Biology subjects

Levy, D. A.

Publications and source records attributed to Levy, D. A..

3 recordsLinked to original sources

bioRxiv2022

Brain substrates of episodic memory for identity, location, and action information: A lesion-behavior mapping study

Brain networks supporting visual memory include extrastriate and other cortical regions associated with visual perception, which manifest domain-specific processing of "where," "how," and various aspects of "what" information. However, whether and how such specialization affects memory for these types of information is still a matter of debate. Functional neuroimaging studies point to dissociable as well as common network components supporting the perception and memory of different aspects of visual information. In the current neuropsychological study, we assess the impact of stroke lesion topography on recall of identity, location, and action of event participants, as assessed by the WMS-III Family Pictures subtest. We used voxel-based lesion-behavior mapping (VLBM) to identify brain lesions specifically implicated in memory deficits for each dimension. Behavioral analysis disclosed impaired performance by both right- and left-hemisphere damage patients, with lesions on each side yielding distinct effects. VLBM analysis revealed a bi-hemispheric network supporting these various aspects of visual memory. In the right hemisphere, the network includes frontal, parietal, and temporal cortical regions and the basal ganglia. In the left hemisphere, the network is more restricted, including visual association areas and medial temporal lobe regions. We further observed that a subset of these regions - those included in the ventral ("what") stream, and in the putative core recollection network - is implicated in multiple aspects of visual memory, whereas other areas are specifically implicated in memory for specific aspects of the visual scene.

neuroscience↗

bioRxiv2022

Electrophysiological correlates of associative recognition memory for identity, spatial, and temporal relations

The formation of associative representations and their retrieval from episodic memory are vital cognitive functions. However, it is unclear to what extent retrieval of the basic component relations of episodic memory - identity, time, and space - requires different or shared brain mechanisms. In the current study, we employed EEG to track the time courses of electrophysiological correlates of retrieval processes of memory for identity relations, temporal order, and spatial configuration. Participants engaged in pair-associate learning of serially presented and spatially configured object picture pairs, followed by discrimination of identity, spatially, or temporally intact and rearranged pairs. Event-related brain potentials (ERPs) revealed distinct patterns of activity during successful retrieval of identity, spatial, and temporal relations that differed by the status of association, across the three retrieval time windows examined (300-500, 500-800, and 800-1000 ms). The identity relations condition was distinguished by a widespread greater negative-going deflection for rearranged relative to intact pairs in all three time windows. For the temporal relations condition, we observed a widespread more negative-going deflection for rearranged than intact pairs, significant in the second time window only. For the spatial relations condition, there was a widespread positive-going deflection greater for rearranged than for intact pairs, significant in the early and in middle time windows. These patterns of activity suggest that retrieval of associative memory traces for identity, spatial, and temporal relationships involve dynamically different processes, which may partially rely on different sets of basic associative mechanisms.

neuroscience↗

bioRxiv2018

Multimodal integration and vividness in the angular gyrus during episodic encoding and retrieval

Much evidence suggests that the angular gyrus (AnG) is involved in episodic memory, but its precise role is yet to be determined. We examined two possible accounts, within the same experimental paradigm: the CoBRA account (Shimamura, 2011), which suggests that the AnG acts as a convergence zone that binds multimodal episodic features; and the Subjectivity account (Yazar et al., 2012), which implicates AnG involvement in subjective mnemonic experience (such as vividness or confidence). fMRI was employed during both encoding and retrieval of paired-associates. During study, female and male human participants memorised picture-pairs of common objects (in the unimodal task) or of an object-picture and an environmental sound (in the crossmodal task). At test, they performed a cued-recall task, and further indicated the vividness of their memory. During retrieval, BOLD activation in the AnG was greatest for vividly remembered associates, consistent with the Subjectivity account. During encoding, the same effect of vividness was found, but this was further modulated by task: Greater activations were associated with subsequent recall in the crossmodal than the unimodal task. Thus, encoding data suggests an additional role to the AnG in cross-modal integration, consistent with its role at retrieval proposed by CoBRA. These results resolve some of the puzzles in the literature and indicate that the AnG can play different roles during encoding and retrieval, determined by the cognitive demands posed by different mnemonic tasks.\n\nSignificance StatementWe offer new insights into the multiplicity of processes that are associated with angular gyrus (AnG) activation during encoding and retrieval of newly formed memories. We used fMRI while human participants learned and subsequently recalled pairs of objects presented to the same sensory modality or to different modalities. We were able to show that the AnG is involved when vivid memories are created and retrieved, as well as when encoded information is integrated across different sensory modalities. These findings provide novel evidence for the contribution of the AnG to our subjective experience of remembering, alongside its role in integrative processes that promote subsequent memory.

neuroscience↗