Memories are central to our personal identity and essential to our every day life. However, how memories are created or recalled remains incompletely understood. What we know though is that the hippocampus, the learning and memory center of the brain, contains millions of neurons that have to synchronize together seemlessly for memory to function.When neurons synchronize brain rhythms can be recorded extracellularly. In the hippocampus, theta frequency rhythm (4-12 Hz) and higher frequency gamma rhythms (40-190 Hz) are the most prominent oscillations and they are necessary for long-term depression and potentiation which are cellular substrates for learning and memory. My laboratory is interested in understanding how different types of neurons, especially GABAergic interneurons , synchronize and participate in generating hippocampal rhythms and memory formation.The laboratory uses an array of unique tools including the recent development of a complete mature hippocampal preparation maintained alive in vitro. The isolated hippocampus preparation offers several key advantages over brain slices because it preserves all neuronal connectivity. Because of normal cellular interactions, the isolated hippocampus has the capacity to self-generate theta rhythm in addition to faster frequency gamma oscillations without the aid of pharmacology. This preparation offers an exceptional opportunity to investigate the cellular mechanisms underlying brain rhythm generation with single-cell patch and field recordings in combination with pharmacology. In addition, we also use a recently developed technique named optogenetics which is a powerful method using light activation to finely control the activity of specific neuronal populations within a network. We pursue 4 main themes of investigation: Theme 1: Discovering the cellular basis for theta and gamma rhythms. A long standing hypothesis suggests that theta rhythm is dependent on a nucleus named the which contains GABAergic, glutamatergic and the classic cholinergic neurons. However, we have recently established that theta is present in the hippocampus without the septum. Moreover, we have determined that there are actually many theta generators located within the hippocampus. We… Read More Theme 2: Understanding the role of the medial-septum/diagonal bands (MS-DBB) in generating hippocampal theta rhythm. The medial septum is essential for learning and memory and this may be due to its important role in pacing hippocampal theta. Our lab is aiming to determine how neurons of the medial septum can modulate and control the different theta oscillators. To answer these questions we combine the use of an isolated preparation in… Read More Theme 3: Discovering early markers of network alterations that will predict memory dysfunction in Alzheimer’s disease. We have recently shown that the interaction of theta and gamma rhythms in hippocampus may predict Alzheimer’s disease in AD mice models. We want to better understand the cellular mechanism underlying these early changes and find which molecules (ie beta-amyloid, etc) that trigger these early changes. Article on this theme: Goutagny et al., 2013. European… Read More Theme 4: Determining the role of hippocampal rhythms in learning and memory. One important goal of the lab is to translate the results uncovered from the isolated hippocampus preparation in vitro to memory related mechanisms in vivo. To do so, we perform optogenetics and electrophysiology in freely-behaving mice performing memory tasks.… Read More
Theme 1: Discovering the cellular basis for theta and gamma rhythms. A long standing hypothesis suggests that theta rhythm is dependent on a nucleus named the which contains GABAergic, glutamatergic and the classic cholinergic neurons. However, we have recently established that theta is present in the hippocampus without the septum. Moreover, we have determined that there are actually many theta generators located within the hippocampus. We… Read More
Theme 2: Understanding the role of the medial-septum/diagonal bands (MS-DBB) in generating hippocampal theta rhythm. The medial septum is essential for learning and memory and this may be due to its important role in pacing hippocampal theta. Our lab is aiming to determine how neurons of the medial septum can modulate and control the different theta oscillators. To answer these questions we combine the use of an isolated preparation in… Read More
Theme 3: Discovering early markers of network alterations that will predict memory dysfunction in Alzheimer’s disease. We have recently shown that the interaction of theta and gamma rhythms in hippocampus may predict Alzheimer’s disease in AD mice models. We want to better understand the cellular mechanism underlying these early changes and find which molecules (ie beta-amyloid, etc) that trigger these early changes. Article on this theme: Goutagny et al., 2013. European… Read More
Theme 4: Determining the role of hippocampal rhythms in learning and memory. One important goal of the lab is to translate the results uncovered from the isolated hippocampus preparation in vitro to memory related mechanisms in vivo. To do so, we perform optogenetics and electrophysiology in freely-behaving mice performing memory tasks.… Read More
