Thursday, Jun 26: 11:30 AM - 12:45 PM
Oral Sessions
Brisbane Convention & Exhibition Centre
Room: P2 (Plaza Level)
Possible title: learning and memory: beyond the temporal lobe? (Jean)
Presentations
Working memory is a fundamental cognitive process essential for guiding our behavior in daily life, where sensory information flows continuously from the external world (Baddeley, 1986; D'Esposito & Postle, 2015). While numerous studies have demonstrated that sensory information maintained in working memory is localized within the corresponding sensory areas (Harrison & Tong, 2009; Kumar et al., 2016; Lee & Baker, 2016; Schmidt & Blankenburg, 2018), a challenge persists in utilizing this retained sensory information without interfering with concurrent sensory input of the same modality (Bettencourt & Xu, 2016; Christophel et al., 2017; Xu, 2017). One plausible hypothesis to address this issue is the dual maintenance of essential information in higher-order cortical areas in a form different from sensory representations (Christophel et al., 2017; Riley & Constantinidis, 2016). However, little empirical evidence supports the existence of such high-level representations. In this study, we provide evidence of two distinct forms of high-level representations by directly comparing working memory of tactile and visual stimuli.
Presenter
Doyoung Park, Seoul National University Seoul
Korea, Republic of
Recognizing objects is fundamental to the construction of episodic memories and the interpretation of our daily experiences. However, studies investigating the neural basis of recognition memory have traditionally employed a limited number of exemplars or trials, failing to capture the complexity and richness of real-world cognition. Furthermore, while prior work has highlighted that large parts of the brain are sensitive to recognition memory1,2, the precise topographical contributions of these regions remain unclear. To address these gaps, here we conducted a continuous recognition memory experiment using dense scanning at ultra-high field 7T fMRI. Participants were tested on their ability to recognize repetitions of 1280 unique images allowing for high-resolution mapping of the neural mechanisms underlying recognition memory.
Complex behavior entails a balance between taking in sensory information from the environment and utilizing previously learned internal information. Experiments in mice have shown that the brain alternates between two modes facilitating visual coding and memory processes respectively, with transitions marked by stereotypical neuronal spiking cascades spanning forebrain structures (Liu et al., 2021; Yang et al., 2023). In humans, multi-second global brain activity observed with functional MRI (fMRI) has been described as propagating waves, moving from low-order sensory-motor (SM) regions to high-order default mode network (DMN) regions (Gu et al., 2021; Raut et al., 2021). Utilizing large-scale fMRI datasets, we investigated whether the fMRI waves and neuronal spiking cascades are the expression of homologous brain dynamics, and if so, whether the alternation between enhanced visual encoding and memory function is similarly across the cycle of fMRI waves in humans.
Presenter
Yifan Yang, The Pennsylvania State University State College, PA
United States
A crucial function of memory is to distinguish between similar experiences. Mnemonic discrimination tasks that require participants to tell apart targets and highly similar lures can probe a brain region's ability to resolve interference (Stark et al., 2019). These tasks implicate hippocampal subfields dentate gyrus (DG) and CA3 in pattern separation (PS), a process to orthogonalize similar stimuli to reduce overlap. Cortical regions may also contribute to PS in a category-specific manner with some regions biased towards objects and others for scenes (Berron et al., 2018). To identify category-specific and -invariant neural correlates of mnemonic discrimination we leveraged 7-Tesla imaging. This method could overcome limitations of prior 3T human functional MRI studies which were unable to distinguish signals from the DG and CA3 hippocampal subfields, did not carry out voxel-wise analyses to assess differences in PS signals in the hippocampal long axis, and left out the amygdala despite its involvement in medial temporal lobe (MTL) memory networks.
Presenter
Helena Gellersen, German Center for Neurodegenerative Diseases Magdeburg, Sachsen-Anhalt
Germany
Autonoetic consciousness (ANC), the ability to re-experience a personal past event is at the crossroad between episodic memory and self-consciousness in the act of remembering (Klein and Nichols, 2012; Tulving, 1985). Bodily self-consciousness (BSC), defined as a unitary sense of self within the bodily boundaries, arises from multisensory and sensorimotor perceptual mechanisms of specific bodily signals (Blanke et al., 2015), and has been argued to be the missing link joining self-conscious sensorimotor context during encoding with later conscious re-living of the encoded event (ANC,Bergouignan, 2021; Gauthier et al., 2020;Iriye and Ehrsson, 2022; Meyer et al., 2024). However, how BSC and its related subjective experience at encoding affect ANC at the neural level remains unknown. In this study, we addressed this question by modulating sensorimotor context and its related BSC (through sense of agency -SoA-, and sense of body ownership - SoO) during the encoding of virtual scenes while simultaneously recording brain activity using fMRI at encoding.
Temporal lobe epilepsy (TLE) and frontal lobe epilepsy (FLE) are the two most common pharmaco-resistant epilepsies, both associated with significant yet distinct declarative memory deficits (Elger, 2002; Helmstaedter, 2002). TLE patients exhibit marked episodic and mild semantic memory difficulties (Barrett-Jones, 2022; Helmstaedter, 2002), while FLE patients may present with mild declarative memory impairment together with difficulties in semantic and overall language-related processes (Caciagli, 2023; Della Rocchetta, 1993). Functional imaging indicates differential patterns of activation and connectivity in the medial temporal and fronto-limbic networks in TLE and FLE, respectively. Yet, activation and connectivity differences have rarely been studied in the same analysis and have not been systematically assessed across these syndromes. Here, we used activity flow mapping (AFM;Cole, 2016) to explore the synergy between intrinsic connectivity and functional activation patterns during declarative states. We also assessed how local disruptions due to lesions relate to cognitive alterations.
Presenter
Donna Gift Cabalo, McGill University
Medicine and Health Sciences
Montreal, Quebec
Canada