| 1. |
- Decety, Jean, et al.
(författare)
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The cerebellum participates in mental activity : tomographic measurements of regional cerebral blood flow
- 1990
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Ingår i: Brain Research. - 0006-8993 .- 1872-6240. ; 535:2, s. 313-317
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Tidskriftsartikel (refereegranskat)abstract
- Measurements in man of regional cerebral blood flow (rCBF) have demonstrated a number of cortical and subcortical events coupled to sensory stimulation or motor performance. It has also been shown that local activity changes take place in the cortex during 'pure' mental activity such as motor imagery (unaccompanied by sensory input or motor output). Thus, our group has previously shown that imagination of hand movements gives predominantly a frontal cortical rCBF activation while the corresponding hand movement activates the rolandic hand area mainly. In this paper we report tomographic rCBF measurements with a 133-Xenon SPECT technique during imagined tennis movements and silent counting. Both procedures gave rise to a significant cerebellar activation in addition to cortical rCBF changes. Apparently, the cerebellum may participate in pure mental activity. It possibly plays a role for the temporal organization of neuronal events related to cognition.
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| 2. |
- Eckert, B., et al.
(författare)
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The recovery of brain function after hypoglycaemia in normal man
- 1992
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Ingår i: Diabetologia, 35, Suppl.1. ; , s. A43-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The aim of the present study was to evaluate the recovery of brain function after moderate hypoglycaemla in normal man. Hypoglycaemia was induced by an intravenous infusion of insulin (2.5 mU/kg) in seven healthy right-handed men aged 25.4+1.1 years (Mean • SD). The brain function was evaluated with P300-amplitude after auditory stimulus, reaction time measurements and EEG before, during (2.4+0.44 mmol/l for 70 min) and three times in the recovery period following hypoglycaemia. Hypoglycaemia caused a reduction in the P300-amplitude, a prolongation in reaction time and minor changes in the EEG-activity. 15 min after normalisation of the blood glucose level, the P300-amplitude was lower than during hypoglycaemia and still 1,5 hrs after normalisation of the blood glucose level, there was a marked reduction in the P3OO-amplitude. 4 hrs after normalisation of the blood glucose, the P300-amplitude was restituted. The reaction time was shorter 15 min after normalisation of the blood glucose compared to hypoglycaemia, but was not nermalised until 1,5 hrs after of recovery following hypoglycaemia. The EEG-changes were normalised 15 min after hypoglycaemia. We conclude that moderate hypglycaemia causes marked effects in P300 and reaction time and that brain function measured as P300 is not restored after 1,5 hrs but at 4 hrs after normalisation of hypoglycaemia.
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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- Lindgren, M., et al.
(författare)
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Restitution of neurophysiological functions, performance, and subjective symptoms after moderate insulin-induced hypoglycaemia in non-diabetic men
- 1996
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Ingår i: Diabetic Medicine. - : Wiley-Blackwell. - 0742-3071 .- 1464-5491. ; 13:3, s. 218-25
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Tidskriftsartikel (refereegranskat)abstract
- The restoration of cognitive function was studied in 10 healthy men aged 26 years (25.5 +/- 1.2 years; mean +/- SD) after insulin-induced hypoglycaemia (arterialized blood glucose 2.5 +/- 0.4 mmol l-1) for 62 +/- 8 min. Another group of six men participated in a single blind sham study for comparison. The hypoglycaemic event caused a significant increase (p = 0.006) in serum adrenaline levels. Ratings of adrenergically mediated symptoms increased during hypoglycaemia (p = 0.006), as did neuroglycopenic symptoms (p = 0.002), although neuroglycopenia ratings increased in both studies. During hypoglycaemia, P300 amplitudes in a relatively demanding visual search task decreased (p = 0.02), whereas easier tasks were unaffected. The amplitudes were restored after 40 min of normoglycaemia. Reaction time deteriorated after restoration of normoglycaemia, suggesting an effect of hypoglycaemia on learning. Thus, hypoglycaemia at a blood glucose level that is common among patients treated with insulin causes clear cognitive dysfunction, although restoration of the cognitive dysfunction to normal was fast.
