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Kjersti Mæhlum Walle

Researcher - Health-, Developmental- and Personality psychology

Email k.m.walle@psykologi.uio.no

Available hours By agreement

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Visiting address Gaustadalléen 30 0373 Oslo

Postal address Postboks 1094 Blindern 0317 Oslo

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I work in the behavioral neuroendocrinology lab, where we study mechanisms of the nervous and endocrine systems, examining how hormonal signaling can influence physiological and psychological processes. We aim to better understand the complex neural interactions that govern our cognitive processes and behavior.

My primary focus is on oxytocin signaling and the role that it plays in cognitive and behavioral flexibility. Cognitive and behavioral flexibility fall under the umbrella term executive functions, which are high-level cognitive processes that govern goal-directed behavior, time management, and resource allocation, and they are essential for daily functioning.

Cognitive and behavioral flexibility help us navigate the complexities of everyday life as we need to adapt our thinking and behavior in response to new, changing, or unexpected events. Understanding the mechanisms behind this flexibility also enhances our insights into neurodevelopmental and psychiatric conditions where these abilities can be impaired.

Academic interests

Neuroendocrinology
Oxytocin
Cognitive and Behavioral Flexibility
Executive functions
Attention
Perception
Mental Health
Neurodevelopment
Neuroplasticity
Cognitive rehabilitation

Teaching

I have previously taught courses on the following topics :

Neuroscience and perception (masters level)
Eyetracking and pupillometry

Background

Employment history

2024 – Researcher, Behavioral Neuroendocrinology Lab, Department of Psychology, University of Oslo.
2019 – 2023 Postdoctoral researcher, Department of Mental Health, Norwegian Institute of Public Health (NIPH).
2019 – 2020 Teaching and grading exams, Inland Norway University of Applied Sciences (INN).
2011 – 2017 Ph.D. Research Fellow, Department of Research (FKL), Sunnaas Rehabilitation Hospital.
2014 – 2014 Visiting Researcher, University of New South Wales, Sydney.
2010 – 2011 Research assistant, Department of Psychology, University of Oslo.

Education

2018 Ph.D. in Psychology, Department of Psychology, University of Oslo.
2011 Master’s degree in Psychology (Cognitive neuroscience), Department of Psychology, University of Oslo.
2005 Project semester in the field of Humanities (HUMPRO), Faculty of Humanities, University of Oslo.
2004 Bachelor’s degree in Psychology, Department of Psychology, University of Oslo.

Research projects:

Unravelling the role of oxytocin in behavioral flexibility
Infection & Immunity - Risk factors for attention deficit hyperactivity disorder (ADHD)
Eye movement camera in mapping visual attention difficulties after stroke
Spatial-sequence synaesthesia
Hearing-motion synaesthesia
Seeing colours that do not exist – Grapheme-colour synaesthesia
Quality in centres for asylum seekers

