Basal ganglia 2010

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Basal ganglia 2010

  1. 1. Basal Ganglia<br />
  2. 2. Subdivision of BG<br />A. Neostriatum or Striatum<br />Putamen<br />Caudate nucleus<br />B. Pallio striatum or Pallidum<br />Globuspallidus<br />C. Lentiform nucleus<br />Putamen<br />GlobusPallidus<br />D. Archistiatum<br />Amygdela<br />E. Substantianigra<br />F. Subthalamic nucleus<br />
  3. 3. Functional organization of BG<br />
  4. 4. Motor Component of Basal Ganglia<br />
  5. 5. BG Input Output in Mamals<br />
  6. 6. Basal nuclei<br />
  7. 7. Gross anatomy of BG<br />
  8. 8. Internal capsule & BG<br />
  9. 9. Basal Forebrain<br />
  10. 10. Stiatum<br />
  11. 11. Subthalamic Nucleus<br />
  12. 12. Globuspallidus (internal)<br />
  13. 13. Substantianigra pars reticulata<br />
  14. 14. Globuspallidus (Externus)<br />
  15. 15. Substantianigra pars compacta<br />
  16. 16. Striatal Parallel Pathway<br />
  17. 17. Efferent of BG<br />
  18. 18. Output of the Basal Ganglia<br />
  19. 19. Outputs of the basal ganglia and their trajectories<br />
  20. 20. BG Effernts<br />
  21. 21. Neruons and Circuits of BG<br />
  22. 22. Dysinhibition<br />
  23. 23. Connections of the Neostriatum with the SubstantiaNigra<br />
  24. 24. Cortical Loop<br />Cortex: 4,6,temporo, parietal and occipital glutamate<br />Striatum spiky GABA<br />Pallidum medial GABA<br />Thalamus VL, VA<br />
  25. 25. BG: Subcortical loops<br />In the case of all sub-cortical loops the position of the thalamic relay is on the input side of the loop<br />Red – Excitatory<br />Blue - Inhibitory<br />
  26. 26. Internal Connections of the Basal Ganglia: Direct Pathway<br />
  27. 27. Indirect Pathways <br />
  28. 28. Projections from the Basal Ganglia to Other Brain Regions<br />
  29. 29. BG Circuits<br />
  30. 30.
  31. 31. Function of BG<br />Voluntary movement<br />Initiation of movement<br />Control of ramp movement<br />Change from one pattern to other<br />Programming and correcting movement while in progress (thalamocortical circuts)<br />Postural control<br />Righting reflex<br />Automatic associated movement (walking)<br />Control of muscle tone<br />Reticulospinal <br />Vestibulospinal<br />
  32. 32. Ablation Study<br />Unilateral lesion minimal effect<br />Denny Brown – Bilateral lesion -> Akinesia + Flexion dystonia<br />Brook – Cooling of GP -> Contralateralcocontraction of antagoniastic muscle -> Flexion, alternate and amplitude of movement <br />Bilateral striatal ablation -> Overactive, does not respond to visual cue – walk to wall<br />Bilateral pallidal ablation -> Hypoactive akinetic<br />Human sterotacticGpi lesion -> tremor >rigidity<br />Subthalamic Nucleus ablation -> Hemibalismus<br />Bilateral CN ablation -> immobile animal<br />VL thalamic cooling -> Ia discharge to stretch reflex -> rigidity by y tone<br />
  33. 33. Stimulation studies<br />CN stimulation -> head and body turn to opposite site, circling movement, or mild hypertonia, late tremor, changes tonic to clonic phase of epilepsy<br />Neostriatal stimulation -> arrest of motion in progress<br />
  34. 34. Microelectrode recording<br />Activity seen during initiation of internally generated movement but not to stimulus triggered movement<br />Activity seen during co-contraction of agonist (stimulus triggered thus control amplitude and velocity of movement<br />Preparation of motor act or programming as MC and SMA<br />React<br />Spontaneous movement of individual body part<br />Alternating movement<br />Visually and kinesthetically triggered movement<br />Postural adjustment to body tilt<br />Rapid ballistic movement <br />Slow ramp movement<br />Isometric muscle contraction<br />SNc – tonic discharge -> postural control<br />SNr - phasic discharge change with limb movement<br />
  35. 35. Cortex<br />Discharge of motor circuit<br />5<br />Phasic activity during movement <br />1<br />No spontaneous discharge, only during limb movement increased phasic activity<br />Striatum<br />2<br />High spontaneous discharge, inhibit tonicaly thalamus<br />GPiSNr<br />3<br />4<br />Phasic reduction of activity during movement due to disinhibition by striatum <br />Thalamus<br />
  36. 36. A conceptual model of action selection by the basal ganglia<br />
  37. 37. Proposed mechanisms for serial selection within the basal ganglia<br />
  38. 38. BG and Eye movement<br />
  39. 39. Reinforcement learning<br />
  40. 40.
  41. 41. Possible Role of Intrinsic Circuits<br />
  42. 42.
  43. 43.
  44. 44. The End<br />

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