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| 7. |
- Lindgren, M, et al.
(författare)
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Restitution of neurophysiological functions, performance, and subjective symptoms after moderate insulin-induced hypoglycaemia in non-diabetic men
- 1996
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Ingår i: Diabetic Medicine. - 1464-5491. ; 13:3, s. 218-225
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Tidskriftsartikel (refereegranskat)abstract
- The restoration of cognitive function was studied in 10 healthy men aged 26 years (25.5 +/- 1.2 years; mean +/- SD) after insulin-induced hypoglycaemia (arterialized blood glucose 2.5 +/- 0.4 mmol l-1) for 62 +/- 8 min. Another group of six men participated in a single blind sham study for comparison. The hypoglycaemic event caused a significant increase (p = 0.006) in serum adrenaline levels. Ratings of adrenergically mediated symptoms increased during hypoglycaemia (p = 0.006), as did neuroglycopenic symptoms (p = 0.002), although neuroglycopenia ratings increased in both studies. During hypoglycaemia, P300 amplitudes in a relatively demanding visual search task decreased (p = 0.02), whereas easier tasks were unaffected. The amplitudes were restored after 40 min of normoglycaemia. Reaction time deteriorated after restoration of normoglycaemia, suggesting an effect of hypoglycaemia on learning. Thus, hypoglycaemia at a blood glucose level that is common among patients treated with insulin causes clear cognitive dysfunction, although restoration of the cognitive dysfunction to normal was fast.
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| 8. |
- Risberg, Jarl, et al.
(författare)
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Regional cerebral blood flow correlates of anxiety and personality traits
- 1991
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Ingår i: Lassen, N.A., Ingvar, D.H., Raichle, M.E., Friberg, L. (eds), Brain work and mental activity. - Copenhagen : Munksgaard. - 8716106989 ; , s. 392-401
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 9. |
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| 10. |
- Ryding, Erik, et al.
(författare)
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Motor imagery activates the cerebellum regionally : a SPECT rCBF study with 99mTc-HMPAO
- 1993
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Ingår i: Cognitive Brain Research. - 0926-6410 .- 1872-6348. ; 1:2, s. 94-99
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Tidskriftsartikel (refereegranskat)abstract
- Our earlier findings of a cerebellar activation during motor imagery (Brain Res., 535 (1990) 313-317) were made with a technique with low regional resolution. Therefore we could not elucidate the distribution of the cerebellar activation. In the present study the cerebellar regional cerebral blood flow (rCBF) changes during motor imagery (MI) was measured with a single photon emission computed tomography (SPECT) rCBF method (99mTc-HMPAO) with higher regional resolution during (1) silent counting, and (2) MI (which included silent counting) in 17 normal subjects. Comparing the SPECT results from the two tasks revealed the regional activations during MI. We confirmed that the most pronounced regional activations during MI were found in the cerebellum, especially in its infero-lateral parts on both sides.
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| 11. |
- Sano, Motoki, et al.
(författare)
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Acute effects of alcohol on regional cerebral blood flow in man
- 1993
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Ingår i: Journal of Studies on Alcohol. - 0096-882X .- 1934-2683. ; 54:3, s. 369-376
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Tidskriftsartikel (refereegranskat)abstract
- Acute effects of alcohol in a low (0.7 g/kg) and a high dose (1.5 g/kg) on regional cerebral blood flow (rCBF) were measured with 133Xe inhalation technique at resting conditions in 13 normals. Mean hemisphere CBF increased globally by 12% at the lower dose and 16% at the higher dose. A normal hyperfrontal flow pattern was seen in both alcohol conditions. There were, however, significant regional differences in response to alcohol. The largest rCBF increase was observed in prefrontal regions at the lower dose, and in temporal regions at the higher. Expressed in relative values (% of the whole brain CBF), the temporal rCBF increased linearly with increasing alcohol dosage, while the prefrontal rCBF showed a increase at the lower dose followed by a decrease at the higher dose. It is concluded that alcohol has two types of acute effects on rCBF, a global vasodilatory effect and some regional effects, most clearly seen in prefrontal and temporal regions. The prefrontal flow augmentation following acute alcohol intake may be related to a transient arousal reaction, which has been reported by others. The temporal flow increase may be related to effects of alcohol on emotions and mood.
