Biology subjects

Ehrsson, H. H.

Publications and source records attributed to Ehrsson, H. H..

17 recordsLinked to original sources

bioRxiv2026

Beta oscillations support somatosensory temporal integration for body ownership

The sense of body ownership, the perceptual experience of what belongs to ones body, relies on the integration of self-related signals across multiple sensory modalities. Alpha oscillations modulate the temporal resolution of visuotactile integration for body ownership by constraining how visual and tactile signals from the body are temporally combined or segregated. However, body ownership can be supported and modulated in the absence of vision, for example during self-touch, raising the question of whether the same alpha-based temporal mechanism supports purely somatosensory integration. Here, we show that individual beta frequency (IBF), rather than alpha, predicts the temporal integration of tactile signals between the two hands in a somatic rubber hand illusion self-touch paradigm. IBF predicted the temporal window within which two tactile stimuli were judged as simultaneous and within which illusory self-touch body ownership was experienced. Moreover, while individual alpha frequency did not contribute to this purely somatosensory integration, IBF also did not predict the temporal resolution of visuotactile integration when visual body-related inputs were available. Together, these findings suggest a double dissociation in which frequency-specific oscillatory processes reflect the temporal integration of bodily signals in a modality-dependent manner: beta frequency emerges as the key correlate of somatosensory integration during self-touch, whereas alpha frequency governs visuotactile integration when vision is available.

neuroscience↗

bioRxiv2025

Parietal alpha frequency shapes own-body perception by modulating the temporal integration of bodily signals

An influential proposal in the field of cognitive neuroscience suggests that alpha-frequency brain oscillations constrain the temporal sampling of external sensory signals, shaping the temporal binding window (TBW)--the interval during which sensory signals are integrated. However, whether alpha frequency modulates the integration of self-related sensory signals and the perception of the body as ones own (body ownership) remains unknown. Here, we demonstrate that individual alpha frequency (IAF) from the parietal cortex predicted TBWs and perceptual sensitivities in body ownership and visuotactile simultaneity judgment tasks, with faster frequencies narrowing TBWs and increasing sensitivities, and vice versa. Modulating IAF through brain stimulation altered TBWs and sensitivities, establishing a causal relationship. Computational modeling linked IAF to uncertainty in asynchrony information within the causal inference process, providing a mechanism. These findings demonstrate that parietal alpha frequency shapes the sense of body ownership by modulating the temporal integration of bodily sensory signals.

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bioRxiv2024

Blind individuals' enhanced ability to sense their own heartbeat is related to the thickness of their occipital cortex

Blindness is associated with heightened sensory abilities, such as improved hearing and tactile acuity. Moreover, recent evidence suggests that blind individuals are better than sighted individuals at perceiving their own heartbeat, suggesting enhanced interoceptive accuracy. Structural changes in the occipital cortex have been hypothesized as the basis of these behavioral enhancements. Indeed, several studies have shown that congenitally blind individuals have increased cortical thickness within occipital areas compared to sighted individuals, but how these structural differences relate to behavioral enhancements is unclear. This study investigated the relationship between cardiac interoceptive accuracy and cortical thickness in 23 congenitally blind individuals and 23 matched sighted controls. Our results show a significant positive correlation between performance in a heartbeat counting task and cortical thickness only in the blind group, indicating a connection between structural changes in occipital areas and blind individuals better ability to perceive heartbeats.

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bioRxiv2023

Dynamic changes in somatosensory and cerebellar activity mediate temporal recalibration of self-touch

An organisms ability to accurately anticipate the sensations caused by its own actions is crucial for a wide range of behavioral, perceptual, and cognitive functions. Notably, the sensorimotor expectations produced when touching ones own body attenuate such sensations, making them feel weaker and less ticklish and rendering them easily distinguishable from potentially harmful touches of external origin. How the brain learns and keeps these action-related sensory expectations updated is unclear. We employed psychophysics and functional magnetic resonance imaging to pinpoint the behavioral and neural substrates of dynamic recalibration of expected temporal delays in self-touch. Psychophysical results revealed that self-touches were less attenuated after systematic exposure to delayed self-generated touches, while responses in the contralateral somatosensory cortex that normally distinguish between delayed and nondelayed self-generated touches became indistinguishable. During the exposure, the ipsilateral anterior cerebellum showed increased activity, supporting its proposed role in recalibrating sensorimotor predictions. Moreover, responses in the cingulate areas gradually increased, suggesting that as delay adaptation progresses, the nondelayed self-touches trigger activity related to cognitive conflict. Together, our results show that sensorimotor predictions in the simplest act of touching ones own body are upheld by a sophisticated and flexible neural mechanism that maintains them accurate in time.

