Christian Krog Tamnes

• Ferschmann, Lia; Fjell, Anders Martin; Vollrath, Margarete E.; Grydeland, Håkon; Walhovd, Kristine B & Tamnes, Christian Krog (2018). Personality Traits Are Associated With Cortical Development Across Adolescence: A Longitudinal Structural MRI Study. Child Development.  ISSN 0009-3920.  89(3), s 811- 822 . doi: 10.1111/cdev.13016
• Haukvik, Unn Kristin H.; Tamnes, Christian Krog; Söderman, Erik & Agartz, Ingrid (2018). Neuroimaging hippocampal subfields in schizophrenia and bipolar disorder: A systematic review and meta-analysis. Journal of Psychiatric Research.  ISSN 0022-3956.  104, s 217- 226 . doi: 10.1016/j.jpsychires.2018.08.012
• Krogsrud, Stine Kleppe; Fjell, Anders Martin; Tamnes, Christian Krog; Grydeland, Håkon; Due-Tønnessen, Paulina; Bjørnerud, Atle; Sampaio-Baptista, Cassandra; Andersson, Jesper; Johansen-Berg, Heidi & Walhovd, Kristine B (2018). Development of white matter microstructure in relation to verbal and visuospatial working memory - A longitudinal study. PLoS ONE.  ISSN 1932-6203.  13:e0195540(4), s 1- 22 . doi: 10.1371/journal.pone.0195540
• Tamnes, Christian Krog; Bos, Marieke G.N.; van de Kamp, Ferdi C.; Peters, Sabine & Crone, Eveline A. (2018). Longitudinal development of hippocampal subregions from childhood to adulthood. Developmental Cognitive Neuroscience.  ISSN 1878-9293.  30, s 212- 222 . doi: 10.1016/j.dcn.2018.03.009
• Vijayakumar, Nandita; Mills, Kathryn L.; Alexander-Bloch, Aaron; Tamnes, Christian Krog & Whittle, Sarah (2018). Structural brain development: A review of methodological approaches and best practices. Developmental Cognitive Neuroscience.  ISSN 1878-9293. . doi: 10.1016/j.dcn.2017.11.008
• Wierenga, Lara M.; Bos, Marieke G.N.; Schreuders, Elisabeth; vd Kamp, Ferdi; Peper, Jiska S.; Tamnes, Christian Krog & Crone, Eveline A. (2018). Unraveling age, puberty and testosterone effects on subcortical brain development across adolescence. Psychoneuroendocrinology.  ISSN 0306-4530.  91, s 105- 114 . doi: 10.1016/j.psyneuen.2018.02.034
• Tamnes, Christian Krog; Herting, Megan M.; Goddings, Anne-Lise; Meuwese, Rosa; Blakemore, Sarah-Jayne; Dahl, Ronald E.; Güroğlu, Berna; Raznahan, Armin; Sowell, Elizabeth R.; Crone, Eveline A. & Mills, Kathryn L. (2017). Development of the cerebral cortex across adolescence: A multisample study of inter-related changes in cortical volume, surface area, and thickness. Journal of Neuroscience.  ISSN 0270-6474.  37(12), s 3402- 3412 . doi: 10.1523/JNEUROSCI.3302-16.2017 Full text in Research Archive.
• Westerhausen, Rene; Friesen, Charline-Marie; Rohani, Darius; Krogsrud, Stine Kleppe; Tamnes, Christian Krog; Skranes, Jon Sverre; Håberg, Asta; Fjell, Anders Martin & Walhovd, Kristine B (2017). The corpus callosum as anatomical marker of intelligence? A critical examination in a large-scale developmental study. Brain Structure and Function.  ISSN 1863-2653.  223, s 285- 296 . doi: 10.1007/s00429-017-1493-0
• Almaas, Astrid; Tamnes, Christian Krog; Nakstad, Britt; Henriksen, Christine; Grydeland, Håkon; Walhovd, Kristine B; Fjell, Anders Martin; Iversen, Per Ole & Drevon, Christian A (2016). Diffusion tensor imaging and behavior in premature infants at 8 years of age, a randomized controlled trial with long-chain polyunsaturated fatty acids. Early Human Development.  ISSN 0378-3782.  95, s 41- 46 . doi: 10.1016/j.earlhumdev.2016.01.021
• Amlien, Inge; Fjell, Anders Martin; Tamnes, Christian Krog; Grydeland, Håkon; Krogsrud, Stine Kleppe; Chaplin, Tristan A.; Rosa, Marcello G.P. & Walhovd, Kristine B (2016). Organizing Principles of Human Cortical Development - Thickness and Area from 4 to 30 Years: Insights from Comparative Primate Neuroanatomy. Cerebral Cortex.  ISSN 1047-3211.  26(1), s 257- 267 . doi: 10.1093/cercor/bhu214
