The aim of this study is to causally dissociate the time course of scene-assisted and isolated object recognition and provide evidence for a direct feedback processing from scene- to object-selective cortex, as well as investigate the role of…
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Brief title
Condition
- Other condition
Synonym
Health condition
Niet van toepassing - onderzoek bij gezonde vrijwilligers
Research involving
Sponsors and support
Intervention
Outcome measures
Primary outcome
In experiment 1 the main parameter is the percentage of correct categorization.
Participants choose between four options for object and scene stimuli. In
experiment 2 the main parameters are percentage of correct animacy detection.
Participants have to categorize an isolated object, or object in scene as
animate (humans, animals, etc.) or inanimate (houses, cars, etc.).
Secondary outcome
In experiment 2 the secondary parameter is reaction time.
Background summary
The human visual cortex is able to rapidly categorize objects. In ambiguous
situations contextual information from the surrounding scene can help this
process. This implies that the early visual cortex, receiving visual
information, object-selective visual cortex and scene-selective cortex have to
interact. Indeed, neuroimaging studies have provided evidence for such
interactions. However, causal evidence as well as the specific timing of when
the visual information is processed remains elusive.
Study objective
The aim of this study is to causally dissociate the time course of
scene-assisted and isolated object recognition and provide evidence for a
direct feedback processing from scene- to object-selective cortex, as well as
investigate the role of feedback to V1.
Study design
A two-part within-subjects design. In the first experimental session
sensitivity to TMS over object- and scene-selective cortex will be determined
by replicating the study of Dilks et al. (2013). Based on participants*
behavioural response to transcranial magnetic stimulation (TMS), they will
perform one of three experiments in the second session. In each of these
experiments participant rate whether an object is animate or inanimate.
Degraded objects will be shown with scene background, or isolated (intact)
objects will be shown. In experiment 2a TMS over right object-selective cortex
will be given at different time points: early (60-100 milliseconds afters
visual presenation), middle (160-200 milliseconds after visual presenation),
and late (260-300 milliseconds after visual presentation). The different
timings allow for investigating the processing of isolated objects versus
objects in scenes. In experiment 2b TMS will be delivered over right
scene-selective cortex at the same time points. This allows for investigating
the role of scene-related information processing during object categorization.
Finally, in experiment 2c TMS will be delivered over V1 at the same time
points. This allows for investigating the role of early visual cortex in object
categorization.
Intervention
TMS will be applied to interfere with ongoing brain activity. In experiment 1
five pulses separated by 100 ms will be given per trial (following the
procedure of Dilks et al., 2013). In experiment 2 two pulses separated by 40 ms
will be given per trial.
Study burden and risks
The currently proposed TMS paradigms do not carry any significant risks. Safety
guidelines as acknowledged by the International Federation of Clinical
Neurophysiology will be followed strictly. Potential side-effects are fatigue
and headache. These are generally mild discomforts that respond promptly to
common analgesics. Volunteers can withdraw from the study at any given time and
there are no direct benefits for the participants.
Montessorilaan 3
Nijmegen 6525HR
NL
Montessorilaan 3
Nijmegen 6525HR
NL
Listed location countries
Age
Inclusion criteria
Between 18-35 years of age years; Right-handed; Non-smoking; Normal or corrected-to-normal vision; Willingness and ability to give written informed consent and willingness and ability to understand the nature and content, to participate and to comply with the study requirements.
Exclusion criteria
1) Average use of more than 3 alcoholic beverages daily; 2) Use of psychotropic medication or recreational drugs; 3) Epilepsy or history of an epileptic insult; 4) A nuclear family member with epilepsy; 5) Pregnancy; 6) Serious head trauma or brain surgery; 7) Neurological or psychiatric disorders; 8) Large or ferromagnetic metal parts in the head (except for a dental wire); 9) Implanted cardiac pacemaker or neurostimulator; 10) Participation in a NBS study in the past 28 days; 11) Previous participation in 10 or more NBS studies.
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 | NL69407.091.19 |