A Developmental Framework of Brain and Cognition f

Authors: Alvaro PascualLeone Margot J Taylor

Publish Date: 2011/08/20

Volume: 24, Issue: 3-4, Pages: 183-

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Abstract

Schematic representations of two views of brain and cognition changes across the lifespan Curve A shows the traditional view of lifespan studies there is a developmental process followed by a stable adult period followed by decline in ageing With this special issue we hope to encourage colleagues to view brain function across the lifespan as a continuing modulating and evolving process curve BThis special issue offers an array of papers which incorporate literature reviews for those not as familiar with the field of brain lifespan studies with their empirical data The studies included are exceptional in their application of complex protocols that assess the neuroplasticity and agerelated changes in structure and/or function from infants through to our most senior citizens and highlight the value of different methodological techniques and approachesStarting this special issue are two letters addressing the topic of measures of brain maturity and providing commentary on Dosenbach et al 2010 Brandeis et al 2011 raise the point that estimation of brain maturity has a long history as it has been assessed for many decades using electrophysiological measures Dosenbach et al 2010 agree with the suggestion that neuroimaging approaches be combined These letters raise the intriguing questions of commonalities across imaging modalities that should be kept in mind for all of the papers in this special issueWe have organized the reports from early to late in the lifespan The topic of the first paper is on the youngest of participants—4monthold infants Trainor and colleagues 2011 presented young infants with one of two types of musical stimuli over the course of a week After only about 160 min of listening experience eventrelated potential ERP responses in the infants from the two different groups reflected the musical exposure of the infant This very interesting paper demonstrates the early and rapid plasticity in the infant brain The following study by Gordon and colleagues 2011 also investigated the neuroplasticity of brain function in this case in infants and children who are deaf and received cochlear implants This paper first provides an excellent review of the issues related to the effects of impaired sensory input and how that impacts the development of the auditory system The data presented are extensive in showing that the timing of the implant can affect different levels of plasticity within the auditory system with less plasticity being seen in the cortical regions in fact This paper is also valuable in its integration of information from human and animal studies In a third study that involved infants Luyster et al 2011 studied 12 month olds who were at high risk for ASD compared to low risk infants As social interactions are often one of the first indications of ASD they studied ERPs to familiar and unfamiliar faces At this early age there were as yet no striking differences between the two groups although there was some evidence for a lag in the high risk group This paper discusses in detail the challenges of early identification of infant ASD and the definition of the ASD endophenotype at a very young ageThe next few studies are focused on childhood The first of these by Pannekamp et al 2011 investigated language discourse examining the complex issue of context and prosody in children from early childhood to preadolescence The language used in the task was German where prosodic accents are very critical only the 12 year olds had ERPs that reflected the contextual information independent of prosody as seen in adults The ERPs of the younger children 8 and 5 yearold age groups demonstrated their successful processing of sentences but they were more influenced by the dominant prosodic information in the dialogue In contrast the paper by Qui et al 2011 assessed brain structure and function relations in the absence of a task examining cortical thickness and DTI measures in relation to resting state functional networks in children with and without ADHD The convergence among structural and functional measures holds great promise for advancing our understanding of typical and atypical brain development as shown in these preliminary dataThe following three papers use the neuroimaging modality of magnetoencephalography MEG In the first of these Pang 2011 reviews the practical aspects of developmental studies using MEG This is an invaluable addition to the literature given the increasing use of MEG in developmental studies including atypical populations Comparable papers have been published for other imaging modalities in particular fMRI but the approaches and issues are different with MEG thus this is an important guide and we are sure will be a widely used reference paper In the following paper by Taylor et al 2011 use MEG to assess face recognition from young children through to adults with a focus on hippocampal and frontal lobe activations They show that right hippocampal activity was visible from 6 years of age but frontal lobe activations emerged only in midchildhood These data demonstrate the parallels between structural and functional development that extend into adulthood The following paper by Herdman and colleagues 2011 also looks at development in children compared to adults in the auditory modality These authors investigated attentional effects to pure tone stimuli and found that the modification of the MEG attentional effects was limited in the 12 year olds They suggest that these findings support the model that with experience