• Fuglset, Tone Seim; Endestad, Tor; Hilland, Eva; Bang, Lasse; Tamnes, Christian Krog; Landrø, Nils Inge & Rø, Øyvind (2016). Brain volumes and regional cortical thickness in young females with anorexia nervosa. BMC Psychiatry.  ISSN 1471-244X.  16(1) . doi: 10.1186/s12888-016-1126-9
• Krogsrud, Stine Kleppe; Fjell, Anders Martin; Tamnes, Christian Krog; Grydeland, Håkon; Ferschmann, Lia; Due-Tønnessen, Paulina; Bjørnerud, Atle; Sampaio-Baptista, Cassandra; Andersson, Jesper; Johansen-Berg, Heidi & Walhovd, Kristine B (2016). Changes in white matter microstructure in the developing brain - A longitudinal diffusion tensor imaging study of children from 4 to 11years of age. NeuroImage.  ISSN 1053-8119.  124, s 473- 486 . doi: 10.1016/j.neuroimage.2015.09.017
• Mills, Kathryn L.; Goddings, Anne-Lise; Herting, Megan M.; Meuwese, Rosa; Blakemore, Sarah-Jayne; Crone, Eveline A.; Dahl, Ronald E.; Güroğlu, Berna; Raznahan, Armin; Sowell, Elizabeth R. & Tamnes, Christian Krog (2016). Structural brain development between childhood and adulthood: Convergence across four longitudinal samples. NeuroImage.  ISSN 1053-8119.  141, s 273- 281 . doi: 10.1016/j.neuroimage.2016.07.044
• Tamnes, Christian Krog & Agartz, Ingrid (2016). White Matter Microstructure in Early-Onset Schizophrenia: A Systematic Review of Diffusion Tensor Imaging Studies. Journal of the American Academy of Child and Adolescent Psychiatry.  ISSN 0890-8567.  55(4), s 269- 279 . doi: 10.1016/j.jaac.2016.01.004
• Walhovd, Kristine B; Krogsrud, Stine Kleppe; Amlien, Inge Kasbohm; Bartsch, Hauke; Bjørnerud, Atle; Due-Tønnessen, Paulina; Grydeland, Håkon; Hagler, D.; Håberg, Asta; Kremen, William S.; Ferschmann, Lia; Nyberg, Lars; Panizzon, Matthew S; Rohani, Darius; Skranes, Jon Sverre; Storsve, Andreas Berg; Sølsnes, Anne Elisabeth; Tamnes, Christian Krog; Thompson, Wesley K.; Reuter, Chase; Dale, Anders & Fjell, Anders Martin (2016). Neurodevelopmental origins of lifespan changes in brain and cognition. Proceedings of the National Academy of Sciences of the United States of America.  ISSN 0027-8424.  113(33), s 9357- 9362 . doi: 10.1073/pnas.1524259113 Full text in Research Archive.
• Almaas, Astrid; Tamnes, Christian Krog; Nakstad, Britt; Henriksen, Christine; Walhovd, Kristine B; Fjell, Anders Martin; Due-Tønnessen, Paulina; Drevon, Christian A & Iversen, Per Ole (2015). Long-chain polyunsaturated fatty acids and cognition in VLBW infants at 8 years: An RCT. Pediatrics.  ISSN 0031-4005.  135(6), s 972- 980 . doi: 10.1542/peds.2014-4094
• Fjell, Anders Martin; Amlien, Inge; Sneve, Markus Handal; Grydeland, Håkon; Tamnes, Christian Krog; Chaplin, Tristan; Rosa, Marcello & Walhovd, Kristine B (2015). The roots of Alzheimer's disease: Are high-expanding cortical areas preferentially targeted?. Cerebral Cortex.  ISSN 1047-3211.  25(9), s 2556- 2565 . doi: 10.1093/cercor/bhu055 Full text in Research Archive.
• Fjell, Anders Martin; Grydeland, Håkon; Krogsrud, Stine Kleppe; Amlien, Inge Kasbohm; Rohani, Darius Adam; Ferschmann, Lia; Storsve, Andreas Berg; Tamnes, Christian Krog; Sala Llonch, Roser; Due-Tønnessen, Paulina; Bjørnerud, Atle; Sølsnes, Anne Elisabeth; Håberg, Asta; Skranes, Jon Sverre; Bartsch, Hauke; Chen, Chi-Hua; Thompson, Wesley K.; Panizzon, Matthew S.; Kremen, William S.; Dale, Anders M. & Walhovd, Kristine B (2015). Development and aging of cortical thickness correspond to genetic organization patterns. Proceedings of the National Academy of Sciences of the United States of America.  ISSN 0027-8424.  112(50), s 15462- 15467 . doi: 10.1073/pnas.1508831112 Full text in Research Archive. Show summary