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bioRxiv2023

The Sense of Body Ownership and the Neural Processes of Memory Encoding and Reinstatement

Every event we experience that results in a memory involves experiencing our conscious self at its heart. The spatial and perceptual experience of ones own body is the most basic form of selfhood. Disrupting bodily selfhood during memory formation impairs functioning of the hippocampus during retrieval, which implies a weakening of encoding mechanisms. However, neural activity present as individuals encode memories during manipulations of bodily selfhood have yet to be assessed. We investigated how body ownership, a core aspect of bodily selfhood, impacts encoding processes in the hippocampus and additional core memory regions (e.g. posterior parietal cortex). Further, we assessed the degree to which memories are reinstated according to body ownership during encoding and vividness during retrieval as a measure of memory strength. Participants viewed immersive videos through VR glasses, which depicted everyday events that included a first-person view of a mannequins body aligned with participants real bodies during fMRI scanning. We manipulated feelings of body ownership over the mannequin using a perceptual full-body illusion. One week later, participants retrieved memories for the videos during fMRI scanning. We observed that patterns of activity in several regions including the hippocampus and posterior parietal cortex distinguished between videos encoded with strong versus weak illusory body ownership. Moreover, these same regions reinstated memories to a greater degree when they were formed with a strong sense of body ownership and retrieved with increasing levels of vividness. Our findings demonstrate how the fundamental sense of owning ones body shape neural signatures of memory formation and strengthen reinstatement at retrieval.

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bioRxiv2022

Brief temporal perturbations in somatosensory reafference disrupt perceptual and neural attenuation and increase supplementary motor-cerebellar connectivity

Intrinsic delays in sensory feedback can be detrimental for motor control. As a compensation strategy, the brain predicts the sensory consequences of movement via a forward model on the basis of a copy of the motor command. Using these predictions, the brain attenuates the somatosensory reafference to facilitate the processing of exafferent information. Theoretically, this predictive attenuation gets disrupted by (even minimal) temporal errors between the predicted and the actual reafference, but direct evidence for such disruption is lacking since previous neuroimaging studies contrasted conditions of nondelayed reafferent input with exafferent one. Here, we combined psychophysics with functional magnetic resonance imaging to test whether subtle perturbations in the timing of somatosensory reafference disrupt its predictive processing. Twenty-eight participants generated touches on their left index finger by tapping a sensor with their right index finger. The touches on the left index finger were delivered at the time of the two fingers contact or with a 100 ms delay. We found that such brief temporal perturbations disrupted the attenuation of the somatosensory reafference both at the perceptual and neural level, leading to greater somatosensory and cerebellar responses and weaker somatosensory connectivity with the cerebellum proportionally to perceptual changes. Moreover, we observed increased connectivity of the supplementary motor area with the cerebellum during the perturbations. We interpret these effects as the failure of the forward model to predictively attenuate the delayed somatosensory reafference and the return of the prediction error to the motor centers, respectively. Significance statementOur brain receives the somatosensory feedback of our movements with delay. To counteract these delays, motor control theories postulate that the brain predicts the timing of the somatosensory consequences of our movements and attenuates sensations received at that timing. This makes a self-generated touch feel weaker than an identical external touch. However, how subtle temporal errors between the predicted and the actual somatosensory feedback perturb this predictive attenuation remains unknown. We show that such errors make the otherwise attenuated touch feel stronger, elicit stronger somatosensory responses, weaken the cerebellar connectivity with somatosensory areas, and increase it with motor areas. These findings show that motor and cerebellar areas are fundamental in forming temporal predictions about the sensory consequences of our movements.