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| 12. |
- Stenberg, Georg, 1947-
(författare)
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Att veta utan att tänka
- 1994
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Ingår i: Ingvar, D. H. (red), Att tänka sig. - Stockholm : Svenska Dagbladet. - 9177383826 ; , s. 57-70
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 13. |
- Stenberg, Georg, 1947-, et al.
(författare)
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Attention and personality in augmenting/reducing of visual evoked potentials
- 1990
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Ingår i: Personality and Individual Differences. - 0191-8869 .- 1873-3549. ; 11:12, s. 1243-1254
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Tidskriftsartikel (refereegranskat)abstract
- Earlier research has shown that extraverts tend to increase their visual evoked potential amplitudes with increasing light intensity (augmenting), while introverts reach their maximum amplitude at lower intensities (reducing). The evoked response has normally been measured from association areas of the brain (at the vertex). The present study measured VEP amplitudes over visual cortex and at the vertex, using four light intensities in two conditions, where attention was either directed towards the light stimuli, or away from them by a concurrent auditory task. Forty subjects were classified as extraverts or introverts based on the Eysenck Personality Inventory. The results show that attention interacted significantly with extraversion. Introverts exhibited a narrower focus of attention, with higher amplitudes and amplitude-intensity functions when attending to the light flashes and lower when distracted. Extraverts showed smaller differences between conditions, indicating a more evenly distributed attention. Higher arousal in introverts is the probable cause of their narrower focus of attention. There were marked differences in the distribution of activity between vertex and occipital cortex. Introverts showed relatively stronger occipital responses and extraverts stronger vertex responses across all intensities and in both conditions. The predisposition for mainly perceptual responses to aversive stimuli in introverts, and for general alerting and motor preparatory responses in extraverts, are interpreted as supportive of Brebner & Cooper's hypothesis that introverts are "geared to inspect" and extraverts are "geared to respond".
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| 14. |
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| 15. |
- Stenberg, Georg, 1947-
(författare)
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Det kognitivt omedvetna
- 1994
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Ingår i: Åström, K., Engström, C., Marklund, K. (red), Nationalencyklopedin. - Höganäs : Bra böcker. ; , s. 440-
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 16. |
- Stenberg, Georg, 1947-, et al.
(författare)
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EEG topography of acute ethanol effects in resting and activated normals
- 1994
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Ingår i: Journal of Studies on Alcohol. - 0096-882X .- 1934-2683. ; 55:6, s. 645-656
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Tidskriftsartikel (refereegranskat)abstract
- Acute effects of ethanol on spectral characteristics of the EEG were studied using 18 recording sites and topographic mapping. The EEG was recorded both at rest and during a mental arithmetic task. Healthy young male volunteers were randomly assigned to an ethanol (n = 22) or a placebo (n = 15) group. The ethanol group received a total dose of 1.0 g/kg, divided into two equal doses given 75 minutes apart. and measurement sessions took place at baseline and after each dose. The placebo group underwent a similar schedule. Power in the theta, alpha and beta bands all increased in the ethanol group, but only the theta and beta bands clearly separated ethanol from placebo. Alpha increases were seen in the placebo group as well. The ethanol-induced changes were greater in the left hemisphere than in the right, having the effect of attenuating the right-over-left asymmetry seen at baseline. Differences between ethanol and placebo were more marked in the mentally activated condition, since the changes seen at rest were inhibited by the activation in the placebo group, but not in the ethanol group. The results indicate (1) that ethanol induces a less differentiated pattern of activity within the brain at rest, and (2) that it impairs the capacity to activate the brain under the challenge of a mental task.
