Biology subjects

Davis, Z. W.

Publications and source records attributed to Davis, Z. W..

6 recordsLinked to original sources

bioRxiv2026

Propofol-induced loss of responsiveness reorganizes cortical traveling waves in the human brain

Consciousness depends on the coordinated propagation of neural activity across cortical networks. Traveling waves, the spatiotemporal patterns of phase-aligned neural activity, are thought to support large-scale cortical communication, yet how these dynamics are altered during general anesthesia remains poorly understood. Here, we examined the effects of propofol on cortical traveling waves recorded with high-density microelectrode arrays in the temporal lobes of two human participants (both men). We identified and characterized changes in neural traveling wave properties as participants underwent general anesthesia. Propofol produced robust, state-dependent reorganization of wave dynamics: increased propagation speed, shifted propagation directions, and altered spectral structure. At the neuronal level, propofol was accompanied by pronounced changes in firing activity and spike-wave relationships, linking mesoscale traveling waves to coordinated changes in neuronal firing dynamics. Together, these findings demonstrate how propofol reshapes the spatiotemporal organization of cortical activity across spatial scales.

neuroscience↗

bioRxiv2026

Spatiotemporal Divergence Between Intrinsic And Evoked Cortical Activity Predicts Visual Detection.

The threshold for sensory detection varies with fluctuations in intrinsic cortical activity. When stimulus-encoding cortical populations are more excitable, stimuli elicit stronger neural responses that are more likely to be detected. However, the detection of a stimulus is also more likely when cortical populations are less excitable because there is less background "noise". Therefore, it is unclear how the variable states of intrinsic and sensory-evoked cortical activity and their interactions impact sensory detection. We hypothesize the answer depends on the spatiotemporal structure of intrinsic activity states across sensory encoding and non-encoding populations. To test this, we examined intrinsic and target-evoked population activity across cortical Area MT in common marmosets while they performed a threshold visual detection task. We compared detection performance based on target-evoked responses and the state of intrinsic activity in the larger surrounding population. We find that the intrinsic activity in the surrounding, non-encoding population predicted trial-by-trial detection performance better than the population encoding the target-evoked response. Furthermore, we find that the detection performance of the monkey was best predicted by the divergence in excitability between the encoding and surrounding non-encoding population. These findings suggest that, rather than a source of noise or irrelevant to sensory processing, the distributed spatiotemporal state of intrinsic activity directly influences how sensory signals are represented in cortical populations and can influence perceptual thresholds in visual detection. Significance StatementPrior research into how variability in neural activity impacts perception has often focused on neural populations that encode relevant sensory information. However, the role of variable intrinsic activity in nearby, non-encoding populations and their contribution to sensory representations is less well understood. We found that the state of intrinsic activity in non-encoding populations was a better predictor of performance on a threshold visual detection task than the evoked-response magnitude. These results suggest that the state activity in broader neural populations plays a larger role in sensory computations relevant to perceptual decisions than previously regarded.

neuroscience↗

bioRxiv2023

Acute Neuropixels recordings in the marmoset monkey

High-density linear probes, like Neuropixels, provide an unprecedented opportunity to understand how neural populations within specific laminar compartments contribute to behavior. Marmoset monkeys, unlike macaque monkeys, have a lissencephalic (smooth) cortex that enables recording perpendicular to the cortical surface, thus making them an ideal animal model for studying laminar computations. Here we present a method for acute Neuropixels recordings in the common marmoset (Callithrix jacchus). The approach replaces the native dura with an artificial silicon-based dura that grants visual access to the cortical surface, which is helpful in avoiding blood vessels, ensures perpendicular penetrations, and could be used in conjunction with optical imaging or optogenetic techniques. The chamber housing the artificial dura is simple to maintain with minimal risk of infection and could be combined with semi-chronic microdrives and wireless recording hardware. This technique enables repeated acute penetrations over a period of several months. With occasional removal of tissue growth on the pial surface, recordings can be performed for a year or more. The approach is fully compatible with Neuropixels probes, enabling the recording of hundreds of single neurons distributed throughout the cortical column.

neuroscience↗

bioRxiv2023

The double-drift illusion biases the marmoset oculomotor system

The double-drift illusion has two unique characteristics: the error between the perceived and physical position of the stimulus grows over time, and saccades to the moving target land much closer to the physical than the perceived location. These results suggest that the perceptual and saccade targeting systems integrate visual information over different timescales. Functional imaging studies in humans have revealed several potential cortical areas of interest, including the prefrontal cortex. However, we currently lack an animal model to study the neural mechanisms of location perception that underlie the double-drift illusion. To fill this gap, we trained two marmoset monkeys to fixate and then saccade to the double drift stimulus. In line with human observers for radial double-drift trajectories, we find that saccade endpoints do show a significant bias that is, as it is in humans, smaller than that seen in perception. This bias is modulated by changes in the external and internal speeds of the stimulus. These results demonstrate that the saccade targeting system of the marmoset monkey is influenced by the double-drift illusion.

animal behavior and cognition↗

bioRxiv2022

Spike-phase coupling patterns reveal laminar identity in primate cortex

The cortical column is one of the fundamental computational circuits in the brain. In order to understand the role neurons in different layers of this circuit play in cortical function it is necessary to identify the boundaries that separate the laminar compartments. While histological approaches can reveal ground truth they are not a practical means of identifying cortical layers in vivo. The gold standard for identifying laminar compartments in electrophysiological recordings is current-source density (CSD) analysis. However, laminar CSD analysis requires averaging across reliably evoked responses that target the input layer in cortex, which may be difficult to generate in less well studied cortical regions. Further the analysis can be susceptible to noise on individual channels resulting in errors in assigning laminar boundaries. Here, we have analyzed linear array recordings in multiple cortical areas in both the common marmoset and the rhesus macaque. We describe a pattern of laminar spike-field phase relationships that reliably identifies the transition between input and deep layers in cortical recordings from multiple cortical areas in two different non-human primate species. This measure corresponds well to estimates of the location of the input layer using CSDs, but does not require averaging or specific evoked activity. Laminar identity can be estimated rapidly with as little as a minute of ongoing data and is invariant to many experimental parameters. This method may serve to validate CSD measurements that might otherwise be unreliable or to estimate laminar boundaries when other methods are not practical.

neuroscience↗

bioRxiv2019

Spontaneous Traveling Cortical Waves Gate Perception in Awake Behaving Primates

Perceptual sensitivity varies from moment to moment. One potential source of variability is spontaneous fluctuations in cortical activity that can travel as a wave. Spontaneous traveling waves have been reported during anesthesia, but questioned as to whether they are relevant to waking cortical function. Using newly developed analytic techniques, we find spontaneous waves of activity in extrastriate visual cortex of awake marmosets (Callithrix jacchus). In monkeys trained to detect faint visual targets, the timing and position of spontaneous traveling waves, prior to target onset, predict the magnitude of evoked activity and the likelihood of detection. In contrast, spatially disorganized fluctuations of neural activity are much less predictive. These results reveal an important role for spontaneous traveling waves in sensory processing through modulating neural and perceptual sensitivity.\n\nOne Sentence SummaryFluctuations in cortical activity often travel as waves, shape incoming sensory information, and affect conscious perception.

neuroscience↗