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CBB talk series

The Cognitive Brown Bag (CBB) is a graduate student organized talk series, primarily attended by the faculty, graduate students, and staff from the cognitive labs at Dartmouth College. A list of past CBB talks can be found here.

The 2022-2023 talk series organizers are: AJ Haskins (Robertson lab), Clara Sava-Segal (Finn lab), and Jae Hyung Woo (Soltani lab).

Fall 2022

Talks will be held 3:30-4:30pm, unless otherwise noted.

  Speaker Title Abstract
Mon, 10/3 Adam Steel (Robertson lab) Vision upside-down: A retinotopic reference frame structures perceptual-mnemonic interactions We encode the visual world retinotopically, imposing a spatial reference frame on visual information processing. However, models of brain organization generally assume that retinotopic coding is replaced by non-retinotopic, abstract coding as information propagates through the visual hierarchy towards memory structures. This view raises a puzzle for constructive accounts of visual memory: how can mnemonic and visual information interact effectively in the brain if they are represented in fundamentally different reference frames? Here, we report that, contrary to the standard model, retinotopic information is preserved within memory areas, and provides a common representational reference frame to structure communication between mnemonic and perceptual areas. Using fine-grained, individual participant functional magnetic resonance imaging (fMRI), we found that just beyond the anterior edge of category-selective visual cortex, category-selective mnemonic areas also exhibit retinotopic coding (they contain visually evoked population receptive fields, pRFs). Strikingly, the transition from perceptual to mnemonic cortex is marked by an inversion in the amplitude of the retinotopic response (i.e., positive to negative pRFs). These +/- pRF populations in perceptual and mnemonic cortex, respectively, are closely matched in their visual field representations and exhibit opponent responses during both top-down memory recall and bottom-up visual processing, suggestive of a functional coupling via competitive push-pull dynamics. Together, these results show that retinotopy provides a common reference frame aligning perceptual and mnemonic processes, thereby scaffolding their dynamic interplay.
Mon, 10/17 Jae Hyung Woo (Soltani lab) & Jamal Williams (Stoermer lab)    
Mon, 10/31 Chandramouli Chandrasekaran (Boston University)