphe nuclei in the brain stem? |
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Definition
|
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Term
|
Definition
| striatal neurons that have relatively small cell bodies & dendrites with numerous spines; more than 70% of striatal neurons |
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Term
| What neurotransmitter is in medium spiny neurons that send their axons out of the striatum to the globus pallidus & the substantia nigra? |
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Definition
| GABA (gamma-aminobutyric acid) |
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|
Term
| How many main subtypes of the medium spiny neuron are there? |
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Definition
|
|
Term
| What is the difference between the two main subtypes of medium spiny neurons? |
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Definition
| one contains substance P in addition to GABA, the other contains enkephalin in addition to GABA |
|
|
Term
| What is the difference in where the two kinds of medium spiny neurons project? |
|
Definition
GABA + substance P = GPi and/or substantia nigra
GABA + enkephalin = GPe |
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|
Term
| What is the difference with regard to expression of dopamine receptors for the two kinds of medium spiny neurons? |
|
Definition
GABA + substance P = express predominantly D1 receptors
GABA + enkephalin = mainly D2 receptors |
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|
Term
| Is there a kind of striatal interneuron that contains ACh? |
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Definition
| yes! it constitutes about 1% of all striatal neurons & has a large cell body & smooth dendrites |
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|
Term
| Via what type of receptors does ACh act on striatal projection neurons with slow, modulatory effects? |
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Definition
|
|
Term
| Does GABAergic inhibition play an important role in the functioning of the striatum? |
|
Definition
| yes! even though about 80% of all synapses are glutamatergic |
|
|
Term
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Definition
| neuronal groups acting either directly on motoneurons or on the motor cortex |
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|
Term
| Are the efferents from the striatum topographically organized? |
|
Definition
| yes! subdivisions of the striatum are connected with specific parts of the pallidum & the nigra |
|
|
Term
| Where does the globus pallidus receive its main afferents from? |
|
Definition
| the striatum (with additional inputs from the subthalamic nucleus) |
|
|
Term
| What is the difference between where the GPi mainly projects its efferents & where the GPe mainly projects its efferents? |
|
Definition
GPi = thalamus & substantia nigra
GPe = subthalamic nucleus |
|
|
Term
| Where do many of the pallidothalamic fibers pass through? |
|
Definition
| the internal capsule (think: they would be damaged by lesions to the internal capsule!) |
|
|
Term
| 2 places where pallidal fibers end in the thalamus |
|
Definition
1. ventral anterior nucleus (VA)
2. ventrolateral nucleus (VL) |
|
|
Term
| Where does the substantia nigra send its fibers? |
|
Definition
| the thalamus (partly in different nuclei than the pallidal fibers) |
|
|
Term
| Where does the caudate nucleus act primarily on after receiving afferents mainly from cortical association areas? |
|
Definition
| the prefrontal cortex (not directly involved in motor control but in cognitive functions such as memory & planning of behavior) |
|
|
Term
| What do lesions of the caudate nucleus result in? |
|
Definition
| symptoms similar to those seen after damage to the prefrontal cortex; ex) reduced performance in tests requiring spatial memory |
|
|
Term
| Do efferents from the basal ganglia reach the reticular formation in the mesencephalon in addition to the thalamus? |
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Definition
|
|
Term
| What is a main symptom of Parkinson's disease? |
|
Definition
| disturbances of muscle tone & locomotion |
|
|
Term
| What do connections form the substantia nigra to the superior colliculus do? |
|
Definition
| participate in the control of coordinated head & eye movements |
|
|
Term
| At least how many loops (circuits) through the basal ganglia exist to keep the flow of information largely segregated? |
