Olgerta Asko

• Olgerta Asko, Vegard Akselsson Volehaugen, Anaïs Llorens, Ingrid Funderud, Sabine Liliana Leske & Jugoslav Ivanovic [Show all 13 contributors for this article] (2025). Predictive encoding of auditory sequences in the human prefrontal cortex. bioRxiv - the preprint server for biology. doi: 10.1101/2025.08.22.671264. Full text in Research Archive Show summary

  Abstract Humans extract regularities from the environment to form expectations that guide perception and optimize behavior. Although the prefrontal cortex (PFC) is central to this process, the relative contributions of orbitofrontal (OFC) and lateral PFC (LPFC) remain unclear. Here, we show that the brain tracks sound regularities in an auditory deviance detection task to predict when a target deviant will occur. Intracranial EEG in epilepsy patients reveals prefrontal engagement, with earlier expectancy-related modulation in OFC and later modulation in LPFC. Connectivity analyses indicate bidirectional and asymmetrical expectancy-related information exchange between the two areas, with a first lead by OFC, consistent with its role in initiating predictive encoding. Converging causal evidence shows that OFC lesions abolish sensitivity to expectancy, whereas LPFC lesions yield only modest effects not significantly different from controls. Together, these results provide electrophysiological and causal evidence for distinct, temporally organized contributions of prefrontal subregions to predictive processing. Significance Statement The human brain builds probabilistic associations capturing the dynamic environmental structure in a predictive manner. The ability to encode and deploy predictive information to anticipate future events relies on the prefrontal cortex (PFC). However, the specific roles of PFC subregions in this process remain unclear. Here, we provide converging electrophysiological and causal lesion evidence on the distinct involvement of the orbital and lateral PFC in generating anticipatory neural signals based on probabilistic auditory structure.

• Olgerta Asko, Alejandro Omar Blenkmann, Sabine Liliana Leske, Maja Dyhre Foldal, Llorens Anais & Ingrid Funderud [Show all 10 contributors for this article] (2024). Altered hierarchical auditory predictive processing after lesions to the orbitofrontal cortex. eLIFE. 13. doi: 10.7554/eLife.86386. Full text in Research Archive

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• Silje Pileberg & Olgerta Asko (2026). Forsker: Vær glad for livets overraskelser. [Internet]. Forskning.no. Full text in Research Archive Show summary

  Hver av dem gjør hjernen din litt mer finjustert.

• Olgerta Asko, Vegard Akselsson Volehaugen, Sabine Liliana Leske, Ingrid Funderud, Anaïs Llorens & Jugoslav Ivanovic [Show all 12 contributors for this article] (2024). Predictive encoding of deviant tone sequences in the human prefrontal cortex. Full text in Research Archive
• Olgerta Asko, Vegard Akselsson Volehaugen, Sabine Liliana Leske, Ingrid Funderud, Llorens Anais & Jugoslav Ivanovic [Show all 12 contributors for this article] (2024). Predictive encoding of deviant tone sequences in the human prefrontal cortex. Full text in Research Archive Show summary

  The ability to use predictive information to guide perception and action relies heavily on the prefrontal cortex (PFC), yet the involvement of its subregions in predictive processes remains unclear. Recent perspectives propose that the orbitofrontal cortex (OFC) generates predictions about perceptual events, actions, and their outcomes while the lateral prefrontal cortex (LPFC) is involved in prospective functions, which support predictive processes, such as selective attention, working memory, response preparation or inhibition. To further delineate the roles of these PFC areas in predictive processing, we investigated whether lesions would impair the ability to build predictions of future events and detect deviations from expected regularities. We used an auditory deviance detection task, in which the structural regularities of played tones were controlled at two hierarchical levels by rules defined at a local (i.e., between tones within sequences) and global (i.e., between sequences) level. We have recently shown that OFC lesions affect detecting prediction violations at two hierarchical levels of rule abstraction, i.e., altered MMN and P3a to local and simultaneous local + global prediction violations (https://doi.org/10.7554/eLife.86386). Now, we focus on the task's predictive aspect and present the latest results showing the involvement of PFC subregions in anticipation of deviances informed by implicit predictive information. Behavioral data shows that deviance expectancy induced faster deviance detection in healthy adults (n=22), suggesting that participants track a state space representation of the task and anticipate upcoming deviant sequences. The analysis of EEG data from patients with focal lesions to the OFC (n = 12) or LPFC (n = 10), and SEEG from the same areas in patients with epilepsy (n = 7), revealed interesting differences. Healthy adults (n = 15) showed modulations of the Contingent Negative Variation (CNV) – a marker of anticipatory activity - tracking the expectancy of deviant tone sequences. However, patients with OFC lesions lacked CNV sensitivity to the predictive context, while patients with LPFC lesions showed moderate sensitivity compared to healthy adults. These results were further supported by intracranial recordings, which revealed expectancy modulation of the high-frequency broadband signal from electrodes in OFC and LPFC, with an earlier latency of activity modulation for the OFC and a later one for the LPFC. Altogether, the complementary approach from behavioral, intracerebral EEG, scalp EEG, and causal lesion data provides compelling evidence for the distinct engagement of the two prefrontal areas in predicting future events and signaling deviations.

