Basal Forebrain Flashcards
the ventral striatopallidal system (ventral striatum) is composed of what structures?
nucleus acumbens, olfactory tubercle and ventral putamen/caudate
what type of neurons are in the ventral striatum?
medium spiny neurons (MSNs)
dopamine for the NAc circuit of the ventral striatum comes from what source?
ventral tegmental area (VTA) - unlike the dorsal striatum circuit, where dopamine comes from the substantia nigra (pars compacta)
the nucleus accumbens of the ventral striatum receives excitatory inputs from what 4 sources?
prefrontal cortex
hippocampus
amygdala
hypothalamus (via orexin neurons)
why is dopamine from the ventral tegmental area excitatory to MSNs in the nucleus accumbens but inhibitory to prefrontal cortex projections?
to suppress voluntary self-scontrol while enhancing systems that are about conditioning, emotions, memory, and feedng (goal-directed behaviors)
VTA provides dopamine to the ventral striatum via the mesostriatal system, and to the cortical structures like the amygdala, limbic cortices, and hippocampus via the mesocortical system. Together these two systems comprise what, travelling where?
mesocorticolimbic system travelling through the medial forebrain bundle
the ventral pallidum and SNr, instead of projecting to the VA (motor) thalamus to engage the premotor cortex in a motor loop, send projections to this thalamic nucleus, which form loops for behaviors
mediodorsal (MD) thalamic nucleus
circuits that connect frontal and limbic cortices, allowing the ventral system (motivation) to influence the dorsal system (motor)
open loop circuits
NAc medium spiny neurons receive extensive excitatory orexin inputs from this structure, which is concerning primarily with driving appetitive behaviors.
lateral hypothalamus
True or false: the ventral striatum sends axons to all parts of the SNc to influence dopamine release in the caudate and putamen, as well as in the VTA.
True. Goal-directed behaviors have motor components, so the ventral striatum needs to be able to influence the dorsal striatum.
describe the mesostriatal “reward pathway”, as it pertains to drinking a cup of coffee
1) LH activates NAc and simultaneously VTA, sending axons in the medial forebrain bundle (MFB)
2) VTA provides dopamine to NAc via MFB, activating a direct behavioral loop (coffee-drinking behavior) by inhibiting the ventral pallidum
3) This frees the MD thalamic nucleus, which projects to (among other places) premotor cortex in the frontal lobe
4) Premotor cortex provides the major input to the basal ganglia system (dorsal striatopallidal system), which has loops for coffee-stirring, coffee-pouring, and other motor acts of coffee indulgence
nucleus of disappointment
habenula
all addictive substances appear to act on the _____ in the ventral striatum, leading to the release of dopamine and the “stamping in” of behaviors leading to reward
VTA
dopmine is involved in the wanting or craving of something, while the experience of liking or enjoying that something comes from ____.
opioids
nucleus that receives inputs from the LH and ventral pallidum, and sends outputs to the SNc and VTA, inhibiting dopaminergic neurons
habenula
