| 1. |
- Cashin, Peter H, et al.
(författare)
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Pharmacokinetics of cisplatin during hyperthermic intraperitoneal treatment of peritoneal carcinomatosis
- 2013
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Ingår i: European Journal of Clinical Pharmacology. - : Springer Science and Business Media LLC. - 0031-6970 .- 1432-1041. ; 69:3, s. 533-540
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Tidskriftsartikel (refereegranskat)abstract
- PurposeCisplatin during hyperthermic intraperitoneal chemotherapy (HIPEC) has not previously been measured with a selective technique. The primary aims were to examine the pharmacokinetics of active cisplatin and its monohydrated complex (MHC) during HIPEC using a specific measuring technique, to compare cisplatin’s systemic absorption with oxaliplatin, and to compare active cisplatin levels to that of total platinum.MethodsTen patients treated with cytoreductive surgery and HIPEC (cisplatin 50 mg/m2,doxorubicin 15 mg/m2) were recruited. Blood and perfusate samples were drawn during and after HIPEC. Cisplatin analysis was conducted using liquid chromatography (LC) with post-column derivatization with diethyldithiocarbamate and compared with inductively coupled plasma-mass spectrometry (ICP-MS).ResultsThe mean half-life (t1/2) of perfusate cisplatin was 18.4 min, with area under the time-concentration curve (AUC) 0–90 min of 2.87 mM·min and estimated 0–60 min of 2.45 mM·min. The absorption t1/2 was 9.0 min for cisplatin and 18.2 min for oxaliplatin. The ratio of total platinum to active cisplatin increased in a linear manner by time of perfusion.ConclusionsCisplatin is absorbed quicker than oxaliplatin. Lowering the perfusion time to 60 min does not significantly change the pharmacokinetics of cisplatin, and is therefore to be considered. As the HIPEC perfusion progresses, the ICP-MS technique does not adequately reflect active cisplatin levels in the perfusate
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| 2. |
- Ehrsson, HH, et al.
(författare)
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Holding an object: neural activity associated with fingertip force adjustments to external perturbations
- 2007
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Ingår i: Journal of neurophysiology. - : American Physiological Society. - 0022-3077 .- 1522-1598. ; 97:2, s. 1342-1352
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Tidskriftsartikel (refereegranskat)abstract
- When you hold an object, a sudden unexpected perturbation can threaten the stability of your grasp. In such situations grasp stability is maintained by fast reflexive-like grip-force responses triggered by the somatosensory feedback. Here we use functional magnetic resonance imaging (fMRI) to investigate the neural mechanisms involved in the grip-force responses associated with unexpected increases (loading) and decreases (unloading) in the load force. Healthy right-handed subjects held an instrumented object (of mass 200 g) between the tips of right index finger and thumb. At some time during an interval of 8 to 45 s the weight of the object was suddenly increased or decreased by 90 g. We analyzed the transient increases in the fMRI signal that corresponded precisely in time to these grip-force responses. Activity in the left primary motor cortex was associated with the loading response, but not with unloading, suggesting that sensorimotor processing in this area mediates the sensory-triggered reflexive increase in grip force during loading. Both the loading and the unloading events activated the cingulate motor area and the medial cerebellum. We suggest that these regions could participate in the updating of the sensorimotor representations of the fingertip forces. Finally, the supplementary somatosensory area located on the medial wall of the parietal lobe showed an increase in activity only during unloading, indicating that this area is involved in the sensorimotor processing generating the unloading response. Taken together, our findings suggest different central mechanisms for the grip-force responses during loading and unloading.
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| 3. |
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| 4. |
- Pfeiffer, P, et al.
