The first goal is to test whether the temporary disruption of the right TPJ leads to changes in the functional connectivity between brain areas that are related to body awareness.Second, the study intends to test how temporary inhibition of the TPJ…
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Brief title
Condition
- Other condition
- Psychiatric disorders NEC
Synonym
Health condition
Basic brain function in healthy humans
Research involving
Sponsors and support
Intervention
Outcome measures
Primary outcome
For the first objective, changes in brain activation and functional
connectivity will be measured before and after a single session of reptitive
trancranial magnetic stimulation (rTMS) on the right temporo-parietal junction
(rTPJ).
The main study parameter will be changes resting-state fMRI measured in the
BOLD (blood-oxygen-level-dependent) signal prior to and after repetitive TMS.
Secondary outcome
For the second objective concerning the out-of-body illusion, the main study
parameters are
1) The self report questionnaires assessing global self attribution of the
virtual body, anomalous body experiences, and depersonalization experiences;
2) The global self-localization assessed by a documented felt shift of
self-location measured in centimetres in a drawn map of the room.
3) Changes in the heart rate after the threat condition during the behavioural
paradigm. Former studies have shown that participants depict elevated skin
conductance response when the virtual body is artificially attacked with a
hammer. Relatedly, we want to use a threat to the illusory body affects the
participants physiology (heart rate) as objective marker to test the illusory
body.
Additionally, it will be investigated if certain trait characteristic influence
functional connectivity and possibly increase susceptibility to the out-of-body
illusion. As such, hallucinatory proneness, alexithymia, depersonalization, and
dissociation will be assessed via validated self-report questionnaires.
Furthermore, former life events and traumatic experiences will investigated. To
control for possible confounding effects, participants will be asked if they
have ever suffered from vestibular dysfunctions and out-of-body experiences.
Background summary
There is good reason to suspect that anomalous body experience, such as the
out-of-body (OBE) experiences, arise to a lack in integrative capacity of the
brain trying to make sense of ambiguous input. Cognitive neuroscientist suggest
that one of the key regions involved in the multisensory integration necessary
to establish a coherent sense of body awareness is the temporo-parietal
junction (TPJ). Perturbation studies employing transcranial magnetic
stimulation to temporarily inhibit a certain brain region indicate that
disruptions in TPJ neural activity affected performances in behavioural
paradigms such as the rubber hand illusion , mental own-body transformations,
or the mirror box illusion. However, causal evidence is scare regarding the
question how a temporary inhibition of the TPJ affects the functional
connectivity with the brain network involved for an integrated sense of
selfhood. Furthermore, little is known about how temporary perturbations at the
TPJ relate to out-of-body-experiences (OBE) and if these changes are associated
with depersonalization.
Study objective
The first goal is to test whether the temporary disruption of the right TPJ
leads to changes in the functional connectivity between brain areas that are
related to body awareness.
Second, the study intends to test how temporary inhibition of the TPJ affects
the perception of bodily self-consciousness tested by an behavioural paradigm
designed to induce out-of body sensations.
Study design
The study will occupy a sham-controlled, randomized, pre-post TMS design.
Participants will randomly assigned into either an active TMS condition or a
sham TMS condition. All participants will follow the same procedure including
answer a set of self-report questionnaires, undergo two fMRI scans, one TMS
session, and take part in a OBE illusory behavioural paradigm before and after
TMS.
Intervention
The intervention consists of an transmagnetic stimulation protocol (TMS).
Participants will receive 600 pulses of continuous theta burst stimulation
(duration: 40 seconds) on the right temporoparietal junction (rTPJ). Before and
after the stimulation, participants will undergo a behavioural paradigm, namely
the out-of-body illusion, to test changes in body awareness, and a
resting-state fMRI scan. During the out-of-body illusion paradigm, participants
are seated in front of a camera filming their back in real-time. Participants
wear a head-mounted device (HDM), which is connected to two cameras
corresponding with the left and right eye. Therefore, the participants observe
their own back from the perspective of someone sitting behind them. To induce
the illusionary experience, the experimenter stands next to the participant and
camera and simultaneous strokes the participants chest and the chest of the
illusory body with a rod. To test if the manipulation was successful, we ask
participants to 1) undergo a "fake" hammer attack in which a hammer will be
moved towards the camera to test for a physiological startle response (heart
rate), 2) indicate their felt sense of self-location by means of a spatial map
of the room, and 3) answer a self-report questionnaire concerning their
out-of-body experience. State dissociation will be assessed after each step of
the experiment.
Study burden and risks
The experiment will take approximately 105 minutes in total. Participants must
undergo one screening session and one experimental session consisting of two
fMRI scans, repetitive TMS, a behavioural paradigm, and answering a set of
questionnaires. So far, few to none risks have been reported regarding exposure
to these study techniques in healthy participants. Possibly, laying in the
scanner, the stimulation or the induction of OBE illusion might create slight
discomfort in some participants. Regular check-ups for the participants*
well-being and other tools, i.e. in-ear plugs for noise reduction, will be in
place to address these issues. Participants do not directly benefit from the
experiment, but will be compensated for their participation.
Grote Kruisstraat 2
Groningen 9712 TS
NL
Grote Kruisstraat 2
Groningen 9712 TS
NL
Listed location countries
Age
Inclusion criteria
In order to be eligible to participate in this study, a subject must meet all of the following criteria:
1) Participants must be 18 years or older
2) Participants must be female
3) Participants must be right-handed
4) Participants must be capable of giving consent
5) Participants must be able to communicate in English
Exclusion criteria
A potential subject who meets any of the following criteria will be excluded from participation in this study:;1) A current diagnosis of a neurological disorder, i.e. epilepsy
2) A current diagnosis of psychiatric disorder
3) Presence of metallic devices, e.g. metal implants, non-removable piercings, or cardiac pacemaker
4) Psychotropic medication intake in the last 6 months
5) Claustrophobia
6) Alcohol or drug abuse
7) Refusal that general practitioner will be informed in the case of incidental findings of structural brain abnormalities
8) Use of medication related with increased epileptic seizure risk
9) Current tinnitus
10) (At risk of being) pregnant
Design
Recruitment
Followed up by the following (possibly more current) registration
No registrations found.
Other (possibly less up-to-date) registrations in this register
No registrations found.
In other registers
| Register | ID |
|---|---|
| CCMO | NL67897.042.18 |