Scientists found that cycling led to greater connectivity between brain regions linked to the disease.
But vigorous "forced" pedalling was key to the changes, which were associated with improvements in co-ordination and balance.
The US research lends support to anecdotal evidence of cycling alleviating Parkinson's symptoms.
Rebels capture helicopter base
Syrian rebels captured a helicopter base just outside Damascus, while the bombardment of a village near the capital killed at least eight children.
Activists said the children were killed when Syrian warplanes bombed Deir al-Asafir.
The village is close to suburbs of the capital that has been witnessing clashes, shelling and air raids between troops and rebels over the past months.
Elton John rocks Beijing
Elton John shocked his Chinese audience when he publicly dedicated his only concert in Beijing to artist and political critic Ai Weiwei.
His comments sent a murmur of shock through audience members accustomed to tight censorship of Western pop events.
Online media sites reported on Elton John's two-performance tour in China, but not the remark.
In 2008, the singer Bjork shouted "Tibet, Tibet" at the close of a song called Declare Independence at a Shanghai performance.
18 injured by gas explosion
A natural gas explosion that injured 18 people and damaged 42 buildings was blamed on a utility worker who accidentally punctured a high-pressure pipeline while looking for a leak.
The worker damaged the underground pipe in Springfield, Mass, while using a metal probe to locate the source of the leak.
The employee was following older markings on a pavement that indicated the location of the gas line, but the markings were incorrect.