attentional gating occurs at increasingly early levels in the auditory system to facilitate automatic processingThe next pair of papers relates to agerelated changes in normal adults and ageing McGinnis and colleagues 2011 focus on cortical thickness changes with ageing They test the popular “last in first out” hypothesis They demonstrate that the cortical thinning does not follow a linear pattern and that the changes between young and middleaged adults are greatest in different areas than those found between the middle and olderaged adults They propose a new model of cortical changes with age and highlight how this model will allow for interventions that are specific to the agerelated changes over the adult lifespan The following paper by Falvo and colleagues 2011 investigates the cortical activation related to motor movements in young and old adults While peripheral measures did not differ as a function of age the cortical activation of three ERP measures related to movement preparation and performance did and suggests that there is less focal activation in older adults during motor movements This paper concludes that the adaptable nature of cortical networks governing motor function may be attenuated in older adults requiring support from additional brain regionsThe final four papers in this special issue compare healthy and pathological ageing processes The first by PascualLeone et al 2011 brings multimodal imaging techniques—TMS EEG and fMRI—to bear on questions of neuroplasticity and how this is affected by age and by various disease states This paper includes an extensive review of the literature and proposes an integrative model The second paper by Foy and colleagues 2011 examines magnetic resonance spectroscopy to determine if there are neurometabolic biomarkers to identify the early stages of Alzheimer’s disease AD The aim is to identify such subjects as soon as possible to allow early interventions—an important clinical issue in ageing This study investigated patients with AD compared to people with mild cognitive impairment and healthy agematched controls and found that some combinations of the MRS data could distinguish amongst the groups To further explore the effects of ageing on memory and other cognitive function Aine et al 2011 review of a series of their studies that examined several of the critical issues related to the reports of agerelated memory decline in the elderly They propose a number of limitations that need to be considered in the interpretation of these data in the literature and that are important for accurate ongoing and future studies The final paper in this issue also deals with the agerelated changes and the models of capacity in the ageing brain BartresFaz and ArenazaUrquijo 2011 focus on the structural capacity of the ageing brain compared to the cognitive capacity or reserve of the brain As with the preceding three papers this review also highlights the responsibility of understanding brain structure in light of brain function with an emphasis on the interactions among aspects of mental activity the neuroprotection and compensatory mechanisms A final point that is raised in this paper as well as in some of the other papers in this special issue is the importance of longitudinal studiesMost of the work included in this special issue of Brain function across the life span does not include longitudinal studies which are extremely difficult to run and to manage over the many years that are required to obtain those data However a number of groups internationally are increasingly including longitudinal aspects in their investigations of development of the brain over the lifespan and this will be an important direction for the futureThis special issue highlights the scope of neuroscience research across the lifespan The studies used protocols and paradigms with ethological validity and emphasize the range of neuroimaging measures that can be utilized in the examination of brain structure and function over the lifetime Infant studies are fundamental and mandatory for our understanding of innate capacities and initial factors that influence early maturation we are grateful for the exceptional work of our colleagues in this timeintensive and demanding field Studies with children demonstrate that brain processing even for simple stimuli and certainly for more complex stimuli such as language is far from mature in childhood there is extensive cognitive development continuing throughout the adolescent years despite what our teenagers tell us Studies in adults moving through middle age and into old age are critical to understand the underlying causes for decline in various functions with age this knowledge will contribute to interventions that will slow the onset or the progression of these agerelated changes The clinical studies complement normative studies by providing atypical cognitive profiles which help define our models of human information processingWe would like to thank the editors Dr Micah Murray and Dr Christoph Michel for the privilege of editing this Special Issue on Brain function across the lifespan and all the authors for their contributions We are grateful for our many reviewers for their careful assessments of the manuscripts constructive and insightful suggestions as well as their willingness to review in a very timely manner We would also like to thank Jared Horvath for his invaluable administrative assistance We hope that this focused special issue will be of interest to a wide range of researchers in the field of cognitive neurosciences neurology and paediatric neurology psychiatry geriatrics and hope that it will help spur further lifespan studies

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