How does the brain process sensory information over time?

Our nervous system is constantly stimulated by sight, sound, touch, and smell in the world. In my research as a PhD student at Duke (Glickfeld lab), I am interested understanding how the brain processes this continuous stream of visual information, using the mouse as a model organism. Here are some of the projects I have led in the lab:

  • A synaptic mechanism for temporal integration in V1

    History-dependent sensory processing enables the nervous system to adjust to features of the environment over time. In primary visual cortex (V1), neuronal responses are modulated by stimulus history ranging from milliseconds to minutes. I investigated how layer 2/3 neurons in V1 adapt to brief stimuli by performing in vivo whole-cell recordings to measure individual neurons’ membrane potential and synaptic inputs. Using optogenetics and in vitro slice recordings, I pinpointed these changes to depression at feedforward synapses from layer 4 to 2/3. This work is currently in review for publication.

    Technical skills: in vivo electrophysiology (intracellular & extracellular), in utero electroporation, in vitro electrophysiology

  • Context dependence of network-level suppression in V1

    Neurons in the visual system are sensitive to specific features such as the size or contrast of a stimulus. Recent studies in awake animals have demonstrated a strong influence of animals’ behavioral state on responses, even in early sensory areas such as V1. Using extracellular recordings in vivo I identified a late-onset suppression in V1 neurons that increases with size of the stimulus presented. This surround suppression effect is specific to behavioral context, as it is greatly reduced when animals are running. Ongoing experiments seek to identify circuit and synaptic mechanisms underlying this phenomenon.

    Technical skills: in vivo electrophysiology (intracellular & extracellular), opto-tagging, population-level analysis of neural spiking data

  • Distinct recruitment of inhibition across HVAs

    V1 projects to multiple cortical areas in parallel to generate increasingly specialized representations of visual stimuli. To understand how this specialization could be generated, my co-authors and I made anatomical and physiological measurements of neurons and their synaptic inputs in four higher visual areas (HVAs). We found evidence for stronger recruitment of inhibition through feed-forward pathways in lateral areas and recurrent pathways in medial areas. Our results suggest that area-specific properties could arise through variations within similar circuit structures that result in preferential activation of different inhibitory pathways. This work has been published in Current Biology (Li et al., 2021).

    Technical skills: in vitro electrophysiology, optogenetics, burr hole injections