(författare)
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Short-time infusion of oxaliplatin in combination with capecitabine (XELOX30) as second-line therapy in patients with advanced colorectal cancer after failure to irinotecan and 5-fluorouracil
- 2006
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Ingår i: Annals of Oncology. - : Elsevier BV. - 0923-7534 .- 1569-8041. ; 17:2, s. 252-258
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Tidskriftsartikel (refereegranskat)abstract
- Background: The efficacy of oxaliplatin combined with capecitabine (XELOX) as second-line therapy in patients with advanced colorectal cancer (ACRC) resistant to irinotecan is not well established. Oxaliplatin induces acute, cold-induced neuropathy in most patients. The incidence is claimed to be infusion rate-dependent and therefore a 2-h infusion is recommended. Patients and methods: For practical and economic reasons, but also for patient's convenience, we performed a phase II study to examine XELOX30 (capecitabine 1000 mg/m2 orally twice daily on days 1-14 and oxaliplatin 130 mg/m2 as a 30 min infusion on day 1) in patients with ACRC resistant to irinotecan. In addition the pharmacokinetics of oxaliplatin was studied. Results: From November 2002 to September 2003, 70 patients with ACRC were treated with XELOX30. Median age was 62 (range 33-74 years) years and median performance status was 1 (range 0-2). The median number of courses was four (range 1-12) and median cumulative dose of oxaliplatin was 530 (range 125-1560) mg/m2. The response rate was 17% (95% CI 10-23), median time to progression (TTP) was 5.4 months (95% CI 4.6-6.4) and median survival 9.5 months (95% CI 8.5-11.2). White blood cell count (WBC) and performance status were significantly correlated to TTP. Neurotoxicity was moderate: grade 1 56%, grade 2 17% and grade 3 6%. Other grade 3 toxicities were nausea/ vomiting 9%, diarrhoea 14% and PPE 8%. The maximum blood concentration and total body clearance of oxaliplatin was higher than previously reported in studies examining 2-h infusions, but the volume of distribution and terminal half-life was in close agreement with previous results. Conclusion: XELOX30 is a very convenient second-line regimen in ACRC with an activity and safety profile similar to other oxaliplatin schedules. © 2005 European Society for Medical Oncology.
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| 5. |
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| 6. |
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| 7. |
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| 8. |
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| 9. |
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| 10. |
- Bergouignan, Loretxu, et al.
(författare)
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Out-of-body-induced hippocampal amnesia
- 2014
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 111:12, s. 4421-4426
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Tidskriftsartikel (refereegranskat)abstract
- Theoretical models have suggested an association between the ongoing experience of the world from the perspective of one's own body and hippocampus-based episodic memory. This link has been supported by clinical reports of long-term episodic memory impairments in psychiatric conditions with dissociative symptoms, in which individuals feel detached from themselves as if having an out-of-body experience. Here, we introduce an experimental approach to examine the necessary role of perceiving the world from the perspective of one's own body for the successful episodic encoding of real-life events. While participants were involved in a social interaction, an out-of-body illusion was elicited, in which the sense of bodily self was displaced from the real body to the other end of the testing room. This condition was compared with a well-matched in-body illusion condition, in which the sense of bodily self was colocalized with the real body. In separate recall sessions, performed similar to 1 wk later, we assessed the participants' episodic memory of these events. The results revealed an episodic recollection deficit for events encoded out-of-body compared with in-body. Functional magnetic resonance imaging indicated that this impairment was specifically associated with activity changes in the posterior hippocampus. Collectively, these findings show that efficient hippocampus-based episodic-memory encoding requires a first-person perspective of the natural spatial relationship between the body and the world. Our observations have important implications for theoretical models of episodic memory, neurocognitive models of self, embodied cognition, and clinical research into memory deficits in psychiatric disorders.
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| 11. |
- Bergouignan, Loretxu, et al.
(författare)
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Out-of-body memory encoding causes third-person perspective at recall
- 2022
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Ingår i: Journal of Cognitive Psychology. - : Taylor & Francis Group. - 2044-5911 .- 2044-592X. ; 34:1, s. 160-178
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Tidskriftsartikel (refereegranskat)abstract
- Sigmund Freud famously noted some memories are recalled with a perspective of “an observer from outside the scene”. According to Freud—and most memory researchers today—the third-person perspective occurs due to reconstructive processes at recall. An alternative possibility is that the third-person perspective have been adopted when the actual event is experienced and later recalled in its original form. Here we test this hypothesis using a perceptual out-of-body illusion during the encoding of real events. Participants took part in a social interaction while experiencing an out-of-body illusion where they viewed the event and their own body from a third-person perspective. In recall sessions ∼1 week later, events encoded in the out-of-body compared to the in-body control condition were significantly less recalled from a first-person perspective. An out-of-body experience leads to more third-person perspective during recollection.
