Background: Schizophrenia (SZ) is a neurodevelopmental disorder often accompanied by disabling cognitive deficits with economic and psychosocial costs [Clouter 2016]. Hippocampal abnormalities [Heckers 2010] and selective postmortem loss of hippocampal interneurons [Konradi 2011] have been demonstrated in SZ. Given the hippocampus’ role in memory replay and consolidation [Born 2012, Latchoumane 2017], hippocampal deficits are a potential target for SZ treatments. Recently, hippocampal activity has been tied to offline performance improvements, or micro-offline gains (MOGs), during inter-trial rest periods on a motor sequence learning task (MST) [Bonstrop 2019, Jacobacci 2020]. We aim to first replicate these results in a sample of healthy controls (HC), then compare MOGs in HC to those of patients with SZ. We hypothesize that, due to hippocampal impairments and resulting memory deficits in this population, our SZ sample will display fewer MOGs than those of HC. This finding
will demonstrate short-term encoding and consolidation deficits in SZ in addition to established oversleep memory consolidation deficits on this task [Manoach 2014, 2019, Goder 2004].
Methods: Twenty-six medicated SZ participants and 29 HC trained on the MST, where they typed a sequence of numbers for 12 30-second training blocks with interspersed 30-second rest blocks. Since memory deficits in SZ were not reflected in overnight MST improvement, we will investigate MOGs as a potential source of between-group differences.
Results: We will calculate MOGs as the difference between average typing speed at the end of one training block compared to average typing speed at the beginning of the following block. We expect to replicate previous findings in HC that MOGs are the primary contributor to rapid performance improvement. MOG differences would point to mechanistic breakdowns in offline memory consolidation in SZ, by extension identifying short-term hippocampal replay as a potential contributor to memory deficits.
Conclusions: We aim to show that MOGs differ between SZ and HC populations, establishing MOGs as a promising metric to measure consolidation deficits tied to hippocampal dysfunction.
Live Zoom Session – April 21st
Bailey J Driscoll, BSc, Megan Thompson, PhD, Dimitrios Mylonas, PhD, Bryan S Baxter, PhD, Dara S Manoach, PhD
Dara S Manoach, PhD