Dias, A. L. | bioRxiv Science

bioRxiv2026

Nasal inhalations and exhalations evoke distinct prefrontal-cortex responses with constant latency

Neuronal activity synchronous to breathing is salient across the mammalian brain. These modulations are typically characterized as oscillating signals phase-locked to the ongoing breathing rhythm and treated as evidence for respiratory entrainment of cortical and subcortical oscillations. Since activation of the olfactory circuitry has been identified as their preponderant source, we wondered whether respiratory brain signals could be better understood as sequences of evoked sensory potentials. To help distinguish between these scenarios, we set out to quantify the detailed alignment of prefrontal cortex local field potentials (LFPs) to the nasal airflow cycle across the natural repertoire of rat breathing. We found that, while LFP and breathing show salient synchrony for all breathing modes, the phase of their locking is a strict linear function of respiratory rate. We explain this by showing that LFPs align to nasal airflow with a constant time lag of 100 ms, irrespective of breathing rate. Segmenting by breathing cycles revealed that LFP peaks and fast-gamma bursts are time-locked to inhalations, while LFP troughs and slow-gamma activity time-lock to exhalations. Our results support the view that respiratory signals across the frontal brain of rodents are sensory potentials evoked by cyclic ortho- and retronasal airflow.

neuroscience↗

bioRxiv2024

Breathing modulates network activity in frontal brain regions during anxiety

Anxiety elicits various physiological responses, including changes in respiratory rate and neuronal activity within specific brain regions such as the medial prefrontal cortex (mPFC). Previous research suggests that the olfactory bulb (OB) modulates the mPFC through respiration-coupled neuronal oscillations (RCOs), which have been linked to fear-related freezing behavior. Nevertheless, the impact of breathing on frontal brain networks during other negative emotional responses, such as anxiety-related states characterized by higher breathing rates, remains unclear. To address this, we subjected rats to the elevated plus maze (EPM) paradigm while simultaneously recording respiration and local field potentials in the OB and mPFC. Our findings demonstrate distinct respiratory patterns during EPM exploration: slower breathing frequencies prevailed in the closed arms, whereas faster frequencies were observed in the open arms, independent of locomotor activity, indicating that anxiety-like states are associated with increased respiratory rates. Additionally, we identified RCOs at different frequencies, mirroring the bimodal distribution of respiratory frequencies. RCOs exhibited higher power during open arm exploration, when they showed greater coherence with breathing at faster frequencies. Furthermore, we confirmed that nasal respiration drives RCOs in frontal brain regions, and found a stronger effect during faster breathing. Interestingly, we observed that the frequency of prefrontal gamma oscillations modulated by respiration increased with heightened anxiety levels and breathing frequency. Overall, our study provides evidence for a significant influence of breathing on prefrontal cortex networks during anxious states, shedding light on the complex interplay between respiratory physiology and emotional processing. Significance StatementUnderstanding how breathing influences brain activity during anxious states could pave the way for novel therapeutic interventions targeting respiratory control to alleviate anxiety symptoms. Our study uncovers a crucial link between respiratory patterns and anxiety-related neural activity in the brain. By investigating the interplay between breathing, neuronal oscillations, and emotional states, we reveal that anxiety induces distinct respiratory patterns, with higher breathing rates correlating with anxious behavior. Importantly, we demonstrate that respiration drives oscillatory activity in the prefrontal cortex, and this effect is potentiated during the fast breathing associated with anxiety. Furthermore, the breathing cycle modulates the emergence of prefrontal gamma oscillations differentially across anxiety levels. This discovery sheds new light on the intricate relationship between respiratory physiology and emotional processing.

neuroscience↗