|
Definition
|
|
Term
| How do the basal ganglia appear to process different kinds of information? |
|
Definition
|
|
Term
| What is the path of the basal ganglia circuit that arises in the SMA, MI, & SI? |
|
Definition
| it passes through the putamen --> via the pallidum & the thalamus, ends mainly in the SMA |
|
|
Term
| What is the path of the basal ganglia circuit that arises in different parts of the prefrontal cortex? |
|
Definition
| passes through the caudate nucleus, the substantia nigra, the VA, & the mediodorsal thalamic nucleus, & back to the prefrontal cortical areas |
|
|
Term
| Is there a basal ganglia circuit that arises in the "limbic" parts of the cortex? |
|
Definition
|
|
Term
| Is there a basal ganglia circuit that is concerned with oculomotor control (area 8 immediately in front of area 6 & area 7)? |
|
Definition
| yes! it arises in parts of the frontal & parietal lobes |
|
|
Term
| What influences all basal ganglia circuits? |
|
Definition
|
|
Term
| Why can deep brain stimulation (electric stimulation of the subthalamic nucleus) aimed at improving motor symptoms in Parkinson's disease give side effects such as mood changes, cognitive decline, & personality changes? |
|
Definition
| all basal ganglia circuits are influenced by the subthalamic nucleus |
|
|
Term
| Are corticostriatal & thalamostriatal fibers excitatory or inhibitory? |
|
Definition
| excitatory (due to the release of glutamate) |
|
|
Term
| Are pallidothalamic fibers from the GPi & the pallidosubthalamic fibers from the GPe excitatory or inhibitory? |
|
Definition
| inhibitory (the neurons in the globus pallidus are GABAergic) |
|
|
Term
| Are the nigrothalamic fibers arising in the pars reticulate excitatory or inhibitory? |
|
Definition
|
|
Term
| Are the thalamocortical fibers excitatory or inhibitory? |
|
Definition
|
|
Term
| At rest, do pallidal neurons & neurons in the pars reticulate of the substantia nigra fire with a high, regular frequency or are the "silent" (not producing action potentials)? |
|
Definition
| they fire with a high, regular frequency (most striatal neurons are "silent") |
|
|
Term
| What does it mean that the disinhibition of premotor neurons by the basal ganglia is a "gating mechanism"? |
|
Definition
| it controls the access of other inputs to the motor cortex |
|
|
Term
| Does the subthalamic nucleus receive excitatory afferents from the motor cortex? |
|
Definition
| yes! this constitutes a cortical input to the basal ganglia in addition to the major corticostriatal pathway |
|
|
Term
| 2 places where most of the efferents from the subthalamic nucleus go |
|
Definition
1. segments of the pallidum
2. the pars reticulate of the substantia nigra |
|
|
Term
| Do subthalamopallidal fibers exert excitatory or inhibitory actions? |
|
Definition
|
|
Term
| What does the subthalamic nucleus do in terms of movements? |
|
Definition
| control or stop ongoing movements (NOT select/initiate movements) |
|
|
Term
|
Definition
| violent involuntary movements of the opposite body half after destruction of the subthalamic nucleus; caused by hyperactivity among thalamocortical neurons |
|
|
Term
| What is the most massive dopaminergic pathway in the CNS? |
|
Definition
| the dopaminergic nigrostriatal pathway |
|
|
Term
| Do striatal neurons express dopamine receptors? |
|
Definition
|
|
Term
| 2 main kinds of dopamine receptors |
|
Definition
|
|
Term
| What is the difference between D1-like dopamine receptors & D2-like dopamine receptors? |
|
Definition
D1 = increase the synthesis of intracellular cyclic AMP
D2 = opposite effect |
|
|
Term
| 2 characteristic modes in which dopaminergic neurons fire |
|
Definition
|
|
Term
| What does dopamine do for the membrane potential? |
|
Definition
| it keeps the membrane potential in the range where the postsynaptic neuron is apt to fire in bursts (in a state suited for efficient signal transmission) |
|
|
Term
| What type of neurons have increased activity due to D1 receptor activation? |
|
Definition
| neurons that receive a strong & focused excitatory input (neurons receiving weak inputs actually get reduced activity) |
|
|
Term
| What can change the activity of many of the nuclei that send their fibers to the nigra? |
|
Definition
| arousal, motivation, & emotionally driven behavior |
|
|
Term
| Do striatonigral neurons change their firing in relation to movements or in relation to stimuli that are unexpected? |
|
Definition
| stimuli that are unexpected |
|
|
Term
|
