We know one insect’s cerebral circuitry.
Neurons fill brains. Neurons continually communicate. The brain works that way, allowing animals to walk, breathe, and think.
A neuron?
Studying human brains with over 80 billion neurons is difficult. Many animals have smaller brains with fewer neurons. They help understand brains.
Scientists have mapped all newborn fruit fly brain neurons for the first time. Researchers discovered cell-cell communication. Connectomes map neuronal connections. This is the most intricate brain wiring diagram ever. Science reported the findings on March 10.
Complex brains
This degree of brain diagramming has only been done on three species. Sea squirts were one. Two others were worms. However, their bodies have little more than 1,500 neurons. The new study sought to explain complicated creatures with thousands of neurons in their brains.
Drosophila melanogaster flies work. Their brains resemble humans more than sea squirt or worm brains. Fruit flies exhibit many human behaviors. They can mix visual and touch data. They also learn. The fruit fly brain presented a fascinating neural mapping task.
Researchers focused on young fruit fly brains. Larvae, or baby fruit flies, can do almost everything adults do except fly and mate. Albert Cardona thinks children have fewer and smaller neurons than adults. He claims this speeds data collection. MRC Laboratory of Molecular Biology neuroscientist Cardona. Cambridge, UK.
Neuron mapping
Marta Zlatic said the scientists sketched the larval fruit fly brain 12 years ago. She’s MRC Laboratory of Molecular Biology’s neuroscientist.
First, Zlatic, Cardona, and colleagues imaged the larval fruit fly brain. An electron microscope helped them do this. Researchers computer-stitched such photos. They meticulously traced each neuron to produce a 3-D virtual representation of all cells.
That model helped the investigators identify neuron-to-neuron interactions. Synaptic connections. Researchers could identify which cell delivers and receives information at each synapse.
The 3-D model showed 3,000 neurons and 550,000 connections.
Connection patterns
Brain circuits process information. The scientists investigated how fruit flies create circuits from many neurons. Neurons directly connected were studied. Like a family tree, they examined distantly connected neurons that are not directly related. Connectivity patterns develop from these neural connections.
Fruit fly brain connection patterns showed 93 neuron types. Each sort of cell connects similarly. Neuron structure and function matched these categories.
Neurons were highly interconnected. They connected to 20 or more neurons. These animals value learning, since 75% of these neuron “hubs” were linked to the brain’s learning center.
Zlatic said technology has progressed greatly since the project began. It would be faster today. Zlatic thinks this whole-brain map might guide brain circuitry researchers. “We have a reference map.”