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| 12. |
- Bremberg, ER, et al.
(författare)
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An evaluation of pharmacist contribution to an oncology ward in a Swedish hospital
- 2006
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Ingår i: Journal of oncology pharmacy practice : official publication of the International Society of Oncology Pharmacy Practitioners. - : SAGE Publications. - 1078-1552. ; 12:2, s. 75-81
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Tidskriftsartikel (refereegranskat)abstract
- Aim. The aim of this project was to establish the importance of a pharmacist in the health-care team in improving drug use in an oncology ward in the Department of Oncology, Karolinska University Hospital, Stockholm, Sweden. Methods and patients. The pharmacist participated in the medical round in the mornings and worked as a member of the health-care team. Drug-related problems (DRPs) were identified by drug chart reviews based on data from medical files, laboratory tests and interviews with patients and/or relatives. A questionnaire to physicians and nurses was used to evaluate their experiences of the pharmacist’s contribution to the oncology ward. Results. In total, 114 DRPs were identified in 58 patients. For each DRP, the pharmacist gave proposals for solutions. Sixty-eight suggestions out of 114 (59.6%) were implemented by the physician. Two suggestions (1.8%) were partly followed. For 32 suggestions (28.0%) it was unclear if they had caused any change in medication. Twelve suggestions (10.5%) were not followed. Most of the physicians and nurses acknowledged the pharmacist’s contribution to improved drug use in the ward. Conclusion. A pharmacist can improve drug use in an oncology ward as a member of the health-care team. The pharmacist contributes with a systematic focus on the patient from a drug perspective.
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| 13. |
- Broomand, Amir, et al.
(författare)
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Oxaliplatin neurotoxicity - No general ion channel surface-charge effect
- 2009
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Ingår i: Journal of Negative Results in BioMedicine. - : Springer Science and Business Media LLC. - 1477-5751. ; 8:1, s. 2-
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Tidskriftsartikel (refereegranskat)abstract
- Background. Oxaliplatin is a platinum-based chemotherapeutic drug. Neurotoxicity is the dose-limiting side effect. Previous investigations have reported that acute neurotoxicity could be mediated via voltage-gated ion channels. A possible mechanism for some of the effects is a modification of surface charges around the ion channel, either because of chelation of extracellular Ca2+, or because of binding of a charged biotransformation product of oxaliplatin to the channel. To elucidate the molecular mechanism, we investigated the effects of oxaliplatin and its chloride complex [Pt(dach)oxCl]- on the voltage-gated Shaker K channel expressed in Xenopus oocytes. The recordings were made with the two-electrode and the cut-open oocyte voltage clamp techniques. Conclusion. To our surprise, we did not see any effects on the current amplitudes, on the current time courses, or on the voltage dependence of the Shaker wild-type channel. Oxaliplatin is expected to bind to cysteines. Therefore, we explored if there could be a specific effect on single (E418C) and double-cysteine (R362C/F416C) mutated Shaker channels previously shown to be sensitive to cysteine-specific reagents. Neither of these channels were affected by oxaliplatin. The clear lack of effect on the Shaker K channel suggests that oxaliplatin or its monochloro complex has no general surface-charge effect on the channels, as has been suggested before, but rather a specific effect to the channels previously shown to be affected.
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| 14. |
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| 15. |
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| 16. |
- Crucianelli, Laura, et al.
(författare)
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Interoception as independent cardiac, thermosensory, nociceptive, and affective touch perceptual submodalities
- 2022
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Ingår i: Biological Psychology. - Stockholm : Karolinska Institutet, Dept of Neuroscience. - 0301-0511 .- 1873-6246.
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Tidskriftsartikel (refereegranskat)abstract
- Interoception includes signals from inner organs and thin afferents in the skin, providing information about the body’s physiological state. However, the functional relationships between interoceptive submodalities are unclear, and thermosensation as skin-based interoception has rarely been considered. We used five tasks to examine the relationships among cardiac awareness, thermosensation, affective touch, and nociception. Thermosensation was probed with a classic temperature detection task and the new dynamic thermal matching task, where participants matched perceived moving thermal stimuli in a range of colder/warmer stimuli around thermoneutrality. We also examined differences between hairy and non-hairy skin and found superior perception of dynamic temperature and static cooling on hairy skin. Notably, no significant correlations were observed across interoceptive submodality accuracies (except for cold and pain perception in the palm), which indicates that interoception at perceptual levels should be conceptualised as a set of relatively independent processes and abilities rather than a single construct.
