Brain networks in childhood – newsletter

This newsletter is intended for parents/guardians of the children who participated in our recent brain training study at the MRC Cognition & Brain Sciences Unit. We report what we have found so far, now that we have made substantial progress in our analysis.

Thanks to the contribution made by you and your child, we have achieved some really interesting new insights into communication between different brain areas in childhood, how particular communication patterns are related to memory, and how these patterns can be affected by brain training.

To quickly review the design of the study: we were interested in connections between brain areas (connectivity) during childhood and how they related to cognitive abilities. We focused on short-term memory and working memory (STM/WM), or the ability to hold pieces of information in memory over short periods of time and to manipulate these pieces of information as they are held in memory. We were helped by 32 junior neuroscientists: our research participants, aged 8-11, who visited the Unit for magnetoencephalography (MEG) scans, which involved two main components.

(1) A memory task, in which participants had to watch a grid on a screen and remember the locations of 4 red dots that popped up consecutively, while ignoring the yellow and orange dots. This task generated data that will allow us to look at what’s going on in the brain at any point during the memory process, e.g. what is the brain activity like when the information about each red dot’s location gets added into memory? What is the brain activity like when participants have to recall which dot was in a particular location? What happens to the brain activity when the participant had to ignore yellow dots (which are easy to ignore because they are obviously different from the red dots) versus orange dots (which are hard to ignore because the colour is much closer to red).

(2) A resting state scan, in which participants just rested with their eyes closed and let their minds wander. Previous research suggests that the brain activity patterns even during rest can be related to cognitive abilities, so we were keen to investigate how resting state connectivity between brain areas was related to STM/WM abilities.

Following the first MEG scan, children went away and performed cognitive training at home. We were interested in investigating two different sorts of memory training – low-intensity and high-intensity. Children who completed the training returned to the Unit for a second MEG scan, so that we could look at how brain connectivity had been changed by the full course of training.

So far in our analysis, we have been focusing on looking at the data obtained from the resting state scans. This has allowed us to set up our analysis procedures on a more simple set of data to start with, as we don’t yet have to consider all the different events that are occurring in the memory task. Now that we are at the end of analysing the resting state date, we will be moving onto analysing the memory task data.

 

Results: before training The first analysis we conducted was based on resting state data collected only in the first MEG session that each child attended, before any brain training was done. We wanted to know whether brain connectivity at rest was related to memory performance, so we examined the connectivity patterns by looking at the synchronisation of activity between separate brain regions. We then investigated whether particular patterns were associated with natural STM/WM memory ability, as measured by the memory tasks each child performed on a laptop outside the MEG scanner. The brain is organised in a complicated hierarchy of specialised and generalised areas that process information and allow us to successfully interact with our environment. Higher-order areas are responsible for more complicated functions like planning, organising and decision-making. Lower-order areas perform more basic functions related to the processing of things like sensory information – the information that comes into our brain from our senses. The different areas throughout the hierarchy in the brain communicate with each other via complex input and output pathways so that the brain as a whole can enable us to act constructively and adaptively in day to day life, and to do critical things like focus our attention, ignore distraction, and remember information accurately. Keeping this information-processing hierarchy of the brain in mind, our research revealed an interesting result.

We found that a child’s natural STM/WM ability was associated with the strength of a connection between a higher-order set of brain areas (called the fronto-parietal cortices) and a lower-order set of brain areas (called the left inferior temporal cortex and posterior cingulate cortex). The stronger that specific connection between these higher-order and lower-order areas, the more information could be stored in STM/WM. More research is needed to more thoroughly understand what is happening here. However, it is possible that a stronger connection allows the higher-order area to influence the lower-order area to more effectively maintain the information stored in memory, or to prevent that stored information from being disrupted by irrelevant information. This could be tested in many different ways in future studies.

 

Results: after training We were also keen to see how the cognitive training had affected memory ability and, again, the resting state connectivity patterns, so we compared data from the after-training MEG scan to data from the before-training MEG scan. In terms of the effect of training on performance, the high-intensity training (having to remember an increasing number of items) significantly improved STM/WM ability. That is, children were able to store more information in their memory after the training. The low-intensity training (having to remember just 2 items) only increased STM/WM ability slightly – not to a significant extent.

The brain connectivity results were very interesting. It seems that cognitive training increased the strength of that connection we previously identified in the other analysis – the connection between higher-order fronto-parietal areas and the lower-order sensory areas. This is a very neat finding as it suggests that the connection associated with natural memory ability is also the one affected by memory training. This is a very significant step forward in our understanding of how brain training affects the brain in order to achieve improved memory performance.

 

Still to come

We are currently analysing the effects of the training on brain activity during the memory task that children performed while in the MEG scanner. It is possible that the training might have had some effects that are only apparent when the children have to actively perform a task that uses their STM/WM.

We will send out another, final newsletter upon the completion of our remaining analyses. If you would prefer not to receive further correspondence, please let us know. If you have any questions about our findings, this study or our research in general, please don’t hesitate to get in touch.

Dr Duncan Astle
Phone: 01223 355294
Email: duncan.astle@mrc-cbu.cam.ac.uk

Dr Jessica Barnes
Phone: 01223 273758
Email: jessica.barnes@mrc-cbu.cam.ac.uk