Speaker: Zinong Yang (Lewis Lab)

Title: Attentional failures after sleep deprivation represent moments of cerebrospinal fluid flow.

Abstract:  Sleep deprivation rapidly disrupts cognitive function, and in the long term contributes to neurological disease. Why sleep deprivation has such profound effects on cognition is not well understood. Here, we use simultaneous fast fMRI-EEG to test how sleep deprivation modulates cognitive, neural, and fluid dynamics in the human brain. We demonstrate that after sleep deprivation, sleep-like pulsatile cerebrospinal fluid (CSF) flow events intrude into the awake state. CSF flow is coupled to attentional function, with high flow during attentional impairment. Furthermore, CSF flow is tightly orchestrated in a series of brain-body changes including broadband neuronal shifts, pupil constriction, and altered systemic physiology, pointing to a coupled system of fluid dynamics and neuromodulatory state. The timing of these dynamics is consistent with a vascular mechanism regulated by neuromodulatory state, in which CSF begins to flow outward when attention fails, and flow reverses when attention recovers. The attentional costs of sleep deprivation may thus reflect an irrepressible need for neuronal rest periods and widespread pulsatile fluid flow.

Speaker: Guy Gaziv (DiCarlo Lab)

Title: Towards Noninvasive, Beneficial Modulation of Neural Population Activity via Natural Vision Perturbations

Abstract:  Precise control of neural activity is generally achieved through invasive techniques. In this talk, I will present our recent work investigating prospects within the primate ventral visual network for precisely modulating neural activity in high-level brain regions. These modulations are achieved through model-guided image perturbations that are adapted to arbitrary natural visual stimuli. In particular, these perturbations can selectively bias the activity of targeted high-level neurons upon presentation of the perturbed stimulus, with minimal effects on the activity of non-targeted neural sites. Motivated by model predictions on the viability of this approach, we tested it in three Macaque IT sub-populations. We found strong quantitative agreement between the model-predicted and biologically-realized modulation effects, allowing the injection of arbitrary neural population bias patterns. These results highlight that current machine executable models of the ventral stream are now powerful enough to design vision-based non-invasive sensory-based neural interventions at neural site-level resolution.