Our brain's ability to rapidly interpret and analyse new information may lie in the musical hum of our brainwaves.
We continuously take in information about the world but establishing new neural connections and pathways – the process thought to underlie memory formation – is too slow to account for our ability to learn rapidly.
Evan Antzoulatos and Earl Miller at the Massachusetts Institute of Technology decided to see if brainwaves – the surges of electricity produced by individual neurons firing en masse – play a role. They used EEG to observe patterns of electrical activity in the brains of monkeys as they taught the animals to categorise patterns of dots into two distinct groups.
At first, they memorised which dots went where, but as the task became harder, they shifted to learning the rules that defined the categories.
The researchers found that, initially, brainwaves of different frequencies were being produced independently by the prefrontal cortex and the striatum – two brain regions involved in learning. But as the monkeys made sense of the game, the waves began to synchronise and "hum" at the same frequency – with each category of dots having its own frequency.
Miller says the synchronised brainwaves indicate the formation of a communication circuit between the two brain regions. He believes this happens before anatomical changes in brain connections take place, giving our minds time to think through various options when presented with new information before the right one gets laid down as a memory. Otherwise, the process is too time-consuming to account for the flexibility and speed of the human mind, says Miller.
Previous studies have shown increased synchrony between the two brain regions during learning, but this is the first study to show specific patterns of synchrony linked to specific thoughts.
"We used to think of electrical activity fluctuations just as proof that the brain is working – like the humming of a car's engine. But the brain is producing all different sounds and different frequencies," says Miller. The research demonstrates that the music the brain produces may actually be central to how it encodes specific thoughts, he adds.
Journal reference: Neuron, DOI: 10.1016/j.neuron.2014.05.005