  There is a growing realization that early life influences have lasting impact on brain function and structure. Recent research has demon- strated that genetic relationships in adults can be used to parcellate the cortex into regions of maximal shared genetic influence, and a major hypothesis is that genetically progr ammed neurodevel opmental events cause a lasting impact on the organization of the cerebral cortex observable decades later. Here we tested how developmental and lifespan changes in cortical thickness fit the underlying genetic organi- zational principles of co rtical thickness in a longitudinal sample of 974 participants between 4.1 and 88.5 y of age with a total of 1,633 scans, including 773 scans from children below 12 y. Genetic clustering of cortical thickness was based on an independent dataset of 406 adult twins. Developmental and adult age- related changes in cortical thick- ness followed closely the genetic organization of the cerebral cortex, with change rates varying as a functi on of genetic similarity between regions. Cortical regions with overlapping genetic architecture showed correlated development al and adult age change trajectories and vice versa for regions with low genetic overlap. Thus, effects of genes on regional variations in cortical thickness in middle age can be traced to regional differences in neurodevelopmental change rates and extrap- olated to further adult aging-related cortical thinning. This finding suggests that genetic factors contribute to cortical changes through life and calls for a lifespan perspective i n research aimed at identifying the genetic and environmental determinants of cortical development and aging.

• Fjell, Anders Martin; Westlye, Lars Tjelta; Amlien, Inge; Tamnes, Christian Krog; Grydeland, Håkon; Engvig, Andreas; Espeseth, Thomas; Reinvang, Ivar; Lundervold, Astri; Lundervold, Arvid & Walhovd, Kristine B (2015). High-expanding cortical regions in human development and evolution are related to higher intellectual abilities. Cerebral Cortex.  ISSN 1047-3211.  25, s 26- 34 . doi: 10.1093/cercor/bht201 Full text in Research Archive.
• Kanellopoulos, Adriani; Andersson, Stein; Zeller, Bernward; Tamnes, Christian Krog; Fjell, Anders Martin; Walhovd, Kristine B; Westlye, Lars Tjelta; Fosså, Sophie Dorothea & Ruud, Ellen (2015). Neurocognitive Outcome in Very Long-Term Survivors of Childhood Acute Lymphoblastic Leukemia After Treatment with Chemotherapy Only. Pediatric Blood & Cancer.  ISSN 1545-5009.  63(1), s 133- 138 . doi: 10.1002/pbc.25690
• Tamnes, Christian Krog; Zeller, Bernward; Amlien, Inge; Kanellopoulos, Adriani; Andersson, Stein; Due-Tønnessen, Paulina; Ruud, Ellen; Walhovd, Kristine B & Fjell, Anders Martin (2015). Cortical surface area and thickness in adult survivors of pediatric acute lymphoblastic leukemia. Pediatric Blood & Cancer.  ISSN 1545-5009.  62(6), s 1027- 1034 . doi: 10.1002/pbc.25386
• Walhovd, Kristine B; Tamnes, Christian Krog; Bjørnerud, Atle; Due-Tønnessen, Paulina; Holland, Dominic; Dale, Anders M. & Fjell, Anders Martin (2015). Maturation of Cortico-Subcortical Structural Networks - Segregation and Overlap of Medial Temporal and Fronto-Striatal Systems in Development. Cerebral Cortex.  ISSN 1047-3211.  25(7), s 1835- 1841 . doi: 10.1093/cercor/bht424
• Zayats, Tetyana; Athanasiu, Lavinia; Sønderby, Ida Elken; Djurovic, Srdjan; Westlye, Lars Tjelta; Tamnes, Christian Krog; Fladby, Tormod; Aase, Heidi; Zeiner, Pål; Reichborn-Kjennerud, Ted; Knappskog, Per; Knudsen, Gun Peggy; Andreassen, Ole Andreas; Johansson, Stefan & Haavik, Jan (2015). Genome-wide analysis of attention deficit hyperactivity disorder in Norway. PLoS ONE.  ISSN 1932-6203.  10(4) . doi: 10.1371/journal.pone.0122501 Full text in Research Archive.
• Douaud, Gwenaëlle; Groves, Adrian; Tamnes, Christian Krog; Westlye, Lars Tjelta; Duff, Eugene; Engvig, Andreas; Walhovd, Kristine B; James, Anthony; Gass, Achim; Monsch, Andreas U.; Matthews, Paul M.; Fjell, Anders Martin; Smith, Stephen & Johansen-Berg, Heidi (2014). A common brain network links development, aging, and vulnerability to disease. Proceedings of the National Academy of Sciences of the United States of America.  ISSN 0027-8424.  111(49), s 17648- 17653 . doi: 10.1073/pnas.1410378111
• Krogsrud, Stine Kleppe; Tamnes, Christian Krog; Fjell, Anders Martin; Amlien, Inge; Grydeland, Håkon; Sulutvedt, Unni; Due-Tønnessen, Paulina; Bjørnerud, Atle; Sølsnes, Anne Elisabeth; Håberg, Asta; Skranes, Jon Sverre & Walhovd, Kristine B (2014). Development of hippocampal subfield volumes from 4 to 22 years. Human Brain Mapping.  ISSN 1065-9471.  35(11), s 5646- 5657 . doi: 10.1002/hbm.22576 Full text in Research Archive.
