Final Report Summary - CRITICALBRAINCHANGES (Development and plasticity of multisensory functions to study the principles of age dependent learning plasticity in humans)
The main aim of the project CriticalBrainChanges was to understand how learning plasticity of the human brain changes during ontogeny and how early experience constraints plasticity later in life. These questions were studied in the context of (multi)sensory functions. A combined behavioural and neuroscientific research strategy was employed in (1) healthy young adults, to uncover the main principles and neural mechanisms of multisensory processes; in (2) healthy infants and children, to characterize typical developmental pathways; in (3) individuals with early sensory deprivation due to an inborn sensory defect (such as blindness and deafness) after sensory restoration, to identify possible sensitive or critical periods in human brain development; and (4) adults involved in multisensory training, to unravel limits of adult plasticity and strategies to increase plasticity.
CriticalBrainChanges uncovered general mechanisms of functional brain development in humans:
1. Predominant learning mechanisms change from early infancy to adulthood from implicit (unsupervised) learning to feedback based (supervised) learning.
2. Functional brain development comprises both regressive and constructive mechanisms. Multisensory development involves a loss of crossmodal connectivity at early processing stages (multisensory perceptual narrowing) and a reorganization and differentiation of crossmodal interactions at later processing sages. Uni- and multisensory development run in parallel.
3. The functional differentiation of neural systems related to object (face) perception requires visual experience during early development, even though related neural systems show a protracted developmental time course and associated functions emerge only in late childhood (sleeper effect). Other systems, such as that involved in biological motion processing, seem to depend less on visual input during early development, demonstrating a dissociation of the neural systems for biological motion processing and face processing.
4. The functional differentiation of neural systems depends on an elaboration of inhibitory networks, which require adequate experience during early brain development. After a transient phase of total blindness from birth, typical neural mechanisms for the precise tuning of brain activity (alpha oscillatory activity) do not recover.
5. Crossmodal reorganization associated with a transient phase of total blindness does not completely retract. Multisensory enhancement effects as a response to crossmodal vs. unimodal stimuli are found for simple but not for complex multisensory tasks; partial crossmodal interference was observed after sight restoration where typically multisensory enhancements are found. Prevailing crossmodal plasticity in cataract-reversal individuals does not seem to introduce a non-visual percept but rather seems modulate genuine visual perception.
6. In healthy young adults, adaptive learning procedures and gamification components improve crossmodal learning.
7. Loss of vision results in more extensive crossmodal plasticity and compensatory behavior than Loss of audition and, as a consequence, functional recovery is higher after hearing restoration than after visual restoration.
CriticalBrainChanges uncovered general mechanisms of functional brain development in humans:
1. Predominant learning mechanisms change from early infancy to adulthood from implicit (unsupervised) learning to feedback based (supervised) learning.
2. Functional brain development comprises both regressive and constructive mechanisms. Multisensory development involves a loss of crossmodal connectivity at early processing stages (multisensory perceptual narrowing) and a reorganization and differentiation of crossmodal interactions at later processing sages. Uni- and multisensory development run in parallel.
3. The functional differentiation of neural systems related to object (face) perception requires visual experience during early development, even though related neural systems show a protracted developmental time course and associated functions emerge only in late childhood (sleeper effect). Other systems, such as that involved in biological motion processing, seem to depend less on visual input during early development, demonstrating a dissociation of the neural systems for biological motion processing and face processing.
4. The functional differentiation of neural systems depends on an elaboration of inhibitory networks, which require adequate experience during early brain development. After a transient phase of total blindness from birth, typical neural mechanisms for the precise tuning of brain activity (alpha oscillatory activity) do not recover.
5. Crossmodal reorganization associated with a transient phase of total blindness does not completely retract. Multisensory enhancement effects as a response to crossmodal vs. unimodal stimuli are found for simple but not for complex multisensory tasks; partial crossmodal interference was observed after sight restoration where typically multisensory enhancements are found. Prevailing crossmodal plasticity in cataract-reversal individuals does not seem to introduce a non-visual percept but rather seems modulate genuine visual perception.
6. In healthy young adults, adaptive learning procedures and gamification components improve crossmodal learning.
7. Loss of vision results in more extensive crossmodal plasticity and compensatory behavior than Loss of audition and, as a consequence, functional recovery is higher after hearing restoration than after visual restoration.