Search PubMed⌕ Search

Biomedical subjects

J M Rusted

Publications and source records attributed to J M Rusted.

18 recordsLinked to original sources
PubMed2005

Nicotine improves memory for delayed intentions.

RATIONALE: The present paper asked first whether the cholinergic agonist nicotine improves memory for delayed intentions (prospective memory, ProM) and second whether pharmacological dissociation would support the psychological distinction that is made between strategic (effortful) and automatic (non-effortful) intention activation in prospective memory. OBJECTIVES: To use nicotine as a pharmacological tool with which to examine the neurochemical bases of prospective memory and to dissociate strategic from automatic components of ProM retrieval. METHODS: In three experiments, minimally deprived (2 h) smokers either smoked or abstained prior to completing a standard prospective memory study. This involved participants in the simultaneous processing of a ProM task and a cover task (ongoing between the setting and the recall of the intention). Here, the ongoing task involved lexical decision (LDT), while the ProM task required a response to pre-specified target items occurring within the LDT stimuli. Variations in task instructions were used to manipulate the processing requirements of the ProM task, the attention allocated to the ProM task and the balance of importance assigned to the ongoing and ProM tasks. RESULTS: In experiment 1, where the ProM processing was automatic, nicotine did not improve ProM accuracy. In experiment 2, where the ProM task involved strategic processing, positive effects of nicotine were observed. In experiment 3, we covaried ProM task instructions, assigned task importance and nicotine conditions. We observed a main effect of nicotine on ProM accuracy, a main effect of task on ProM accuracy and a main effect of assigned task importance on ProM accuracy. There were no interactions between the factors. CONCLUSIONS: Employing both direct and indirect manipulations of strategic engagement, we demonstrated nicotine-induced enhancement of performance on the ProM task. The results are consistent with the view that relatively small changes in instruction and in task variables engage strategic processing in a ProM task and that when these conditions stretch cognitive resources, nicotine may significantly improve performance.

Adolescent↗
PubMed2002

Verbal fluency facilitated by the cholinergic blocker, scopolamine.

This study was designed to explore putative facilitatory effects of low doses of scopolamine (SP) on phonemic (letter) and semantic (category) verbal fluency. A double-blind, parallel-group design was used with 36 subjects who completed a test battery before and 2 h after 0.6 mg or 1.2 mg of SP or placebo. Fluency measures included total number of words generated, clustering (the production of words within semantic or phonemic subcategories) and switching (the ability to shift efficiently to new subcategories). Low doses of scopolamine increased phonemic fluency, as has been shown previously. Semantic fluency was not increased by SP, although subjects treated with 1.2 mg of SP generated higher-frequency words. SP did not affect clustering or switching. It is suggested that phonemic and semantic fluency reflect distinct cognitive processes.

Adolescent↗
PubMed2000

Nicotinic treatment for degenerative neuropsychiatric disorders such as Alzheimer's disease and Parkinson's disease.

Nicotinic systems play an important role in the neural basis of working memory and attention. Recent progress in understanding of the structure, function, and distribution of central nervous system (CNS) nicotinic receptors and their pharmacology has opened up new possibilities for novel CNS therapeutics with nicotinic agents. In this paper, we review the theoretical justification and the experimental evidence supporting these developments. We focus on the applications of nicotinic agonists in CNS disorders that are degenerative in nature, namely Parkinson's disease and Alzheimer's disease. We suggest that there is considerable potential for therapeutic applications in the near future. Clinically, two major issues remain: (a) the selectivity of effects, that is, developing compounds which are selective in producing improvement in cognition, motor function, attention, or pain without significant side-effects; and (b) the realistic likelihood of long-term improvements in everyday functioning in people who have degenerative diseases.

Alzheimer Disease↗
PubMed2000

Moving out of the laboratory: does nicotine improve everyday attention?

The most robust demonstrations of the nicotine-related performance effects on human cognitive processes are seen in tasks that measure attention. If nicotine does have some potential for enhancing attention, the obvious question to ask is whether the effects demonstrated in the laboratory hold any significance for real-life performance. This paper describes three studies that compare the effects in smokers of a single own brand cigarette on laboratory tests of attention and on everyday analogues of these laboratory tasks. In the laboratory measures of sustained attention and in the everyday analogue, performance advantages were registered in the smoking condition. These benefits were observed in smokers who abstained for a self-determined period of not less than 2 h. The studies were unable to replicate previous research reporting positive effects of smoking on a laboratory task of selective attention, the Stroop task. Small but significant improvements in performance were registered in the everyday analogues, which involved sustaining attention in a dual task situation, a telephone directory search task and a map search task. In addition, smokers showed a significant colour-naming decrement for smoking-related stimuli in the Stroop task. This attentional bias towards smoking-related words occurred independent of whether they had abstained or recently smoked an own brand cigarette. The effect is discussed in terms of the two-component model of processing bias for emotionally valenced stimuli.