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| 17. |
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| 18. |
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| 19. |
- Stenberg, Georg, 1947-, et al.
(författare)
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Extraversion and regional blood flow
- 1990
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Ingår i: Journal of Psychophysiology, vol. 4, no. 1. ; , s. 66-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 20. |
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| 21. |
- Stenberg, Georg, 1947-
(författare)
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Extraversion and the P300 in a visual classification task
- 1994
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Ingår i: Personality and Individual Differences. - 0191-8869 .- 1873-3549. ; 16:4, s. 543-560
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Tidskriftsartikel (refereegranskat)abstract
- Amplitude differences between extraverts and introverts in the P300 component of visual event-related potentials were examined in a picture classification task. A set of pictorial stimuli was used with three types of instructions, requiring responses based on colour, semantic category, or a combination of both criteria. Forty university students (22 men, 18 women) served as subjects. Based on their scores on the Eysenck Personality Inventory, they were divided into 3 groups of Low, Medium or High Extraversion. The pictures evoked large late positivities, with higher amplitude in the right hemisphere. P300 amplitude increased with increasing degrees of extraversion. The effect of extraversion on amplitude (High > Medium > Low) was larger for target stimuli in posterior derivations. The extraversion effect was mainly attributable to the impulsivity subtrait. Whereas some earlier studies have found higher P300 amplitudes for introverts in tasks inducing habituation or attention decrement, the present tasks differed by using more varied stimuli and by requiring more processing. The results are discussed in relation to theories on the biological basis of extraversion.
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| 22. |
- Stenberg, Georg, 1947-, et al.
(författare)
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Judging words at face value : interference in a word processing task reveals automatic processing of affective facial expressions
- 1998
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Ingår i: Cognition & Emotion. - 0269-9931 .- 1464-0600. ; 12:6, s. 755-782
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Tidskriftsartikel (refereegranskat)abstract
- Earlier research has indicated that some characteristics of facial expressions may be automatically processed. This study investigated automaticity as evidenced by involuntary interference in a word evaluation task. Compound stimuli, consisting of words superimposed on pictures of affective faces, were presented to subjects who were given the task of evaluating the affective valence of the words while disregarding the faces. Results of three experiments showed that word evaluation was influenced by the concurrently shown affective faces. Overall, negative words were found to require longer latencies, indicating that more processing resources are invested in negative than in positive stimuli. This speed advantage for positive words was modified by the faces. Negative words were facilitated, relative to positive ones, when shown with a negative expression, e.g. a sad face. Correspondingly, negative words were inhibited, relative to positive ones, when shown with a positive expression, e.g. a happy face. The results are consistent with automatic, involuntary semantic processing of affective facial expressions.
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| 23. |
- Stenberg, Georg, 1947-
(författare)
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Känsloliv, personlighet och hjärnaktivitet
- 1991
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Ingår i: Ingvar, D. H. (red), Hjärna, psyke och tid. - Höganäs : Wiken. - 9171190694 ; , s. 76-83
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 24. |
- Stenberg, Georg, 1947-, et al.