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bioRxiv2022

Neural substrates of body ownership and agency during voluntary movement

Body ownership and the sense of agency are two central aspects of bodily self-consciousness. While multiple neuroimaging studies have investigated the neural correlates of body ownership and agency in isolation, few have investigated their relationship during voluntary movement when such experiences naturally combine. By eliciting the moving rubber hand illusion with active or passive finger movements during functional magnetic resonance imaging, we isolated activations reflecting the sense of body ownership and agency, respectively, as well as their interaction, and assessed their overlap and anatomical segregation. We found that perceived hand ownership was associated with activity in premotor, posterior parietal and cerebellar regions whereas the sense of agency over the hands movements was related to activity in the dorsal premotor cortex and superior temporal cortex. Moreover, one section of the dorsal premotor cortex showed overlapping activity for ownership and agency, and somatosensory cortical activity reflected the interaction of ownership and agency with higher activity when both agency and ownership was experienced. We further found that activations previously attributed to agency in the left insular cortex and right temporoparietal junction reflected the synchrony or asynchrony of the visuo-proprioceptive stimuli rather than agency. Collectively, these results identify the neural bases of agency and ownership during voluntary movement. Although the neural representations of these two experiences are largely distinct, there are functional neuroanatomical overlap and interactions during their combination, which has bearing on theories on bodily self-consciousness.

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bioRxiv2022

Cardiac interoception is enhanced in blind individuals

Blind individuals have superior abilities to perform perceptual tasks that rely on exteroceptive information, since visual deprivation is associated with massive cross-modal plasticity. However, it is unknown whether neuroplasticity after visual loss also affects interoception, i.e., the sensations arising from ones inner organs that convey information about the physiological state of the body. Herein, we examine the influence of blindness on cardiac interoception, which is an interoceptive submodality that has important links to emotional processing and bodily self-awareness. We tested 36 blind and 36 age-and sex-matched sighted volunteers and examined their cardiac interoceptive ability using a well-established heartbeat counting task. The results showed that blind individuals had significantly higher accuracy in perceiving their heartbeat than did individuals in a matched sighted control group. In contrast, there were no significant differences between the groups in the metacognitive dimensions of cardiac interception or the purely physiological measurement of heart rate, thereby underscoring that the improved accuracy likely reflects a superior perceptual sensitivity to cardiac interoceptive signals in blind individuals. We conclude that visual deprivation leads to enhanced interoception, which has important implications for the study of the extent of massive cross-modal plasticity after visual loss, understanding emotional processing in blind individuals, and learning how bodily self-awareness can develop and be sustained in the absence of visual experience.

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bioRxiv2022

Modeling tactile pleasantness across skin types at the individual level reveals a reliable and stable basic function

Touch is perceived most pleasant when delivered at velocities known to optimally activate C Tactile afferents. At the group level, pleasantness ratings of touch delivered at velocities in the range 0.3-30 cm/s follows an inverted-U shape curve, with maximum pleasantness between 1 and 10 cm/s. However, the prevalence, reliability, and stability of this function at the individual level and across skin types remains unknown. Here, we tested a range of seven velocities delivered with a soft brush, on both hairy and non-hairy skin in 123 participants. We showed that the relationship between pleasantness and velocity of touch is significantly best described by a negative quadratic model at the individual level in the majority of participants both on hairy (67.1%) and non-hairy skin (62.6%). Higher interoceptive accuracy and self-reported depression were related to a better fit of the quadratic model and to the steepness of the curve, respectively. The prevalence of the quadratic model was stable across body sites (62.6%), across two experimental sessions (73-78%,), and regardless of the number of trials. Thus, the individual perception of tactile pleasantness follows a characteristic velocity-dependent function across skin types and shows trait characteristics, making it a possible biomarker for mental health disorders.

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bioRxiv2021

Thermosensation as a novel method to probe interoception and its relationship with other interoceptive modalities

Interoception includes signals originating both from inside the body and from its surface, the skin. Here, we focused on the perception of temperature, a crucial modality for the maintenance of homeostasis. We used a classic (static) thermal detection task and developed a new dynamic thermal matching task, in which participants have to match a previously perceived moving thermal stimulus on the skin to a range of colder or warmer stimuli, presented in increasing or decreasing order. We investigated both hairy (forearm) and non-hairy (palm) skin, in keeping with previous tactile studies targeting the potential involvement of C-tactile fibres, which are part of an afferent homeostatic system found mainly on hairy skin. We also aimed at investigating the relationship between performance on the two thermal tasks and on three other tasks in different interoceptive sub-modalities: cardiac perception, affective touch, and pain detection. We found a significantly more accurate perception of dynamic temperature on hairy compared to non-hairy skin overall, particularly when the temperature was decreasing. Static perception of cooling was also superior on hairy skin and was related to dynamic temperature and pain only on non-hairy skin. Thus, our results suggest that hairy skin may have higher thermosensitivity than non-hairy skin and that dynamic thermosensation might offer a promising avenue to investigate thermosensation as a skin-based interoceptive submodality. Critically, we did not find any other significant relationship in performance among the four interoceptive modalities examined, which indicates independent processing and that interoception might be best quantified using a battery of tests.