Deilhaug, Elisabeth; Moerkerke, Matthijs; Sartorius, Alina I.; Kang, Heemin; Bull, Emilie Meyer & Walle, Kjersti M. [Show all 11 contributors for this article] (2026). Using EEG to Measure the Neural Effects of Oxytocin Administration: A Meta‐Analysis and Systematic Review. Psychophysiology. ISSN 0048-5772. 63(6). doi: 10.1111/psyp.70334. Full text in Research Archive Show summary
Electroencephalography (EEG) has emerged as a key method for investigating the neural mechanisms through which oxytocin influences cognition and behavior. EEG is cost‐effective, has excellent temporal precision, and may elucidate neural correlates of emotional and cognitive processes. EEG studies evaluating oxytocin's electrophysiological effects have, however, yielded mixed results, which is likely driven by heterogeneity in EEG measures, study designs, dosages, and samples. To investigate the effect of oxytocin administration on EEG measures, we performed two multilevel random effects meta‐analyses: The first meta‐analysis synthesized studies investigating the effects of oxytocin administration on different neural correlates of social and cognitive processing; the second meta‐analysis synthesized studies evaluating effects of oxytocin administration on exploratory, less task‐specific neural activity measures, such as the modulation of microstates. Across both meta‐analyses, we synthesized 161 effect sizes from 28 randomized controlled trials with a total of 1361 participants from different population groups. These multilevel meta‐analyses yielded statistically significant, small effect sizes of oxytocin administration across different EEG measures reflecting social and cognitive processes (Hedges' g = 0.14), and exploratory neural activity (Hedges' g = 0.28) with significant heterogeneity estimates ( p < 0.01 and p < 0.001, respectively). Moderator analyses revealed that the different EEG measurements of interest (e.g., event‐related potentials) and the proportion of female participants were found to significantly moderate the effect of oxytocin on neural EEG activity. Altogether, these meta‐analyses present tentative evidence for oxytocin administration modulating a wide range of EEG‐based markers of neural activity. We observed substantial heterogeneity across studies—in terms of study designs, experimental paradigms and EEG measurements, and participant characteristics. More research is warranted to map out the context‐specific effects of oxytocin administration on different neural markers, to better understand the neurobiological mechanisms of oxytocin.
Walle, Kjersti Mæhlum; Sartorius, Alina I.; Deilhaug, Elisabeth; Kang, Heemin; Nærland, Terje & Andreassen, Ole [Show all 8 contributors for this article] (2026). Reframing oxytocin as a behavioral flexibility hormone. Neuroscience and Biobehavioral Reviews. ISSN 0149-7634. 185. doi: 10.1016/j.neubiorev.2026.106628. Full text in Research Archive
Kang, Heemin; Deilhaug, Elisabeth; Walle, Kjersti Mæhlum; Sartorius, Alina Marie & Quintana, Daniel S. (2025). A multiverse meta-analysis of oxytocin administration studies. Biological Psychology. ISSN 0301-0511. 201, p. 1–10. doi: 10.1016/j.biopsycho.2025.109112. Full text in Research Archive Show summary
Oxytocin administration is a valuable approach for experimentally increasing central oxytocin levels to investigate its impact on brain function and behavior. Despite considerable research interest, results have shown considerable variability across studies. Several meta-analyses have been conducted to help address this inconsistency. However, conducting a meta-analysis requires researchers to make numerous decisions, such as defining inclusion criteria and analytical techniques. In response to this challenge, a ‘multiverse’ approach can be used to simultaneously explore a range of different potential and realistic scenarios by systematically varying these analytical decisions. In this study, we performed a multiverse meta-analysis to investigate how researcher decisions can influence outcomes in meta-analyses of oxytocin administration studies. We systematically varied inclusion criteria, data synthesis models, and methods for correcting publication bias across 530 effect sizes derived from 185 studies, conducting 256 distinct meta-analyses. Our results demonstrate that summary effect estimates can vary considerably depending on meta-analytic decisions (from d = −0.16 to d = 1.45). Notably, meta-analyses with neurotypical populations tended to yield larger effect sizes than non-neurotypical populations, and multiple administrations studies tended to yield larger effect sizes than single administration studies. Furthermore, summary effect estimates can substantially vary according to the applied publication bias correction method. Our findings also demonstrated that the current evidence mostly supports the presence of the effect of oxytocin across domains, regardless of meta-analytic choices, as over 90% of the observed meta-analyses exceeded the range of bootstrapped meta-analyses assuming a null effect. These results warrant future research on how different contexts may impact the robustness of the effects of oxytocin, while underscoring the value of meta-analysis pre-registration to facilitate the transparent evaluation of meta-analyst decision-making.
