Developmental neurobiology

Cramer laboratory | UC Irvine | Sep 2012 – Jun 2013

The mammalian brain is an incredibly complex organ. Brains in mice contain over 70 million neurons, and in humans, a staggering, 80-100 billion neurons. Yet despite these overwhelming numbers the cells still manage to self organise into a structure that is reproduced time and time again. A key aim in neurobiology is to determine how neurons navigate to the correct brain region to recapitulate the same structure between individuals.

It’s thought that in later stages of brain development, the brain creates a map telling the new neurons where to go. The older, established neurons make “molecular guidance cues” that attract or repel different types of neurons. The identity of the younger neuron thus effects how it behaves in the developing brain. The older neurons effectively guide the younger ones to the correct position.

My project honed in on a really small part of this map in mice: the auditory brainstem, a region of the brain involved with hearing. Normally neurons from part of the auditory brainstem form connections on the other side of the brain but, importantly, not on the same side. My project investigated whether a gene called Ephrin A5 acted to prevent these neurons from forming abnormal connections on the same side of the brain.

Filling in this map is a tremendous undertaking and extremely important. Understanding the brain from a fundamental mechanistic and developmental perspective will ultimately help future researchers investigate diseases or develop treatments.