Bio

Professional Education


  • Doctor of Philosophy, Universitat Zurich (2018)
  • Master of Science, Universitat Zurich (2013)
  • Bachelor of Science, Universitat Zurich (2010)

Stanford Advisors


Publications

All Publications


  • Valence-dependent coupling of prefrontal-amygdala effective connectivity during facial affect processing. eNeuro Willinger, D., Karipidis, I. I., Beltrani, S., Pietro, S. V., Sladky, R., Walitza, S., Stampfli, P., Brem, S. 2019

    Abstract

    Despite the importance of the prefrontal-amygdala network for emotion processing, valence-dependent coupling within this network remains elusive. In this study, we assessed the effect of emotional valence on brain activity and effective connectivity. We tested which functional pathways within the prefrontal-amygdala network are specifically engaged during the processing of emotional valence. Thirty-three healthy adults were examined with functional magnetic resonance imaging while performing a dynamic faces and dynamic shapes matching task. The valence of the facial expressions varied systematically between positive, negative, and neutral across the task. Functional contrasts determined core areas of the emotion processing circuitry, comprising the medial prefrontal cortex (MPFC), the right lateral prefrontal cortex, the amygdala and the right fusiform face area. Dynamic causal modelling demonstrated that the bidirectional coupling within the prefrontal-amygdala circuitry is modulated by emotional valence. Additionally, Bayesian model averaging showed significant bottom-up connectivity from the amygdala to the MPFC during negative and neutral, but not positive, valence. Thus, our study provides strong evidence for alterations of bottom-up coupling within the prefrontal-amygdala network as a function of emotional valence. Thereby our results not only advance the understanding of the human prefrontal-amygdala circuitry in varying valence context, but, moreover, provide a model to examine mechanisms of valence-sensitive emotional dysregulation in neuropsychiatric disorders.Significance statement Recent neuroimaging studies have emphasized the importance of valence-sensitivity within the prefrontal-amygdala network during emotion processing. Yet, it remains elusive which specific pathways are involved in processing affective information, and how this information is integrated in the brain's network. In particular, the amygdala's role in signaling valence information to the cortex is subject to ongoing discussions. Moreover, as aberrant brain function has been found in the amygdala and the prefrontal cortex in various debilitating psychiatric disorders, understanding the mechanisms of processing emotional stimuli with different valence (positive, negative, neutral) is particularly relevant for the field. Our findings indicate changes in coupling strength as a function of emotional valence within the prefrontal-amygdala network.

    View details for DOI 10.1523/ENEURO.0079-19.2019

    View details for PubMedID 31289107

  • Emerging neural specialization of the ventral occipitotemporal cortex to characters through phonological association learning in preschool children NEUROIMAGE Pleisch, G., Karipidis, I. I., Brauchli, C., Rothlisberger, M., Hofstetter, C., Stampfli, P., Walitza, S., Brem, S. 2019; 189: 813–31

    Abstract

    The ventral occipitotemporal (vOT) cortex serves as a core region for visual processing, and specific areas of this region show preferential activation for various visual categories such as faces and print. The emergence of such functional specialization in the human cortex represents a pivotal developmental process, which provides a basis for targeted and efficient information processing. For example, functional specialization to print in the left vOT is an important prerequisite for fluent reading. However, it remains unclear, which processes initiate the preferential cortical activations to characters arising in the vOT during child development. Using a multimodal neuroimaging approach with preschool children at familial risk for developmental dyslexia, we demonstrate how varying levels of expertise modulate the neural response to single characters, which represent the building blocks of print units. The level of expertise to characters was manipulated firstly through brief training of false-font speech-sound associations and secondly by comparing characters for which children differed in their level of familiarity and expertise accumulated through abundant exposure in their everyday environment. Neural correlates of character processing were tracked with simultaneous high-density electroencephalography and functional magnetic resonance imaging in a target detection task. We found training performance and expertise-dependent modulation of the visual event-related potential around 220 ms (N1) and the corresponding vOT activation. Additionally, trained false-font characters revealed stronger functional connectivity between the left fusiform gyrus (FFG) seed and left superior parietal/lateral occipital cortex regions with higher training performance. In sum, our results demonstrate that learning artificial-character speech-sound associations enhances activation to trained characters in the vOT and that the magnitude of this activation and the functional connectivity of the left FFG to the parieto-occipital cortex depends on learning performance. This pattern of results suggests emerging development of the reading network after brief training that parallels network specialization during reading acquisition.