Walle, Kjersti Mæhlum; Gustavson, Kristin; Mjaaland, Siri; Askeland, Ragna Bugge; Magnus, Per Minor & Susser, Ezra [Show all 12 contributors for this article] (2025). Maternal immune-mediated conditions and ADHD risk in offspring. BMC Medicine. 23, p. 1–15. doi: 10.1186/s12916-025-04227-3. Full text in Research Archive Show summary
Background Maternal immune-mediated conditions during pregnancy have been linked with increased risk of attention-deficit/hyperactivity disorder (ADHD) in offspring. The relative contributions of maternal inflammatory/immune responses versus shared genetic predispositions remain unclear. This study uses paternal immune-mediated conditions as a negative control to explore these factors, as we investigate associations between maternal immune-mediated conditions during pregnancy and offspring ADHD. Methods Prospective data from the Norwegian Mother, Father, and Child Cohort Study (MoBa) was linked with the Medical Birth Registry of Norway (MBRN) and the Norwegian Patient Registry (NPR) to assess associations between prenatal exposure to maternal immune-mediated conditions and offspring ADHD risk up to age 18. Nationwide recruitment from 1999 to 2008 yielded 104,270 eligible mother–child pairs, with 21,340 children exposed to maternal allergic conditions (asthma, allergies, atopic conditions) and 7478 to other immune conditions (autoimmune, inflammatory). Paternal self-reported immune conditions served as negative controls. Children’s ADHD diagnoses were obtained from NPR, and Cox proportional hazard models estimated hazard ratios for ADHD. Results Both overall categories were associated with increased offspring ADHD risk (allergic conditions HR 1.23, 95% CI, 1.14–1.34; other immune conditions HR 1.36, 95% CI, 1.21–1.53). Specific associations included maternal asthma (HR 1.47, 95% CI, 1.30–1.67), allergies (HR 1.20, 95% CI, 1.10–1.31), rheumatologic/musculoskeletal conditions (HR 1.64, 95% CI, 1.28–2.10), Crohn’s disease/ulcerative colitis (adjusted HR 1.95, 95% CI, 1.23–3.09), and endocrine conditions (HR 1.42, 95% CI, 1.15–1.77), specifically, type 1 diabetes (adjusted HR 2.50, 95% CI, 1.66–3.75). Although some paternal immune-mediated conditions (psoriasis, ulcerative colitis, Crohn’s disease) showed similar trends in ADHD risk, only paternal asthma was significantly associated (adjusted HR 1.26, 95% CI, 1.10–1.45). Conclusions Several maternal immune-mediated conditions were associated with increased offspring ADHD risk. The higher, more consistent ADHD risk estimates with maternal conditions compared to paternal ones indicate that unmeasured genetic confounding does not fully explain these associations. These results suggest direct effects on fetal development through events at the maternal–fetal interface which may alter fetal immune responses and lead to greater ADHD risk in offspring. Asthma may be an exception to this mechanism, as paternal asthma was also linked with offspring ADHD risk.
Walle, Kjersti Mæhlum; Askeland, Ragna Bugge; Gustavson, Kristin; Mjaaland, Siri; Ystrøm, Eivind & Lipkin, W. Ian [Show all 13 contributors for this article] (2022). Risk of attention-deficit hyperactivity disorder in offspring of mothers with infections during pregnancy. JCPP Advances. 2(2), p. 1–11. doi: 10.1002/jcv2.12070. Full text in Research Archive Show summary
Background Maternal infections during pregnancy are common events that have been suggested to be risk factors for Attention-deficit hyperactivity disorder (ADHD) in offspring. Only a few studies have been conducted to date and results are conflicting. The current study investigates the associations between specific groups of prenatal maternal infections and offspring ADHD, considering timing of exposure and the role of fever. Methods We used data from the prospective Norwegian Mother, Father and Child Cohort Study (MoBa), including more than 112,000 pregnancies, linked with data from the Medical Birth Registry of Norway and the Norwegian Patient Registry to estimate odds ratios for the likelihood that children develop ADHD after being exposed to maternal infections during gestation. Results Children exposed to any maternal infection