Task 3 Flashcards
What are the four principal structures of the basal ganglia?
striatum,
globus pallidus,
substantia nigra, and subthalamic nucleus
What is the role of the ventral regions of the basal ganglia?
They play a key role in reward and reinforcement, important in the development of addictive behaviors and habit formation
What cognitive functions are the central areas of the basal ganglia involved in?
They are involved in cognitive functions such as procedural learning and working memory tasks
How is the striatum divided?
The striatum is divided by the internal capsule into the caudate nucleus and putamen
What is the major role of the striatum in the basal ganglia?
It serves as the major input structure of the basal ganglia, receiving projections from the cerebral cortex, brain stem, and thalamus
What are the two pathways that axons from the striatum follow to the output nuclei?
They follow a direct monosynaptic connection and an indirect polysynaptic pathway
What is the most common neuronal cell type in the striatum, and what are its inputs?
1.The most common type is the GABAergic medium spiny neuron
2.receiving inputs from the cerebral cortex, thalamus, local interneurons, and dopaminergic neurons from the substantia nigra pars compacta and the ventral tegmental area
What structures are included in the ventral striatum (VS)?
The VS includes:
the nucleus accumbens
medial & ventral portions of the caudate and putamen,
the striatal cells of the olfactory tubercle, and anterior perforated substance
What are the three major sources of afferent projections to the striatum?
The cerebral cortex, thalamus, and brain stem dopaminergic cells
What are the two segments of the globus pallidus, and what are their functions?
The external segment (GPe) is part of intrinsic circuitry, and the internal segment (GPi) is one of the major output structures of the basal ganglia
What are the major output structures of the basal ganglia, and where do they project?
The GPi and substantia nigra pars reticulata (SNr) are major output structures that project to the thalamus, which then projects back to the cortex
What are the two separate nuclei in the substantia nigra?
The pars compacta and pars reticulata
What structures are included in the dopaminergic system?
The substantia nigra pars compacta (SNc), ventral tegmental area (VTA), and retrorubral group
What are the functions of the direct and indirect pathways in the basal ganglia?
The direct pathway initiates movement by disinhibiting motor programs,
Indirect pathway serves as a brake on movement by disinhibiting basal ganglia outputs and suppressing downstream motor programs
What is the hyperdirect pathway in the basal ganglia?
It involves cortical inputs to the subthalamic nucleus and related subthalamopallidal projections
What is the role of the cortico-basal ganglia-thalamocortical circuits?
These circuits develop and carry out complex behaviors, maintain and focus on execution of specific behaviors, and adapt to external and internal stimuli
What are the general functional regions of the frontal cortex involved in?
Emotions and motivation (orbital and medial prefrontal cortex),
higher cognitive processes (dorsolateral prefrontal cortex),
motor planning (premotor areas),
and execution of motor plans (motor cortex)
Where do corticostriatal terminals primarily come from
They primarily come from:
layer 5
deep-layer-3
pyramidal neurons of the cerebral cortex
How are cortical areas projected onto the striatum?
In a highly topographic manner, establishing functional domains replicated throughout the basal ganglia-thalamocortical circuits
What evidence supports functional integration between terminals from different cortical areas in the striatum?
regions of interface between terminals from different cortical areas converge at the dorsal-medial striatum
where all the different systems in the basal ganglia converge
What is the unique role of midbrain dopaminergic neurons in basal ganglia circuits?
They modulate a broad range of behaviors from learning and working memory to motor control and play a key role in the acquisition of new behaviors
How are projections from the dorsal and ventral tiers of dopaminergic neurons organized?
The dorsal tier projects to the ventral striatum,
the ventral tier projects centrally and throughout different regions of the striatum
What is the significance of the striato-nigro-striatal projection system’s organization?
It demonstrates a loose topographic and functional organization that allows information from the limbic system to reach the motor system
How does the “ballot box” metaphor describe the striatum’s function?
It suggests that the striatum serves as a site where various sensory modalities, motivation networks, and cognitive systems “vote” for a limited set of behavioral responses
How do the direct and indirect pathways “vote” in the action selection process?
The direct pathway “votes for” a movement (Go), while the indirect pathway “votes against” a movement (No-Go)
What cognitive impairment is commonly associated with Parkinson’s disease?
A specific deficit in externally guided set shifting, which is uncontaminated by impairments in learning, working memory, or general cognitive slowing
What role does the striatum play in decision making?
The striatum acts as a central arbiter for comparing the value of different choices and encodes values associated with actions and other task-relevant decision variables
How does the stability of value signals differ in the striatum?
The stability of value signals may differ in different subregions of the dorsal striatum
What is the significance of the cortico-striatal pathway in generating motor responses?
Activation of the cortico-striatal pathway is sufficient to bias choices,
integrating relevant information from a wide range of sources
What are the three control processes involved in working memory?
Input control (selectively store information), output control (deploy subsets of information for behavior), and reallocation (eliminate obsolete representations)