Adolescent↗
PubMed1998

Effortful processing is a requirement for nicotine-induced improvements in memory.

We report two studies examining the effects of nicotine on memory in minimally deprived smokers. In experiment 1, semantically related words were recalled significantly better than unrelated words following nicotine, even when volunteers were explicitly instructed to target the unrelated word set for recall. Experiment 2 examined the effect of nicotine on two different types of lexical association: association by joint category membership (semantically related items), and association by derived meaning ("encapsulated" word pairs). Nicotine-induced improvements in recall were observed only for category associates and not for encapsulated word pairs. This implies that explicit, effortful processing of material in the presence of nicotine is necessary for improved recall performance to be observed.

Adult↗
PubMed1998

Deprivation state but not nicotine content of the cigarette affects responding by smokers on a progressive ratio task.

In two experiments, we used a progressive ratio schedule to explore factors associated with smoking motivation. In study 1, smokers who had abstained for more than 8 h bar-pressed for longer to obtain puffs on a cigarette than did non-deprived smokers. Neither group, however, showed nicotine-induced improvements in performance on an attention-demanding task. In the second study, two groups of minimally deprived smokers worked on the progressive ratio task for puffs of either a standard or an ultralow nicotine cigarette. The amount of work expended for puffs was the same for both cigarettes. The groups were also indistinguishable in terms of their subjective experience of the impact of smoking. These results suggest that the addition of nicotine to the cigarette may not have an immediate impact on the effort expended for a puff on that cigarette, and that short term changes in craving may be observed independent of satiety effects associated with nicotine ingestion. We conclude that the progressive ratio task is a useful and sensitive measure of desire to smoke, although the two experiments highlight the complexity of the relationship between subjective, objective and behavioural measures of smoking and nicotine ingestion in humans.

Adolescent↗
PubMed1996

Methodological considerations in nicotine research: the use of "denicotinised" cigarettes as the control condition in smoking studies.

In this study, we report on the comparability of the subjective experience and smoking style elicited by two commercially available cigarettes which differ in nicotine levels, one containing a 'regular' delivery of 0.7 mg and the other containing minimal (0.1 mg) nicotine. Our findings suggest subtle differences in the smoking of these two cigarettes, with the 'denicotinised' cigarette being smoked for longer and with more puffs taken. While these subtle differences have little significance for studies concerned with the effects of nicotine on cognitive performance measures, they are certainly important for studies concerned with the role of nicotine in maintaining smoking behaviour.

Adult↗
PubMed1996

Structuring the acquisition and retrieval environment to facilitate learning in individuals with dementia of the Alzheimer type.

Three experiments using variations of the Subject Performed Task (SPT) paradigm examined whether structuring the learning and retrieval environment would improve learning in individuals with mild to moderate dementia of the Alzheimer type (DAT). Experiment 1 examined the role of enactment at encoding and retrieval, and found that with appropriate retrieval support DAT volunteers do benefit from enactment at encoding. Experiment 2 showed that recall was further enhanced when the list of SPTs formed a cohesive, goal-directed sequence of actions. In Experiment 3, DAT subjects acquired a more complex action-based sequence and maintained it accurately over a short period of time. It is concluded that the provision of contextual support at encoding and at retrieval can enhance residual memory in individuals with DAT.

Aged↗
PubMed1993

Cholinergic control of cognitive resources.

In this paper, we describe our approach to the investigation of cholinergic modulation of human information processing. In a continuing series of studies from our laboratories, we have systematically examined the extent to which current psychological models of information processing provide an adequate framework for the interpretation of the modulatory effects of cholinergic agents on cognitive performance measures. We suggest that the data are consistent with the view of attention and memory as processes which operate through a common, limited capacity executive mechanism, rather than separable serial processes described in the traditional modular models of memory.

Animals↗
PubMed1992

A comparison of the attentional and consolidation hypotheses for the facilitation of memory by nicotine.

Studies examining facilitation of human memory by the administration of nicotine have given equivocal results and it has been argued that the positive findings on memory may have resulted indirectly from an effect on attention, rather than from a direct effect on memory storage. This study compared the "attentional" and the "mnemonic" hypotheses directly, by using both immediate and delayed recall tasks in a verbal free recall study, in which volunteers smoked on a fixed regime during presentation of a 32 word list (namely, one puff after each of eight 4-word blocks). The serial position curve for immediate recall demonstrated a significant improvement on the later blocks of the list (an attentional effect) when volunteers smoked a nicotine-containing cigarette. However, improved performance was found for items at the beginning of the list on the delayed recall measure and this improvement was significant on the first block of 4 words. Since nicotine input had been taken after presentation of this information, the results demonstrate post-learning facilitation of memory by nicotine.

Adult↗
PubMed1992

Facilitation of memory by post-trial administration of nicotine: evidence for an attentional explanation.

