We are both a systems and developmental neuroscience lab.

Our lab is fascinated by the brain. How does it work? What can it do? And our favorite question: …

How does the brain develop?

Before the onset of sensory experience, the brain is not silent - it generates its own neural activity! Our lab aims to understand how this activity shapes the development of the brain.

Development of the visual system

Early in development, prior to vision, the retina exhibits spontaneously-produced bursts of activity, termed retinal waves. The movie on the left shows examples of retinal waves from an embryonic retina where the genetically encoded calcium indicator GCaMP6s is expressed in retinal ganglion cells. Retinal waves are present in many species, including humans, but they are perhaps best studied in mice due to the accessibility of genetic tools. In mice, retinal waves start embryonically and continue for the first two weeks of postnatal life. The circuit mechanisms that mediate the spatiotemporal properties of waves is dynamic during this period of development.

Historically, retinal waves are known to refine retinotopic maps and eye-specific segregation in the visual thalamus and superior colliculus. Recently, retinal waves have been implicated in the development of retinal and collicular direction selectivity, though the mechanisms via which this happens are unclear. A central goal of the lab is to understand how retinal waves set up visual circuitry in the retina and other visual brain areas.

Why do we twitch when we sleep?

We sleep most when we are young. Human newborns spend 16 hours asleep, 8 of which are spent in rapid eye movement (REM) sleep. As adults, we are lucky to net 8 hours of sleep per day, only 2 of which are spent in REM sleep. The large amount of time that newborns spend asleep, particularly in REM sleep, is a strong indicator that sleep plays a sizeable role in the development of the nervous system.

The rapid eye movements that give REM sleep its name are caused by myoclonic twitches of the extraocular muscles. However, these muscles are not unique since virtually all skeletal muscles of the body twitch during REM sleep. We have all observed our pets or family members twitch during sleep (for example, please explore this database of twitching across the animal kingdom).

Why do we twitch when we sleep? Our knee jerk response to this question is that twitches are the remnants of an imperfect blockade of the motor system during sleep that prevents us from acting out our dreams. This response, while appealing, is nothing more than a shortcut that essentially classifies twitches as a functionless byproduct. I think twitches play a central role during development and here’s why:

  • During development, twitches are the primary driver of neural activity. For example, when the forelimb twitches, the whole sensory axis that represents the forelimb, from brainstem nuclei to cortex, is activated.

  • In primary somatosensory cortex, the activity produced by twitches is similar to that produced by retinal waves in visual cortex.

As such, another central goal of the lab is to discover the function of REM sleep twitches. We will achieve this goal by using pharmacology, genetic, optogenetic, and pharmacogenetic tools to manipulate twitches. The consequences of these manipulations will be assessed using imaging techniques of sensorimotor circuits and behavioral assessment of motor function.