Functional Anatomy, Physiology and Clinical Aspects of Basal Ganglia

Ensuring coordination of the nervous system functioning, communication between various structures, adjusting the functions to the changes in internal and external environment depends on processing of substantial amount of information (Groenewegen, 2007; Groenewegen & van Dongen, 2007). The concept of cortico-subcortical loops is one of the explanations of the physiological control of the majority of motor, emotional and cognitive functions. The most important elements are striatum and cerebral cortex. Especially in the pyramidal cells of the cerebral cortex and medium spiny neurons of the striatum there is capacity for plastic changes relating to the control of broadly defined mental functions (motor, emotional, cognitive). The cerebral cortex is linked to the striatum via cortico-subcortical pathways, from where information is transmitted to the globus pallidus pars internalis or the substantia nigra pars reticulata (which physiologically and anatomically constitute one structure) or via the ventral globus pallidus reach the thalamus and the cerebral cortex subsequently. The evidence of the anatomical and physiological brain research supported by clinical data and theoretical models suggests there are at least five loops (also called circuits) related to motor, emotional and cognitive functioning control (Alexander et all., 1986; DeLong et all., 1998). The loops division as well as the control of functions assigned to these loops has more model and didactic character rather than it reflects the real character and complexity of the functions controlling these loops. The following cortico-subcortical loops have been described: 1. motor between additional motor area of the cerebral cortex and the lateral part of dorsal striatum – putamen; 2. oculomotor between the frontal visual eye field of the cerebral cortex and the corpus of the caudate (nucleus caudatus) belonging to the medial part of dorsal striatum; 3. prefrontal (associative) between dorso-lateral prefrontal cortex and the dorso-lateral part of the head of caudate (nucleus caudatus) (the frontal part of the medial part of dorsal striatum); 4. latero-orbito-frontal between lateral orbito-frontal cerebral cortex and the ventromedial part of the head of caudate (medial part of the dorsal striatum); 5. limbic (circuit of the anterior part of the cingular gyrus) between the anterior part of the anterior cingulate gyrus and the ventral striatum (of which the main part is the nucleus accumbens). According to the classic description (Alexander et all., 1986) these circuits pass through various areas of cerebral cortex and subcortical structures and they have similar principles