In human studies, reported performance improvements with post-trial administration of nicotine have all involved associative learning (Mangan and Golding 1983; Colrain et al. 1992; Warburton et al. 1992). In this study, post-trial nicotine, obtained through smoking a cigarette, improved free recall of lists of unrelated words under conditions which limited the opportunity for associative learning. However, the nicotine-induced advantage was not observed when volunteers were required to complete a secondary (attention) task during the post-trial period in which they smoked. The results suggest that post-trial effects depend on the opportunity for stimulus processing after input, and that nicotine improves performance by increasing the attentional resources available for such strategic processing.

Adolescent↗
PubMed1991

A comparison of the effects of scopolamine and diazepam on working memory.

Two drug models of memory dysfunction, namely the benzodiazepine and the cholinergic models, have emerged from the considerable number of studies which have examined drug effects on information processing. The reported impairments produced by administration of compounds from these two families appear to be more similar than dissimilar, and to date, direct comparisons on traditional memory tasks have failed to differentiate the models. This study compared the effects of diazepam and scopolamine on tasks associated with separable components of working memory. The results indicate that this model also fails to discriminate between the drug models; both compounds selectively impaired tasks associated with the central executive mechanism and failed to disrupt tasks associated with the articulatory loop or the visuospatial scratchpad.

Adolescent↗
PubMed1989

Cognitive models and cholinergic drugs.

This paper reviews the use of cognitive models in human psychopharmacology to examine the role of the cholinergic system in memory and attention. We suggest that while studies of attention have continued to keep pace with developments in psychology, few studies have been reported which selectively test memory functions specified by current cognitive models of memory. We report the work from our laboratory which has demonstrated effects of cholinergic blockade on attention and memory, with particular emphasis on the work examining selective cholinergic mediation in working memory.

Attention↗
PubMed1989

Effects of scopolamine on verbal memory; a retrieval or acquisition deficit?

This study examines the relationship between encoding and retrieval factors in producing the well-documented scopolamine-induced deficits in verbal memory. Subjects were required to learn word lists of 10 items, and were given a total of 8 acquisition trials per list. While the placebo group achieved criterion within 4 acquisition trials, the group treated with scopolamine failed to reach criterion at all, with recall levelling off within 4 acquisition trials. Acquisition curves for subjects treated with scopolamine paralleled those obtained for the placebo group. Performance on delayed recall and recognition tests indicated that the subjects had in fact successfully encoded items in long-term memory, but had been unable to retrieve them in free recall. The results suggest a retrieval problem in what has traditionally been considered a scopolamine-induced encoding deficit. We suggest that scopolamine may disrupt the organization of material at input, so that items which have achieved durable storage are not accessible for free recall.

Adolescent↗
PubMed1988

The effects of scopolamine on working memory in healthy young volunteers.

Twenty healthy young adults completed a series of nonverbal and problem solving tasks in a repeated measures design involving placebo and 0.6 mg scopolamine, administered by subcutaneous injection. Subjects completed the test battery under standard presentation conditions and with concurrent articulation, which precludes verbal recoding of test material. Under standard presentation conditions, scopolamine significantly impaired performance on the problem solving task and on tasks of visuo-spatial and spatial memory; memory for abstract shapes was not impaired. Concurrent articulation impaired performance on the shape recognition and interacted with drug treatment on the problem solving task. The results suggest that scopolamine impairs working memory, and that the decrement is at the level of the central executive mechanisms rather than the subsystems which it controls.

Adolescent↗
PubMed1988

Dissociative effects of scopolamine on working memory in healthy young volunteers.

Performance on tasks of digit span, mental rotation and immediate free recall of supraspan word lists was measured before and after oral administration of 1.2 mg scopolamine or placebo to healthy young volunteers. Digit span and mental rotation were sensitive to task-specific interference from articulatory suppression and spatial tapping tasks, respectively. Neither task was affected by scopolamine when completed alone or in combination with a secondary task. A concurrent secondary task reduced immediate free recall in a nonspecific fashion (i.e., spatial tapping or articulatory suppression impaired performance equally). Scopolamine significantly reduced the number of words recalled under all conditions. The results are interpreted as evidence for selective impairment of the central executive mechanism by scopolamine without disruption of function in the articulatory loop or visuospatial scratch pad.

Adolescent↗
PubMedDate not supplied

Effects of caffeine given before and after lunch on sustained attention.

Previous research has shown that caffeine increases alertness and improves sustained attention. In contrast to this, consumption of lunch leads to a decline in the ability to maintain attention. The main aim of the present study was to determine whether caffeine removes or reduces the postlunch drop in performance, an issue which is of considerable practical importance and theoretical interest. The results showed that caffeine improved performance on the Bakan vigilance task and removed the post-lunch dip observed in the decaffeinated condition. Similar effects were observed in one of the conditions of a mental rotation task. The lunch X caffeine interaction observed in the Bakan task did not change over the course of the task. In contrast to the performance data, lunch X caffeine interactions were not observed in analyses of cardiovascular function or subjective mood.

Adult↗