Victoria McLelland and Ryan Stevenson, Psychology Department, St. George Campus, University of Toronto
Victoria McLelland Title: Memory for the Future: The Encoding and Phenomenology of Episodic Simulations
Ryan Stevenson Title: Perceptual Binding Across Sensory Modalities in Autism Spectrum Disorders
Ebbinghaus Empire Series 2013-2014
Abstract (Victoria McLelland): Neuroimaging and neuropsychological research has established that our capacity to imagine future events is dependent on our capacity to remember the past. Both tasks engage a common core network of brain regions, which suggests that they share similar underlying neural and cognitive processes. The hippocampus, a medial temporal lobe structure known to be critical for episodic memory, has a controversial role in imagining the future. The hippocampus might serve to encode and store imagined future events in memory, just as it does for real-life events. In a series of experiments, I have used functional MRI and novel behavioural methods to provide insight into how imagined future events are encoded. I will present evidence that the hippocampus contributes to the encoding of imagined events. I will also show that the interaction of the hippocampus with a wider whole-brain network is important for the imagination of future events, and that this connectivity is modulated by encoding success. Finally, I will discuss the interaction of episodic encoding, familiarity, and detail generation, in the context of findings that recall rates are higher for imagined events rated by participants as being more detailed and more plausible, and for those rated as involving more familiar people and places. Broadly, these findings expand our knowledge of the role of the hippocampus in the encoding of episodic representations, including future simulations. They also highlight the contributions of the episodic system to our ability to make, encode and execute plans for the future.
Abstract (Ryan Stevenson): Sensory signals from a given external event are rarely isolated within a single sensory modality, but instead are multisensory in nature. Processing sensory signals in an integrated manner across modalities has widespread behavioral benefits reflecting more efficient neural processing of such stimuli. To accomplish accurate multisensory binding, stimulus cues must be used to identify which sensory signals convey information about the same external event, one of the most salient being the temporal coincidence of two sensory inputs. In short, the more temporally coincident two inputs are, the more likely they are to be perceptually bound and processed in a unified manner. Individuals with autism spectrum disorders (ASD) show impairments in the ability to perceptually bind sensory inputs, and a concurrent impairment in temporal processing. In this presentation, I will explore the connections between multisensory temporal processing and multisensory perceptual binding, and how these two may be related in ASD. Data from both behavioral psychophysical experiments and pilot fMRI data will be presented, and the hypothesis that deficits in lower-level sensory processing may have a cascading effect, contributing to higher-order perceptual deficits seen in ASD will be discussed.
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