| 1. |
- 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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| 2. |
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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- 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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| 7. |
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| 9. |
- 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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| 10. |
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