• Mills, Kathryn L. & Tamnes, Christian Krog (2014). Methods and considerations for longitudinal structural brain imaging analysis across development. Developmental Cognitive Neuroscience.  ISSN 1878-9293.  9, s 172- 190 . doi: 10.1016/j.dcn.2014.04.004
• Sexton, Claire E; Walhovd, Kristine B; Storsve, Andreas Berg; Tamnes, Christian Krog; Westlye, Lars Tjelta; Johansen-Berg, Heidi & Fjell, Anders Martin (2014). Accelerated changes in white matter microstructure during aging: A longitudinal diffusion tensor imaging study. Journal of Neuroscience.  ISSN 0270-6474.  34(46), s 15425- 15436 . doi: 10.1523/JNEUROSCI.0203-14.2014
• Storsve, Andreas Berg; Fjell, Anders Martin; Tamnes, Christian Krog; Westlye, Lars Tjelta; Øverbye, Knut; Aasland, Hilde Wiede & Walhovd, Kristine B (2014). Differential longitudinal changes in cortical thickness, surface area and volume across the adult lifespan: Regions of accelerating and decelerating change. Journal of Neuroscience.  ISSN 0270-6474.  34(25), s 8488- 8498 . doi: 10.1523/JNEUROSCI.0391-14.2014 Full text in Research Archive.
• Tamnes, Christian Krog; Walhovd, Kristine B; Engvig, Andreas; Grydeland, Håkon; Krogsrud, Stine Kleppe; Østby, Ylva; Holland, Dominic; Dale, Anders & Fjell, Anders Martin (2014). Regional hippocampal volumes and development predict learning and memory. Developmental Neuroscience.  ISSN 0378-5866.  36(3-4), s 161- 174 . doi: 10.1159/000362445 Full text in Research Archive.
• Walhovd, Kristine B; Tamnes, Christian Krog & Fjell, Anders Martin (2014). Brain structural maturation and the foundations of cognitive behavioral development. Current Opinion in Neurology.  ISSN 1350-7540.  27(2), s 176- 184 . doi: 10.1097/WCO.0000000000000074 Full text in Research Archive.
• Grydeland, Håkon; Walhovd, Kristine B; Tamnes, Christian Krog; Westlye, Lars Tjelta & Fjell, Anders Martin (2013). Intracortical Myelin Links with Performance Variability across the Human Lifespan: Results from T1-and T2-Weighted MRI Myelin Mapping and Diffusion Tensor Imaging. Journal of Neuroscience.  ISSN 0270-6474.  33(47), s 18618- 18630 . doi: 10.1523/JNEUROSCI.2811-13.2013
• Tamnes, Christian Krog; Walhovd, Kristine B; Dale, Anders M.; Østby, Ylva; Grydeland, Håkon; Richardson, George; Westlye, Lars Tjelta; Roddey, J Cooper; Hagler, Donald J.; Due-Tønnessen, Paulina; Holland, Dominic; Fjell, Anders Martin & Database, ADNI (2013). Brain development and aging: Overlapping and unique patterns of change. NeuroImage.  ISSN 1053-8119.  68, s 63- 74 . doi: 10.1016/j.neuroimage.2012.11.039
• Tamnes, Christian Krog; Walhovd, Kristine B; Grydeland, Håkon; Holland, Dominic; Østby, Ylva; Dale, Anders M. & Fjell, Anders Martin (2013). Longitudinal Working Memory Development Is Related to Structural Maturation of Frontal and Parietal Cortices. Journal of cognitive neuroscience.  ISSN 0898-929X.  25(10), s 1611- 1623 . doi: 10.1162/jocn_a_00434 Full text in Research Archive.
• Tamnes, Christian Krog; Walhovd, Kristine B; Torstveit, Mari; Sells, Victoria Torp & Fjell, Anders Martin (2013). Performance monitoring in children and adolescents: A review of developmental changes in the error-related negativity and brain maturation. Developmental Cognitive Neuroscience.  ISSN 1878-9293.  6, s 1- 13 . doi: 10.1016/j.dcn.2013.05.001 Full text in Research Archive.
• Thormodsen, Rune; Rimol, Lars Morten; Tamnes, Christian Krog; Juuhl-Langseth, Monica; Holmen, Aina; Emblem, Kyrre Eeg; Rund, Bjørn Rishovd & Agartz, Ingrid (2013). Age-related cortical thickness differences in adolescents with early-onset schizophrenia compared with healthy adolescents. Psychiatry Research : Neuroimaging.  ISSN 0925-4927.  214(3), s 190- 196 . doi: 10.1016/j.pscychresns.2013.07.003
• Zeller, Bernward; Tamnes, Christian Krog; Kanellopoulos, Adriani; Amlien, Inge; Andersson, Stein; Due-Tønnessen, Paulina; Fjell, Anders Martin; Walhovd, Kristine B; Westlye, Lars Tjelta & Ruud, Ellen (2013). Reduced Neuroanatomic Volumes in Long-Term Survivors of Childhood Acute Lymphoblastic Leukemia. Journal of Clinical Oncology.  ISSN 0732-183X.  31, s 2078- 2085 . doi: 10.1200/JCO.2012.47.4031
• Groves, Adrian; Smith, Stephen M.; Fjell, Anders Martin; Tamnes, Christian Krog; Walhovd, Kristine B; Douaud, Gwenaëlle; Woolrich, Mark & Westlye, Lars Tjelta (2012). Benefits of multi-modal fusion analysis on a large-scale dataset: Life-span patterns of inter-subject variability in cortical morphometry and white matter microstructure. NeuroImage.  ISSN 1053-8119.  63(1), s 365- 380 . doi: 10.1016/j.neuroimage.2012.06.038 Show summary

