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Dopamine regulates working memory and its cellular correlates in the PFC

Dopamine regulates working memory and its cellular correlates in the PFC. Adapted from: Sawaguchi et al. (1986; 1988; 1990a,b). How does dopamine regulate working memory at the cellular level in the PFC?. Study effects of dopamine on intrinsic properties of PFC neurons.

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Dopamine regulates working memory and its cellular correlates in the PFC

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  1. Dopamine regulates working memory and its cellularcorrelates in the PFC

  2. Adapted from: Sawaguchi et al. (1986; 1988; 1990a,b)

  3. How does dopamine regulate working memory at the cellular level in the PFC? • Study effects of dopamine on intrinsic properties of PFC neurons. • Study effects of dopamine on synaptic inputs to PFC neurons. • Make a model incorporating these data and see if you can answer the above question.

  4. Experimental Set-up

  5. Overview

  6. Effects of D1 receptor activation on pyramidal cell firing

  7. D1 receptor activation enhances evoked firing by shifting INAP activation

  8. D1 receptor activation sustains evoked firing by Slowing INAP inactivation by 42%

  9. D1 receptor activation also sustains evoked firing by reducing a slowly-inactivating K+ current

  10. Effects of dopamine on excitatory transmission

  11. D1 agonists have no effect on low frequency inputs but enhance high frequency inputs.

  12. D1 receptor activation increases NMDA EPSCs selectively

  13. D1 receptor stimulation reduces release probability very slightly. Minimal Stimulation MK-801 Blocking Function 12.2 ± 7%

  14. D1 receptor activation increases post-synaptic NMDA conductance Voltage-Clamp(Cs, TTX, Cd) Control D1 Agonist 2.5pA 100ms Control D1 Agonist GNMDA= 5.9 1+e-0.0038(v-(-35)) GNMDA GNMDA= 5.07 1+e-0.0038(v-(-25)) Vm

  15. D1 agonists do not enhance response to trains when NMDA receptors are blocked

  16. Models indicate that the selective increase in depolarization is due to both reduced Pr and enhanced NMDA conductance Simulated D1 Data Simulation D1 condition control GNMDA shift + depression shift GNMDA shift alone Data

  17. Effects of dopamine on inhibitory transmission

  18. Dopamine has bi-directional effects on IPSCs D2 D1

  19. Dopamine can switch IPSCs from a reduced state (D2-mediated) to an enhanced state (D1-mediated)

  20. D1 agonists increase action-potential evoked Spontaneous IPSCs but notMini IPSCs.

  21. Dopamine via D1 but not D2 receptors directly excites interneurons

  22. D2-mediated reduction of IPSCs is blocked by a muscarinic acetylcholine antagonist (Atropine)

  23. Summary of the Physiological Effects of Dopamine

  24. Linking cellular mechanisms to the functions of dopamine in the PFC Computational Modeling (Daniel Durstewitz)

  25. Simulation of D1 effects leads to reduction in spontaneous but large enhancement in evoked “delay-period” activity

  26. The model reproduces qualitative aspects of dopamine’s actions in vivo

  27. How does dopamine regulate working memory at the cellular level in the PFC? • It gates the flow of synaptic input into the PFC and regulates network activity via its effects on inhibition. • It aids in establishing and stabilizing up-states (delay-period activity) via its actions on INAP, IKS, INMDA, & glutamate release.

  28. Supervisors Anthony Phillips (UBC) Charles Yang (UBC, Lilly Research Labs. ) Natalia Gorelova (UBC) Terry Sejnowski (Salk Institute) Charles Stevens (Salk Institute) Collaborators Stan Floresco (UBC) Daniel Durstewitz (Salk Institute)

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