AI Insight
Researchers analyzed brain recordings from 19 neurosurgical patients and found that 27% of neurons fire preferentially at specific oscillatory frequencies, particularly below 10 Hz, a phenomenon they call "frequency tuning." This firing pattern was distinct from the previously known "phase tuning" and occurred across multiple brain regions including the hippocampus, entorhinal cortex, and cingulate cortex. The study demonstrates that the instantaneous frequency of brain oscillations directly modulates when individual neurons fire.
Why it matters
This discovery reveals a previously underappreciated mechanism by which the brain processes information, suggesting that oscillation frequency itself carries functional significance beyond timing. The findings could enable more precise frequency-targeted therapeutic brain stimulation for neurological and psychiatric conditions.
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by Zahra Jourahmad, Raissa K. Mathura, Layth S. Mattar, Melissa C. Franch, Danika L. Paulo, Mohammed Hasen, Nicole R. Provenza, Benjamin Y. Hayden, Sameer A. Sheth, Eleonora Bartoli, Andrew J. Watrous
Neural oscillations play a critical role in shaping neuronal firing patterns. While phase-locked neuronal firing (“phase tuning”) has been extensively studied in animal models and human invasive recordings, much less is known about whether neurons show preferential firing at specific oscillatory frequencies, termed frequency tuning. Here, we employ human intracranial recordings across several brain regions including hippocampus, entorhinal cortex, anterior and posterior cingulate cortex, and orbitofrontal cortex to test the hypothesis that neurons exhibit frequency-specific firing. We analyzed 357 single units recorded simultaneously with local field potentials in 19 neurosurgical patients during awake resting. We estimated the instantaneous frequency of the LFP using adaptive spectral decomposition and assessed frequency tuning of each neuron while controlling for changes in firing rate unrelated to frequency changes. We found 27% of neurons exhibited increased or decreased firing within specific frequencies, most commonly within the low-frequency range (<10 Hz). Neurons exhibiting frequency tuning were distinct from those displaying phase tuning, and both types of tuning were observed across multiple brain regions with no anatomical preference. Together, our results demonstrate that the instantaneous frequency of neural oscillations modulates neuronal firing which may serve as an additional mechanism for information processing in the human brain, opening new avenues for frequency-targeted neural stimulation.
Source: Human neuronal firing varies with the frequency of local field potential oscillations