(författare)
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Personality and augmenting/reducing in visual and auditory evoked potentials
- 1988
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Ingår i: Personality and Individual Differences. - 0191-8869 .- 1873-3549. ; 9:3, s. 571-579
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies have indicated a relationship between evoked potential augmenting/reducing and extraversion or sensation seeking. However, the proposed mechanism of protective inhibition can account for this fact only if the relationship generalizes across different modalities and response definitions. The present study was designed to test this, using six intensities of visual and six intensities of auditory stimuli along with the EPI and SSS questionnaires.For the visual stimuli, the slope of the P90-N120 amplitude at the vertex correlated significantly with both the extraversion and the disinhibition scales in the way that augmenting/reducing theory predicts. However, over the primary visual area, no component showed the same personality relationship as the vertex wave, and one early component showed the opposite. This result suggests that personality differences in VEPs may reflect different ways of allocating processing resources between primary and association areas, rather than a generalized tendency to inhibit strong stimuli. In the auditory modality, personality differences were not apparent in the amplitude slopes, possibly due to the confluence from primary and association areas in AEPs in the vertex lead. There was a general tendency for latencies to correalte positively with extraversion and disinhibition, in congruence with Eysenck's theory on the biological basis of extraversion.
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| 25. |
- Stenberg, Georg, 1947-
(författare)
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Personality and the EEG : arousal and emotional arousability
- 1992
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Ingår i: Personality and Individual Differences. - 0191-8869 .- 1873-3549. ; 13:10, s. 1097-1113
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Tidskriftsartikel (refereegranskat)abstract
- Eysenck's theory asserts that low cortical arousal accompanies extraversion (or the sub-component impulsivity). In Gray's theory, impulsivity is associated with high sensitivity to signals of reward, and anxiety with high sensitivity to signals of punishment. These hypotheses were tested by recording EEG signs of arousal and phasic arousability in emotional imagery, using 17 EEG channels and frequency analysis by Fourier transform. Three conditions were used: a neutral control task, and two emotional conditions involving imagery about pleasant and unpleasant personal memories. Forty subjects participated (23 men, 17 women; median age 23 years). Orthogonal personality dimensions of impulsivity and anxiety were derived from a joint analysis of the EPI and KSP questionnaires. The results showed, as expected, lower arousal, defined by more posterior theta activity, in impulsive subjects than in non-impulsives. These differences extended across all conditions. The EEG responses to the emotional conditions, in relation to the neutral one, consisted primarily of a right-lateralized frontal theta increase and changes in temporal beta activity (an increase in the positive condition, and a decrease in the negative one). These responses were expected to be amplified for impulsive subjects in positive emotion, and for anxious subjects in negative emotion. The right-sided frontal theta activity was stronger in high-anxious subjects than in low-anxious ones across all conditions, suggesting higher overall emotionality. For the temporal beta activity, the expected amplification of the response to negative emotion in the high anxiety group was confirmed, but the corresponding prediction for impulsives and positive emotion was not upheld. It is concluded that anxiety is related to EEG signs of heightened emotionality, especially in negative affect, and that impulsivity is associated with lowered arousal.
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| 26. |
- Stenberg, Georg, 1947-, et al.
(författare)
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Personality dimensions and regional cerebral blood flow
- 1996
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Ingår i: International Journal of Psychology, vol. 31, no. 3-4. ; , s. 331-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Measures of regional cerebral blood flow (rCBF) indicate patterns of brain activity with great potential usefulness for exploring the biological bases of personality traits. We have examined the distribution of cortical rCBF induced by spontaneous mental activity in the resting state, and correlated regional activation with questionnaire measures of personality traits. Our main interest has been in the dimension of extraversion-/introversion. Over a series of three studies (total N=75), results have consistently shown a relationship between high temporal lobe activity and introversion. Task-induced mental activation has tended to diminish the personality differences found at rest.
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| 27. |
- Stenberg, Georg, 1947-, et al.
