Intrinsic dynamics in neuronal networks. II. experiment

Area of Science:

• Neuroscience
• Computational Neuroscience
• Cellular Neuroscience

Background:

• Neurons in the mammalian central nervous system (CNS) exhibit spontaneous activity, including steady firing and rhythmic bursting.
• The mechanisms maintaining these firing patterns and the transitions between them, particularly under recurrent excitation, are not fully understood.

Purpose of the Study:

• To experimentally investigate the role of endogenously active cells in maintaining spontaneous neuronal firing patterns in the CNS.
• To validate theoretical predictions regarding the relationship between the fraction of endogenously active cells and network firing states.

Main Methods:

• Experimental manipulation of neuronal cultures to alter the fraction of endogenously active cells.
• Observation and analysis of resulting changes in network firing patterns (steady firing vs. bursting).

Main Results:

• All spontaneously, steadily firing neuronal cultures contained endogenously active cells.
• Reducing the proportion of endogenously active cells in these cultures induced a transition from steady firing to bursting.
• These experimental findings corroborate previous theoretical models on firing pattern control.

Conclusions:

• The fraction of endogenously active cells is a critical determinant of spontaneous neuronal firing patterns in the CNS.
• A sufficient proportion of endogenously active cells is necessary to maintain steady firing; below a threshold, bursting occurs, and at zero, silence ensues.
• Experimental results strongly support the theoretical framework linking endogenous activity to network dynamics.