Wiring the fly

The fundamental unit of brain function is the nerve cell, or neuron. Typically, each of our neurons receives signals at one end, processes this information, transmits it along its length, and signals across synapses to other nerve cells. Inputs to our nervous system come from the world around us — light, sound, smell, taste, and so on — and are 'fed' into regions of the brain specialised to process each type of input. Signal processing across multiple layers in the brain is by neurons connecting to other neurons to form 'circuits' somewhat similar to electrical circuits. The human brain is a massively parallel set of computers with over 85 billion neurons, and trillions of connections or synapses. Understanding how the brain works in health and disease seems an impossible task.