| 1. |
- Lindgren, Magnus, et al.
(författare)
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Directed forgetting, event-related potentials and nicotine
- 1999
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Ingår i: Human Psychopharmacology. - 0885-6222 .- 1099-1077. ; 14, s. 19-29
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Tidskriftsartikel (refereegranskat)abstract
- Fifteen male users of oral snuff performed a directed forgetting task after over-night abstinence and after administration of oral snuff. Directed forgetting tasks use cues to classify items for differential reporting at test, emphasising the need for strategic encoding. Recognition was better after nicotine administration, but we found no evidence for greater strategic control, as hypothetically reflected in successful compliance with the directed forgetting instructions. Reaction time decreased after nicotine administration. Performance among fifteen controls was unaffected over two sessions.
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| 2. |
- Lindgren, Magnus, et al.
(författare)
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Effects of nicotine in a bimodal attention task
- 1998
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Ingår i: Neuropsychobiology. - 0302-282X .- 1423-0224. ; 38, s. 42-49
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Tidskriftsartikel (refereegranskat)abstract
- Fifteen male users of oral snuff participated in an experiment where we used an auditory-visual vigilance task to study nicotine effects on P300 and response parameters. Quantitative EEG was also studied. Fifteen male non-users served as a control group.We found some decrease of response times, and slightly improved signal detection. P300 parameters were not affected in this study. Quantitative EEG-analysis indicated an expected increase of arousal, as activity within the alpha band shifted towards higher frequencies.
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| 3. |
- Lindgren, Magnus, et al.
(författare)
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Effects of nicotine in visual attention tasks
- 1996
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Ingår i: Human Psychopharmacology. - 0885-6222 .- 1099-1077. ; 11, s. 47-51
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Tidskriftsartikel (refereegranskat)abstract
- Thirty-five male volunteers (18 nicotine-users and 17 controls) participated in an experiment where a flanker task and a search task were used. It was hypothesized that if nicotine affects selective attention, effects of distracting flanker stimuli should be diminished, and effects of allocation strategies in the search task should be more marked. Nicotine-users performed the tasks after an over-night abstinence, and after administration of oral snuff. In both tasks nicotine users improved more than controls, but there was no indication of nicotine effects on selective attention in either task. Our results point towards a non-specific arousing effect of nicotine.
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| 4. |
- Stenberg, Georg, 1947-, et al.
(författare)
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Semantic processing of words without conscious identification : an ERP study
- 1998
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Ingår i: International Journal of Psychophysiology, vol. 30. no. 1-2. ; , s. 97-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This study examined the question whether semantic content can be accessed from words that are displayed under conditions (brief exposure, pattern masking) where they are not consciously identified. Thirty subjects performed a combined categorization and word identification task. Category labels (e.g. "fruit") were shown followed by masked, briefly exposed words, either validly cued by the category (e.g. "apple") or invalidly cued (e.g. "horse"). The subjects' task was to verify the category by pressing a button, and to identify the word by a verbal response. Exposure durations were selected to allow the subjects to identify approximately 50 % of the words. Four ERP averages were formed: for identified/unidentified words * validly/invalidly cued words. For identified words, there was a marked difference in the ERP response between validly and invalidly cued words. The difference was due to an N400 component for the invalidly cued words. For unidentified words, there was also a significant difference between validly and invalidly cued words, although smaller in size (23 % of that for the identified words). It had the same direction, and appeared in the same time range and with the same general topography as for the identified words. The results show that some semantic processing can operate on words that are not consciously identified
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| 5. |
- Lindgren, Magnus
(författare)
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Applications of event-related potentials in the study of attention
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Event-related potentials were measured in a series of studies where issues concerning attention were of special interest. In particular, the P300 was used as an index of controlled attention. Papers I and III studied nicotine effects on the P300. If nicotine effects were reflected in the P300, decreased latencies and increased amplitudes would be expected. No systematic nicotine effects were found on the P300. In contrast, nicotine had clear dose-response effects on the EEG in Paper I. EEG findings indicated increased arousal, and similar, if less marked, results were obtained in Paper III. Paper II tested nicotine effects on reaction time in tasks involving response competition and visual search, respectively. A focusing effect of nicotine would implicate smaller effects of distracting or less salient information. No such specific effects were found, but response times generally decreased after nicotine administration. Paper IV focused on nicotine effects in a demanding memory test. Recognition memory improved after nicotine administration. A special question concerned whether nicotine would improve strategic encoding, as manipulated by the instructions. We found no evidence for such an effect. Nicotine administration did not affect event-related potentials. In general, nicotine administration decreased response times in studies II, III and IV. Paper V studied the restitution of cognitive function after insulin-induced hypoglycaemia. During hypoglycaemia P300 amplitude decreased in a relatively complicated visual task, while remaining unaffected in the easier tasks used. Amplitudes were restituted after approximately 40 minutes. Paper VI studied P300 in patients diagnosed with toxic encephalopathy with or without neuropsychological impairment. Patients were studied in both simple and complex tasks, and the P300 amplitude was lower in both patient groups.
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| 6. |
- Lindgren, Magnus, et al.
(författare)
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Solvent-induced toxic encephalopathy : Electrophysiological data in relation to neuropsychological findings
- 1997
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Ingår i: Journal of Clinical and Experimental Neuropsychology. - : Informa UK Limited. - 1380-3395 .- 1744-411X. ; 19:5, s. 772-783
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Tidskriftsartikel (refereegranskat)abstract
- Male subjects with type 2A (n = 12) and 2B (n = 12) solvent-induced toxic encephalopathy and a reference group of healthy men (n = 12) without previous solvent exposure were studied using quantitative EEG and event- related potentials from an odd-ball and a dual-task paradigm. Subjects with toxic encephalopathy of types 2A and 2B showed markedly lower P300 amplitudes than did controls in both paradigms. In the relatively complex dual-task setting, subjects with 2A and 2B showed lower signal detection than did controls.
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