Biology subjects

Kelz, M. B.

Publications and source records attributed to Kelz, M. B..

3 recordsLinked to original sources

bioRxiv2023

Neural assemblies coordinated by cortical waves are associated with waking and hallucinatory brain states

The relationship between sensory stimuli and perceptions is brain-state dependent: in wakefulness stimuli evoke perceptions; under anesthesia perceptions are abolished; during dreaming and in dissociated states, percepts are internally generated. Here, we exploit this state dependence to identify brain activity associated with internally generated or stimulus-evoked perception. In awake mice, visual stimuli phase reset spontaneous cortical waves to elicit 3-6 Hz feedback traveling waves. These stimulus-evoked waves traverse the cortex and entrain visual and parietal neurons. Under anesthesia and during ketamine-induced dissociation, visual stimuli do not disrupt spontaneous waves. Uniquely in the dissociated state, spontaneous waves traverse the cortex caudally and entrain visual and parietal neurons, akin to stimulus-evoked waves in wakefulness. Thus, coordinated neuronal assemblies orchestrated by traveling cortical waves emerge in states in which perception can manifest. The awake state is privileged in that this coordination is elicited by specifically by external visual stimuli.

neuroscience↗

bioRxiv2021

Visual evoked feedforward-feedback travelling waves organize neural activity across the cortical hierarchy in mice

Sensory processing is distributed among many brain regions that interact via feedforward and feedback signaling. It has been hypothesized that neuronal oscillations mediating feedforward and feedback interactions organize into travelling waves. However, stimulus evoked travelling waves of sufficient spatial scale have never been demonstrated directly. Here, we show that simple visual stimuli reliably evoke two traveling waves with spatial wavelengths that cover much of the cerebral hemisphere in awake mice. 30-50Hz feedforward waves arise in primary visual cortex (V1) and propagate rostrally, while 3-6Hz feedback waves originate in the association cortex and flow caudally. The phase of the feedback wave modulates the amplitude of the feedforward wave and synchronizes firing between V1 and parietal cortex. Altogether, these results provide direct experimental evidence that visual evoked travelling waves percolate through the cerebral cortex and coordinate neuronal activity across broadly distributed networks mediating visual processing.

neuroscience↗

bioRxiv2020

Brain network motifs are markers of loss and recovery of consciousness

Motifs are patterns of inter-connections between nodes of a network, and have been investigated as building blocks of directed networks. This study explored the re-organization of 3-node motifs during loss and recovery of consciousness. Nine healthy subjects underwent a 3-hour anesthetic protocol while 128-channel electroencephalography (EEG) was recorded. In the alpha (8-13 Hz) band, five-minute epochs of EEG were extracted for: baseline; induction; unconscious; 30-, 10- and 5-minutes pre-recovery of responsiveness; 30- and 180-minutes post-recovery of responsiveness. We constructed a functional brain network using the weighted and directed phase lag index, on which we calculated the frequency and topology of 3-node motifs. Three motifs (motifs 1, 2 and 5) were significantly present across participants and epochs, when compared to random networks (p<0.05). The topology of motifs 1 and 5 changed significantly between responsive and unresponsive epochs (p<0.01). Motif 1 was constituted by long-range chain-like connections, while motif 5 was constituted by short-range, loop-like connections. Our results suggest that anesthetic-induced unconsciousness is associated with a topological re-organization of network motifs. As motif topological re-organization may precede (motif 5) or accompany (motif 1) the return of responsiveness, motifs could contribute to the understanding of the neural correlates of consciousness.

neuroscience↗