Mechanisms and Sequential Progression of Plasticity
Yana Fandakova (until 10/2022)
Elisabeth Wenger (until 04/2023)
Lieke de Boer (08/2020–03/2021)
Maike M. Kleemeyer (until 03/2021)
Ziyong Lin (until 06/2021)
Sarah E. Polk (until 04/2023)
Sina A. Schwarze (as of 01/2021)
André Werner (composer)
Plasticity in the Auditory Domain: The Case of Musical Expertise
This project investigates the role of brain plasticity in behavioral development across the lifespan. It makes use of training studies to probe the antecedents, mechanisms, and consequences of plastic change across different age groups and functional domains. Special attention is given to articulate the dynamics of plastic changes across structural, functional, and behavioral levels of analysis.
The human brain is plastic, that is, it possesses the capacity to implement lasting structural changes that alter its functional and behavioral repertoire in response to environmental demands (Lindenberger, 2018; Wenger & Kühn, 2021). Plasticity is metabolically costly and competes with the need for stability, which facilitates the development of a well-orchestrated set of habits and skills. The resulting interplay of mechanisms promoting plasticity versus stability organizes development into multiple alternating and sequentially structured periods that together support the hierarchical organization of cerebral functions and behavior. In earlier work on plastic change during motor skill acquisition, we have observed a pattern of initial tissue expansion followed by partial renormalization (Wenger et al., 2017). We have proposed that this pattern might be indicative of a more general pattern of plastic change, framed within the exploration–selection–refinement model (Lövdén, Garzon, & Lindenberger, 2020).
In the following, we report on four domains of inquiry. A fifth domain, undertaken together with Simone Kühn and Maike Hille, is reported elsewhere (cf. Spotlight Magazine; see also LIP Introduction). Recently, the two project leaders, Yana Fandakova and Elisabeth Wenger, have accepted tenured professor positions at universities in Germany. Ulman Lindenberger will restructure and continue to lead this project, which is deemed central to the research mission of the Center for Lifespan Psychology.
Plasticity in the Auditory Domain: The Case of Musical Expertise
Music training and musical expertise offer promising opportunities for studying how specific experiences interact with individual predispositions in shaping developmental change. In a series of studies, we investigated plastic changes in aspiring professional musicians who were preparing for an entrance exam at a university of the arts, comparing these changes to those in skilled amateur musicians. Over the course of 6 months, we observed decrements in estimates of gray matter volume among aspiring professional musicians in the left planum polare, a core region of auditory processing, along with increasing functional connectivity of this region to other regions that are relevant for musical expertise (Wenger et al., 2021). These results support the expansion–renormalization pattern previously observed in the motor domain if we assume that the group of aspiring musicians had entered later phases of an exploration–selection–refinement cycle.
Additionally, we were interested in how music-related aspects of functional brain organization differed between aspiring professional musicians and skilled amateur musicians (Dissertation Eleftheria Papadaki; Papadaki et al., in press). We used an interval-recognition task to define a listening-relevant network and computed functional connectivity and graph-theory metrics in this network on separately acquired resting state data. Aspiring professional musicians showed significantly greater global efficiency in the absence of any task. Critically, global efficiency was correlated with interval-recognition performance both inside and outside the scanner, as assessed by the Berlin Gehoerbildung Scale, a test of musical expertise that has been newly developed and validated by project members (Lin et al., 2021; see Figure 1).
Widening the scope of processes under examination, we also examined neurofunctional group differences while listening to a classical-baroque piece by Johann Sebastian Bach and a modern-classical piece by Anton Webern. For all participants, listening to the modern-classical piece was associated with a brain state characterized by higher overall connectivity and lower modularity relative to the classical-baroque piece. In addition, when listening to the modern-classical piece, aspiring musicians exhibited higher global efficiency and utilized more music-related and overall processing brain regions as hubs and between-network connectors to flexibly adapt to the condition demands than skilled amateur musicians.
Effects of Physical Exercise on the Aging Brain
In the context of Energizing the Hippocampus in Aging Individuals (EnergI), a consortium funded by the Federal Ministry of Education and Research, we conducted AKTIV, a training study with 160 healthy older adults to investigate the separate and combined effects of physical exercise (i.e., riding an exercise bike) and learning a language (i.e., Spanish) on brain and behavior, with particular emphasis on the hippocampal formation. Using structural equation modeling to define a latent factor of gray matter (GM) integrity, we found that physical exercise exerted a protective effect on GM integrity in regions previously reported to be affected by exercise (Dissertation Sarah Polk). Exercising participants with greater fitness gains also showed more positive changes in GM integrity (Polk et al., 2022). We also hypothesized that aerobic exercise might counteract declines in white matter (WM). In line with this expectation, we observed maintained WM volume in the corpus callosum of exercisers, and positive change–change correlations between WM volume and fitness, and between WM volume and perceptual speed (Polk et al., 2023).
