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The concept of impulsivity covers a wide range of "actions that are poorly conceived, prematurely expressed, unduly risky, or inappropriate to the situation and that often result in undesirable outcomes". As such it plays an important role in normal behaviour, as well as, in a pathological form, in many kinds of mental illness such as mania, personality(More)
Five experiments examined the effects of destruction of the dorsal noradrenergic bundle (DNAB), arising in the locus coeruleus, both on brightness and spatial visual discrimination, and selective attention. An analogue o Leonard's 5-choice serial reaction task for human subjects was used. Hungry rats were trained to detect brief (0.5 sec) flashes of light(More)
Groups of patients with dementia of Alzheimer type (DAT) and idiopathic Parkinson's disease, together with age and IQ-matched normal controls, were compared on several computerized tests of visuospatial memory and learning. Two different groups of parkinsonian patients were studied: (1) a newly diagnosed group, early in the course of the disease, not(More)
Impulsivity can often be an important clinical problem in psychiatry and neurology. In psychiatry, the manifestation of impulsive behaviour in syndromes such as personality disorders, attention deficit hyperactivity disorder and in substance abuse may be different, and this has led to conflicting definitions. There has also been a tendency to concentrate on(More)
Groups of patients with Parkinson's disease, either medicated, or unmedicated and early in the course, together with age- and IQ-matched control subjects were tested in two paradigms measuring different aspects of selective attention. The first set of tests compared visual discrimination learning following intra- and extra-dimensional shifts, using a "total(More)
The higher level cognitive function of planning was studied in a group of medicated Parkinson's disease patients and a group of matched control subjects, using a computerised version of Shallice's Tower of London task. Baseline measurement of the ability to execute a given plan of action, to generate low level strategies required for efficient searching,(More)
Impulsivity is widely considered to be multifactorial. One factor, frequently termed "reflection-impulsivity", refers to the need to give time to information analysis and reflection before making a response. In most reaction time tasks employed for non-human subjects, responding is expected immediately after a specific stimulus has been presented. In the(More)
An impulsive cognitive style may affect behaviour in several different ways, including rapid decision making, intolerance of the delay of reward and a tendency to terminate chains of responses prematurely. It has been proposed to measure the last of these in rats using fixed consecutive number (FCN) schedules. The present study uses a modified version of(More)
RATIONALE Tolerance to delay of reinforcement has been proposed as an important facet of self-control in both animals and man. Poor self-control, leading to impulsive behaviour, can be a major problem if it reaches pathological levels. OBJECTIVES The effects of five serotonergic drugs were compared to those of ethanol on a procedure for measuring(More)
RATIONALE The serotonergic systems have been implicated in the pathological impulsive behaviour on the basis of both clinical and preclinical data. However, impulsivity is probably made up of several independent factors, and the involvement of the diverse regulatory mechanisms of the serotonergic systems has not been widely studied. OBJECTIVE The(More)