(författare)
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Regional cerebral blood flow and extraversion
- 1993
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Ingår i: Personality and Individual Differences. - 0191-8869 .- 1873-3549. ; 15:5, s. 547-554
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Tidskriftsartikel (refereegranskat)abstract
- Regional cerebral blood flow was examined in a group of 17 subjects (8 men, 9 women, ages 22-35) at rest and during three mental activations, inducing perceptual and spatial processing. The subjects completed two personality questionnaires, the Eysenck Personality Inventory and the Karolinska Scales of Personality. The aim of the study was to examine the relation between rCBF and the extraversion-introversion dimension. Earlier studies of rCBF at rest have found higher blood flow in the temporal lobes for introverts than for extraverts, and a negative correlation between extraversion and global cerebral blood flow among women. Both findings were confirmed in this group. The importance of related personality dimensions, such as impulsivity and anxiety, for rCBF differences between extraverts and introverts were examined, using scales from the KSP questionnaire. It was found that anxiety-proneness aspects of introversion were more important in determining high temporal blood flow than low-impulsivity aspects. Global CBF in women, as a measure of general arousal, was mainly related to the sensation-seeking aspects of extraversion. Results from the spatial processing tasks showed more right-hemispheric activation for introverts than extraverts in a mental rotation task.
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| 28. |
- Stenberg, Georg, 1947-, et al.
(författare)
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Regional patterns of cortical blood flow distinguish extraverts from introverts
- 1990
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Ingår i: Personality and Individual Differences. - 0191-8869 .- 1873-3549. ; 11:7, s. 663-673
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Tidskriftsartikel (refereegranskat)abstract
- Eysenck's hypothesis of higher cortical arousal in introverts was examined using regional cerebral blood flow measurement in 37 healthy subjects . The measurement was made at rest, using the133Xe-inhalation method. Estimates of gray matter flow were obtained for 32 brain regions. There was no significant evidence of personality differences in general arousal, as measured by the mean flow level, averaged over all regions. There were, however, regional differences. An overall test of the blood flow distribution indicated different patterns of activity in introverts and extraverts. Follow-up tests attributed this to higher flow in the temporal lobes for introverts than for extraverts. Higher temporal lobe activity in introverts may be interpreted as increased functional connections between cortex and the limbic system.
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| 29. |
- 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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| 30. |
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| 31. |
- Stenberg, Georg, 1947-
(författare)
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Subliminal perception
- 1995
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Ingår i: Åström, K., Engström, C., Marklund, K. (red), Nationalencyklopedin. - Höganäs : Bra böcker. ; , s. 392-
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 32. |
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| 33. |
- Stenberg, Georg, 1947-, et al.
(författare)
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The picture superiority effect in a cross-modality recognition task
- 1995
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Ingår i: Memory & Cognition. - 0090-502X .- 1532-5946. ; 23:4, s. 425-441
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Tidskriftsartikel (refereegranskat)abstract
- Words and pictures were studied, and recognition tests were given in which each studied object was to be recognized in both word and picture format. The main dependent variable was the latency of the recognition decision. The purpose was to investigate the effects of study modality (word or picture), of congruence between study and test modalities, and of priming resulting from repeated testing. Experiments 1 and 2 used the same basic design, but the latter also varied retention interval. Exp. 3 added a manipulation of instructions to name studied objects, and Exp. 4 deviated from the others by presenting both picture and word referring to the same object together for study. The results showed that congruence between study and test modalities consistently facilitated recognition. Furthermore, items studied as pictures were more rapidly recognized than items studied as words. With repeated testing, the second instance was affected by its predecessor, but the facilitating effect of picture-to-word priming exceeded that of word-to-picture priming. The findings suggest a two-stage recognition process, in which the first is based on perceptual familiarity, and the second uses semantic links for a retrieval search. Common-code theories which grant privileged access to the semantic code for pictures are supported by the findings, or alternatively dual-code theories which assume mnemonic superiority for the image code. Explanations of the picture superiority effect as resulting from dual encoding of pictures are not supported by the data.
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| 34. |
- Tallroth, G., et al.
