Alternative strategy for driving voltage-oscillator in neocortex of rats

• Published in: Neuroscience research 2023-06, Vol.191, p.28-37
• Main Authors: Fukuda, Takako, Tominaga, Takashi, Tominaga, Yoko, Kanayama, Hiroyuki, Kato, Nobuo, Yoshimura, Hiroshi
• Format: Article
• Language: English
• Subjects: Animals; Caffeine; Caffeine - pharmacology; Electric Stimulation; Neocortex; Optical recording; Oscillation; Rats; Rats, Wistar; Signal propagation; Visual cortex; Voltage-oscillator
• ISSN: 0168-0102; 1872-8111
• DOI: 10.1016/j.neures.2023.01.002

Information integration in the brain requires functional connectivity between local neural networks. Here, we investigated the interregional coupling mechanism from the viewpoint of oscillations using optical recording methods. Low-frequency electrical stimulation of rat neocortical slices in a caffeine-containing medium induced oscillatory activity between the primary visual cortex (Oc1) and medial secondary visual cortex (Oc2M), in which the oscillation generator was located in the Oc2M and was triggered by a feedforward signal. During to-and-fro oscillatory activity, neural excitation was marked in layer II/III. When the upper layer was disrupted between Oc1 and Oc2M, feedforward signals could propagate through the deep layer and switch on the oscillator in the Oc2M. When the lower layer was disrupted between Oc1 and Oc2M, feedforward signals could propagate through the upper layer and switch on the oscillator in the Oc2M. In the backward direction, neither the upper layer cut nor the lower layer cut disrupted the propagation of the oscillations. In all cases, the horizontal and vertical pathways were used as needed. Fluctuations in the oscillatory waveforms of the local field potential at the upper and lower layers in the Oc2M were reversed, suggesting that the oscillation originated between the two layers. Thus, the neocortex may work as a safety device for interregional communications in an alternative way to drive voltage oscillators in the neocortex. •Caffeine-assisted oscillations are composed of initial propagation and backward propagation between the Oc2M to Oc1.•Neural oscillator is equipped in the Oc2M.•Roles of upper- and lower-layer pathways as well as vertical pathways are conveying signals safely as needed.•Vertical columns might form neural oscillator, and upper layer may work as a booster for signal delivery.