Definition
| part of the ventral striatum that connects the caudate nucleus & the putamen ventrally |
|
|
Term
| What does the ventral pallidum merge with? |
|
Definition
| the dorsal well-defined parts of the globus pallidus |
|
|
Term
| 2 places where the nucleus accumbens sends efferent fibers |
|
Definition
1. hypothalamus
2. mesencephalic reticular formation |
|
|
Term
| Does the ventral striatum receive many or few dopaminergic fibers? |
|
Definition
| many (those projecting to the ventral striatum are located mainly dorsomedially to the substantia nigra in the ventral tegmental area) |
|
|
Term
| mesolimbic dopaminergic system |
|
Definition
| the dopaminergic neurons in the VTA that project primarily to the ventral striatum, the prefrontal cortex, & other cell groups that are closely linked with limbic structures |
|
|
Term
| 3 places where the VTA gets afferents from |
|
Definition
1. prefrontal cortex
2. nucleus accumbens
3. PPN |
|
|
Term
| What system makes up the "reward pathway"? |
|
Definition
| the dopaminergic mesolimbic connections; the reason why release of dopamine in the nucleus accumbens causes pleasurable feelings (ex. drugs) |
|
|
Term
| 3 places of major output from the basal ganglia |
|
Definition
1. SMA
2. PMA
3. prefrontal cortical areas |
|
|
Term
| What is the basal ganglia important for in terms of movement? |
|
Definition
| the planning phase (such as when several single-joint movements have to be put together to produce a complex movement, or when sensory stimuli or stored information has to be translated into an adequate motor response) |
|
|
Term
| Is the basal ganglia participating when movements are learned by repetition or when movements are learned by gaining insight into the nature of the task? |
|
Definition
| learned by repetition (the basal ganglia enable automatic performance of well-rehearsed movements by the use of motor programs located elsewhere in the CNS) |
|
|
Term
| Do the basal ganglia contribute to the linking of motivation & emotions to the execution of movements? |
|
Definition
|
|
Term
| Are the basal ganglia important for the selection & shift of behavior? |
|
Definition
|
|
Term
| What is the difference in brain structures involved in evaluation of movement VS brain structures involved in execution of behavioral switching? |
|
Definition
evaluation = cooperation between the prefrontal cortex & the limbic structures
execution of behavioral switching = basal ganglia |
|
|
Term
| Are the basal ganglia involved in interval timing (the ability to judge intervals & duration)? |
|
Definition
|
|
Term
| What does the basal ganglia's role in interval timing allow us to do? |
|
Definition
| form temporal expectations & predictions about ongoing & future events |
|
|
Term
|
Definition
| a disease of the basal ganglia that impedes the initiation of movement |
|
|
Term
|
Definition
| a disease of the basal ganglia that causes movements, when started, to be slower & of smaller amplitude than normal |
|
|
Term
|
Definition
| a disease of the basal ganglia that causes more or less pronounced involuntary movements |
|
|
Term
| 2 main kinds of basal ganglia diseases |
|
Definition
1. hyperkinetic
2. hypokinetic |
|
|
Term
| Parkison's disease is caused by a neuronal loss in the _____ & dopamine decrease in the _____ |
|
Definition
| substantia nigra; striatum |
|
|
Term
|
Definition
| a marked cell loss in the striatum that causes involuntary, jerky, often "dance-like" movements |
|
|
Term
|
Definition
| sudden, involuntary muscular contractions, occurring with uneven intervals; a sign of some basal ganglia diseases |
|
|
Term
| Is Tourette's syndrome caused by dysfunction of the basal ganglia? |
|
Definition
|
|
Term
| Does Parkinson's result in disturbances of postural reflexes? |
|
Definition
|
|
Term
| 2 autonomic nervous system disturbances associated with Parkinson's |
|
Definition
1. increased salivation
2. increased secretion from sebaceous glands of the skin |
|
|
Term
| When is the Parkinson's tremor most pronounced? |
|
Definition
| at rest (they occur at a frequency of 3 to 6 per second) |
|
|
Term
|
Definition
| the increased muscle tone associated with Parkinson's |
|
|
Term
| Do patients with Parkinson's have damage to the central motor pathways? |
|
Definition
|
|
Term
| How can you visually see Parkinson's in someone's brain? |
|
Definition
| a profound loss of pigmented neurons in the pars compacta of the substantia nigra |
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