Sleeping with Hippocampal Damage

Goffredina Spanò, Frederik D. Weber, Gloria Pizzamiglio, Cornelia McCormick, Thomas D. Miller, Clive R. Rosenthal, Jamie O. Edgin, Eleanor A. Maguire

Research output: Contribution to journalArticle

Abstract

The hippocampus plays a critical role in sleep-related memory processes [1–3], but it is unclear which specific sleep features are dependent upon this brain structure. The examination of sleep physiology in patients with focal bilateral hippocampal damage and amnesia could supply important evidence regarding these links. However, there is a dearth of such studies, despite these patients providing compelling insights into awake cognition [4, 5]. Here, we sought to identify the contribution of the hippocampus to the sleep phenotype by characterizing sleep via comprehensive qualitative and quantitative analyses in memory-impaired patients with selective bilateral hippocampal damage and matched control participants using in-home polysomnography on 4 nights. We found that, compared to control participants, patients had significantly reduced slow-wave sleep—likely due to decreased density of slow waves—as well as slow-wave activity. In contrast, slow and fast spindles were indistinguishable from those of control participants. Moreover, patients expressed slow oscillations (SOs), and SO-fast spindle coupling was observed. However, on closer scrutiny, we noted that the timing of spindles within the SO cycle was delayed in the patients. The shift of patients’ spindles into the later phase of the up-state within the SO cycle may indicate a mismatch in timing across the SO-spindle-ripple events that are associated with memory consolidation [6, 7]. The substantial effect of selective bilateral hippocampal damage on large-scale oscillatory activity in the cortex suggests that, as with awake cognition, the hippocampus plays a significant role in sleep physiology, which may, in turn, be necessary for efficacious episodic memory. By examining sleep physiology in patients with focal bilateral hippocampal damage, Spanò et al. show that hippocampal integrity seems necessary for slow-wave sleep regulation and for fine-tuning the timing of slow oscillation-fast spindle coupling, both of which are held to be necessary for memory consolidation during sleep.

Original languageEnglish (US)
Pages (from-to)523-529.e3
JournalCurrent Biology
Volume30
Issue number3
DOIs
StatePublished - Feb 3 2020

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Keywords

  • amnesia
  • episodic memory
  • fast spindles
  • hippocampus
  • memory consolidation
  • polysomnography
  • ripples
  • sleep
  • slow oscillations
  • slow-wave sleep

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

Cite this

Spanò, G., Weber, F. D., Pizzamiglio, G., McCormick, C., Miller, T. D., Rosenthal, C. R., Edgin, J. O., & Maguire, E. A. (2020). Sleeping with Hippocampal Damage. Current Biology, 30(3), 523-529.e3. https://doi.org/10.1016/j.cub.2019.11.072