Biology subjects

Igloi, K.

Publications and source records attributed to Igloi, K..

6 recordsLinked to original sources

bioRxiv2026

Emotional modulation of visual cortical reactivation during true and false memories

Previous research revealed that memory retrieval is associated with a reactivation of sensory cortices reflecting the content of the memory. Further, such reactivation is stronger when retrieval is cued with emotional information as compared with neutral information. However, past studies focused on correct retrieval, and it remains unknown whether a similar reactivation occurs during memory errors, and whether this is enhanced in emotional contexts. Here, we hypothesized that emotion may influence memory errors due to an increase of sensory cortical reactivation at the cost of recovering episodic details (i.e. leading to incorrect retrieval of non-specific associations shared with other cues). We compared brain activations during successful memory retrieval and memory errors in 18 healthy participants who encoded unique negative or neutral scenes paired with one of four associated faces, shared with other trials. Participants were tested the next day with a scene-cued associative retrieval test, while undergoing functional magnetic resonance imaging (fMRI). Results from a face-responsive region of interest in fusiform cortex (unlike a control place-responsive region in parahippocampal cortex) showed stronger activation for both Hits ("Old" | Target) and False Alarms ("Old" | Foil), as compared with Misses ("New" | Target) and Correct Rejections ("New" | Foil). The emotional content of scene cues did not modulate activation patterns during correct retrieval but produced specific effects on Misattribution errors (incorrect "Old" | Target, i.e., retrieval of an incorrect face cued by a previously seen scene). Specifically, Misattributions were accompanied by increased fusiform activation comparable to Hits when cued by negative scenes, but low fusiform activation similar to Misses when cued by neutral scenes. Unlike Misattributions, however, Hits cued by emotional information recruited a distinctive network previously linked to personal episodic memories, including medial prefrontal, cingulate, and hippocampal regions, together with enhanced functional coupling between the latter and fusiform cortex. No implicit effect of previous face exposure was observed in the fusiform during Misses, regardless of emotion context. Our results suggest that the reactivation of sensory areas follows subjective memory experience during retrieval, and that emotion can enhance such mechanism when the cue is recognized but detailed episodic memory mediated by fronto-hippocampal circuits is absent, leading to the retrieval of inappropriate associations and false memories.

neuroscience↗

bioRxiv2025

Neural correlates of approach and avoidance tendencies toward physical activity and sedentary stimuli: An fMRI study

Automatic tendencies toward physical activity and sedentary stimuli are involved in the regulation of physical activity behavior. However, the brain regions underlying these automatic tendencies remain largely unknown. Here, we used an approach-avoidance task and magnetic resonance imaging (MRI) in 42 healthy young adults to investigate whether cortical and subcortical brain regions underpinning reward processing and executive function are associated with these tendencies. At the behavioral level, results showed more errors in avoidance behavior following sedentary stimuli than physical activity stimuli. At the brain level, avoidance behavior following sedentary stimuli was associated with more activation of the motor control network (dorsolateral-prefrontal cortex, primary and secondary motor cortices, somatosensory cortex). In addition, increased activation of the bilateral parahippocampal gyrus -- and structural deformation of the right hippocampus - were associated with a tendency toward approaching sedentary stimuli. Together, these results suggest that avoiding sedentary stimuli requires higher levels of behavioral control than avoiding physical activity stimuli.

neuroscience↗

bioRxiv2022

Salient 40 Hz sounds probe affective aversion and neural excitability

The human auditory system is not equally reactive to all frequencies of the audible spectrum. Emotional and behavioral reactions to loud or aversive acoustic features can vary from one individual to another, to the point that some exhibit exaggerated or even pathological responses to certain sounds. The neural mechanisms underlying these interindividual differences remain unclear. Whether distinct aversion profiles map onto neural excitability at the individual level needs to be tested. Here, we measured behavioral and EEG responses to click trains (from 10 to 250 Hz, spanning the roughness and pitch perceptual ranges) to test the hypothesis that interindividual variability in aversion to rough sounds is reflected in neural response differences between participants. Linking subjective aversion to 40 Hz steady-state EEG responses, we demonstrate that participants experiencing enhanced aversion to roughness also show stronger neural responses to this attribute. Interestingly, this pattern also correlates with inter-individual anxiety levels, suggesting that this personality trait might interact with subjective sensitivity and neural excitability to these sounds. These results support the idea that 40 Hz sounds can probe the excitability of non-canonical auditory systems involved in exogenous salience processing and aversive responses at the individual level. By linking subjective aversion to neural excitability, 40 Hz sounds provide neuromarkers relevant to a variety of pathological conditions, such as those featuring enhanced emotional sensitivity (hyperacusis, anxiety) or aberrant neural responses at 40 Hz (autism, schizophrenia).

