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The roles of occipital and parietal regions in visual awareness: A Transcranial Magnetic Stimulation study

The roles of occipital and parietal regions in visual awareness: A Transcranial Magnetic Stimulation study - TMS for visual awareness

Status
Recruiting
Phases
Unknown
Study type
Interventional
Source
NL-OMON
Registry ID
NL-OMON33292
Enrollment
60
Registered
2009-05-29
Start date
2009-07-01
Completion date
Unknown
Last updated
2024-05-06

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

niet van toepassing nvt

Interventions

We will use 40-second continuous theta-burst stimulation (cTBS). cTBS refers to a simulation paradigm in which participants receive brief trains of pulses of 50 Hz in a 5 Hz (the theta frequency) rh
Classen & Stefan 2007), but recent studies showed an effect of cTBS on V1 (Franca et al., 2006), PPC, and vertex (Hilgetag et al. 2001
Nyffeler et al., 2008). Thus, cTBS has already been tested and found safe as a method of stimulating all the regions that we will target in the present study.

Sponsors

Radboud Universiteit Nijmegen
Lead Sponsor

Eligibility

Age
18 Years to 99 Years

Inclusion criteria

Inclusion criteria: Right-handed individuals, with normal or corrected-to-normal vision and no history of neurological or psychological disorders are included.

Exclusion criteria

Exclusion criteria: - Pacemaker - Metal parts in head or mouth - History of brain surgery - History of epilepsy or first-grade family member with epilepsy - Psychological or neurological disorder - Pregnancy

Design outcomes

Primary

MeasureTime frame
The effect of TMS on the three stimulation sites in the main experiment will be assessed using a visual task performed in an fMRI scanner. We will test whether stimulation to V1, PPC, and vertex differentially affected subjects* visibility ratings. We predict that V1 stimulation will lead to decrease in visibility ratings for gratings presented anywhere in the visual field, while PPC stimulation will only affect the visibility of gratings in the contralateral visual field. Vertex stimulation is not expected to have any effects on visibility ratings. Further, we predict that the changes in visibility rating will be mediated by changes in the activation patterns in the prefrontal cortex and will test for that in the fMRI part of the experiment.

Secondary

MeasureTime frame
The effectiveness of TMS stimulation will be assessed in a pilot experiment. We will test whether stimulation to V1, PPC, and vertex differentially affected subjects* visibility ratings. Again, we predict that V1 stimulation will lead to decrease in visibility ratings for gratings presented anywhere in the visual field, while PPC stimulation will only affect the visibility of gratings in the contralateral visual field. Vertex stimulation is not expected to have any effects on visibility ratings. In the pilot experiment we will only collect behavioural data in order to assess the effectiveness of TMS.

Countries

Netherlands

Outcome results

None listed

Source: NL-OMON (via WHO ICTRP)