  Neuroimaging studies have become increasingly multimodal in recent years, with researchers typically acquiring several different types of MRI data and processing them along separate pipelines that provide a set of complementary windows into each subject's brain. However, few attempts have been made to integrate the various modalities in the same analysis. Linked ICA is a robust data fusion model that takes multi-modal data and characterizes inter-subject variability in terms of a set of multi-modal components. This paper examines the types of components found when running Linked ICA on a large magnetic resonance imaging (MRI) morphometric and diffusion tensor imaging (DTI) data set comprising 484 healthy subjects ranging from 8 to 85 years of age. We find several strong global features related to age, sex, and intracranial volume; in particular, one component predicts age to a high accuracy (r=0.95). Most of the remaining components describe spatially localized modes of variability in white or gray matter, with many components including both tissue types. The multimodal components tend to be located in anatomically-related brain areas, suggesting a morphological and possibly functional relationship. The local components show relationships between surface-based cortical thickness and arealization, voxel-based morphometry (VBM), and between three different DTI measures. Further, we report components related to artifacts (e.g. scanner software upgrades) which would be expected in a dataset of this size. Most of the 100 extracted components showed interpretable spatial patterns and were found to be reliable using split-half validation. This work provides novel information about normal inter-subject variability in brain structure, and demonstrates the potential of Linked ICA as a feature-extracting data fusion approach across modalities. This exploratory approach automatically generates models to explain structure in the data, and may prove especially powerful for large-scale studies, where the population variability can be explored in increased detail.

• Tamnes, Christian Krog; Fjell, Anders Martin; Westlye, Lars Tjelta; Østby, Ylva & Walhovd, Kristine B (2012). Becoming Consistent: Developmental Reductions in Intraindividual Variability in Reaction Time Are Related to White Matter Integrity. Journal of Neuroscience.  ISSN 0270-6474.  32(3), s 972- 982 . doi: 10.1523/JNEUROSCI.4779-11.2012
• Walhovd, Kristine B; Tamnes, Christian Krog; Østby, Ylva; Due-Tønnessen, Paulina & Fjell, Anders Martin (2012). Normal variation in behavioral adjustment relates to regional differences in cortical thickness in children. European Child and Adolescent Psychiatry.  ISSN 1018-8827.  21(3), s 133- 140 . doi: 10.1007/s00787-012-0241-5
• Østby, Ylva; Tamnes, Christian Krog; Fjell, Anders Martin & Walhovd, Kristine B (2012). Dissociating memory processes in the developing brain: The role of hippocampal volume and cortical thickness in recall after minutes versus days. Cerebral Cortex.  ISSN 1047-3211.  22(2), s 381- 390 . doi: 10.1093/cercor/bhr116
• Østby, Ylva; Walhovd, Kristine B; Tamnes, Christian Krog; Grydeland, Håkon; Westlye, Lars Tjelta & Fjell, Anders Martin (2012). Mental time travel and default-mode network functional connectivity in the developing brain. Proceedings of the National Academy of Sciences of the United States of America.  ISSN 0027-8424.  109(42), s 16800- 16804 . doi: 10.1073/pnas.1210627109 Show summary