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| 17. |
- Crucianelli, Laura, et al.
(författare)
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The role of the skin in interoception : a neglected organ?
- 2022
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Ingår i: Perspectives on Psychological Science. - Stockholm : Karolinska Institutet, Dept of Neuroscience. - 1745-6916 .- 1745-6924.
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Tidskriftsartikel (refereegranskat)abstract
- In the past two decades, interoception has received increasing attention in the fields of psychology and cognitive science, as well as neuroscience and physiology. A plethora of studies adopted the perception of cardiac signals as a proxy for interoception. However, recent findings have cast doubt to the methodological and intrinsic validity of the tasks used thus far. Therefore, there is an ongoing effort to improve the existing cardiac interoceptive tasks and to identify novel channels to target the perception of the physiological state of the body. Amid such scientific abundancy, one could question whether the field has been partially neglecting one of our widest organs in terms of dimensions and functions, the skin. According to some views grounded on anatomical and physiological evidence, skin-mediated signals such as affective touch, pain, and temperature have been re-defined as interoceptive. Nevertheless, there is no agreement at this regard. Here, we discuss some of the anatomical, physiological, and experimental arguments supporting the scientific study of interoception by means of skin-mediated signals. We argue that more attention should be paid to the skin as a sensory organ that monitors the bodily physiological state, and further propose thermosensation as a particularly attractive model of skin-mediated interoception.
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| 18. |
- Crucianelli, Laura, et al.
(författare)
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Visuo-thermal congruency modulates the sense of body ownership
- 2022
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Ingår i: Communications Biology. - Stockholm : Karolinska Institutet, Dept of Neuroscience. - 2399-3642.
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Tidskriftsartikel (refereegranskat)abstract
- Thermosensation has been redefined as an interoceptive modality that provides information about the homeostatic state of the body. However, the contribution of thermosensory signals to the sense of body ownership remains unclear. Across two rubber hand illusion (RHI) experiments (N = 73), we manipulated the visuo-thermal congruency between the felt and seen temperature, on the real and rubber hand respectively. We measured the subjectively experienced RHI, the perceived hand location and temperature of touch, and monitored skin temperature. We found that visuo-thermal incongruencies between the seen and felt touch reduced the subjective and behavioural RHI experience (Experiment 1). Visuo-thermal incongruencies also gave rise to a visuo-thermal illusion effect, but only when the rubber hand was placed in a plausible position (Experiment 2) and when considering individual differences in interoceptive sensibility. Thus, thermosensation contributes to the sense of body ownership by a mechanism of dynamic integration of visual and thermosensory signals.
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| 19. |
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| 20. |
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| 21. |
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| 22. |
- Ehrsson, HH, et al.
(författare)
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Cortical activity in precision- versus power-grip tasks: an fMRI study
- 2000
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Ingår i: Journal of neurophysiology. - : American Physiological Society. - 0022-3077 .- 1522-1598. ; 83:1, s. 528-536
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Tidskriftsartikel (refereegranskat)abstract
- Most manual grips can be divided in precision and power grips on the basis of phylogenetic and functional considerations. We used functional magnetic resonance imaging to compare human brain activity during force production by the right hand when subjects used a precision grip and a power grip. During the precision-grip task, subjects applied fine grip forces between the tips of the index finger and the thumb. During the power-grip task, subjects squeezed a cylindrical object using all digits in a palmar opposition grasp. The activity recorded in the primary sensory and motor cortex contralateral to the operating hand was higher when the power grip was applied than when subjects applied force with a precision grip. In contrast, the activity in the ipsilateral ventral premotor area, the rostral cingulate motor area, and at several locations in the posterior parietal and prefrontal cortices was stronger while making the precision grip than during the power grip. The power grip was associated predominately with contralateral left-sided activity, whereas the precision-grip task involved extensive activations in both hemispheres. Thus our findings indicate that in addition to the primary motor cortex, premotor and parietal areas are important for control of fingertip forces during precision grip. Moreover, the ipsilateral hemisphere appears to be strongly engaged in the control of precision-grip tasks performed with the right hand.
