OUTLINE

INTRODUCTION

ANATOMY OF THE BASAL GANGLIA

NEUROTRANSMITTERS INVOLVED

DIRECT AND INDIRECT PATHWAYS

BASAL GANGLIA CIRCUITS

RELEVANT PSYCHIATRIC CONDITONS

MOVEMENT DISORDERS WITH PSYCHIATRIC FEATURES

PHARMACOLOGICAL IMPLICATIONS

SUMMARY / CONCLUSION

REFERENCES

INTRODUCTION

Definition Of The Basal Ganglia

•The basal nuclei (or basal ganglia) (BG) are large masses of grey matter situated at the cerebral hemispheres.

•The BG, like the cerebellum, are another accessory motor system that functions usually not by itself but in close association with the cerebral cortex and corticospinal motor system. In fact, the BG receive virtually all their input signals from the cortex itself and also return almost all their output signals back to the cortex.

•The BG ‘bias’ the automatic manner in which sensory inputs are interpreted and movements selected. These nuclei serve to integrate and modulate cerebral cortex control with sensory feedback for the generation of voluntary movement. The BG serves as a component of parallel loops, in combination with the cortex and the thalamus via connections mediated through the internal and external capsules, forming the extrapyramidal motor system. The BG is thought to modulate the initiation, cessation, and timing of voluntary movements.