| 1. |
- Bergouignan, Loretxu, et al.
(author)
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Out-of-body-induced hippocampal amnesia
- 2014
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In: 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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Journal article (peer-reviewed)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.
(author)
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Out-of-body memory encoding causes third-person perspective at recall
- 2022
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In: Journal of Cognitive Psychology. - : Taylor & Francis Group. - 2044-5911 .- 2044-592X. ; 34:1, s. 160-178
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Journal article (peer-reviewed)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. |
- Crucianelli, Laura, et al.
(author)
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Interoception as independent cardiac, thermosensory, nociceptive, and affective touch perceptual submodalities
- 2022
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In: Biological Psychology. - Stockholm : Karolinska Institutet, Dept of Neuroscience. - 0301-0511 .- 1873-6246.
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Journal article (peer-reviewed)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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| 4. |
- Crucianelli, Laura, et al.
(author)
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The role of the skin in interoception : a neglected organ?
- 2022
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In: Perspectives on Psychological Science. - Stockholm : Karolinska Institutet, Dept of Neuroscience. - 1745-6916 .- 1745-6924.
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Journal article (peer-reviewed)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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| 5. |
- Crucianelli, Laura, et al.
(author)
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Visuo-thermal congruency modulates the sense of body ownership
- 2022
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In: Communications Biology. - Stockholm : Karolinska Institutet, Dept of Neuroscience. - 2399-3642.
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Journal article (peer-reviewed)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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| 6. |
- Ehrsson, H Henrik, et al.
(author)
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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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In: Journal of Neurophysiology. - : American Physiological Society. - 0022-3077 .- 1522-1598. ; 90:5, s. 2978-2986
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Journal article (peer-reviewed)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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| 7. |
- Ehrsson, H Henrik
(author)
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Neural correlates of skilled movement : functional mapping of the human brain with fMRI and PET
- 2001
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Doctoral thesis (other academic/artistic)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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| 8. |
- Ehrsson, H. Henrik, et al.
(author)
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Upper limb amputees can be induced to experience a rubber hand as their own
- 2008
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In: Brain. - : Oxford University Press (OUP). - 1460-2156 .- 0006-8950. ; 131:12, s. 3443-3452
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Journal article (peer-reviewed)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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| 9. |
- Gentile, Giovanni, et al.
(author)
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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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In: NeuroImage. - : Elsevier. - 1053-8119 .- 1095-9572. ; 109, s. 328-340
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Journal article (peer-reviewed)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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| 10. |
- Guterstam, Arvid, et al.
(author)
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Decoding illusory self-location from activity in the human hippocampus
- 2015
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In: Frontiers in Human Neuroscience. - : FRONTIERS MEDIA SA. - 1662-5161. ; 9:412
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Journal article (peer-reviewed)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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| 11. |
- Guterstam, Arvid, et al.
(author)
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Posterior Cingulate Cortex Integrates the Senses of Self-Location and Body Ownership
- 2015
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In: Current Biology. - : Elsevier (Cell Press). - 0960-9822 .- 1879-0445. ; 25:11, s. 1416-1425
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Journal article (peer-reviewed)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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| 12. |
- Jenmalm, Per, et al.
(author)
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Lighter or heavier than predicted : neural correlates of corrective mechanisms during erroneously programmed lifts
- 2006
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In: Journal of Neuroscience. - Bethesda, Md. : Society for Neuroscience. - 0270-6474 .- 1529-2401. ; 26:35, s. 9015-9021
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Journal article (peer-reviewed)abstract
- A central concept in neuroscience is that the CNS signals the sensory discrepancy between the predicted and actual sensory consequences of action. It has been proposed that the cerebellum and parietal cortex are involved in this process. A discrepancy will trigger preprogrammed corrective responses and update the engaged sensorimotor memories. Here we use functional magnetic resonance imaging with an event-related design to investigate the neuronal correlates of such discrepancies. Healthy adults repeatedly lifted an object between their right index fingers and thumbs, and on some lifting trials, the weight of the object was unpredictably changed between light (230 g) and heavy (830 g). Regardless of whether the weight was heavier or lighter than predicted, activity was found in the right inferior parietal cortex (supramarginal gyrus). This suggests that this region is involved in the comparison of the predicted and actual sensory input and the updating of the sensorimotor memories. When the object was lighter or heavier than predicted, two different types of preprogrammed force corrections occurred. There was a slow force increase when the weight of the object was heavier than predicted. This corrective response was associated with activity in the left primary motor and somatosensory cortices. The fast termination of the excessive force when the object was lighter than predicted activated the right cerebellum. These findings show how the parietal cortex, cerebellum, and motor cortex are involved in the signaling of the discrepancy between predicated and actual sensory feedback and the associated corrective mechanisms.
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| 13. |
- Petkova, Valeria I, et al.
(author)
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From part- to whole-body ownership in the multisensory brain.
