Infragranular layers lead information flow during slow oscillations according to information directionality...

Area of Science:

• Neuroscience
• Computational Neuroscience

Background:

• The cerebral cortex generates slow oscillations (ca 1 Hz), characterized by rhythmic firing and silence.
• These oscillations are prominent during sleep and anesthesia and can arise from isolated cortical networks.
• Corticothalamic interactions shape slow oscillations in vivo, but the precise directionality of information flow remains debated.

Purpose of the Study:

• To investigate the directionality of information flow within the corticothalamic network during spontaneous slow oscillations.
• To determine the leading elements in the initiation of activity waves within the corticothalamic loop.

Main Methods:

• Recorded multilayer local field potentials from the rat visual cortex and lateral geniculate nucleus (thalamus) under deep anesthesia.
• Applied information-theoretic measures including transfer entropy, symbolic transfer entropy, and transcript mutual information.
• Analyzed information flow between the thalamus, infragranular cortical layers (5 and 6), and supragranular cortical layers (2/3).

Main Results:

• Consistent findings across three information-theoretic indicators revealed a leading role for infragranular cortical layers.
• Information flow was directed from infragranular layers towards supragranular layers.
• Information flow was also directed from infragranular layers towards the connected thalamus.

Conclusions:

• Infragranular cortical layers (5 and 6) initiate and direct information flow during slow oscillations in the corticothalamic network.
• This finding clarifies the mechanism of wave initiation in the corticothalamic loop.
• The results highlight the critical role of deep cortical layers in orchestrating network activity.