Timing of developmental sequences in different brain structures: physiological and pathological implications.

Area of Science:

• Neuroscience
• Developmental Biology
• Neurophysiology

Background:

• The developing brain exhibits unique electrical activity patterns distinct from adult brains.
• Early neuronal network patterns, including voltage- and transmitter-gated currents, follow a specific developmental trajectory.
• These patterns are crucial for neuronal connectivity rather than sensory processing.

Purpose of the Study:

• To investigate the developmental sequence of electrical activity in the developing striatum.
• To identify the mechanisms responsible for silencing immature network patterns.
• To understand the relationship between developmental patterns and the onset of behavior.

Main Methods:

• Electrophysiological recordings in developing brain structures (cortical and subcortical).
• Analysis of voltage-gated ion currents (calcium, potassium) and neurotransmitter actions (GABA, NMDA receptors).
• Correlation of developmental pattern changes with behavioral milestones like locomotion.

Main Results:

• The developing striatum exhibits a sequence where immature patterns are replaced by mature activity.
• This transition coincides with the onset of pup locomotion.
• Key mechanisms include the loss of long-lasting NMDA-NR2C/D receptor currents and the emergence of voltage-gated K+ currents.
• GABA/glycine polarity shifts and functional spinal cord inputs also contribute to ending developmental patterns.

Conclusions:

• The striatum's developmental sequence involves silencing immature patterns via specific molecular and electrical changes.
• This silencing is timed with the emergence of coordinated motor behavior.
• Perturbations in these developmental sequences may represent early markers for neurodevelopmental disorders.