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| 23. |
- Ehrsson, HH, et al.
(författare)
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Differential fronto-parietal activation depending on force used in a precision grip task: an fMRI study
- 2001
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Ingår i: Journal of neurophysiology. - : American Physiological Society. - 0022-3077 .- 1522-1598. ; 85:6, s. 2613-2623
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Tidskriftsartikel (refereegranskat)abstract
- Recent functional magnetic resonance imaging (fMRI) studies suggest that the control of fingertip forces between the index finger and the thumb (precision grips) is dependent on bilateral frontal and parietal regions in addition to the primary motor cortex contralateral to the grasping hand. Here we use fMRI to examine the hypothesis that some of the areas of the brain associated with precision grips are more strongly engaged when subjects generate small grip forces than when they employ large grip forces. Subjects grasped a stationary object using a precision grip and employed a small force (3.8 N) that was representative of the forces that are typically used when manipulating small objects with precision grips in everyday situations or a large force (16.6 N) that represents a somewhat excessive force compared with normal everyday usage. Both force conditions involved the generation of time-variant static and dynamic grip forces under isometric conditions guided by auditory and tactile cues. The main finding was that we observed stronger activity in the bilateral cortex lining the inferior part of the precentral sulcus (area 44/ventral premotor cortex), the rostral cingulate motor area, and the right intraparietal cortex when subjects applied a small force in comparison to when they generated a larger force. This observation suggests that secondary sensorimotor related areas in the frontal and parietal lobes play an important role in the control of fine precision grip forces in the range typically used for the manipulation of small objects.
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| 24. |
- Ehrsson, H Henrik, et al.
(författare)
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Evidence for the involvement of the posterior parietal cortex in coordination of fingertip forces for grasp stability in manipulation
- 2003
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Ingår i: Journal of Neurophysiology. - : American Physiological Society. - 0022-3077 .- 1522-1598. ; 90:5, s. 2978-2986
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Tidskriftsartikel (refereegranskat)abstract
- Grasp stability during object manipulation is achieved by the grip forces applied normal to the grasped surfaces increasing and decreasing in phase with increases and decreases of destabilizing load forces applied tangential to the grasped surfaces. This force coordination requires that the CNS anticipates the grip forces that match the requirements imposed by the self-generated load forces. Here, we use functional MRI (fMRI) to study neural correlates of the grip-load force coordination in a grip-load force task in which six healthy humans attempted to lift an immovable test object held between the tips of the right index finger and thumb. The recorded brain activity was compared with the brain activity obtained in two control tasks in which the same pair of digits generated forces with similar time courses and magnitudes; i.e., a grip force task where the subjects only pinched the object and did not apply load forces, and a load force task, in which the subjects applied vertical forces to the object without generating grip forces. Thus neither the load force task nor the grip force task involved coordinated grip-load forces, but together they involved the same grip force and load force output. We found that the grip-load force task was specifically associated with activation of a section of the right intraparietal cortex, which is the first evidence for involvement of the posterior parietal cortex in the sensorimotor control of coordinated grip and load forces in manipulation. We suggest that this area might represents a node in the network of cortical and subcortical regions that implement anticipatory control of fingertip forces for grasp stability.
