Biology subjects

Hellerstedt, R.

Publications and source records attributed to Hellerstedt, R..

5 recordsLinked to original sources

bioRxiv2026

Contribution of the Late Positive Potential to Emotional Memory: A Joint Neuro-Cognitive Approach to Memory Prediction

Emotional events are better remembered than neutral events. The emotional Context Maintenance and Retrieval model (eCMR) explains this effect by simulating preferential encoding of emotional items, implemented by a free parameter that scales the learning rate. Incorporating a neural signal measured during encoding could make the model's account more specific, permitting a prediction not only of average increased recall but also which emotional items are likely to be recalled. We investigated whether the late positive potential (LPP) event-related potential (ERP) effect could provide this item-specific information in a secondary analysis of EEG recorded while 38 participants encoded negative and neutral pictures for an immediate free recall test (Zarubin et al. 2020). First, we established that the LPP effect was modulated by emotion in an early (400-1000 ms) and a late (1000-2000 ms) time window and this modulation was reliable in 73.7% and 50% of the participants respectively. Second, we investigated at what level the LPP was related to subsequent memory. Emotion-enhanced LPP did not covary with emotion-enhanced memory between participants or across lists within participants, but the early LPP specifically predicted memory for emotional items on a single-trial level. Third, we compared eCMR variants to test whether trial-level early LPP should scale learning for both categories or only for emotional items, and whether it could replace or complement a common learning-rate increase for all emotional items. The best-fitting model combined emotion-specific LPP scaling with the common learning-rate increase. The finding that early LPP predicted enhanced recall only for emotional items is difficult to reconcile with accounts on which the LPP reflects attention or stimulus significance more generally, which predict a relationship to memory for neutral items as well. These results pave the way to quantitative prediction of internal recall trajectories by individual participants without requiring behavioural output.

neuroscience↗

bioRxiv2025

Emotional amnesia in humans with focal temporal pole lesions

Memory is typically better for emotional relative to neutral events, a process involving amygdala modulation of hippocampal activity1-6. These structures, however, form part of a larger emotional brain network, which in humans includes the temporal pole7, a cortical node whose functional role in emotional cognition remains poorly understood8-10. Here, we show, in pharmaco-resistant epilepsy patients performing verbal and visual emotional episodic memory tasks, a selective impairment in recalling verbal emotional memories in left ventral temporal pole (vTP) lesioned patients compared with control patients. Memory for neutral words, and verbal comprehension performance on standard neuropsychological testing, were intact in these patients, indicating absence of general episodic memory or semantic impairment. All patients underwent recordings with intracranial electrodes during memory task performance. Left vTP lesioned patients showed no differences in amygdala or hippocampal electrophysiological responses to emotional words, compared with control patients, putatively isolating a vTP role in emotional memory. Unlike verbal emotional recall, left vTP lesioned patients showed memory enhancement for emotional vs. neutral pictures, whereas two patients with right vTP lesions showed the opposite pattern: impaired memory for emotional pictures but intact verbal emotional memory. These observations establish a critical, lateralized, modality-specific role for human vTP in emotional memory, imply emotional memory deficits in neurological conditions affecting this region, and advance the vTP as a target for neuromodulation in diseases characterized by maladaptive emotional memories.

neuroscience↗

bioRxiv2022

Can neural correlates of encoding explain the context dependence of reward-enhanced memory?

Selective encoding can be studied by manipulating how valuable it is for participants to remember specific stimuli, for instance by varying the monetary reward participants receive for recalling a particular stimulus in a subsequent memory test. It would be reasonable for participants to strategically attend more to high-reward items compared to low-reward items in mixed list contexts, but to attend both types of items equally in pure list contexts, where all items are of equal value. Reward-enhanced memory may be driven by automatic dopaminergic interactions between reward circuitry and the hippocampus and thus be insensitive to list context; or it may be driven by meta-cognitive strategies, and thus context-dependent. We contrasted these alternatives by manipulating list composition, and tracked selective encoding through multiple EEG measures of attention and rehearsal. Behavioural results were context-dependent, such that recall of high-reward items was increased only in mixed lists. This result and aspects of the recall dynamics confirm predictions of the eCMR (emotional Context Maintenance and Retrieval) model. The power of ssVEPs was lower for high-reward items regardless of list composition, suggesting decreased visual processing of high-reward stimuli and that ssVEPs may index the modulation of context-to-item associations predicted by eCMR. By contrast, reward modulated the amplitude of Late Positive Potential and Frontal Slow Wave only in mixed lists. Taken together the results provide evidence that reward-enhanced memory is caused by an interplay between strategic processes applied when high- and low-reward items compete for cognitive resources during encoding and context-dependent mechanisms operating during recall.

neuroscience↗

bioRxiv2022

EEG evidence that morally relevant autobiographical memories can be suppressed

Remembering unpleasant events can trigger negative feelings. Fortunately, research indicates that unwanted memories can be suppressed to prevent them from intruding into awareness, improving our mental state. The current scientific understanding of memory suppression is, however, based mostly on simpler memories such as associations between words or pictures, which may not reflect how people control unpleasant memory intrusions in everyday life. Here, we investigated the neural and behavioural dynamics of suppressing personal and emotional autobiographical memories using a modified version of the Think/No-Think task. We asked participants to suppress memories of their own past immoral actions, which were hypothesised to be both highly intrusive and motivating to suppress. We report novel evidence from behavioural, ERP and EEG oscillation measures that autobiographical memory retrieval can be suppressed and suggest that autobiographical suppression recruits similar neurocognitive mechanisms as suppression of simple laboratory associations. Suppression did fail sometimes, and EEG oscillations indicated that such memory intrusions occurred from lapses in sustained control. Importantly however, participants improved at limiting intrusions with repeated practice. Furthermore, both behavioural and EEG evidence indicated that intentional suppression may be more difficult for memories of our morally wrong actions than memories of our morally right actions. The findings elucidate the neurocognitive correlates of autobiographical retrieval suppression and have implications for theories of morally motivated memory control.

neuroscience↗

bioRxiv2020

Aging Reduces EEG Markers of Recognition Despite Intact Performance: Implications for Forensic Memory Detection

ERP-based forensic memory detection is based on the logic that guilty suspects will hold incriminating knowledge about crimes they have committed, and therefore should show parietal ERP positivities related to recognition when presented with reminders of their crimes. We predicted that such forensic memory detection might however be inaccurate in older adults, because of changes to recognition-related brain activity that occurs with aging. We measured both ERPs and EEG oscillations associated with episodic old/new recognition and forensic memory detection in 30 younger (age < 30) and 30 older (age > 65) adults. EEG oscillations were included as a complementary measure which is less sensitive to temporal variability and component overlap than ERPs. In line with predictions, recognition-related parietal ERP positivities were significantly reduced in the older compared to younger group in both tasks, despite highly similar behavioural performance. We also observed ageing-related reductions in oscillatory markers of recognition in the forensic memory detection test, while the oscillatory effects associated with episodic recognition were similar across age groups. This pattern of results suggests that while both forensic memory detection and episodic recognition are accompanied by ageing-induced reductions in parietal ERP positivities, these reductions may be caused by non-overlapping mechanisms across the two tasks. Our findings suggest that EEG-based forensic memory detection tests are invalid in older populations, limiting their practical applications.

neuroscience↗