neuroscience↗

bioRxiv2020

Effect of acute physical exercise on motor sequence memory

Acute physical exercise improves memory functions by increasing neural plasticity in the hippocampus. In animals, a single session of physical exercise has been shown to boost anandamide (AEA), an endocannabinoid known to promote hippocampal plasticity. Hippocampal neuronal networks encode episodic memory representations, including the temporal organization of elements, and can thus benefit motor sequence learning. While previous work established that acute physical exercise has positive effects on declarative memory linked to hippocampal plasticity mechanisms, its influence on memory for motor sequences, and especially on neural mechanisms underlying possible effects, has been less investigated. Here we studied the impact of acute physical exercise on motor sequence learning, and its underlying neurophysiological mechanisms in humans, using a cross-over randomized within-subjects design. We measured behavior, fMRI activity, and circulating AEA levels in fifteen healthy participants while they performed a serial reaction time task (SRTT) before and after a short period of exercise (moderate or high intensity) or rest. We show that exercise enhanced motor sequence memory, significantly for high intensity exercise and tending towards significance for moderate intensity exercise. This enhancement correlated with AEA increase, and dovetailed with local increases in caudate nucleus and hippocampus activity. These findings demonstrate that acute physical exercise promotes sequence learning, thus attesting the overarching benefit of exercise to hippocampus-related memory functions.

neuroscience↗

bioRxiv2019

Human discrimination and categorization of emotions in voices: a functional Near-Infrared Spectroscopy (fNIRS) study

Variations of the vocal tone of the voice during speech production, known as prosody, provide information about the emotional state of the speaker. In recent years, functional imaging has suggested a role of both right and left inferior frontal cortices in attentive decoding and cognitive evaluation of emotional cues in human vocalizations. Here, we investigated the suitability of functional Near-Infrared Spectroscopy (fNIRS) to study frontal lateralization of human emotion vocalization processing during explicit and implicit categorization and discrimination. Participants listened to speech-like but semantically meaningless words spoken in a neutral, angry or fearful tone and had to categorize or discriminate them based on their emotional or linguistic content. Behaviorally, participants were faster to discriminate than to categorize and they processed the linguistic content of stimuli faster than their emotional content, while an interaction between condition (emotion/word) and task (discrimination/categorization) influenced accuracy. At the brain level, we found a four-way interaction in the fNIRS signal between condition, task, emotion and channel, highlighting the involvement of the right hemisphere to process fear stimuli, and of both hemispheres to treat anger stimuli. Our results show that fNIRS is suitable to study vocal emotion evaluation in humans, fostering its application to study emotional appraisal.

neuroscience↗

bioRxiv2017

Acute physical exercise improves memory consolidation in humans via BDNF and endocannabinoid signaling

Regular physical exercise enhances memory functions and neurogenesis in the hippocampus, an effect partially mediated by BDNF (Brain Derived Neurotrophic Factor). Acute exercise promotes the release of endocannabinoids (especially anandamide, AEA), which enhance BDNF release and improve hippocampal plasticity in rodents. How acute exercise affects BDNF and AEA levels and influences memory performance in humans remains to date unknown. Here we combined blood biomarkers, behavioral and fMRI measurements to assess the impact of acute physical exercise on associative memory and underlying neurophysiological mechanisms. For each participant, memory was tested after three conditions: rest, moderate or high exercise intensity. A long-term memory retest took place 3 months later. At both test and retest, memory performance increased after moderate but not high intensity exercise or rest. We also show that memory benefited from exercise-related increases in both AEA and BNDF levels: AEA boosted hippocampal activity during memory recall, while BDNF enhanced hippocampal memory representations and long-term performance.

neuroscience↗