    View details for DOI 10.1016/j.neuroimage.2019.01.046

    View details for Web of Science ID 000461166900070

    View details for PubMedID 30677503

  • Reply to "Dyslexia: Still Not a Neurodevelopmental Disorder" BRAIN SCIENCES Gonzalez, G., Karipidis, I. I., Tijms, J. 2019; 9 (3)

    Abstract

    In a recent opinion article, we explained why we think that defining developmental dyslexia as a neurodevelopmental disorder and neuroimaging studies on dyslexia are useful. A recent response has made some claims of generalized misinterpretation and misconception in the field. Since that was a direct reply to our article, we would like to clarify our opinion on some of those claims.

    View details for DOI 10.3390/brainsci9030061

    View details for Web of Science ID 000464372800001

    View details for PubMedID 30875810

    View details for PubMedCentralID PMC6468896

  • Dyslexia as a Neurodevelopmental Disorder and What Makes It Different from a Chess Disorder BRAIN SCIENCES Gonzalez, G., Karipidis, I. I., Tijms, J. 2018; 8 (10)

    Abstract

    The convenience of referring to dyslexia as a neurodevelopmental disorder has been repeatedly brought into question. In this opinion article, we argue in favor of the current diagnosis of dyslexia based on the criteria of harm and dysfunction. We discuss the favorable clinical and educational outcomes of a neuroscience-informed approach of dyslexia as a disorder. Furthermore, we discuss insights derived from neuroimaging studies and their importance to address problems related to developmental dyslexia.

    View details for DOI 10.3390/brainsci8100189

    View details for Web of Science ID 000448655700012

    View details for PubMedID 30347764

    View details for PubMedCentralID PMC6209961

  • Simulating reading acquisition: The link between reading outcome and multimodal brain signatures of letter-speech sound learning in prereaders SCIENTIFIC REPORTS Karipidis, I. I., Pleisch, G., Brandeis, D., Roth, A., Rothlisberger, M., Schneebeli, M., Walitza, S., Brem, S. 2018; 8: 7121

    Abstract

    During reading acquisition, neural reorganization of the human brain facilitates the integration of letters and speech sounds, which enables successful reading. Neuroimaging and behavioural studies have established that impaired audiovisual integration of letters and speech sounds is a core deficit in individuals with developmental dyslexia. This longitudinal study aimed to identify neural and behavioural markers of audiovisual integration that are related to future reading fluency. We simulated the first step of reading acquisition by performing artificial-letter training with prereading children at risk for dyslexia. Multiple logistic regressions revealed that our training provides new precursors of reading fluency at the beginning of reading acquisition. In addition, an event-related potential around 400 ms and functional magnetic resonance imaging activation patterns in the left planum temporale to audiovisual correspondences improved cross-validated prediction of future poor readers. Finally, an exploratory analysis combining simultaneously acquired electroencephalography and hemodynamic data suggested that modulation of temporoparietal brain regions depended on future reading skills. The multimodal approach demonstrates neural adaptations to audiovisual integration in the developing brain that are related to reading outcome. Despite potential limitations arising from the restricted sample size, our results may have promising implications both for identifying poor-reading children and for monitoring early interventions.

    View details for DOI 10.1038/s41598-018-24909-8

    View details for Web of Science ID 000431622700001

    View details for PubMedID 29740067

    View details for PubMedCentralID PMC5940897

  • Increasing expertise to a novel script modulates the visual N1 ERP in healthy adults INTERNATIONAL JOURNAL OF BEHAVIORAL DEVELOPMENT Brem, S., Hunkeler, E., Machler, M., Kronschnabel, J., Karipidis, I., Pleisch, G., Brandeis, D. 2018; 42 (3): 333–41
  • The dopaminergic reward system underpins gender differences in social preferences NATURE HUMAN BEHAVIOUR Soutschek, A., Burke, C. J., Beharelle, A., Schreiber, R., Weber, S. C., Karipidis, I. I., ten Velden, J., Weber, B., Haker, H., Kalenscher, T., Tobler, P. N. 2017; 1 (11): 819–27

    Abstract

    Women are known to have stronger prosocial preferences than men, but it remains an open question as to how these behavioural differences arise from differences in brain functioning. Here, we provide a neurobiological account for the hypothesized gender difference. In a pharmacological study and an independent neuroimaging study, we tested the hypothesis that the neural reward system encodes the value of sharing money with others more strongly in women than in men. In the pharmacological study, we reduced receptor type-specific actions of dopamine, a neurotransmitter related to reward processing, which resulted in more selfish decisions in women and more prosocial decisions in men. Converging findings from an independent neuroimaging study revealed gender-related activity in neural reward circuits during prosocial decisions. Thus, the neural reward system appears to be more sensitive to prosocial rewards in women than in men, providing a neurobiological account for why women often behave more prosocially than men.

