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Rhythms of the brain: uncovering a subcortical circuit that modulates cortical GABAergic neurons
Department Somogyi Group
11 June 2019
Minas Salib, in the group led by Tim Viney and Peter Somogyi, has discovered a new type of neuronal pathway that may be important in memory. For the encoding and recall of episodic memories, nerve cells in the cerebral cortex are activated in precisely timed sequences. Rhythmicity facilitates the coordination of neuronal activity and these rhythms are detected as oscillations of different frequencies, such as 5–12 Hz theta oscillations. Degradation of these rhythms, such as through neurodegeneration, causes memory deficits. The medial septum, a part of the basal forebrain that innervates the hippocampal formation, contains neurons that fire with a high degree of rhythmicity (HRNs) and others that fire with a low degree of rhythmicity (LRNs). These distinct types of neuron may contribute differentially to the coordination of cortical neuronal activity. Minas and colleagues discovered that GABAergic LRNs preferentially innervate the dentate gyrus and the CA3 area of the hippocampus, regions important for episodic memory. These neurons act in parallel with the HRNs mostly via transient inhibition of inhibitory neurons. A figure from the paper describing these results was chosen to illustrate the front cover of the 5 June issue of Journal of Neuroscience.
Rhythmic networks in the brain that help us find our way in the world
Department Somogyi Group
18 April 2018
The Somogyi group discovered a rhythmic subcortical inhibitory (GABAergic) nerve cell population in a part of the mouse brain called the medial septum that projects to both the dorsal presubiculum and entorhinal cortex but avoids the hippocampus. As set out in a recent paper published in eLife, the group named these nerve cells ‘orchid cells’ based on the shape of the axonal trajectories