TNFα Signaling Maintains the Ability of Cortical Synapses to Express Synaptic Scaling

The brain has billions of neurons that receive, analyze, and store information about internal and external conditions, and are highly interconnected. To prevent either hyperexcitability (epilepsy) or hyopexcitability (catatonia) of brain circuits, neurons possess an array of “homeostatic” plasticity mechanisms that serve to stabilize average neuronal firing.

Synaptic scaling is one such form of homeostatic plasticity that acts like a synaptic thermostat, and allows neurons to turn up or down the gain of synaptic transmission to stabilize average activity. The signaling pathways that allow neurons to perform this neat trick are incompletely understood, and it has been controversial whether neurons do this in a cell-autonomous manner, or whether synaptic scaling is induced in response to release of soluble factors such as the pro-inflammatory cytokine TNFα.

A study published this week in Journal of Neuroscience by Brandeis postdoctoral fellow Celine Steinmetz and Professor Gina Turrigiano helps to resolve this controversy by showing that TNFα is not instructive for synaptic scaling, but instead is critical for maintaining  synapses in a plastic state in which they are able to express synaptic scaling. This study suggests that glial cells serve a permissive role in maintaining synaptic plasticity through release of soluble factors such as TNFα, while neurons actively adjust their synaptic thermostat in response to cell-autonomous changes in their own activity.

Temporal Pattern Recognition through Short-Term Plasticity

The Brandeis Neuroscience graduate students and postdocs are pleased to announce the upcoming visit of their invited speaker for the Ruth Ann & Nathan Perlmutter Science Forum for this year, Dr. Bruce Carlson from Washington University at St.Louis.  Prof. Carlson will be presenting the following talk:

Temporal Pattern Recognition through Short-Term Plasticity
Monday (April 26th) at 4 pm in Gzang 121

There will be a reception immediately be following the talk in the Shapiro Science Center Atrium.

electric fish logo

Bruce Carlson’s lab uses electric fish as a model for sensory signal production, processing and representation. These fish generate series of electric pulses that they continually monitor in order to navigate and communicate social information such as sex and dominance. The pulse trains are both the input and output of the system and pulse train patterns can be used to ask how the parameters of the pulses (i.e. amplitude and phase) are encoded by the sensory system. Carlson previously found that in these fish, hindbrain neurons receiving input from electric organ sensory afferents categorically respond to different features of a temporally patterned electric pulse input. Furthermore, he has suggested that these neurons’ response differences can largely be explained by alterations in short-term plasticity.


References:

1. Temporal-pattern recognition by single neurons in a sensory pathway devoted to social communication behavior. Carlson BA (2009) Journal of Neuroscience 29: 9417-9428.
2. From stimulus estimation to combination sensitivity: encoding and processing of amplitude and timing information in parallel, convergent sensory pathways. Carlson BA and Kawasaki M (2008). Journal of Computational Neuroscience 25: 1-24.

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