The effects of language learning are still being analyzed. When modeling changes in cognitive performance at the latent level, we observed a selective effect of language learning on untrained tests of episodic memory. Spanish learners showed behavioral improvements in episodic memory during the first 3 months of training, while average change in episodic memory was absent in the control group. At the neural level, we observed a group-by-time interaction in the left inferior frontal gyrus, with Spanish learners showing greater increases in gray matter volume than control participants. The gray matter volume changes observed in Spanish learners were paralleled by changes in mean diffusivity and proton density, presumably pointing to increasing tissue density in this region. Counter to expectations, we have thus far found no behavioral or neural evidence for the benefit of combining language and exercise training.
Task Switching During Childhood: Interactions Between Maturation and Training
Childhood is characterized by maturational changes in brain structure, brain function, and the organization of behavior. During middle and late childhood, such changes are particularly pronounced for cognitive control processes, such as the ability to flexibly shift between different task sets (Dissertation Sina Schwarze). Hence, in the context of a priority program funded by the German Research Foundation, we conducted an extensive training study of task-switching performance in children aged 8 to 11 years to explore how these maturational changes interact with training. The study is being conducted in close collaboration with Silvia Bunge (University of California, Berkeley, USA).
Initial analyses focused on age differences at baseline, examining how age differences in task switching are related to the protracted maturation of its neural substrates (Schwarze et al., 2023). Compared to adults, children showed less upregulation of brain activation with increased task-switching demands, and a larger increase in connectivity with increased task-switching demands between the inferior frontal junction (IFJ), a key task-switching region, and lateral prefrontal cortex (lPFC; see Figure 2a–b). Increased connectivity might offer an alternative and possibly developmentally earlier mechanism to manage task-switching demands. For children who showed less adult-like activation, increased IFJ-lPFC connectivity was associated with higher performance, whereas for children who showed more adult-like activation, increased connectivity was associated with lower performance (see Figure 2c–d).
During the training period, which was restricted to children and consisted of 27 sessions spread out over 9 weeks, participants in the experimental group practiced switching between a large number of different task sets. An active control group trained the identical tasks but with a markedly lower switching frequency. Children exposed to higher switching demands showed increasing drift rates during task switching in the course of training, suggesting increasingly fast evidence accumulation for correct responses. These behavioral changes were accompanied by reduced activation in dorsolateral prefrontal and superior parietal regions (Figure 3a–b). These analyses suggest that task-switching training enhances the efficiency of regions that support task switching in children, rather than moving children’s activation patterns more rapidly towards an adult-like pattern. With respect to behavioral manifestations of plasticity, ongoing analyses focus on individual differences in trajectories of change and their relations to untrained measures of task switching, processing speed, and working memory (Dissertation Neda Khosravani).
Metacognition and Curiosity During Early Phases of Learning
Metacognitive processes related to the monitoring and control of behavior, as well as curiosity, or the desire to acquire new information, contribute to plasticity, especially while individuals are exploring a new task space. We experimentally dissociated objective learning success from subjective performance ratings and demonstrated that participants based future decisions more strongly on their subjective ratings (Fandakova, Johnson, & Ghetti, 2021), thereby highlighting the role of metacognitive monitoring for learning. Following up on these findings, we examined age differences between early and later phases of motor sequence learning between adults and 7- to 10-year-old children. Early during learning, children showed reduced activation in core regions associated with metacognitive monitoring, including the dorsolateral prefrontal cortex and the dorsal anterior cingulate. During later phases, the left motor cortex showed greater engagement in both age groups, whereas activation in a homologous right motor area was enhanced in children relative to adults.
To examine the effects of curiosity on learning, we asked children aged 10 to 14 years trivia questions (Fandakova & Gruber, 2021). Children of all ages showed better memory for questions they were curious about. In contrast, higher post-answer surprise, or the discrepancy between children’s initial curiosity and their interest in the actual trivia answer, benefited learning more strongly in adolescents than in children. These results point to motivational effects on learning, presumably through individual and age-related differences in dopaminergic modulation (Gruber & Fandakova, 2021).