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| 25. |
- Ehrsson, H Henrik
(författare)
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Neural correlates of skilled movement : functional mapping of the human brain with fMRI and PET
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Humans have unique abilities to perform certain types of skilled voluntary movements. In this thesis we examine the neural substrates of. (i) fine digit actions, in particular the control of fingertip forces during manipulation, and (ii) the coordination of voluntary movements of different limbs. In addition, (iii) we investigate the neural correlates of the kinesthetic perception and imagery of limb movement. Functional magnetic resonance imaging and positron emission tomography were used to measure the blood oxygenation level dependent contrast and regional cerebral blood flow as indexes of neuronal activity. (i) We investigated the active cortical areas associated with the control of fingertip forces and production of hand postures with independent movements of the digits. In the fingertip force experiments the subjects used the right index finger and thumb to apply forces to a fixed object. These precision grip tasks consistently activated a set of bilateral fronto-parietal areas including the primary motor cortex (MI), the nonprimary motor areas and the posterior parietal cortex (PPC). It was found that the control of small grip forces during precision grips is more dependent on non-primary Eronto-parietal areas than when the force is excessively large or when a power grip is used between all digits and the palm. Specifically, we show that the bilateral ventral premotor cortex, area 44, supramarginal cortex and the right intraparietal cortex (IPS) are involved in the control of small precision grip forces. Furthermore, areas in the left PPC are involved in the control of lift forces for object displacement whereas the right posterior IPS might support the coordination of grip-lift forces during precision grips. Further, we show that M1 is particularly active during forceful gripping, but also so when holding an object close to the slip point requiring very precise force control. The SMA, CMA and left supramarginal cortex are also active in this latter task. We also demonstrate that the control of independent movements of the digits during the production of hand postures involves the SMA, the bilateral dorsal premotor cortex, postcentral cortex, cerebellum, and the left anterior IPS. In. summary, we conclude that fine digit actions in humans depend on a network of bilateral fronto-parietal areas that are active in a task-dependent manner. (ii) The brain regions controlling coordinated movements of limbs were examined. A main conclusion is that coordinated movements of two limbs are controlled by the areas that control isolated movements of the same limbs. In addition, we show that two natural pattems of bimanual temporal coordination are supported by distinct regions: the left anterior cerebellar lobe (and caudal CMA and precuneus) is associated with synchronous finger tapping, whilst alternating finger tapping strongly engages bilateral fronto-parieto-temporal areas. Furthermore, the media] cerebellum is strongly activated in polyrhythmic tasks. These results are discussed in relation to the hypothesis that different brain regions support temporal and spatial inter-limb coordination. (iii) The neural correlates of the kinesthetic perception and imagery of limb movement were examined. We show that when subjects experience an illusory limb movement elicited by vibration stimuli (~80 Hz) applied to the skin over the tendon of a muscle, the contralateral M1, S1, SMA, and CMA are active. Likewise, when subjects imagine that they are executing movements of their fingers, toes and tongue, some of the coffesponding gross somatotopical zones of the frontal motor areas are recruited. Thus the frontal motor areas are involved in the kinesthetic perception and imagery of limb movement, in addition to the execution of action.
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| 26. |
- Ehrsson, H. Henrik, et al.
(författare)
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Upper limb amputees can be induced to experience a rubber hand as their own
- 2008
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Ingår i: Brain. - : Oxford University Press (OUP). - 1460-2156 .- 0006-8950. ; 131:12, s. 3443-3452
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Tidskriftsartikel (refereegranskat)abstract
- We describe how upper limb amputees can be made to experience a rubber hand as part of their own body. This was accomplished by applying synchronous touches to the stump, which was out of view, and to the index finger of a rubber hand, placed in full view (26 cm medial to the stump). This elicited an illusion of sensing touch on the artificial hand, rather than on the stump and a feeling of ownership of the rubber hand developed. This effect was supported by quantitative subjective reports in the form of questionnaires, behavioural data in the form of misreaching in a pointing task when asked to localize the position of the touch, and physiological evidence obtained by skin conductance responses when threatening the hand prosthesis. Our findings outline a simple method for transferring tactile sensations from the stump to a prosthetic limb by tricking the brain, thereby making an important contribution to the field of neuroprosthetics where a major goal is to develop artificial limbs that feel like a real parts of the body.
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| 27. |
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| 28. |
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| 29. |
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| 30. |
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| 31. |
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| 32. |
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| 33. |
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| 34. |
- Elfsson, B, et al.
(författare)
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Stability of 5-aminolevulinic acid in aqueous solution
- 1999
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Ingår i: European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987. ; 7:2, s. 87-91
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Tidskriftsartikel (refereegranskat)
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| 35. |
- Gentile, Giovanni, et al.
