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Task 3: (Chatham et.al (Working memory (output control, reallocation,…

- - - - stimuli are associated with both currently relevant tasks and the irrelevant competing task (both leter and number)
    - - Patients with Parkinson’s disease exhibited significantly increased switch costs compared with control subjects, but only in the ‘cross-talk’ condition (inhibition of competing information was necessary))
      - patients showed significantly greater increases in terms of overall RTs, but not in terms of switch costs, compared with controls
      - switching deficit is due to impairments in selection mechanisms, necesssary for disengaging from a previous task-set and engaging a new task-set in the face of distraction
- - - - Striatum (main input nucleus: cerebral cortex, brain stem and thalamus)
        
        caudate nucleus
        
        putamen
        
        striatal GABAergic medium spiny neurons
        
        nucleus accumbens
      - globus pallidus (GABAergic)
        
        internal segment (major output)
        
        external segment (part of internal circuitry)
      - substantia nigra
        
        pars compacta (dopaminergic cells projecting to striatum and other nuclei of basal ganglia, dopaminergic)
        
        pars reticulara (major output, GABAergic)
      - subthalamic nucleus (STN) (between thalamus and SN)
        
        output to globus pallidus externalis and internalis and SN pars reticulata
        
        input from globus pallidus externalis, Cerebral cortex, thalamus and brain stem
    - - direct monosynaptic pathway (SNpc->GPi) (releases thalamus from tonic inhibition, facilitating initiation of volitional movement)
      - indirect monosynaptic pathway (striaum->GPe->Gpi+SNpr [directly or via STN]) (has D2 inhibitory neurons, acs in oposition to the disinhibition of the direct pathway
      - hyperdirect pathway (cortical input -> STN)
      - final output pathways:
        
        cortex
        
        superior colliculus
    - - Oculomotor loop
      - Prefrontal loop
      - Body movement loop
      - Limbic loop
- - - - orbital and medial prefrontal cortex = emotion and motivation
      - dorsolateral PFC = higher cognitive processes/executive functions
      - premotor areas = different aspects of motor planning
      - motor cortex = execution of those plans
    - - dPFC/associative corical areas -> central striatum (caudate nucleus)-> cognition, procedural learning, working memory
      - PFC+ACC+amygdala (limbic areas) -> ventromedial striatum (caudate, putamen, nucleus accumbens) -> reward, reinforcement, emotion, addictive behaviors
      - M1/sensory-motor areas (FEF->dorsolateral striatum [putamen] -> motor control, sensorimotor, planing, learning, saccades
    - - Functional integration
        
        midbrain DA neurons
        
        spiralling system (information can flow from limbic to cognitive to motor circuits, providing mechanism by which motivation and cognition can influence motor decision-making processes and appropriate responses to environmental cues - not a strict parallel processing system)
    - - spiral connections between striatum and mibrain dopamine neurons
      - all these loops through basal ganglia work together to produce meaningful goal oriented behavior
      - topographical organisatino of stratum and SNpc
      - every endogenously generated meaningful behavior starts with motivation, through the overlap of projections of cortex to striatum, spiraling connections between striatum and midbrain dopamine neurons-> motivation triggers cognitive atterntional and motor options
      - feedforward organization of connections
      - info: limbic->cognitive->motor circuits
- - - - dorsal striatum = actor (action selection = response iwth the highest value is selected based upon differential activity in the direct and indirect pathway
      - Ventral striatum = critic: evaluates outcomes to support learning that guides future actions
      - iterative trial and error learning: dorsal and ventral striatal value systems may interact, with the critic giving instructions to the actor via spiraling connections between striatum and dopaminergic regions of the midbrain