during pregnancy showed increased risk of receiving an ADHD diagnosis (OR = 1.15, CI = 1.03–1.27). Specifically, increased ADHD risk was observed after exposure to genitourinary infections in second (OR = 1.42, CI = 1.06–1.90) or third trimester (OR = 2.04, CI = 1.19–3.49), and to respiratory infections in second trimester (OR = 1.31, CI = 1.12–1.54), provided these infections were accompanied by episodes of fever. Increased ADHD risk was also observed after exposure to diarrhea without fever in the third trimester (OR = 1.25, CI = 1.07–1.46). Conclusions Overall, our results suggest that prenatal exposure to maternal infections, particularly with co-occurring episodes of fever, are risk factors for ADHD. Fever (or severity of the infection) appears to be more important in mid-pregnancy associations. Our results indicate that type of infection and timing of exposure might influence the associations, but small effect sizes require careful interpretations. The association between infection and ADHD should be estimated using discordant siblings or other negative control designs that give better adjustment for unmeasured familial confounding.
Gustavson, Kristin; Ystrøm, Eivind; Ask, Helga; Torvik, Fartein Ask; Hornig, Mady & Susser, Ezra [Show all 16 contributors for this article] (2021). Acetaminophen use during pregnancy and offspring attention deficit hyperactivity disorder - a longitudinal sibling control study. JCPP Advances. 1(2). doi: 10.1002/jcv2.12020. Full text in Research Archive Show summary
Background: Maternal acetaminophen use during pregnancy is associated with increased risk of ADHD in the child. This could reflect causal influence of acetaminophen on fetal neurodevelopment or could be due to confounding factors. The aim of the current study was to examine unmeasured familial confounding factors of this association. Methods: We used data from 26,613 children from 12,902 families participating in the prospective Norwegian Mother, Father, and Child Cohort Study (MoBa). The MoBa was linked to the Norwegian Medical Birth Register and the Norwegian Patient Registry. Siblings discordant for prenatal acetaminophen exposure were compared regarding risk of having an ADHD diagnosis. Results: Children exposed to acetaminophen up to 28 days during pregnancy did not have increased risk of receiving an ADHD diagnosis compared to unexposed children. The adjusted Hazard ratio (aHR) was 0.87 (95% C.I. = 0.70-1.08) for exposure 1 to 7 days, and 1.13 (95% C.I. = 0.82–1.49) for 8–28 days. Long-term exposure (29 days or more) was associated with a two-fold increase in risk of ADHD diagnosis (aHR = 2.02, 95% C.I = 1.17–3.25). In the sibling control model, the association between long-term acetaminophen use and ADHD in the child was aHR = 2.77 (95% C.I. = 1.48–5.05) at the between-family level, and aHR = 1.06 (95% C.I. = 0.51–2.05) at the within-family level. Conclusions: Both the exposed and the unexposed children of mothers with long-term use of acetaminophen in one of the pregnancies had increased risk of receiving an ADHD diagnosis. This indicates that the observed association between long-term acetaminophen use during pregnancy and ADHD in the child may at least partly be confounded by unobserved family factors.
Laeng, Bruno; Flaaten, Camilla Barthel; Walle, Kjersti Maehlum; Hochkeppler, Anne & Specht, Karsten (2021). “Mickey Mousing” in the Brain: Motion-Sound Synesthesia and the Subcortical Substrate of Audio-Visual Integration. Frontiers in Human Neuroscience. 15. doi: 10.3389/fnhum.2021.605166. Full text in Research Archive Show summary
Motion-sound synesthesia is characterized by illusory auditory sensations linked to the pattern and rhythms of motion (dubbed “Mickey Mousing” as in cinema) of visually experienced but soundless object, like an optical flow array, a ball bouncing or a horse galloping. In an MRI study with a group of three synesthetes and a group of eighteen control participants, we found structural changes in the brains of synesthetes in the subcortical multisensory areas of the superior and inferior colliculi. In addition, functional magnetic resonance imaging data showed activity in motion-sensitive regions, as well as temporal and occipital areas, and the cerebellum. However, the synesthetes had a higher activation within the left and right cuneus, with stronger activations when viewing optical flow stimuli. There was also a general difference in connectivity of the colliculi with the above mentioned regions between the two groups. These findings implicate low-level mechanisms within the human neuroaxis as a substrate for local connectivity and cross activity between perceptual processes that are “distant” in terms of cortical topography. The present findings underline the importance of considering the role of subcortical systems and their connectivity to multimodal regions of the cortex and they strengthen a parsimonious account of synesthesia, at the least of the visual-auditory type.
