Article summary with Training the developing brain: a neurocognitive perspective by Jolles & Crone - 2012

Introduction

The human brain is very plastic and can quickly adapt to new experiences. Not only the brain structure but also the brain function can be influenced by training. In particular, much is learned during childhood. The authors state that childhood is a special period in which training has specific effects. To date, little is known about how training-related plasticity differs between children and adults, while that science offers many opportunities for creating optimal learning situations.

Learning during childhood

During development, major changes take place in neural efficiency, but there also may be limits to the effects of training due to the level of structural brain development and cognitive functioning in the child. Neuroimaging research can provide insight into the underlying cognitive and neural processes that are active during training. This article looks at neuroscientific training in the domain of cognitive control and working memory. In adults, these domains are associated with certain areas in the prefrontal and parietal cortex.

Cognitive training

Cognitive training is defined as being the process of improving cognitive functioning through exercise and / or conscious instructions. Cognitive training has always focused on two goals. Firstly, on application, that is, the training has focused on improving practical effectiveness. Secondly on theory. For example, empirical questions were answered about the functions that were trained and about the process that had to take place for the desired change.

Cognitive training paradigms

Different approaches can be distinguished within cognitive training. The process-based approach involves repeated execution of executive function tasks. The strategy-based approach uses more explicit task instructions. Process-based training would be better for domain-general improvement, while strategy-based training would be more effective for improving a certain skill. However, new research has also been conducted that suggests that strategy-based training may be more effective if it is preceded by process-based training.

Other factors in cognitive training

In addition to the general distinction between the types of training mentioned above, other factors are important, such as the length of the training, the complexity of the task and the variability of the stimuli. These factors depend on the purpose of the training (e.g. whether it is about improving a single skill, or a general domain; e.g. theory versus implementation). It is also important to change the stimuli and to adjust the difficulty, because this keeps the participant motivated and automatism can be prevented.

Dependent variables in training effectiveness

There are different ways to measure the effectiveness of a training. For example, by measuring the accuracy, response times, number of applications of a strategy. If performance during training is also measured, a learning curve can also be developed that shows how quickly learning takes place. The long-term effects can also be measured by conducting another study after a long time. In addition to the sustainability of the training, this also tests for cumulative effects.

Test retest and transfer effects

To exclude test-retest effects, the performance of the participants must be compared to a control group that has not received any training or a placebo training. However, it is difficult to set up a placebo training that is similar to the real training, but that will have no effects. That is why training programs are often compared that focus on different cognitive functions. The generalizability of a training can be investigated by investigating transfer effects.

Distorting variables

The interpretation of training effects is hampered by the presence of disturbing variables. These are the most important general disruptive variables that people are confronted with during research:

• Expected effects (expectancy effects). Participants improve simply because they expect that their participation in the training will help them. Similar to placebo effect.

• Familiarity. The participants have become familiar with the test and therefore they perform better.

• Motivation and feedback issues. The groups can receive different rewards and feedback, so that they are motivated differently.

• Cohort effects. Group differences do not only have to be related to the factor being trained (think about that children will be better at training computer games than the elderly).

Disruptive variables in neuroimaging research

• Irrelevant task processing. If a participant becomes better at performing the task, he needs less time for implementation and more time to think about other things. This leads to increased activation in the so-called 'default mode network'.

• Task performance. Changes in neural activity may be related to the difficulty, trouble with, or reduced time for the task, rather than changes in the process being looked at.

• Task awareness. Changes in activation may occur due to increased task awareness.

• Task B problem. A lot of neuroimaging research compares the activation during a task with a control condition. The training effects can then be confused with activation changes in the control condition.

• Morphological changes. Activation changes can be influenced by changes in the underlying brain structure.

• Instability of the scanner.

• Scanner fear. Participants are often less nervous at the second scan.

Solutions

It is not possible to compensate for all disrupting factors. A number of examples of strategies are the use of a fake scanner to reduce the effect of scanner anxiety, influencing the level of difficulty to keep it the same between groups, the use of transfer tasks to better understand the underlying processes and monitoring of the underlying processes. strategy use, motivation and commitment. 

