Infants are superior in implicit crossmodal learning and use other learning mechanisms than adults

Abstract

During development internal models of the sensory world must be acquired which have to be continuously adapted later. We used event-related potentials (ERP) to test the hypothesis that infants extract crossmodal statistics implicitly while adults learn them when task relevant. Participants were passively exposed to frequent standard audio-visual combinations (A1V1, A2V2, p=0.35 each), rare recombinations of these standard stimuli (A1V2, A2V1, p=0.10 each), and a rare audio-visual deviant with infrequent auditory and visual elements (A3V3, p=0.10). While both six-month-old infants and adults differentiated between rare deviants and standards involving early neural processing stages only infants were sensitive to crossmodal statistics as indicated by a late ERP difference between standard and recombined stimuli. A second experiment revealed that adults differentiated recombined and standard combinations when crossmodal combinations were task relevant. These results demonstrate a heightened sensitivity for crossmodal statistics in infants and a change in learning mode from infancy to adulthood.

Crossmodal associations modulate multisensory spatial integration

“…In the latter case, the colors of the visual stimuli that signified the congruent or incongruent status might become the primary determinant of the winning visual attractor, and this effect may generalize to a new sound. These findings are consistent with previous research showing that adults' ability in differentiating congruent versus recombined AV pairs depend largely on stimulus context and task relevance (Rohlf, Habets, von Frieling, & Röder, 2017). Importantly, we found that the shift in the perceived location towards V1 was smaller for A2 (incongruent) than for A1 (congruent) and for A3 (new).…”

Two tales of one neural link predict blind individual’s Braille reading proficiency

“…Our finding of the task-specific top-down influence on left LOC activity is in accord with a study that showed stronger task-induced 'visual' cortex activity in individuals with acquired blindness due to active task interpretation (Murphy et al, 2016) as well. This top-down mediated plasticity in late blind humans is compatible with the typical adult neural learning mechanisms demonstrated by several human and non-human animal studies (Keuroghlian and Knudsen, 2007;Bavelier et al, 2010;Rohlf et al, 2017;Röder, Kekunnaya and Guerreiro, 2021). Additionally, as suggested by researchers (Batardière et al, 2002;Magrou et al, 2018;Röder, Kekunnaya and Guerreiro, 2021) that the elaboration of feedback connectivity might require stimulusdriven input, our results further implied that in Braille reading, the bottom-up left LOC-IFC effective connectivity provided Braille shape information input to the IFC; thus, the genuine language area, left IFC, predicted the pattern of activity within the 'visual' area, left LOC, based on the prior association of tactile Braille characteristics with semantic and conceptual knowledge (Price and Devlin, 2011) and then delivered topdown modulation to the LOC.…”

“…This neural mechanism is essential for the rapid acquisition of new skills because it might be relatively difficult for late blind humans to extract crossmodal characteristics exclusively via bottom-up stimulus input, with their visual deprivation occurring after the pruning of exuberant crossmodal connectivity during the typical early development (Batardière et al, 2002; Röder et al, 2021). Such a top-down controlled learning mechanism in late blind humans is also compatible with the typical adult learning characteristics demonstrated by human and non-human animal studies (Keuroghlian and Knudsen, 2007; Rohlf et al, 2017).…”

“…In particular, the asymmetrically stronger taskrelevant top-down modulation of the left IFC-to-LOC connection during Braille reading (Figure 4C) provides important evidence for the top-down controlled learning mechanism in late blind humans (Röder, Kekunnaya and Guerreiro, 2021); that is, the crossmodal capacities of the genuine visual cortex in late blind individuals are possibly mediated by feedback connections from higher-order neural systems tuned during taskrelevant learning (Röder, Kekunnaya and Guerreiro, 2021). This is likely essential for late blind individuals because their visual deprivation onset occurs after the pruning of exuberant crossmodal connectivity during the early phases of typical development (Batardière et al, 2002;Röder, Kekunnaya and Guerreiro, 2021); therefore, it might be relatively difficult for them to extract crossmodal characteristics exclusively via bottom-up, stimulus-driven input (Rohlf et al, 2017;Röder, Kekunnaya and Guerreiro, 2021). Our finding of the task-specific top-down influence on left LOC activity is in accord with a study that showed stronger task-induced 'visual' cortex activity in individuals with acquired blindness due to active task interpretation (Murphy et al, 2016) as well.…”

Cross-Talk of Low-Level Sensory and High-Level Cognitive Processing: Development, Mechanisms, and Relevance for Cross-Modal Abilities of the Brain

“…A lack of multisensory perceptive capabilities, makes it more sophisticated to acquire other cognitive computations and to function autonomously. Continuous learning of robotic systems is crucial, because internal models of the multisensory world must be acquired and adapted throughout development in order for multisensory processing capabilities to emerge (section "The Emergence of Sensory-Cognitive Interplay During Cross-Modal Development") (Rohlf et al, 2017). Recent endeavors led to the creation of an open source humanoid called NICO (Neuro-Inspired COmpanion), which due to its flexible design and open and modular hardware and software framework can adapt to individual experimental set-ups and opens the door to multimodal human-robot interaction research with the aim of developing autonomous agents and cognitive robots (Kerzel et al, 2017).…”