Long-lasting cortical plasticity in the object naming system Elise Seip & Anouk van Loon
Outline • Introduction • Hypothesis • Method • Results - Behavioral - fMRI • Conclusion • Implication & Discussion • Further Research
Introduction • Repetition priming Naming an object once facilitates naming the same object again Sparser representation & reorganization of brain circuity • Object-naming system Perceptual vs lexical-semantic information (higher order) • Cortical Changes (Plasticity) Short-lasting or long-lasting?
Hypothesis • What to investigate? The modulation of neural activity for perception and higher order levels in object naming system for long and short time intervals.
Hypothesis • Lexical-semantic Repeated presentation of nameable objects changes neural activity in the object-naming pathway. • Creation of sparser representations long-lasting reductions in activity in occipital-temporal regions for both nonsense objects as nameable object.
Method • 8 subjects • Training: Look at line drawings and name the real object (not the nonsense objects) • fMRI • Visual-noise stimuli intermixed to create a low-level visual baseline condition • Stimuli: novel, 30-second delay, 3-day delay • Rapid presentation 200ms
ResultsBehavioral data Confirms repetition priming
Results fMRIBaseline • Increase of activity with immediate representation: -Nonsense objects: ventral occipitotemporal cortex bilaterally -Nameable objects activated also higher order regions (ventral occipitotemporal cortex bilaterally, left inferior frontal, left insula, premotor and cingulate cortex)
Conclusion • Immediate change in posterior regions => sparser object representation. • Slower developing changes in anterior regions may reflect an experience-induced reorganization of the brain circuitry. • Long lasting changes at the lexical-semantic and the perceptual level for object naming.
Implication & Discussion • Long-lasting cortical plasticity after single exposure with an object. • What is long-lasting? • Continuing sparser representation (grandmother cells)? • Are the neural changes in the distinct brain regions permanent.
Further Research • Object presentation without naming. • Mere-exposure. • Long-term interval.