Walle, Kjersti Mæhlum; Nordvik, Jan Egil; Becker, Frank; Espeseth, Thomas; Sneve, Markus Handal & Laeng, Bruno (2019). Unilateral neglect post stroke: Eye movement frequencies indicate directional hypokinesia while fixation distributions suggest compensational mechanism. Brain and Behavior. 9:e01170(1). doi: 10.1002/brb3.1170. Full text in Research Archive Show summary
Introduction: Eye movements and spatial attention are closely related, and eye‐tracking can provide valuable information in research on visual attention. We investigated the pathology of overt attention in right hemisphere (RH) stroke patients differing in their severity of neglect symptoms by using eye‐tracking during a dynamic attention task. Methods: Eye movements were recorded in 26 RH stroke patients (13 with and 13 without unilateral spatial neglect, and a matched group of 26 healthy controls during a Multiple Object Tracking task. We assessed the frequency and spatial distributions of fixations, as well as frequencies of eye movements to the left and to the right side of visual space so as to investigate individuals’ efficiency of visual processing, distribution of attentional processing resources, and oculomotoric orienting mechanisms. Results: Both patient groups showed increased fixation frequencies compared to controls. A spatial bias was found in neglect patients’ fixation distribution, depending on neglect severity (indexed by scores on the Behavioral Inattention Test). Patients with more severe neglect had more fixations within the right field, while patients with less severe neglect had more fixations within their left field. Eye movement frequencies were dependent on direction in the neglect patient group, as they made more eye movements toward the right than toward the left. Conclusion: The patient groups’ higher fixation rates suggest that patients are generally less efficient in visual processing. The spatial bias in fixation distribution, dependent on neglect severity, suggested that patients with less severe neglect were able to use compensational mechanisms in their contralesional space. The observed relation between eye movement rates and directions observed in neglect patients provides a measure of the degree of difficulty these patients may encounter during dynamic situations in daily life and supports the idea that directional oculomotor hypokinesia may be a relevant component in this syndrome.
Walle, Kjersti Mæhlum; Nordvik, Jan Egil; Espeseth, Thomas; Becker, Frank & Laeng, Bruno (2018). Multiple object tracking and pupillometry reveal deficits in both selective and intensive attention in unilateral spatial neglect. Journal of Clinical and Experimental Neuropsychology. ISSN 1380-3395. 49(3), p. 270–289. doi: 10.1080/13803395.2018.1536735. Full text in Research Archive
Walle, Kjersti Mæhlum; Kyler, Hillary Lynn; Nordvik, Jan Egil; Becker, Frank & Laeng, Bruno (2017). Binocular rivalry after right-hemisphere stroke: Effects of attention impairment on perceptual dominance patterns. Brain and Cognition. ISSN 0278-2626. 117, p. 84–96. doi: 10.1016/j.bandc.2017.06.007. Full text in Research Archive
Nordvik, Jan Egil; Walle, Kjersti Mæhlum; Nyberg, Claudia; Fjell, Anders Martin; Walhovd, Kristine B & Westlye, Lars Tjelta [Show all 7 contributors for this article] (2014). Bridging the gap between clinical neuroscience and cognitive rehabilitation: The role of cognitive training, models of neuroplasticity and advanced neuroimaging in future brain injury rehabilitation. NeuroRehabilitation (Reading, MA). ISSN 1053-8135. 34(1), p. 81–85. doi: 10.3233/NRE-131017. Full text in Research Archive

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Walle, Kjersti Mæhlum; Ask, Helga & Gustavson, Kristin (2022). Risk of ADHD in offspring of mothers with infections during pregnancy. Full text in Research Archive
Walle, Kjersti Mæhlum; Ask, Helga & Gustavson, Kristin (2022). Maternal autoimmune disorders in pregnancy and risk of ADHD in offspring. Full text in Research Archive
Walle, Kjersti Mæhlum; Kyler, Hillary Lynn; Nordvik, Jan Egil; Becker, Frank & Laeng, Bruno (2018). Corrigendum to "Binocular rivalry after right-hemisphere stroke: Effects of attention impairment on perceptual dominance patterns" [Brain Cogn. 117 (2017) 84–96]. Brain and Cognition. ISSN 0278-2626. 123, p. 89–91. doi: 10.1016/j.bandc.2018.03.001. Full text in Research Archive

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Published Sep. 13, 2024 12:20 PM - Last modified Nov. 6, 2024 12:12 AM