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Induced cross-modal synaesthetic experience without abnormal neuronal connections
Roi Cohen Kadosh1, Avishai Henik, Andres Catena
1Department of Psychology, Institute of Cognitive Neuroscience, University College London, London, United Kingdom. r.cohenkadosh@ucl.ac.uk
Psychological Science
|January 30, 2009
Summary
Abnormal cross-modal experiences, like those in synaesthesia, may stem from reduced inhibition between brain areas, not necessarily new or strengthened connections. This study used posthypnotic suggestion to explore this phenomenon.
Area of Science:
- Neuroscience
- Cognitive Psychology
Background:
- Cross-modal interactions are crucial for sensory integration.
- Abnormal cross-modal experiences occur in synaesthesia and after brain damage.
- The underlying mechanisms (hyperconnectivity vs. disinhibition) are debated.
Purpose of the Study:
- To investigate the mechanisms behind abnormal cross-modal experiences.
- To determine if synaesthesia-like experiences can be induced via suggestion.
- To test the hypothesis that disinhibition, rather than hyperconnectivity, underlies these phenomena.
Main Methods:
- Utilized posthypnotic suggestion to induce altered cross-modal perception.
- Compared induced experiences to congenital grapheme-color synaesthesia.
- Controlled for the short experimental timeframe to infer neural changes.
Main Results:
- Posthypnotic suggestion successfully induced abnormal cross-modal experiences.
- The induced experiences mimicked those seen in congenital grapheme-color synaesthesia.
- The rapid induction suggests a lack of need for new neural connections.
Conclusions:
- Synaesthesia-like experiences can arise from disinhibition between brain areas.
- This challenges the exclusive focus on hyperconnectivity as the cause.
- Suggests that transient states of reduced inhibition can create synaesthetic phenomena.
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