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bioRxiv2021

No evidence for somatosensory attenuationduring action observation of self-touch

The discovery of mirror neurons in the macaque brain in the 1990s triggered investigations on putative human mirror neurons and their potential functionality. The leading proposed function has been action understanding: accordingly, we understand the actions of others by simulating them in our own motor system through a direct matching of the visual information to our own motor programs. Furthermore, it has been proposed that this simulation involves the prediction of the sensory consequences of the observed action, similar to the prediction of the sensory consequences of our executed actions. Here, we tested this proposal by quantifying somatosensory attenuation behaviorally during action observation. Somatosensory attenuation manifests during voluntary action and refers to the perception of self-generated touches as less intense than identical externally generated touches because the self-generated touches are predicted from the motor command. Therefore, we reasoned that if an observer simulates the observed action and, thus, he/she predicts its somatosensory consequences, then he/she should attenuate tactile stimuli simultaneously delivered to his/her corresponding body part. In three separate experiments, we found a systematic attenuation of touches during executed self-touch actions, but we found no evidence for attenuation when such actions were observed. Failure to observe somatosensory attenuation during observation of self-touch is not compatible with the hypothesis that the putative human mirror neuron system automatically simulates the observed action. In contrast, our findings emphasize a sharp distinction between the motor representations of self and others.

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bioRxiv2020

Predictive attenuation of touch and tactile gating are distinct perceptual phenomena

In recent decades, research on somatosensory perception has led to two important observations. First, self-generated touches that are predicted by voluntary movements become attenuated compared to externally generated touches of the same intensity (attenuation). Second, externally generated touches feel weaker and are more difficult to detect during movement than at rest (gating). Currently, researchers often consider gating and attenuation the same suppression process; however, this assumption is unwarranted because, despite more than forty years of research, no study has combined them in a single paradigm. We quantified how people perceive self-generated and externally generated touches during movement and rest. We show that whereas voluntary movement gates the precision of both self-generated and externally generated touch, the amplitude of self-generated touch is robustly attenuated compared to externally generated touch. Furthermore, attenuation and gating do not interact and are not correlated, and we conclude that they represent distinct perceptual phenomena.

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bioRxiv2020

The contribution of stimulating multiple body parts simultaneously to the illusion of owning an entire artificial body

The full-body ownership illusion exploits multisensory perception to induce a feeling of ownership for an entire artificial body. Whilst previous research has shown that the synchronous visuotactile stimulation of a single body part is sufficient for illusory ownership over the whole body, the effect of combining multisensory stimulation across multiple body parts remains unknown. Therefore, 48 healthy adults participated in conditions of a full-body ownership illusion involving synchronous or asynchronous visuotactile stimulation to one, two or three body parts simultaneously (2 x 3 design). We developed a novel questionnaire to isolate the sense of ownership of five specific body parts (left leg, right leg, left arm, right arm, and trunk) from the full-body ownership experience and sought not only to test for greater (part and whole) body ownership in synchronous versus asynchronous stimulation, but also, potentially varying degrees of illusion intensity related to the number of body parts stimulated. As expected, illusory full-body ownership and all five body-part ownership ratings were significantly higher following synchronous stimulation (all p values [≤].01). Since non-stimulated body parts also received significantly higher ownership ratings following synchronous stimulation, the results are consistent with an illusion engaging the entire body. We further noted that ownership ratings for the right body parts (often stimulated) were significantly higher than ownership ratings for the left body parts (never stimulated). Regarding explicit feelings of full-body ownership, subjective ratings were not significantly enhanced by increasing the number of synchronously stimulated body parts (synchronicity x number stimulated interaction; p.099). Instead, median ratings indicated a moderate affirmation (+1) of full-body illusory sensation for all three synchronous conditions; a finding mirrored by full-body illusion onset time. The results support the notion that feelings of full-body ownership are mediated by a generalisation from stimulated part(s)-to-whole, supported by processes related to multisensory body perception.

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bioRxiv2020

Fluidity of gender identity induced by illusory body-sex change.

Gender identity is the inner sense of being male, female, both, or neither. How this sense is linked to the perception of ones own masculine or feminine body remains unclear. Here, in a series of three behavioral experiments conducted on a large group of healthy volunteers (N=140), we show that a perceptual illusion of having the opposite-sex body was associated with a shift toward more balanced identification with both genders and less gender-stereotypical beliefs about ones own personality characteristics, as indicated by subjective reports and implicit behavioral measures. These findings demonstrate that the ongoing perception of ones own body affects the sense of ones own gender in a dynamic, robust, and automatic manner.