  A core brain network is engaged in remembering the past and envisioning the future. This network overlaps with the so-called default-mode network, the activity of which increases when demands for focused attention are low. Because of their shared brain substrates, an intriguing hypothesis is that default-mode activity, measured at rest, is related to performance in separate attention-focused recall and imagination tasks. However, we do not know how functional connectivity of the default-mode network is related to individual differences in reconstruction of the past and imagination of the future. Here, we show that functional connectivity of the default-mode network in children and adolescents is related to the quality of past remembering and marginally to future imagination. These results corroborate previous findings of a common neuronal substrate for memory and imagination and provide evidence suggesting that mental time travel is modulated by the task-independent functional architecture of the default-mode network in the developing brain. A further analysis showed that local cortical arealization also contributed to explain recall of the past and imagination of the future, underscoring the benefits of studying both functional and structural properties to understand the brain basis for complex human cognition.

• Tamnes, Christian Krog; Fjell, Anders Martin; Østby, Ylva; Westlye, Lars Tjelta; Due-Tønnessen, Paulina; Bjørnerud, Atle & Walhovd, Kristine B (2011). The brain dynamics of intellectual development: Waxing and waning white and gray matter. Neuropsychologia.  ISSN 0028-3932.  49(13), s 3605- 3611 . doi: 10.1016/j.neuropsychologia.2011.09.012 Show summary

  Distributed brain areas support intellectual abilities in adults. How structural maturation of these areas in childhood enables development of intelligence is not established. Neuroimaging can be used to monitor brain development, but studies to date have typically considered single imaging modalities. To explore the impact of structural brain maturation on the development of intelligence, we used a combination of cortical thickness, white matter (WM) volume and WM microstructure in 168 healthy participants aged 8-30 years. Principal component analyses (PCAs) were conducted separately for cortical thickness, WM volume, fractional anisotropy (FA) and mean diffusivity (MD) in 64 different brain regions. For all four parameters, the PCAs revealed a general factor explaining between 40% and 53% of the variance across regions. When tested separately, negative age-independent relationships were found between intellectual abilities and cortical thickness and MD, respectively, while WM volume and FA were positively associated with intellectual abilities. The relationships between intellectual abilities and brain structure varied with age, with stronger relationships seen in children and adolescents than in young adults. Multiple regression analysis with the different imaging measures as simultaneous predictors, showed that cortical thickness, WM volume and MD all yielded unique information in explaining intellectual abilities in development. The present study demonstrates that different imaging modalities and measures give complementary information about the neural substrates of intellectual abilities in development, emphasizing the importance of multimodal imaging in investigations of neurocognitive development.

• Østby, Ylva; Tamnes, Christian Krog; Fjell, Anders Martin & Walhovd, Kristine B (2011). Morphometry and connectivity of the fronto-parietal verbal working memory network in development. Neuropsychologia.  ISSN 0028-3932.  49(14), s 3854- 3862 . doi: 10.1016/j.neuropsychologia.2011.10.001
• Fjell, Anders Martin; Walhovd, Kristine B; Westlye, Lars Tjelta; Østby, Ylva; Tamnes, Christian Krog; Jernigan, TL; Gamst, Anthony & Dale, Anders M. (2010). When does brain aging accelerate? Dangers of quadratic fits in cross-sectional studies. NeuroImage.  ISSN 1053-8119.  50(4), s 1376- 1383 . doi: 10.1016/j.neuroimage.2010.01.061
• Westlye, Lars Tjelta; Walhovd, Kristine B; Dale, Anders M.; Bjørnerud, Atle; Due-Tønnessen, Paulina; Engvig, Andreas; Grydeland, Håkon; Tamnes, Christian Krog; Østby, Ylva & Fjell, Anders Martin (2010). Differentiating maturational and aging-related changes of the cerebral cortex by use of thickness and signal intensity. NeuroImage.  ISSN 1053-8119.  52(1), s 172- 185 . doi: 10.1016/j.neuroimage.2010.03.056 Show summary

