ICLM Journal Club
This Week - 2 November 2018 (9:30 a.m., Gonda 2nd Floor Conference Room)
Speaker: Panayiota Poirazi
Title: Challenging the point neuron dogma: FS basket cells as 2-stage nonlinear integrators
Abstract: Fast Spiking (FS) basket cells constitute one of the main types of hippocampal and neocortical interneurons. While their importance in controlling executive functions is extensively recognized, most studies focus on their molecular and anatomical features, completely ignoring their dendritic processing. Exciting new findings reveal that the dendrites of certain interneuron types exhibit non-linear integration. These findings question the dominant hypothesis that interneurons act as linear summing units, also known as point neurons.
To address this issue, we developed detailed, biologically constrained biophysical models of FS basket cells using anatomical reconstructions of both hippocampal and cortical neurons. Synaptic stimulation within their dendrites, predicts the co-existence of two distinct integration modes: supralinear and sublinear. Morphological features such as dendritic length and/or diameter influence the integration mode and these features differ between hippocampal and cortical neurons. By generating a large number of different spatial patterns of synaptic activation we find that spatially dispersed inputs lead to higher firing rates than inputs clustered within a few dendrites in both Hippocampus and PFC models. These nonlinear dendritic features provide resource savings when it comes to learning in large neuronal networks. Moreover, a 2-layer Artificial Neural Network (ANN) with both sub- and supralinear hidden nodes can predict the firing rate of the aforementioned models much better than a linear ANN.
Our predictions challenge the current dogma, whereby interneurons are treated as linear summing devices, essentially void of dendrites. We propose that FS basket cells, like pyramidal neurons, also operate like a 2-stage processing device.
Relevant Paper(s): https://www.biorxiv.org/content/early/2018/01/22/251314
About Us
Introduction
The Integrative Center for Learning and Memory (ICLM) is a multidisciplinary center of UCLA labs devoted to understanding the neural basis of learning and memory and its disorders. This will require a unified approach across different levels of analysis, including;
1. Elucidating the molecular cellular and systems mechanisms that allow neurons and synapses to undergo the long-term changes that ultimately correspond to 'neural memories'.
2. Understanding how functional dynamics and computations emerge from complex circuits of neurons, and how plasticity governs these processes.
3. Describing the neural systems in which different forms of learning and memory take place, and how these systems interact to ultimately generate behavior and cognition.
History of ICLM
The Integrative Center for Learning and Memory formally LMP started in its current form in 1998, and has served as a platform for many interactions and collaborations within UCLA. A key event organized by the group is the weekly ICLM Journal Club. For more than 10 years, graduate students, postdocs, principal investigators, and invited speakers have presented on topics ranging from the molecular mechanisms of synaptic plasticity, through computational models of learning, to behavior and cognition. Dean Buonomano oversees the ICLM journal club with help of student/post doctoral organizers. For other events organized by ICLM go to http://www.iclm.ucla.edu/Events.html.
Current Organizers:
Current Faculty Advisor:
Past Organizers:
i) Anna Matynia(Aug 2004 - Jun 2008) (Silva Lab)
ii) Robert Brown (Aug 2008 - Jun 2009) (Balleine Lab)
iii) Balaji Jayaprakash (Aug 2008 - Nov 2011) (Silva Lab)
iv) Justin Shobe & Thomas Rogerson (Dec 2011 - June 2013) (Silva Lab)
v) Walt Babiec (O'Dell Lab) (2013-2014)
vi) Walt Babiec (O'Dell Lab) & Helen Motanis (Buonomano Lab) (2014-2017)
vii) Helen Motanis (Buonomano Lab) & Shonali Dhingra (Mehta Lab) (2017-2018)
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