Working memory training has been shown to provide widespread cognitive benefits, but how exactly does it change our brains?
New research reveals that a demanding “dual n-back” training program alters functional connectivity even during rest, shedding light on the neural mechanisms underlying training-induced plasticity.
Key Facts:
- Dual n-back training increased connectivity of the ventral default mode network in right inferior frontal gyrus.
- Training-related gains in connectivity correlated with improved performance on an untrained working memory task.
- Results suggest that intensive training strengthens frontal executive control regions, enhancing communication within default mode regions.
- Findings show training can alter the brain’s intrinsic functional architecture after just 16 days of practice.
Source: Sci Rep.
Brain Activation at Rest: Default Mode Network
The brain is never truly at rest. Even when we are not engaged in focused mental tasks, intrinsic neural networks continue to hum along in the background.
This restful “default mode network” activates a reliable cast of brain regions, including medial prefrontal cortex, posterior cingulate, and inferior parietal areas.
What can fluctuations in this network tell us about the lasting impact of cognitive training?
A new study by researchers at the Max Planck Institute for Human Development provides intriguing clues.
The team subjected groups of young adults to 16 days of intensive working memory training using the “dual n-back” task.
This challenging exercise requires simultaneously tracking visual and auditory stimuli and responding when they match items presented n steps earlier.
The training groups were compared against an active control practicing single n-back tasks separately by modality.
Resting state fMRI scans were performed before and after training to map changes in intrinsic functional connectivity across the default mode network.
Frontal Reconfiguration with Dual-N Back
Following dual n-back training, the researchers uncovered increased connectivity within frontal hub regions of the default network.
Specifically, coupling strengthened between right inferior frontal gyrus and other default mode areas.
This effect was absent in the active control group, pointing to the unique demands of the dual task training.
Fascinatingly, connectivity increases correlated positively with training-induced behavioral gains on an untrained working memory task.
The inferior frontal gyrus (IFG) is known to play key roles in cognitive control and inhibitory processing.
The researchers suggest that intensive training likely honed IFG-mediated executive functions, bolstering top-down signals within the default network.
In turn, this frontal remodeling may support improved performance on unrelated working memory challenges.
Overall, the work elegantly demonstrates how taxing cognitive exercises can reconfigure core neural communication pathways even at rest.
Rapid Reorganization: Neuroplasticity in Action
Notably, increased IFG coupling emerged after just 16 days of practice.
An important implication is that the brain’s functional architecture can be altered quite rapidly with intensive training.
Previous studies demonstrating training-induced effects on intrinsic connectivity have generally involved more extended interventions, on the order of 4 weeks or more.
The current findings indicate robust neuroplasticity on much faster timescales.
The results complement structural changes like white matter growth and gray matter thickening observed following weeks or months of cognitive training.
Together, this body of work highlights the brain’s agility to reorganize both function and anatomy in response to sustained challenges.
Executive Hub: Right Inferior Frontal Gyrus
The critical role of inferior frontal gyrus is telling.
As a core node of cognitive control networks, the right IFG appears particularly capable of functional remodeling from intensive training.
Studies of expertise acquisition have similarly observed expanded IFG connectivity related to domain mastery.
Along with medial prefrontal areas, the right IFG may represent a nexus where executive processes can be broadly strengthened.
Notably, the researchers also found decreased default network coupling in left superior parietal cortex following dual n-back training.
This likely reflects shifting network dynamics toward frontal control regions as training progresses.
Dual N-Back vs. Single N-Back: Cognitive Load
The lack of effects in the single n-back group warrants discussion.
The dual task’s greater cognitive load seems crucial for altering connectivity during rest.
Listening to sounds and tracking locations taxes working memory, attention, and cognitive flexibility in a way the single tasks do not.
These results highlight the importance of sufficiently challenging, multidimensional training for driving neural changes.
Not all cognitive “exercise” elicits plasticity. The training must provide a progressively demanding “workout” for the brain to spur reorganization.
Future Directions of Dual-N Back Research
Follow-up efforts can build on these findings in multiple ways.
As the study was restricted to young adults, it will be important to probe training-induced plasticity across different ages.
Older groups with declining executive functions may show amplified network changes following training.
Longitudinal tracking of functional and structural connectivity changes will provide richer details on their interplay.
It remains unclear whether the right IFG exhibits innate properties that enable its plasticity or if certain forms of training preferentially target this region.
Finally, harnessing neurofeedback and brain stimulation techniques may further enhance training outcomes by directly modulating frontal hub dynamics.
Targeting frontal executive processes could be key for maximizing improvements.
Brain Training to Significantly Alter Connectivity
Overall, this work provides compelling evidence that intensive cognitive training can sculpt intrinsic functional connections, not merely task-related activation patterns.
Even in the absence of focused effort, prior training history leaves an imprint on communication rhythms across the resting brain.
Far from resting dormantly, network interactions during repose continue to reflect past experiences.
The brain replays its training, strengthening essential connections for the challenges to come.
With time and consistent effort, we can shape our neural workspace and expand the horizons of the mind.
References
- Study: Dual n-back training improves functional connectivity of the right inferior frontal gyrus at rest
- Authors: Tiina Salminen et al. (2020)
