Poster F84, Tuesday, March 28, 8:00 – 10:00 am, Pacific Concourse
Functional connectivity between the dorsomedial thalamus and the medial temporal lobe supports familiarity memory
Alex Kafkas1, Elizabeth Keene1, Andrew Mayes1, Daniela Montaldi1; 1Memory Research Unit, Division of Neuroscience & Experimental Psychology, School of Biological Sciences, University of Manchester
An fMRI was conducted to explore the extent to which activity related to familiarity and recollection for different types of pictorial stimuli (objects, faces and scenes) is shared or distinct. In a mixed event-related/block design, we combined three types of pictorial stimuli and participants (n = 17) were asked to take familiarity and recollection decisions for previously studied and unstudied materials. The present analysis focused on extra-Medial Temporal Lobe (MTL) responses to isolate material-selective and non-material selective familiarity responses and to explore connectivity patterns within the isolated network. Material-selective and non-selective areas responding to familiarity were found in frontal, parietal, temporal and subcortical regions. Importantly, the dorsomedial thalamus showed a material-independent role selectively in familiarity-based recognition, whereas the anterior thalamus only responded to recollection. Material-selective regions within the thalamus that responded to familiarity for scenes (ventral posteromedial and pulvinar nuclei) and familiarity for faces (left ventrolateral thalamic nucleus) were also found. Moreover, connectivity analyses (psychophysiological interactions) showed increased connectivity between the dorsomedial thalamus and the parahippocampal and perirhinal cortices with increases in familiarity confidence. Finally, increased coupling between the ventrolateral thalamus and MTL regions (amygdala, perirhinal cortex) and the fusiform gyrus were found when weak (versus strong) familiarity feelings for faces were reported. This set of findings has important new implications for the role of the thalamic regions in recognition memory and illustrates that enhanced communication between the thalamus and selective MTL structures supports familiarity memory.
Topic Area: LONG-TERM MEMORY: Episodic