The basal ganglia: focused selection and inhibition of competing motor programs.

Functional anatomy of the basal ganglia. I. The cortico-basal ganglia-thalamo-cortical loop

Although the mammalian basal ganglia have long been implicated in motor behavior, it is generally recognized that the behavioral functions of this subcortical group of structures are not exclusively motoric in nature. Extensive evidence now indicates a role for the basal ganglia, in particular the dorsal striatum, in learning and memory. One prominent hypothesis is that this brain region mediates a form of learning in which stimulus-response (S-R) associations or habits are incrementally acquired. Support for this hypothesis is provided by numerous neurobehavioral studies in different mammalian species, including rats, monkeys, and humans. In rats and monkeys, localized brain lesion and pharmacological approaches have been used to examine the role of the basal ganglia in S-R learning. In humans, study of patients with neurodegenerative diseases that compromise the basal ganglia, as well as research using brain neuroimaging techniques, also provide evidence of a role for the basal ganglia in habit learning. Several of these studies have dissociated the role of the basal ganglia in S-R learning from those of a cognitive or declarative medial temporal lobe memory system that includes the hippocampus as a primary component. Evidence suggests that during learning, basal ganglia and medial temporal lobe memory systems are activated simultaneously and that in some learning situations competitive interference exists between these two systems.

Learning and memory functions of the Basal Ganglia.

Scientists in many different fields have been attracted to the study of habits because of the power habits have over behavior and because they invoke a dichotomy between the conscious, voluntary control over behavior, considered the essence of higher-order deliberative behavioral control, and lower-order behavioral control that is scarcely available to consciousness. A broad spectrum of behavioral routines and rituals can become habitual and stereotyped through learning. Others have a strong innate basis. Repetitive behaviors can also appear as cardinal symptoms in a broad range of neurological and neuropsychiatric illness and in addictive states. This review suggests that many of these behaviors could emerge as a result of experience-dependent plasticity in basal ganglia–based circuits that can influence not only overt behaviors but also cognitive activity. Culturally based rituals may reflect privileged interactions between the basal ganglia and cortically based circuits that influence social, emotional...

Habits, Rituals, and the Evaluative Brain

New perspectives in basal forebrain organization of special relevance for neuropsychiatric disorders: the striatopallidal, amygdaloid, and corticopetal components of substantia innominata.

Publisher Summary This chapter highlights the cognitive functions of the neostriatum (NS). The NS seems to take part in mediating a phylogenetically widespread, supramodal function, which is largely independent of response topography and which is operative under a rather well-defined range of circumstances. The chapter reviews tsources of the information to be processed by the NS, the nature of local NS processing, and psychological analysis of this innominate function. Studies in several species have shown that only a limited portion of NS is of critical importance for delayed response-type tasks. The focal NS region is the recipient of information from that subdivision of the prefrontal cortex, which is the neocortical center for the same class of behavior and probably also from the mediodorsal thalamic nucleus. The electrophysiological and neurochemical basis for NS involvement in delayed response tasks is insufficiently investigated, and the available evidence does not particularly illuminate the fate, within the NS, of the information arriving from the frontal lobes.

“Cognitive” Functions of the Neostriatum

The basal ganglia and the control of movement: Levels of motor planning Cognition and the control of movement

Publisher Summary This chapter presents current conceptions of neostriatal functions history. Authoritative reviews have suggested that the neostriatum (NS) takes part in regulation of intentional movements by suppressing and screening additional motor mechanisms in some functional association with the nonspecific thalamoreticular system and in the initiation and control of locomotion by virtue of activities that are postural. A much-cited hypothesis states that the basal ganglia serve as a ramp generator for slow voluntary smooth movements of different speeds. The caudate nucleus has been claimed to be concerned in the integrative balance of cortical responses to environmental contact stimuli with those of visual context and the putamen has been conceived as a selective resonator for cortical activity. There is an involvement of striatal function in sensorimotor integration, and the caudate nucleus contains or is contained in a basic system that enables the organism to perform biologically adaptive responses.

R. Gunilla E. Öberg

Papers

“Cognitive” Functions of the Neostriatum

The basal ganglia and the control of movement: Levels of motor planning Cognition and the control of movement

Current Conceptions of Neostriatal Functions History and an Evaluation

Recall of life experiences in an alcoholic Korsakoff patient: a naturalistic approach.