(författare)
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Patterns of neural activity in the human ventral premotor cortex reflect a whole-body multisensory percept
- 2015
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Ingår i: NeuroImage. - : Elsevier. - 1053-8119 .- 1095-9572. ; 109, s. 328-340
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Tidskriftsartikel (refereegranskat)abstract
- Previous research has shown that the integration of multisensory signals from the body in fronto-parietal association areas underlies the perception of a body part as belonging to ones physical self. What are the neural mechanisms that enable the perception of ones entire body as a unified entity? In one behavioral and one fMRI multivoxel pattern analysis experiment, we used a full-body illusion to investigate how congruent visuo-tactile signals from a single body part facilitate the emergence of the sense of ownership of the entire body. To elicit this illusion, participants viewed the body of a mannequin from the first-person perspective via head-mounted displays while synchronous touches were applied to the hand, abdomen, or leg of the bodies of the participant and the mannequin; asynchronous visuo-tactile stimuli served as controls. The psychometric data indicated that the participants perceived ownership of the entire artificial body regardless of the body segment that received the synchronous visuo-tactile stimuli. Based on multivoxel pattern analysis, we found that the neural responses in the left ventral premotor cortex displayed illusion-specific activity patterns that generalized across all tested pairs of body parts. Crucially, a tripartite generalization analysis revealed the whole-body specificity of these premotor activity patterns. Finally, we also identified multivoxel patterns in the premotor, intraparietal, and lateral occipital cortices and in the putamen that reflected multisensory responses specific to individual body parts. Based on these results, we propose that the dynamic formation of a whole-body percept may be mediated by neuronal populations in the ventral premotor cortex that contain visuo-tactile receptive fields encompassing multiple body segments.
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| 36. |
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| 37. |
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| 38. |
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| 39. |
- Guterstam, Arvid, et al.
(författare)
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Decoding illusory self-location from activity in the human hippocampus
- 2015
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Ingår i: Frontiers in Human Neuroscience. - : FRONTIERS MEDIA SA. - 1662-5161. ; 9:412
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Tidskriftsartikel (refereegranskat)abstract
- Decades of research have demonstrated a role for the hippocampus in spatial navigation and episodic and spatial memory. However, empirical evidence linking hippocampal activity to the perceptual experience of being physically located at a particular place in the environment is lacking. In this study, we used a multisensory out-of-body illusion to perceptually teleport six healthy participants between two different locations in the scanner room during high-resolution functional magnetic resonance imaging (fMRI). The participants were fitted with MRI-compatible head-mounted displays that changed their first-person visual perspective to that of a pair of cameras placed in one of two corners of the scanner room. To elicit the illusion of being physically located in this position, we delivered synchronous visuo-tactile stimulation in the form of an object moving toward the cameras coupled with touches applied to the participants chest. Asynchronous visuo-tactile stimulation did not induce the illusion and served as a control condition. We found that illusory self-location could be successfully decoded from patterns of activity in the hippocampus in all of the participants in the synchronous (P less than 0.05) but not in the asynchronous condition (Pgreater than 0.05). At the group-level, the decoding accuracy was significantly higher in the synchronous than in the asynchronous condition (P = 0.012). These findings associate hippocampal activity with the perceived location of the bodily self in space, which suggests that the human hippocampus is involved not only in spatial navigation and memory but also in the construction of our sense of bodily self-location.
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| 40. |
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| 41. |
- Guterstam, Arvid, et al.
(författare)
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Posterior Cingulate Cortex Integrates the Senses of Self-Location and Body Ownership
- 2015
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Ingår i: Current Biology. - : Elsevier (Cell Press). - 0960-9822 .- 1879-0445. ; 25:11, s. 1416-1425
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Tidskriftsartikel (refereegranskat)abstract
- The senses of owning a body and being localized somewhere in space are two key components of human self-consciousness. Despite a wealth of neurophysiological and neuroimaging research on the representations of the spatial environment in the parietal and medial temporal cortices, the relationship between body ownership and self-location remains unexplored. To investigate this relationship, we used a multisensory out-of-body illusion to manipulate healthy participants perceived self-location, head direction, and sense of body ownership during high-resolution fMRI. Activity patterns in the hippocampus and the posterior cingulate, retrosplenial, and intraparietal cortices reflected the sense of self-location, whereas the sense of body ownership was associated with premotor-intraparietal activity. The functional interplay between these two sets of areas was mediated by the posterior cingulate cortex. These results extend our understanding of the role of the posterior parietal and medial temporal cortices in spatial cognition by demonstrating that these areas not only are important for ecological behaviors, such as navigation and perspective taking, but also support the perceptual representation of the bodily self in space. Our results further suggest that the posterior cingulate cortex has a key role in integrating the neural representations of self-location and body ownership.
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