[show abstract][hide abstract] ABSTRACT: The involvement of the prefrontal cortex in executive control has been well established. It is, however, as yet unclear whether the basal ganglia and the cerebellum as components of frontostriatal/frontocerebellar networks also contribute to the executive domains multitasking and response inhibition. To investigate this issue, groups of patients with selective vascular lesions of the basal ganglia (n=13) or the cerebellum (n=14) were compared with matched healthy control groups. Several paradigms assessing the ability to process concurrent visual and auditory input and to simultaneously perform verbal and manual responses as well as the inhibition of habitual or newly acquired response tendencies were administered. Basal ganglia patients showed marked response slowing during coordination of sensory input from different modalities and high error rates during the inhibition of overlearned responses. There was no clear evidence of a cerebellar involvement in multitasking or response suppression. Taken together, the findings provided evidence for a striatal involvement in both multitasking and response inhibition, emphasizing the functional implication of subcortical components in frontostriatal circuits.
Behavioural Brain Research 01/2009; 194(2):214-22. · 3.33 Impact Factor
[show abstract][hide abstract] ABSTRACT: Normal aging has been associated with executive control deficits, but it is as yet unclear whether different executive subprocesses are differentially affected during the course of aging. The present study aimed to investigate age effects on a range of executive control subcomponents. Four consecutive age groups (20-30 years, 31-45 years, 46-60 years, 61-75 years), matched on present state IQ and mood, were compared on tasks of strategic memory processing, verbal fluency, reasoning, inhibition, task management, and self-rating of executive abilities. Deficits concerning the suppression of habitual and experimentally induced prepotent response tendencies and the ability to efficiently divide attention were observed in subjects over 60 years of age compared to the younger groups, while memory, verbal fluency, and reasoning were largely unaffected. Results suggest a sharp decline of executive function after age 60 and a differential course of different executive subcomponents across aging, adding further support to a multi-dimensional model of executive function.
Aging Neuropsychology and Cognition 08/2007; 14(4):370-93. · 1.07 Impact Factor
[show abstract][hide abstract] ABSTRACT: The term "executive functions" refers to a range of cognitive processes, their common feature being the coordination of information processing and action control. Cortico-subcortical circuits which connect the prefrontal cortex (PFC), the basal ganglia and the cerebellum via the thalamus are believed to serve as neuroanatomical substrates of executive processing. This paper focuses on information processing related to executive functions by the PFC and related subcortical regions. Findings are mainly derived from neuropsychological investigations of brain-damaged patients but also from imaging studies in healthy subjects. There is evidence for subtle differences between these regions with respect to the cognitive mechanisms contributing to inhibition of habitual responses, task management/multitasking and set shifting, although the data base is sparse so far.