    View details for DOI 10.1038/s41562-017-0226-y

    View details for Web of Science ID 000418854500016

    View details for PubMedID 31024122

  • Neural initialization of audiovisual integration in prereaders at varying risk for developmental dyslexia HUMAN BRAIN MAPPING Karipidis, I. I., Pleisch, G., Rothlisberger, M., Hofstetter, C., Dornbierer, D., Stampfli, P., Brem, S. 2017; 38 (2): 1038–55

    Abstract

    Learning letter-speech sound correspondences is a major step in reading acquisition and is severely impaired in children with dyslexia. Up to now, it remains largely unknown how quickly neural networks adopt specific functions during audiovisual integration of linguistic information when prereading children learn letter-speech sound correspondences. Here, we simulated the process of learning letter-speech sound correspondences in 20 prereading children (6.13-7.17 years) at varying risk for dyslexia by training artificial letter-speech sound correspondences within a single experimental session. Subsequently, we acquired simultaneously event-related potentials (ERP) and functional magnetic resonance imaging (fMRI) scans during implicit audiovisual presentation of trained and untrained pairs. Audiovisual integration of trained pairs correlated with individual learning rates in right superior temporal, left inferior temporal, and bilateral parietal areas and with phonological awareness in left temporal areas. In correspondence, a differential left-lateralized parietooccipitotemporal ERP at 400 ms for trained pairs correlated with learning achievement and familial risk. Finally, a late (650 ms) posterior negativity indicating audiovisual congruency of trained pairs was associated with increased fMRI activation in the left occipital cortex. Taken together, a short (<30 min) letter-speech sound training initializes audiovisual integration in neural systems that are responsible for processing linguistic information in proficient readers. To conclude, the ability to learn grapheme-phoneme correspondences, the familial history of reading disability, and phonological awareness of prereading children account for the degree of audiovisual integration in a distributed brain network. Such findings on emerging linguistic audiovisual integration could allow for distinguishing between children with typical and atypical reading development. Hum Brain Mapp 38:1038-1055, 2017. © 2016 Wiley Periodicals, Inc.

    View details for DOI 10.1002/hbm.23437

    View details for Web of Science ID 000393786500034

    View details for PubMedID 27739608

  • Social discounting involves modulation of neural value signals by temporoparietal junction PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Strombach, T., Weber, B., Hangebrauk, Z., Kenning, P., Karipidis, I. I., Tobler, P. N., Kalenscher, T. 2015; 112 (5): 1619–24

    Abstract

    Most people are generous, but not toward everyone alike: generosity usually declines with social distance between individuals, a phenomenon called social discounting. Despite the pervasiveness of social discounting, social distance between actors has been surprisingly neglected in economic theory and neuroscientific research. We used functional magnetic resonance imaging (fMRI) to study the neural basis of this process to understand the neural underpinnings of social decision making. Participants chose between selfish and generous alternatives, yielding either a large reward for the participant alone, or smaller rewards for the participant and another individual at a particular social distance. We found that generous choices engaged the temporoparietal junction (TPJ). In particular, the TPJ activity was scaled to the social-distance-dependent conflict between selfish and generous motives during prosocial choice, consistent with ideas that the TPJ promotes generosity by facilitating overcoming egoism bias. Based on functional coupling data, we propose and provide evidence for a biologically plausible neural model according to which the TPJ supports social discounting by modulating basic neural value signals in the ventromedial prefrontal cortex to incorporate social-distance-dependent other-regarding preferences into an otherwise exclusively own-reward value representation.

    View details for DOI 10.1073/pnas.1414715112

    View details for Web of Science ID 000349087700087

    View details for PubMedID 25605887

    View details for PubMedCentralID PMC4321268

  • Swiss GraphoGame: Concept and design presentation of a computerised reading intervention for children with high risk for poor reading outcomes Rothlisberger, M., Karipidis, I. I., Pleisch, G., Dellwo, V., Richardson, U., Brem, S., ISCA-INT SPEECH COMMUN ASSOC ISCA-INT SPEECH COMMUNICATION ASSOC. 2015: 1878–79