  Cortical thickness decreases from childhood throughout life, as estimated by magnetic resonance imaging (MRI). This monotone trajectory does not reflect the fundamentally different neurobiological processes underlying morphometric changes in development versus aging. We hypothesized that intracortical gray matter (GM) and subjacent white matter (WM) T1-weighted signal intensity would distinguish developmental and age-related changes in the cortex better than thickness. Intracortical GM and subjacent WM signal intensity and cortical thickness was measured across the brain surface in a healthy life span sample (n = 429, 8–85 years). We also computed the relaxation rate of T2* (R2*) from multiecho sequences and mapped intracortical GM and subjacent WM values to the surface to delineate age-related variability in R2* and to adjust the T1 signal intensity for possible confounds of accumulated iron. While monotone age-related reductions in thickness were found, both intracortical GM and subcortical WM signal intensity showed inverted U patterns with peaks from eight to approximately 30 years of age. The spatial pattern of intracortical neurodevelopment followed a posterior–anterior gradient, with earliest maturation of occipital visual cortices and most protracted in superior frontal regions. From 50 s and 60 s, substantial signal reductions were observed in several regions, including the insula, cingulate, and inferior temporal gyrus. R2* showed similar patterns but peaked much later than the T1-weighted signal intensity measures. The results are presented as animations yielding detailed depictions of the dynamic regional variability in cortical neurodevelopment and aging and demonstrate that cortical thickness and T1-weighted signal intensity are sensitive to different cortical maturational and aging-related processes.

• Westlye, Lars Tjelta; Walhovd, Kristine B; Dale, Anders M; Bjørnerud, Atle; Due-Tønnessen, Paulina; Engvig, Andreas; Grydeland, Håkon; Tamnes, Christian Krog; Østby, Ylva & Fjell, Anders Martin (2010). Life-Span Changes of the Human Brain White Matter: Diffusion Tensor Imaging (DTI) and Volumetry. Cerebral Cortex.  ISSN 1047-3211.  20(9), s 2055- 2068 . doi: 10.1093/cercor/bhp280 Show summary

  Magnetic resonance imaging volumetry studies report inverted U-patterns with increasing white-matter (WM) volume into middle age suggesting protracted WM maturation compared with the cortical gray matter. Diffusion tensor imaging (DTI) is sensitive to degree and direction of water permeability in biological tissues, providing in vivo indices of WM microstructure. The aim of this cross-sectional study was to delineate age trajectories of WM volume and DTI indices in 430 healthy subjects ranging 8–85 years of age. We used automated regional brain volume segmentation and tract-based statistics of fractional anisotropy, mean, and radial diffusivity as markers of WM integrity. Nonparametric regressions were used to fit the age trajectories and to estimate the timing of maximum development and deterioration in aging. Although the volumetric data supported protracted growth into the sixth decade, DTI indices plateaued early in the fourth decade across all tested regions and then declined slowly into late adulthood followed by an accelerating decrease in senescence. Tractwise and voxel-based analyses yielded regional differences in development and aging but did not provide ample evidence in support of a simple last-in-first-out hypothesis of life-span changes.

• Tamnes, Christian Krog; Østby, Ylva; Fjell, Anders Martin; Westlye, Lars Tjelta; Due-Tønnessen, Paulina & Walhovd, Kristine B (2010). Brain Maturation in Adolescence and Young Adulthood: Regional Age-Related Changes in Cortical Thickness and White Matter Volume and Microstructure. Cerebral Cortex.  ISSN 1047-3211.  20(3), s 534- 548 . doi: 10.1093/cercor/bhp118
• Tamnes, Christian Krog; Østby, Ylva; Walhovd, Kristine B; Westlye, Lars Tjelta; Due-Tønnessen, Paulina & Fjell, Anders Martin (2010). Intellectual Abilities and White Matter Microstructure in Development: A Diffusion Tensor Imaging Study. Human Brain Mapping.  ISSN 1065-9471.  31(10), s 1609- 1625 . doi: 10.1002/hbm.20962 Show summary

