Trial lecture
Designated topic: The role of episodic memory in future thinking and decision-making.
Public defence
Thesis introduction:
The first opponent:?
The second opponent:
Evaluation committee
- Professor Lesley Fellows, McGill University, Canada
- Associate Professor Iria SanMiguel, University of Barcelona, Spain
- Professor Sascha Frühholz, Department of Psychology, University of Oslo
Chair of the defence
Professor Stein Andersson, Department of Psychology, University of Oslo
Supervisors
- Professor Anne-Kristin Solbakk, Department of Psychology, University of Oslo
- Associate Professor Tor Endestad, Department of Psychology, University of Oslo
- Researcher Alejandro O. Blenkmann, RITMO, University of Oslo
Dissertation abstract
Predictive processing refers to brain functions that integrate past and present information to anticipate future states of the body or environment. This anticipatory orientation is adaptive and constitutes one of the fundamental principles of neural computations. Within this framework, mismatches between expected and actual input, i.e., prediction violations, play a central role in shaping neural, cognitive, and behavioral responses. This dissertation defines and operationalizes two distinct components of the predictive processing: prediction violation detection and top-down expectation/anticipation. With the main aim to investigate how the human prefrontal cortex (PFC) contributes to these processes, the dissertation examines the effects of focal lesions to the orbitofrontal cortex (OFC) and/or lateral PFC (LPFC) on the electrophysiological correlates of these predictive functions. It complements the findings by adding intracranial electrophysiological evidence from the same prefrontal areas in patients with drug-resistant epilepsy.
Paper I identifies neural signatures of prediction violation during auditory sequence perception, structured hierarchically by rules defined at a local (i.e., between tones within sequences) and at a global (i.e., between sequences) level. Violations at both levels produce enhanced event-related potentials (ERPs), with larger amplitudes and longer durations, compared to responses to either local or global violations alone. This suggests an amplified prediction violation signal, where bottom-up signals from local deviations are integrated with disruptions of learned global patterns (top-down signals). Paper I further shows that OFC lesions affect these neural responses by attenuating mismatch negativity (MMN) and P3a responses to local violations, as well as a diminished MMN followed by a delayed P3a to combined local and global violations. Lesions to the LPFC show no such effect, suggesting anatomical specificity to the altered predictive processing resulting from OFC lesion.
Paper II extends the findings by examining the Contingent Negative Variation (CNV), a neural signature of expectation/anticipation. In healthy control participants, the CNV is modulated by the expectancy of global violations, reflecting ongoing tracking of regularity to guide behavior. Damage to the OFC disrupts this modulation, indicating impaired anticipation, while damage to the LPFC produces a weak attenuation. Complementing this, intracerebrally recorded high-frequency broadband (HFB) activity in both areas also tracks expectancy, with OFC signaling the expectancy-related modulation earlier, whereas LPFC becoming engaged later. Connectivity analysis shows bidirectional exchange of predictive information between the two regions, with a first lead of OFC.
By integrating a range of methodological approaches, this dissertation provides novel insights into the role of OFC in establishing expectancy and modulating anticipatory and mismatch signals within a predictive processing framework, an area previously underexplored. Causal evidence regarding LPFC remains inconclusive (no significant lesion effects), whereas intracranial recordings indicate a later involvement of LPFC relative to OFC, with the two areas exchanging predictive information. This temporal ordering may suggest that OFC provides contextual signals that are subsequently integrated by LPFC. Further research should clarify the causal contribution of LPFC and test the proposed dynamics of the interregional communication.
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