• Olgerta Asko, Anne-Kristin Solbakk, Sabine Liliana Leske, Torstein Ragnar Meling, Robert T. Knight & Tor Endestad [Show all 7 contributors for this article] (2023). The orbitofrontal cortex (OFC) has a critical role in the generation of high-level expectations. Full text in Research Archive
• Alejandro Omar Blenkmann, Olgerta Asko, Vegard Volehaugen, Maja Dyhre Foldal, Sandra Solli & Sabine Liliana Leske [Show all 9 contributors for this article] (2023). Auditory perception, memory, and predictions. Full text in Research Archive
• Olgerta Asko, Anne-Kristin Solbakk, Sabine Liliana Leske, Torstein Ragnar Meling, Robert T. Knight & Tor Endestad [Show all 7 contributors for this article] (2023). Orbitofrontal lesion impacts formation of auditory expectations. Full text in Research Archive Show summary

  Current findings of orbitofrontal cortex (OFC) function suggest that this region might have a role in the generation of prediction error signals associated with top-down expectation of upcoming stimuli. We investigated the impact of lesions to the OFC on the Contingent Negative Variation (CNV), an electrophysiological marker of cognitive expectation and time perception. Twelve OFC patients and fifteen healthy controls performed an auditory local-global paradigm while brain electrical activity was recorded. The structural regularities of the tones were controlled at two hierarchical levels by rules defined at a local (i.e., between tones within sequences) level with a short timescale and at a global (i.e., between sequences) level with a longer timescale. At the global level, deviant tone sequences were interspersed among standard tone sequences in a pseudorandom order, rendering some deviant sequences more anticipated than others. We found that healthy controls exhibited CNV build-up before the occurrence of deviant sequences. The CNV drift rate was modulated by the expectancy of deviant sequences (i.e., the higher the expectancy, the higher the CNV drift rate), reflecting their ability to anticipate when a deviant tone sequence would occur. However, patients with OFC lesions did not show CNV drift modulations by the expectancy of the deviant tone sequences, indicating impaired anticipation of these upcoming events. These findings suggest involvement of the OFC in generating auditory expectations based on the contextual and temporal structure of the task.

• Leonardo Bonetti, Maja Dyhre Foldal, Sabine Liliana Leske, Olgerta Asko, Vegard Akselsson Volehaugen & Sandra Solli [Show all 7 contributors for this article] (2023). Auditory perception, memory, and predictions. Full text in Research Archive
• Olgerta Asko, Alejandro Omar Blenkmann, Sabine Liliana Leske, Maja Dyhre Foldal, Anaïs Llorens & Ingrid Funderud [Show all 10 contributors for this article] (2022). Altered hierarchical auditory predictive processing after lesions to the orbitofrontal cortex. Full text in Research Archive Show summary

  In this study, we tested the causal involvement of the OFC in noticing breaches of predictions (i.e., PEs) at different hierarchical levels of task structural complexity. With this aim, we examined the event-related potentials (ERPs) of patients with focal OFC lesions and healthy adults while performing an auditory local-global oddball paradigm. Altogether, we found that after OFC damage, low-level PEs (i.e., processing of stimuli that are unpredicted at the local level) and combined low- and high-level PEs (i.e., processing of stimuli that are unpredicted at both the local and global level) were impacted. However, the processing of standard tones was not affected. We conclude that the OFC may contribute to a top-down process that modulates the deviance detection system in the primary auditory cortices, and may be involved in connecting PEs at lower hierarchical areas with predictions at higher areas. The study sheds new light on the poorly explored deficits of hierarchical auditory prediction in patients with damaged OFC.

• Maria Stavrinou, Olgerta Asko, Thomas Hagen, Maja Dyhre Foldal & Thomas Espeseth (2017). The long term effects of reward on spatial priority maps studied with Electroencephalography and Pupillometry. Full text in Research Archive
• Olgerta Asko (2026). Predictive Processing in Human Prefrontal Cortex: Causal Contributions of Orbitofrontal and Lateral Prefrontal Subregions. University of Oslo (UiO). Full text in Research Archive Show summary

  The human brain is not a passive receiver. It is a prediction engine that continuously integrates what has happened with what is happening to anticipate what comes next. This dissertation investigates how orbitofrontal (OFC) and lateral prefrontal (LPFC) subregions causally contribute to hierarchical predictive processing in the auditory domain, within a predictive coding framework. Combining focal lesions with EEG and iEEG, it shows that OFC damage weakens and delays neural responses to local and local+global rule violations and disrupts expectancy-related modulation of anticipatory (CNV) signals, whereas LPFC damage has more modest effects. Intracranial recordings confirm OFC involvement, with expectancy-dependent activity emerging earlier in OFC than LPFC and recurrent cross-talk initiated from OFC to LPFC. Moving beyond simple deviance-detection paradigms, the work targets the hierarchical and anticipatory nature of prediction and separates genuine prediction from repetition-based adaptation. Together, it highlights OFC as a key, previously underexplored region in human predictive processing.

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