- 2011
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In: Current Biology. - Cambridge, MA, United States : Cell Press. - 0960-9822 .- 1879-0445. ; 21:13, s. 1118-1122
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Journal article (peer-reviewed)abstract
- The question of how we experience ownership of an entire body distinct from the external world is a fundamental problem in psychology and neuroscience [1-6]. Earlier studies suggest that integration of visual, tactile, and proprioceptive information in multisensory areas [7-11] mediates self-attribution of single limbs. However, it is still unknown how ownership of individual body parts translates into the unitary experience of owning a whole body. Here, we used a "body-swap" illusion [12], in which people experienced an artificial body to be their own, in combination with functional magnetic resonance imaging to reveal a coupling between the experience of full-body ownership and neural responses in bilateral ventral premotor and left intraparietal cortices, and left putamen. Importantly, activity in the ventral premotor cortex reflected the construction of ownership of a whole body from the parts, because it was stronger when the stimulated body part was attached to a body, was present irrespective of whether the illusion was triggered by stimulation of the hand or the abdomen, and displayed multivoxel patterns carrying information about full-body ownership. These findings suggest that the unitary experience of owning an entire body is produced by neuronal populations that integrate multisensory information across body segments.
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| 14. |
- Radziun, Dominika, et al.
(author)
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Limits of cross-modal plasticity? Short-term visual deprivation does not enhance cardiac interoception, thermosensation, or tactile spatial acuity
- 2022
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In: Biological Psychology. - Stockholm : Karolinska Institutet, Dept of Neuroscience. - 0301-0511 .- 1873-6246.
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Journal article (peer-reviewed)abstract
- In the present study, we investigated the effect of short-term visual deprivation on discriminative touch, cardiac interoception, and thermosensation by asking 64 healthy volunteers to perform four behavioral tasks. The experimental group contained 32 subjects who were blindfolded and kept in complete darkness for 110 minutes, while the control group consisted of 32 volunteers who were not blindfolded but were otherwise kept under identical experimental conditions. Both groups performed the required tasks three times: before and directly after deprivation (or control) and after an additional washout period of 40 minutes, in which all participants were exposed to normal light conditions. Our results showed that short- term visual deprivation had no effect on any of the senses tested. This finding suggests that short-term visual deprivation does not modulate basic bodily senses and extends this principle beyond tactile processing to the interoceptive modalities of cardiac and thermal sensations.
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| 15. |
- Rosén, Birgitta, et al.
(author)
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Referral of sensation to an advanced humanoid robotic hand prosthesis.
- 2009
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In: Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery. - : Informa UK Limited. - 1651-2073 .- 0284-4311. ; 43:5, s. 260-266
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Journal article (peer-reviewed)abstract
- Hand prostheses that are currently available on the market are used by amputees to only a limited extent, partly because of lack of sensory feedback from the artificial hand. We report a pilot study that showed how amputees can experience a robot-like advanced hand prosthesis as part of their own body. We induced a perceptual illusion by which touch applied to the stump of the arm was experienced from the artificial hand. This illusion was elicited by applying synchronous tactile stimulation to the hidden amputation stump and the robotic hand prosthesis in full view. In five people who had had upper limb amputations this stimulation caused referral touch sensation from the stump to the artificial hand, and the prosthesis was experienced more like a real hand. We also showed that this illusion can work when the amputee controls the movements of the artificial hand by recordings of the arm muscle activity with electromyograms. These observations indicate that the previously described "rubber hand illusion" is also valid for an advanced hand prosthesis, even when it has a robotic-like appearance.
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| 16. |
- Schmitz, Christina, et al.
(author)
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Brain activity during predictable and unpredictable weight changes when lifting objects.
- 2005
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In: Journal of Neurophysiology. - : American Physiological Society. - 0022-3077 .- 1522-1598. ; 93:3, s. 1498-509
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Journal article (peer-reviewed)abstract
- When humans repetitively lift the same object, the fingertip forces are targeted to the weight of the object. The anticipatory programming of the forces depends on sensorimotor memory representations that provide information on the object weight. In the present study, we investigate the neural substrates of these sensorimotor memory systems by recording the neural activity during predictable or unpredictable changes in the weight of an object in a lifting task. An unpredictable change in weight leads to erroneous programming of the fingertip forces. This triggers corrective mechanisms and an update of the sensorimotor memories. In the present fMRI study, healthy right-handed subjects repetitively lifted an object between right index finger and thumb. In the constant condition, which served as a control, the weight of the object remained constant (either 230 or 830 g). The weight alternated between 230 and 830 g during the regular condition and was irregularly changed between the two weights during the irregular condition. When we contrasted regular minus constant and irregular minus constant, we found activations in the right inferior frontal gyrus pars opercularis (area 44), the left parietal operculum and the right supramarginal gyrus. Furthermore, irregular was associated with stronger activation in the right inferior frontal cortex as compared with regular. Taken together, these results suggest that the updating of sensorimotor memory representations and the corrective reactions that occur when we manipulate different objects correspond to changes in synaptic activity in these fronto-parietal circuits.
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