(författare)
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Neurophysiological changes during hypoglycaemia in type 1 (insulin- dependent) diabetes mellitus and in normal man
- 1990
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Ingår i: Diabetologia. - 0012-186X .- 1432-0428. ; 33:5, s. 319-323
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Tidskriftsartikel (refereegranskat)abstract
- Hypoglycaemia (median venous blood glucose 1.8 mmol/l; range 1.6-2.3) was induced by an intravenous infusion of regular insulin in eight patients with Type 1 (insulin-dependent) diabetes mellitus (age 28.0 +/- 7.4 years; mean +/- SD, duration 15.5 +/- 5.1 years) and in 12 age- matched healthy male control subjects. Multi-channel frequency analysis of electroencephalogram (electrophysiologic brain mapping) and recording of P300 and somatosensory evoked potentials were performed before, during and immediately after the hypoglycaemic period. The hypoglycaemia produced a significant increase in low frequency electroencephalographic activity in both groups, most pronounced over anterior regions of the brain. The electroencephalographic activity was normalised immediately after the hypoglycaemic period. The patients with diabetes showed somewhat longer P300 latencies during the initial normoglycaemic examination. Hypoglycaemia caused a marked reduction of the P300 amplitude in both groups of subjects and the amplitude was not restored immediately after normalisation of blood glucose levels. The somatosensory cortical responses were not affected by hypoglycaemia. We conclude that hypoglycaemia results in impairment in cerebral function, as measured by neurophysiological techniques, which is not immediately normalised when blood glucose is restored to normal.
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| 35. |
- Tallroth, G, et al.
(författare)
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Neurophysiological changes during insulin-induced hypoglycaemia and in the recovery period following glucose infusion in type 1 (insulin-dependent) diabetes mellitus and in normal man
- 1990
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Ingår i: Diabetologia. - 1432-0428. ; 33:5, s. 319-323
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Tidskriftsartikel (refereegranskat)abstract
- Hypoglycaemia (median venous blood glucose 1.8 mmol/l; range 1.6-2.3) was induced by an intravenous infusion of regular insulin in eight patients with Type 1 (insulin-dependent) diabetes mellitus (age 28.0 +/- 7.4 years; mean +/- SD, duration 15.5 +/- 5.1 years) and in 12 age-matched healthy male control subjects. Multi-channel frequency analysis of electroencephalogram (electrophysiologic brain mapping) and recording of P300 and somatosensory evoked potentials were performed before, during and immediately after the hypoglycaemic period. The hypoglycaemia produced a significant increase in low frequency electroencephalographic activity in both groups, most pronounced over anterior regions of the brain. The electroencephalographic activity was normalised immediately after the hypoglycaemic period. The patients with diabetes showed somewhat longer P300 latencies during the initial normoglycaemic examination. Hypoglycaemia caused a marked reduction of the P300 amplitude in both groups of subjects and the amplitude was not restored immediately after normalisation of blood glucose levels. The somatosensory cortical responses were not affected by hypoglycaemia. We conclude that hypoglycaemia results in impairment in cerebral function, as measured by neurophysiological techniques, which is not immediately normalised when blood glucose is restored to normal.
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| 36. |
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| 37. |
- Wendt, Peter E., et al.
(författare)
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Ethanol reduces asymmetry of visual rCBF responses
- 1994
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Ingår i: Journal of Cerebral Blood Flow and Metabolism. - 0271-678X .- 1559-7016. ; 14:6, s. 963-973
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Tidskriftsartikel (refereegranskat)abstract
- Visual regional CBF (rCBF) responses were measured in 10 healthy male subjects before and after an ethanol dose of 1 g/kg body weight. This dose induces well-established cerebral vasodilatation. However, significant bilateral occipital increases were found in both conditions. Apparently, the coupling between neuronal activity and rCBF is preserved following ethanol. The occipital and posterior parietal flow increases were, however, larger on the right than the left side in the sober state. During inebriation the asymmetry disappeared, possibly representing a more undifferentiated processing of visual information. We propose that ethanol causes a reduced inhibition of the left posterior cortex and a reduction of right-hemisphere information processing.
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| 38. |
- Wendt, Peter E., et al.
