Mike Anderson

Understanding the development of the brain’s neural networks can reveal critical insights into the cognitive changes that occur from infancy to late childhood. Behavioural metrics including: task accuracy, stimuli recognition, and reaction time show dramatic changes over childhood. In this study we investigated response control using the Erikson Flanker task. In a dataset of 45 EEG recordings, we calculated spectral coherence to measure connectivity between all possible electrode pairs. Coherence measures were performed on two different trial conditions –congruent (where there is no response conflict) and incongruent (where response conflict is induced). The increase in incongruent coherence compared to the congruent was investigated for each electrode pair over 45 healthy subjects aged seven years. The same calculation was then performed on the same group of subjects two years later when they were aged nine years. The results revealed that at age seven years, increased coherence was detected in the left prefrontal to right and left parieto-occipital – i.e. an anatomical region located between the parietal and occipital lobes - within theta band. No increase was found for the older group-at age nine years- which may indicate cognitive development in conflict processing mechanism.

Assessing cognitive development in children is of paramount importance in understanding the development of critical neural pathways of the brain. In particular, recognition of stimuli, task accuracy and response time are key features that can inform on stages of brain cognition with respect to age and within age group differences. In this study we investigate neurophysiological responses of the Eriksen Flanker task - an experimental paradigm for assessing attention and cognition - in middle childhood ages (seven-nine years). We analyse EEG data in two age groups: 45 healthy subjects aged seven years with a follow-up study on the same subjects at age nine years. We examine spectral coherence - a method for analysing the correlation between electrode pairs - for all possible combination of pairs. Comparisons of coherence values based on Flanker task conditions (incongruent versus congruent) were assessed in each age group. Consequently, these assessments were used as indicators to the cognitive conflict induced by Flanker incongruent stimuli. For both age groups (seven and nine years) inter-hemispherical coherence increased in the right hemisphere. Moreover, the older children showed less Flanker conflict compared with children aged seven years, especially within the theta band. This decrease in the effect of the cognitive conflict may indicate age-related cognitive developments.

Diabetes mellitus type 1 (T1DM) has been associated with cognitive dysfunction and structural abnormalities across the cortex. It has been argued that there are critical periods in the lifespan where the brain is particularly vulnerable to the neural insults of Diabetes (Biessels, Deary & Ryan, 2008). In this MRI study, we used voxel-based morphometry to compare a group of T1DM patients to sibling controls during young adulthood. We had previously shown that when 7 years younger there was no effect of T1DM on IQ (Strudwick et al., 2005) and while there was still no effect on IQ, there was a suggestion of difficulties in executive functioning (EF; Ly et al., 2011). In this follow-up study we explored whether differences in brain structure related to T1DM might explain the difference in EF. There were 61 participants (Mage = 19.3) who participated in the MRI scanning (T1DM N = 31) with an approximately equal gender balance (54% female). Participants' T1-weighted volumes at 1mm3 voxel size were obtained from a 3T Siemens scanner. MRI scans were analysed using the SPM8 toolbox (Wellcome Trust) in MATLAB (The Mathworks, Inc). When performing voxel-wise comparisons across the cortex, there were no significant differences in grey matter density between T1DM and sibling controls (corrected p =. 05). Lowering the statistical criteria to an uncorrected p =. 001 revealed sibling controls had higher grey matter density in four left-lateralised clusters (middle temporal gyrus, cuneus, superior frontal gyrus and postcentral gyrus). The largest effects were for T1DM patients to have reduced grey matter density in the middle temporal gyrus"”a cortical region associated with semantic processing and risk factor for developing Dementia, and in the superior frontal gyrus"”a cortical region implicated in EF. These results reveal consistent, yet subtle, structural brain differences between T1DM patients and controls in young adulthood.

Diabetes mellitus type 1 (T1DM) has been associated with cognitive dysfunction and structural abnormalities across the cortex. It has been argued that there are critical periods in the lifespan where the brain is particularly vulnerable to the neural insults of Diabetes (Biessels, Deary & Ryan, 2008). In this MRI study, we used voxel-based morphometry to compare a group of T1DM patients to sibling controls during young adulthood. We had previously shown that when 7 years younger there was no effect of T1DM on IQ (Strudwick et al., 2005) and while there was still no effect on IQ, there was a suggestion of difficulties in executive functioning (EF; Ly et al., 2011). In this follow-up study we explored whether differences in brain structure related to T1DM might explain the difference in EF. There were 61 participants (Mage = 19.3) who participated in the MRI scanning (T1DM N = 31) with an approximately equal gender balance (54% female). Participants' T1-weighted volumes at 1mm3 voxel size were obtained from a 3T Siemens scanner. MRI scans were analysed using the SPM8 toolbox (Wellcome Trust) in MATLAB (The Mathworks, Inc). When performing voxel-wise comparisons across the cortex, there were no significant differences in grey matter density between T1DM and sibling controls (corrected p =. 05). Lowering the statistical criteria to an uncorrected p =. 001 revealed sibling controls had higher grey matter density in four left-lateralised clusters (middle temporal gyrus, cuneus, superior frontal gyrus and postcentral gyrus). The largest effects were for T1DM patients to have reduced grey matter density in the middle temporal gyrus"”a cortical region associated with semantic processing and risk factor for developing Dementia, and in the superior frontal gyrus"”a cortical region implicated in EF. These results reveal consistent, yet subtle, structural brain differences between T1DM patients and controls in young adulthood.

Background: Executive functions (EFs) are commonly theorised to be related yet separable constructs in adults, and specific EFs, such as prepotent response inhibition and working memory, are thought to have clear and distinct neural underpinnings. However, recent evidence suggests that EFs are unitary in children up to about 9 years of age. The aim of the current study was to test the hypothesis that event-related potential (ERP) components of individual EFs are related to behavioural performance, despite EFs being psychometrically indistinguishable in children. Specifically, P3b ERP (associated with updating of working memory), N2 ERP, and N2 difference waveform (both associated with inhibition) latent variables were created and entered into confirmatory factor analysis and structural equation models with a unitary executive functioning factor. Methods: Children aged 7-9 years (N = 215) completed eight measures of inhibition, working memory, and shifting. A modified flanker task was also completed during which EEG data were recorded. Results: The P3b ERP and the N2 difference waveform factors both significantly correlated with (and were predictors of) the executive functioning factor; however, the N2 ERP factor was not. Discussion: These results provide support for the utility of ERPs as a counterpoint to psychometric measures of executive functioning, and, more broadly, for the relationship between brain and behaviour.