Views on neurocognitive development

Mark Johnson, an English cognitive neuroscientist, states that there are three points of view within science about neurocognitive development. From the maturational point of view, cognitive functions develop when the underlying brain regions reach maturity. According to the interactive specialization position, the specialization of a certain brain region is the result of interaction and competition with other brain regions about the development process. This point of view also looks at the role of experience in brain development and states that general structural development may be genetically programmed, while the specific details are the result of activity-dependent processes of the environment. The third position is the skill-learning approach. This states that the change patterns that one sees during development are similar to the change patterns that one sees when acquiring skills from adults.

Training effects and current development level

The limitations of an immature brain

Adult training will mainly influence existing neural networks, while training in young children can influence the construction of neural networks. An undeveloped brain structure can limit the amount that can be learned with training. For example, the speed and efficiency of information processing are determined by the degree of myelination and the pattern of synaptic connectivity. The training also depends on cognitive development (a child cannot learn more difficult things if the more primitive processes on which they build have not yet been learned). Certain age differences can therefore be strengthened by training instead of reduced.

The benefits of an immature brain

Increasing specialization and integration into brain networks during development would be at the expense of plasticity. There would also be 'sensitive' periods in brain development in which certain experiences can have their greatest effects. Whether these periods also exist for cognitive functions has not yet been confirmed. The flexible nature of higher cognitive functions suggests that these depend on neural mechanisms with lifelong plasticity.

Experience-related development

Even the sensitive periods are influenced by experiences. If a neural network is shaped by a certain input, it is difficult to change it again through a different experience. These effects do not depend on age. At the same time, if an input has never been received, the network can still be sensitive to a new input and can therefore be designed. This suggests that the periods of increased sensitivity to training effects are determined not only by age, but also by experience-related development.

Sustainable changes or flexibility

Training-related changes are not always the result of sustainable changes in the brain structure. They can also reflect flexibility of the brain function. Structural changes would only take place if there is a difference between the environmental requirements and the possibilities of the current structural system. This is called the mismatch hypothesis. This would explain why adaptive training is sometimes more effective than non-adaptive training. This mismatch is a requirement, but not always sufficient for sustainable structural changes; some structural changes are not possible. The training must be long enough and not too difficult. The plasticity also depends on the individual (think of genetic factors and environmental influences).

The influence of training on development

Training can accelerate development in such a way that cognitive processing and brain structure after training is comparable to older children. But training and development do not have the same underlying mechanisms. Early development depends on experience-expectant neural mechanisms. These are neural processes that take place during certain stages of development and are driven by the environmental input that all people are confronted with. Training is more influenced by experience-dependent processes. These processes are driven by input and are more specific to the individual and contain neural processes that are available throughout life. This difference suggests that training can influence the brain structure in a different way than development.

Possible disadvantages of training

Some scientists argue that the immature brain has a number of important evolutionary benefits. Accelerating the development of cognitive skills could sometimes even have a negative effect. For example, language learning would be especially successful in neural networks with limited cognitive control and working memory. High levels and knowledge and experience also lead to routines that ensure less attention and creativity. However, during development, things will be learned and things will be forgotten, and the profits will probably outweigh the costs.

Neuroimaging research into cognitive training

Neuroimaging research provides insight into the underlying mechanisms of training effects and can be used to make predictions about transfer effects.

Changes in brain activation

Cognitive training can lead to more activation, less activation and / or a change in the spatial pattern of activation. The strength and direction of training-related activation is probably dependent on specific task requirements and the difficulty of the task. It is thought that cognitive training only leads to less activation if the task does not exceed capacity limits. Scientific research has also shown that a change in strategy leads to a change in the spatial pattern of functional activation, increased activation and a change in the dynamics of activation.

Changes in functional connectivity

Training can bring about changes in the interaction between brain regions. Such interactions can be measured with functional connectivity and effective connectivity. These changes have also been observed during the periods of rest, suggesting that changes in interregional interactions are not specific to task conditions.

Closing

Training effects can be better understood when viewed in relation to the developing brain, because they arise from a dynamic interaction between learning, brain development, genetic differences and previous experiences. Depending on the training and the level of development of the individual, the training can lead to faster development or an improvement of the genetic potential of the individual. An immature brain structure can limit the limits of the effectiveness of the training, but sometimes the immatureness can also be an advantage. Neuroimaging research in particular can provide more insight into the underlying cognitive and neural processes used during training, rather than just investigating whether the training has been effective. Neuroimaging research is very sensitive and precise, but also very complex.