Ramping activity in the striatum

Published on August 1, 2022

Imagine the brain as a conductor of an orchestra. To play a symphony, the conductor needs to carefully coordinate the timing of each instrument to produce harmonious music. In the same way, our behavior relies on the precise timing controlled by a region in the brain called the basal ganglia (BG). Scientists have discovered that disruptions in the BG can impair our ability to accurately perceive and act on the passage of time. This is where medium spiny neurons (MSN) in the striatum, the main input structure of the BG, come into play. These neurons display a unique pattern of activity known as ramping activity, which is thought to be crucial for our perception of time intervals. However, the exact mechanisms behind this activity have remained a mystery… until now! Researchers have developed a dynamic network model of MSN and applied it to a task that requires interval discrimination. They found that when certain parameters are set just right, the model naturally generates populations of ramping neurons that enable accurate task performance. The researchers’ findings align closely with real-life observations and shed light on how dysfunction in MSN networks may affect our perception of time. Can’t get enough of this fascinating research? Check out the full article for all the details!

Control of the timing of behavior is thought to require the basal ganglia (BG) and BG pathologies impair performance in timing tasks. Temporal interval discrimination depends on the ramping activity of medium spiny neurons (MSN) in the main BG input structure, the striatum, but the underlying mechanisms driving this activity are unclear. Here, we combine an MSN dynamical network model with an action selection system applied to an interval discrimination task. We find that when network parameters are appropriate for the striatum so that slowly fluctuating marginally stable dynamics are intrinsically generated, up and down ramping populations naturally emerge which enable significantly above chance task performance. We show that emergent population activity is in very good agreement with empirical studies and discuss how MSN network dysfunction in disease may alter temporal perception.

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