1. |
- 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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2. |
- 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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3. |
- Björkman, Anders, et al.
(författare)
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Phantom digit somatotopy: a functional magnetic resonance imaging study in forearm amputees.
- 2012
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Ingår i: European Journal of Neuroscience. - : Wiley. - 1460-9568 .- 0953-816X. ; 36:1, s. 2098-2106
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Tidskriftsartikel (refereegranskat)abstract
- Forearm amputees often experience non-painful sensations in their phantom when the amputation stump is touched. Cutaneous stimulation of specific stump areas may be perceived as stimulation of specific phantom fingers (stump hand map). The neuronal basis of referred phantom limb sensations is unknown. We used functional magnetic resonance imaging to demonstrate a somatotopic map of the phantom fingers in the hand region of the primary somatosensory cortex after tactile stump stimulation. The location and extent of phantom finger activation in the primary somatosensory cortex corresponded well to the location of normal fingers in a reference population. Stimulation of the stump hand map resulted in an increased bilateral activation of the primary somatosensory cortex compared with stimulation of forearm regions outside the stump hand map. Increased activation was also seen in contralateral posterior parietal cortex and premotor cortex. Ipsilateral primary somatosensory cortex activation might represent a compensatory mechanism and activation of the non-primary fronto-parietal areas might correspond to awareness of the phantom limb, which is enhanced when experiencing the referred sensations. It is concluded that phantom sensation elicited by stimulation of stump hand map areas is associated with activation of finger-specific somatotopical representations in the primary somatosensory cortex. This suggests that the primary somatosensory cortex could be a neural substrate of non-painful phantom sensations. The stump hand map phenomenon might be useful in the development of prosthetic hand devices.
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4. |
- 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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5. |
- 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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6. |
- 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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7. |
- 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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8. |
- 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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9. |
- 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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10. |
- 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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