Task 3 Flashcards
(44 cards)
3.1: What are the functions of the basal ganglia (=BG) loops?
movement, cognition & emotion
3.1: What are the structures of the BG?
Striatum (caudaute nucleus & putamen), substantia nigra pars compacta & pars reticulata (SNc&SNr), Globus pallidus internal&external (GPi&GPe) + subthalamic nucleus (STN)
3.1. What are the main input & output structures of the BG?
- Input: Striatum
- Output: GPi
3.1: Which areas does the striatum get its input from?
Thalamus, cortex & brainstem
3.1: Direct BG pathway
-Cortex transiently excites striatum (GLU) –> Striatum transiently inhibit GPi (GABA) –> tonic inhibition of GPi on thalamus released (DISINHIBITION) –> Thalamus transiently excites cortex (GLU)
3.1: Role of SNc in direct pathway
D1 receptor –> transiently excites striatum as well (like cortex) but with DOPAMINE
3.1: Direct pathway of BG leads to what?
Movement (GO-pathway)
3.1: Indirect BG pathway
-Cortex transiently excites striatum (GLU) –> transiently inhibits GPe (GABA) –> GPe usually tonically inhibts STN (GABA) –> STN disinhibited (because GPe inhibited) –> STN transiently excites GPi (GLU) –> GPi tonically inhibits thalamus (GABA) –> so thalamus CANNOT excite cortex
3.1: SNc: D1 &D2 receptors
- D1: DOPA excites
- D2: DOPA inhibits
- -> both have effect on striatum
3.1: Indirect pathway of BG leads to what?
NO movement (NO-GO pathway)
3.1: What are the 4 different BG loops?
Motor, occulomotor, executive/associative & emotional/motivational loop
3.2: What are the two anatomical observations by Haber (2016)?
(1) Cortical inputs to striatum from functionally different regions of PFC strongly overlap in dorsal-medial striatum
(2) Spiral of connections between functionally matching topographical parts of striatum & midbrain dopamine region
3.2: What is seen in the striatum in terms of projections from other areas?
- great overlap of projections of cortex to striatum
- overlap of projections from vmPFC, OFC & dACC ==> hubs for integrating reward value, predictability & salience
- also functionally diverse projections overlap in striatum (e.g. input from dPFC)
3.2: Where in the striatum is there the most convergence of input?
anterior (rostral) striatum (see figure 1 in Haber (2016))
3.2: What do both the DA-striatal pathway & the striatal input to the DA neurons show in terms of their organization?
general inverse dorsal-ventral topographic organization
3.2: What does the spiraling of information faciliate in DA-striatal pathway?
through this spiral, information can flow from limbic to cognitive to motor circuits
3.2: How is info always channeled (from where to where?)
from limbic to cognitive to motor circuits
3.2: Is there strictly parallel processing in BG?
no, there are many interconnections
3.2: What does motivation trigger in BG (limbic loop)?
- Triggers cognitive considerations (rules that apply in the situation, do’s and dont’s)
- Triggers attentional priorities (what objects, stimuli, are relevant to realize this goal; are all the conditions met?
- Triggers action patterns (which actions can accomplish my goal?)
3.3: Where does DOPA originate from?
Substantia nigra (midbrain)
3.3: What’s the role of DOPA in the direct pathway?
- D1 receptors (stimulates)
- Stimulating stimulation
- Striatum more inhibitory – disinhibiting Thalamus
- Learning: LTP/ strengthening connection
-‚Pressing gas‘
= stronger go-signal 🡪 increases trigger readiness
3.3: What’s the role of DOPA in the indirect pathway?
- D2 receptors (inhibits)
- Inhibiting inhibition (disinhibition) = less inhibition
- Striatum less inhibitory –-> unable to completely inhibit Thalamus
- Learning: LTD / weakening inhibitory connections (if no dopamine, LTD converts to LTP)
-`Releasing brake‘
= weaker no-go signal 🡪 increases trigger readiness
3.3: Which NTs are drivers?
- Glutamate (+) & GABA (-)
- in/decreases likelihood of firing of neurons
3.3: Which NTs are modulators?
- DOPA & serotonin
- able to effect large number of neurons at the same time 🡪 affect strength of signal between the neurons
