Alex Thiele and other researchers at Newcastle University, northeastern England, trained three macaque monkeys to concentrate on a flashing light on a computer screen.
The animals were rewarded with fruit juice when they focussed on the light rather than on another light that could also appear distractingly on the screen.
The team then injected tiny doses of acetylcholine into the monkeys' visual cortex, where spatial attention is processed, to see how this affected their performance.
Small quantities indeed sharpened the primates' attention, they found.
The researchers confirmed the outcome by using other chemicals to block the receptor, or location on the brain-cell surface, where the acetylcholine molecule docks, and the monkeys' attention dived.
"Acetylcholine improves the ability of these neurons, which represent the locus of attention, to integrate specific forms of information," Thiele told AFP.
Still unclear is what role this, or other, neurotransmitters play in non-visual attention, such as touch or hearing, he said.
Thiele said the results pointed to caution as whether, one day, acetylcholine-boosting drugs might emerge to boost attention, helping for instance fatigued soldiers or pilots.
"I don't think so, because we also demonstrated that if we applied too much, the cells in the monkeys got worse. The monkeys didn't suffer any side-effects, but certainly their performance got worse," he said.
"It needs a very fine and right balance of acetylcholine in the brain. In practice, there would be a huge amount of obstacles to making sure it (the drug) gets to the right location and in the right quantities."
© 2008 AFP
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