Science, Vol 377, Issue 6603, pp. 324, 15 July 2022

Neurogliaform Cells Decouple Neuronal Synchrony Between Brain Areas

Ece Sakalar, et.al.

Division of Cognitive Neurobiology, Center for Brain Research, Medical University of Vienna, Vienna, Austria.

[paraphrase]

Effective communication across brain areas requires distributed neuronal networks to dynamically synchronize or decouple their ongoing activity. GABAergic interneurons lock ensembles to network oscillations, but there remain questions regarding how synchrony is actively disengaged to allow for new communication partners. We recorded the activity of identified interneurons in the CA1 hippocampus of awake mice. Neurogliaform cells (NGFCs)—which provide GABAergic inhibition to distal dendrites of pyramidal cells—strongly coupled their firing to those gamma oscillations synchronizing local networks with cortical inputs. Rather than strengthening such synchrony, action potentials of NGFCs    decoupled pyramidal cell activity    from cortical gamma oscillations    but did not reduce their firing nor affect local oscillations. Thus, NGFCs regulate information transfer by temporarily disengaging the synchrony without decreasing the activity of communicating networks.

The brain is a complex system of networks interacting through concerted activity patterns broadcast through intricately structured connections.    Rhythmic activation of neuronal assemblies    in 10-to-30–ms time windows    facilitates parsing of information by reader networks and generates transient gamma frequency (30 to 150 Hz) local field potential (LFP) oscillations.    Gamma oscillations allow dynamic information routing and neuronal circuits can perform active input selection if converging input pathways oscillate at different frequencies. However, many of the underlying brain mechanisms and network substrates remain unknown. In the hippocampus, sensory and mnemonic information from the entorhinal cortex and the CA3 area converge in the CA1 area in which coordinated synaptic activity in terminals of temporoammonic (cortical) and Schaffer collateral (CA3) pathways give rise to mid-frequency (gamma_M; 75 Hz) and slow gamma oscillations (gamma_S; 37 Hz) in strata lacunosum-moleculare and radiatum, respectively. The association between afferent pathways and gamma oscillations paralleled by layer-specific arborizations of (GABAergic) interneuron types make the rodent CA1 area a good candidate to explore input selection mechanisms. 

[end of paraphrase]

Science, Vol 377, Issue 6603, pp. 324, 15 July 2022

Neurogliaform Cells Decouple Neuronal Synchrony Between Brain Areas

Ece Sakalar, et.al.

Division of Cognitive Neurobiology, Center for Brain Research, Medical University of Vienna, Vienna, Austria.

[paraphrase]

Effective communication across brain areas requires distributed neuronal networks to dynamically synchronize or decouple their ongoing activity. GABAergic interneurons lock ensembles to network oscillations, but there remain questions regarding how synchrony is actively disengaged to allow for new communication partners. We recorded the activity of identified interneurons in the CA1 hippocampus of awake mice. Neurogliaform cells (NGFCs)—which provide GABAergic inhibition to distal dendrites of pyramidal cells—strongly coupled their firing to those gamma oscillations synchronizing local networks with cortical inputs. Rather than strengthening such synchrony, action potentials of NGFCs    decoupled pyramidal cell activity    from cortical gamma oscillations    but did not reduce their firing nor affect local oscillations. Thus, NGFCs regulate information transfer by temporarily disengaging the synchrony without decreasing the activity of communicating networks.

The brain is a complex system of networks interacting through concerted activity patterns broadcast through intricately structured connections.    Rhythmic activation of neuronal assemblies    in 10-to-30–ms time windows    facilitates parsing of information by reader networks and generates transient gamma frequency (30 to 150 Hz) local field potential (LFP) oscillations.    Gamma oscillations allow dynamic information routing and neuronal circuits can perform active input selection if converging input pathways oscillate at different frequencies. However, many of the underlying brain mechanisms and network substrates remain unknown. In the hippocampus, sensory and mnemonic information from the entorhinal cortex and the CA3 area converge in the CA1 area in which coordinated synaptic activity in terminals of temporoammonic (cortical) and Schaffer collateral (CA3) pathways give rise to mid-frequency (gamma_M; 75 Hz) and slow gamma oscillations (gamma_S; 37 Hz) in strata lacunosum-moleculare and radiatum, respectively. The association between afferent pathways and gamma oscillations paralleled by layer-specific arborizations of (GABAergic) interneuron types make the rodent CA1 area a good candidate to explore input selection mechanisms. 

[end of paraphrase]