Electrical Oscillations of Isolated Brain Microtubules

BRENDA C. GUTIERREZ; MARÍA DEL ROCÍO CANTERO; HORACIO F. CANTIELLO

VIRTUAL

Congreso; Reunión Anual de la SAFIS; 2021

SAFIS/ALACF 2021

Brain waves are coherent patterns of synchronized electrical oscillations thought to represent the activity of neurons that is evidenced by electroencephalogram (EEG) and local field potential (LFP) recordings. However, oscillatory electrical activities in the mammalian brain have also been observed across phyla. Insect brains generate oscillatory activity patterns that resemble their vertebrate counterparts. Microtubules (MTs) are highly charged polymers, and important structures of the cytoskeleton in neurons. Recent studies (Cantero et al, 2016; 2018; 2019) demonstrated that different assemblies of brain MTs, including the isolated polymers generate spontaneous and self-sustained electrical oscillations. To gain insight into the electrical oscillatory activity of MTs in the brain of an animal model, we isolated brains and MT sheets from the honeybee (Apis mellifera). The patch clamp technique was applied to MT sheets of purified honeybee brain MTs. High resistance seal patches showed electrical oscillations that linearly depended on the holding potential between ±200 mV and had a mean conductance ± SEM of 9.2 ± 0.3 nS (n = 14). To place these oscillations in the context of the brain, we also explored LFP recordings from the Triton X-permeabilized whole brain of worker honeybees that unmasked spontaneous oscillations after, but not before tissue permeabilization. There is no evidence of a particular region producing robust electrical activity; however, the mushroom bodies could be related to it. Frequency domain spectral analysis of time records indicated at least two major peaks at approximately ~38 Hz and ~93 Hz in both preparations. These oscillations were partially similar to those observed in similar preparations of mammalian MTs, and represented low and high gamma brain waves, usually reported in humans and other animals. The present data provide evidence that MT electrical oscillations are a novel signaling mechanism implicated in brain wave activity, associated with cognitive function in other animal models.