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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)
Impulsive behaviour is an important component of many psychiatric syndromes. It is often expressed as aggressive or violent behaviour, but may also be non-violent. One important factor which might lead to aggression or violence is an inability to tolerate a delay of gratification, leading to frustration and aggressive outbursts. In animals and in man,(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)
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)
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)
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)
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)
Four experiments examined the effects of d-amphetamine on response switching and perseveration in apparatus allowing a choice of response location. The relative ‘cost’ of a switch between two response locations and repetitive responding at a single location by rats was manipulated in the various test settings to provide baseline probabilities of switching.(More)