Sylvain Williams, PhD

Sylvain Williams, PhD



6875 Boulevard LaSalle
Montréal, QC
H4H 1R3

 Office:E-2106, Perry Pavilion

 Office phone: (514) 761-6131 x5937

  Lab website:

Canada Research Chair, Neural circuits of learning and memory – Tier 1

Researcher, Douglas Research Centre
Full Professor, Department of Psychiatry, McGill University

Lab name: Williams Hippocampal Rhythm Lab

Theme-Based Group: Aging, Cognition, and Alzheimer’s Disease
Division: Basic Neuroscience


My laboratory is using a combination of techniques to understand how neurons of the hippocampus play a role a role in memory encoding and recall in freely behaving mice.  We are also interested in how neurons of the the medial septum, a region well known to project massively to hippocampus, can enhance learning and memory. We perform the experiments using electrophysiology to determine brain-states, optogenetics to manipulate brain circuits and miniature epifluorescent microscope (also named UCLA miniscopes) to understand neuronal dynamics at the population level during memory tasks.  We also have an interest in revealing how sleep, and especially REM sleep, enhances memory consolidation (Boyce et al., 2016). The overarching goal of my laboratory is to understand the neuronal mechanisms underlying memory function in normal and in Alzheimer’s disease.

Understanding how cell assemblies code for memory encoding and recall. 

We are interested in determining how neurons in the hippocampus and its sub-regions can code and recall memory events. Why do the neural circuits in the CA1 and subiculum have such a distinct role than other hippocampal areas? These investigations are done using calcium imaging, electrophysiology and optogenetics in freely behaving mice performing cognitive tasks.

What is the neural mechanism of memory consolidation during sleep?

The hippocampus and other brain regions play important role in enhancing the conversion of memory to long-term memory during sleep. However, there are at least two different states in sleep; slow-wave and rapid-eye movement (REM)-sleep. How do these two sleep states contribute to memory consolidation? We are interested in identifying the mechanisms underlying these two states in memory consolidation.

Investigating the role of the septum in memory

The septum is divided into the medial and the lateral septum. The medial septum provides a powerful input to the hippocampus and entorhinal cortex and has been shown to play a critical role in memory-related hippocampal oscillations while the lateral part receives a massive input from the hippocampus and provide a circuit important for the association between spatial contextual cues and reward. We are interested in understanding how the different cell types of the medial and lateral septum contribute to memory encoding and recall in freely behaving mice.

Developing new methods to visualize and manipulate memory- related neurons  during behaviour.

There is a revolution going on in neuroscience concerning the recent developments of research tools for observing and manipulating neurons during cognition. My laboratory as invested a great deal of efforts to develop the latest methods of optogenetics, electrophysiology, and, more recently, calcium imaging of neuronal populations using miniature microscopes in freely behaving mice.

How circuits are altered in Alzheimer’s disease and finding approaches to reverse memory deficits in AD.

While there is ample evidence of how individual neurons are affected in AD, we poorly understand how neuronal dynamics at the population level are affected. One important goal we have is to use optogenetics to re-establish normal population dynamics and memory function in AD mice models.


Link to lab website

Following a PhD at Université de Montréal in the neurological sciences with Dr Jean-Claude Lacaille (1989-94), I was a postdoctoral fellow with Drs Michel Muhlethaler and Laurent Bernheim at Geneva University in Switzerland (1994-97). There I explored the role of physiological properties of septal and basal forebrain cells in producing network activity. I also did a one year postdoc at the University of Calgary with Brian MacVicar to study cytokines, imaging and neuromodulation. In February 1999, I moved to the Douglas Hospital to set-up my own laboratory. I was named assistant professor of psychiatry at McGill in 1999, associate professor in 2007, and full professor in 2015.

  • Frédéric Manseau, Research Associate
  • Jean-Bastien Bott, Research Associate
  • Lorène Penazzi, Research Associate
  • Coralie-Anne Mosser, postdoctoral fellow
  • James “Eric” Carmichael, postdoctoral fellow
  • Jisu Choi, Ph.D. student
  • Ingrid Inema, Ph.D. student
  • Zeeshan Haqqee, Ph.D. student
  • Bryan Alexis Contreras Mercado, M.Sc. student
  • Salodin Al-Achkar, M.Sc. student

Key publications

Full publication record


Selected publications

  • Etter, G., van der Veldt, S., Choi, J. and Williams, S., 2021. Optogenetic scrambling of hippocampal theta oscillations alters working memory retrieval but not hippocampal spatiotemporal codes. bioRxiv. In press 2022 Nat Comm
  • Bott JB, Robinson J, Manseau F, Gauthier-Lafrenière E, Williams S. Medial septum glutamate neurons are essential for spatial goal-directed memory. bioRxiv. 2022 Jan 1.
  • van der Veldt S, Etter G, Mosser CA, Manseau F, Williams S. Conjunctive spatial and self-motion codes are topographically organized in the GABAergic cells of the lateral septum. PLoS biology. 2021 Aug 30;19(8):e3001383.
  • Etter G, van der Veldt S, Manseau F, Zarrinkoub I, Trillaud-Doppia E, Williams S. Optogenetic gamma stimulation rescues memory impairments in an Alzheimer’s disease mouse model. Nat Commun. 2019 Nov 22;10(1):5322. doi: 10.1038/s41467-019-13260-9. PMID: 31757962; PMCID: PMC6876640.
  • Boyce R, Glasgow SD, Williams S, Adamantidis A. Causal evidence for the role of REM sleep theta rhythm in contextual memory consolidation. Science. 2016 May 13;352(6287):812-6. doi: 10.1126/science.aad5252. PMID: 27174984.