| 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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