  Higher-order cognitive functions are supported by distributed networks of multiple interconnected cortical and subcortical regions. Efficient cognitive processing depends on fast communication between these regions, so the integrity of the connections between them is of great importance. It is known that white matter (WM) development is a slow process, continuing into adulthood. While the significance of cortical maturation for intellectual development is described, less is known about the relationships between cognitive functions and maturation of WM connectivity. In this cross-sectional study, we investigated the associations between intellectual abilities and development of diffusion tensor imaging (DTI) derived measures of WM microstructure in 168 right-handed participants aged 8-30 years. Independently of age and sex, both verbal and performance abilities were positively related to fractional anisotropy (FA) and negatively related to mean diffusivity (MD) and radial diffusivity (RD), predominantly in the left hemisphere. Further, verbal, but not performance abilities, were associated with developmental differences in DTI indices in widespread regions in both hemispheres. Regional analyses showed relations with both FA and RD bilaterally in the anterior thalamic radiation and the cortico-spinal tract and in the right superior longitudinal fasciculus. In these regions, our results suggest that participants with high verbal abilities may show accelerated WM development in late childhood and a subsequent earlier developmental plateau, in contrast to a steadier and prolonged development in participants with average verbal abilities. Longitudinal data are needed to validate these interpretations. The results provide insight into the neurobiological underpinnings of intellectual development.

• Tamnes, Christian Krog; Østby, Ylva; Walhovd, Kristine B; Westlye, Lars Tjelta; Due-Tønnessen, Paulina & Fjell, Anders Martin (2010). Neuroanatomical correlates of executive functions in children and adolescents: A magnetic resonance imaging (MRI) study of cortical thickness. Neuropsychologia.  ISSN 0028-3932.  48(9), s 2496- 2508 . doi: 10.1016/j.neuropsychologia.2010.04.024
• Østby, Ylva; Tamnes, Christian Krog; Fjell, Anders Martin; Westlye, Lars Tjelta; Due-Tønnessen, Paulina & Walhovd, Kristine B (2009). Heterogeneity in Subcortical Brain Development: A Structural Magnetic Resonance Imaging Study of Brain Maturation from 8 to 30 Years. Journal of Neuroscience.  ISSN 0270-6474.  29(38), s 11772- 11782 . doi: 10.1523/JNEUROSCI.1242-09.2009
• Lund, Ole Christer H.; Tamnes, Christian Krog; Moestue, Cathrine; Buss, David M. & Vollrath, Margarete Erika (2007). Tactics of hierarchy negotiation. journal of Research in Personality.  ISSN 0092-6566.  41, s 25- 44 . doi: 10.1016/j.jrp.2006.01.002

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• Tamnes, Christian Krog (2016). Hjerneutvikling fra fosterlivet til voksen alder: Tidlige faktorer og erfaringers betydning, I: Hanne Holme; Ellen Solstad Olavesen; Lisbeth Valla & Marit Bergum Hansen (red.),  Helsestasjonstjenesten: barns psykiske helse og utvikling.  Gyldendal Norsk Forlag A/S.  ISBN 9788205486294.  Kapittel 2.  s 27 - 39
• Tamnes, Christian Krog (2016). Neuroimaging studies of normal brain development and their relevance for understanding mental illness.
• Tamnes, Christian Krog (2015). Longitudinal development of white matter microstructure and working memory across childhood.
• Tamnes, Christian Krog (2015). Principles of structural brain development across adolescence.
• Tamnes, Christian Krog; Krogsrud, Stine Kleppe; Fjell, Anders Martin & Walhovd, Kristine B (2015). Regional development of hippocampal subfield volumes and its associations with cognition and memory.
• Zeller, Bernward; Tamnes, Christian Krog; Kanellopoulos, Adriani; Amlien, Inge Kasbohm; Andersson, Stein; Due-Tønnessen, Paulina; Fjell, Anders Martin; Walhovd, Kristine B; Westlye, Lars Tjelta & Ruud, Ellen (2014). Response to A.A.M. van der Veldt et al. Journal of Clinical Oncology.  ISSN 0732-183X.  32(8), s 852- 853 . doi: 10.1200/JCO.2013.52.5725
• Storsve, Andreas Berg; Walhovd, Kristine B; Sneve, Markus Handal; Tamnes, Christian Krog; Krogsrud, Stine Kleppe & Fjell, Anders Martin (2013). Hukommelse gjennom livet - Nevrovitenskapelige perspektiver.
• Tamnes, Christian Krog (2013). Structural brain maturation and working memory development.
• Kanellopoulos, Adriani; Andersson, Stein; Zeller, Bernward; Fjell, Anders Martin; Walhovd, Kristine B; Westlye, Lars Tjelta; Tamnes, Christian Krog; Amlien, Inge; Fossa, Sophie D. & Ruud, Ellen (2012). Neurocognitive function is reduced in long-term survivors of acute lymphoblastic leukemia treated with chemotherapy only - but poorer performance is not associated with higher treatment burden. Pediatric Blood & Cancer.  ISSN 1545-5009.  59(6), s 1106- 1106

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