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bioRxiv2019

Functional connectivity between the cerebellum and somatosensory areas implements the attenuation of self-generated touch

Since the early 1970s, numerous behavioral studies have shown that self-generated touch feels less intense than the same touch applied externally. Computational motor control theories have suggested that cerebellar internal models predict the somatosensory consequences of our movements and that these predictions attenuate the perception of the actual touch. Despite this influential theoretical framework, little is known about the neural basis of this predictive attenuation. This is due to the limited number of neuroimaging studies, the presence of conflicting results about the role and the location of cerebellar activity, and the lack of behavioral measures accompanying the neural findings. Here, we combined psychophysics with functional magnetic resonance imaging to detect the neural processes underlying somatosensory attenuation in male and female healthy human participants. Activity in bilateral secondary somatosensory areas was attenuated when the touch was presented during a self-generated movement (self-generated touch) than in the absence of movement (external touch). An additional attenuation effect was observed in the cerebellum that is ipsilateral to the passive limb receiving the touch. Importantly, we further found that the degree of functional connectivity between the ipsilateral cerebellum and the contralateral primary and bilateral secondary somatosensory areas was linearly and positively related to the degree of behaviorally assessed attenuation; that is, the more participants perceptually attenuated their self-generated touches, the stronger this corticocerebellar coupling. Collectively, these results suggest that the ipsilateral cerebellum is fundamental in predicting self-generated touch and that this structure implements somatosensory attenuation via its functional connectivity with somatosensory areas.\n\nSignificance statementWhen we touch our hand with the other, the resulting sensation feels less intense than when another person or a machine touches our hand with the same intensity. Early computational motor control theories have proposed that the cerebellum predicts and cancels the sensory consequences of our movements; however, the neural correlates of this cancelation remain unknown. By means of functional magnetic resonance imaging, we show that the more participants attenuate the perception of their self-generated touch, the stronger the functional connectivity between the cerebellum and the somatosensory cortical areas. This provides conclusive evidence about the role of the cerebellum in predicting the sensory feedback of our movements and in attenuating the associated percepts via its connections to early somatosensory areas.

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bioRxiv2019

Efference copy is necessary for the attenuation of self-generated touch

A self-generated touch feels less intense than an external touch of the exact same intensity. According to a prevalent computational theory of motor control, this attenuation occurs because the brain uses internal forward models to predict the somatosensory consequences of our movements using a copy of the motor command, i.e., the efference copy. These tactile predictions are then used to suppress the perceived intensity of the actual tactile feedback. Despite being highly influential, the core assumption of theory has never been tested; that is, whether the efference copy is necessary for somatosensory attenuation. A possible alternative hypothesis is that a predictable contact of two of ones own body parts is sufficient. Using a psychophysical task, we quantified the attenuation of touch applied on the participants left index finger when the touch was triggered by the active or passive movement of the participants right index finger and when it was externally generated in the absence of any movement. We observed somatosensory attenuation only when the touch was triggered by the voluntary movement of the participants finger. In contrast, during the passive movement, the intensity of the touch was perceived to be as strong as when the touch was externally triggered. In both active and passive movement conditions, the participants showed the same discrimination capacity. Electromyographic recordings confirmed minimal activity of the right hand during the passive movement. Together, our results suggest that the efference copy is necessary for computing the somatosensory predictions that produce the attenuation of self-generated touch.

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bioRxiv2019

Rapid learning and unlearning of predicted sensory delays in self-generated touch

Self-generated touch feels less intense and less ticklish than identical externally generated touch. This somatosensory attenuation occurs because the brain predicts the tactile consequences of our self-generated movements. To produce attenuation, the tactile predictions need to be time-locked to the movement, but how the brain maintains this temporal tuning remains unknown. Using a bimanual self-touch paradigm, we demonstrate that people can rapidly unlearn to attenuate touch immediately after their movement and learn to attenuate delayed touch instead, after repeated exposure to a systematic delay between the movement and the resulting touch. The magnitudes of the unlearning and learning effects are correlated and dependent on the number of trials that participants have been exposed to. We further show that delayed touches feel less ticklish and non-delayed touches more ticklish after exposure to the systematic delay. These findings demonstrate that the attenuation of self-generated touch is adaptive.

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