(författare)
-
Ethanol reduces asymmetry of visual rCBF responses
- 1994
-
Ingår i: Journal of Cerebral Blood Flow and Metabolism. - : SAGE Publications Inc.. - 0271-678X .- 1559-7016. ; 14:6, s. 963-973
-
Tidskriftsartikel (refereegranskat)abstract
- Visual regional CBF (rCBF) responses were measured in 10 healthy male subjects before and after an ethanol dose of 1 g/kg body weight. This dose induces well-established cerebral vasodilatation. However, significant bilateral occipital increases were found in both conditions. Apparently, the coupling between neuronal activity and rCBF is preserved following ethanol. The occipital and posterior parietal flow increases were, however, larger on the right than the left side in the sober state. During inebriation the asymmetry disappeared, possibly representing a more undifferentiated processing of visual information. We propose that ethanol causes a reduced inhibition of the left posterior cortex and a reduction of right-hemisphere information processing.
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| 39. |
- Wirsen, A., et al.
(författare)
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Quantified EEG and cortical evoked responses in patients with chronic traumatic frontal lesions
- 1992
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Ingår i: Electroencephalography and Clinical Neurophysiology / Evoked Potentials Section. - 0168-5597 .- 1872-6224. ; 84:2, s. 127-138
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Tidskriftsartikel (refereegranskat)abstract
- Eighteen frontal trauma patients and 17 age-matched control subjects had quantified EEGs and measurements of sensory (SEP) and auditory evoked potentials (P300) using a Biologic Brain Atlas III system. The findings were compared to the conventional paper EEG, and to the frontal lesion volumes, severity of head injury, and outcome variables. The quantified EEG confirmed the pathological findings detected by visual inspection, but some regional abnormalities were more easily detected by topographic mapping. The regional distribution of pathological slowing corresponded well with the morphological lesions in most patients. The modal frequency of EEG correlated both with lesion volume and injury severity and with the outcome variables. There were no pathological findings in the SEPs, and all but one patient had clearly distinguishable P300 responses. There was a significant reduction in P300 amplitude in the frontal patients at the anterior, but not at the posterior electrodes. The topographical distribution of the P300 changes corresponded well with the morphological lesions. Our findings indicate that the P300 potential is, in part, dependent upon the prefrontal cortical areas. The present study thus supports P300 investigations which have shown amplitude reduction in other disorders (e.g., schizophrenia) with a presumed prefrontal dysfunction.
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| 40. |
- Wirsen, A., et al.
(författare)
-
Quantified EEG and cortical evoked responses in patients with chronic traumatic frontal lesions
- 1992
-
Ingår i: Electroencephalography and Clinical Neurophysiology / Evoked Potentials Section. - : Elsevier BV. - 0168-5597. ; 84:2, s. 127-138
-
Tidskriftsartikel (refereegranskat)abstract
- Eighteen frontal trauma patients and 17 age-matched control subjects had quantified EEGs and measurements of sensory (SEP) and auditory evoked potentials (P300) using a Biologic Brain Atlas III system. The findings were compared to the conventional paper EEG, and to the frontal lesion volumes, severity of head injury, and outcome variables. The quantified EEG confirmed the pathological findings detected by visual inspection, but some regional abnormalities were more easily detected by topographic mapping. The regional distribution of pathological slowing corresponded well with the morphological lesions in most patients. The modal frequency of EEG correlated both with lesion volume and injury severity and with the outcome variables. There were no pathological findings in the SEPs, and all but one patient had clearly distinguishable P300 responses. There was a significant reduction in P300 amplitude in the frontal patients at the anterior, but not at the posterior electrodes. The topographical distribution of the P300 changes corresponded well with the morphological lesions. Our findings indicate that the P300 potential is, in part, dependent upon the prefrontal cortical areas. The present study thus supports P300 investigations which have shown amplitude reduction in other disorders (e.g., schizophrenia) with a presumed prefrontal dysfunction.
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