A man with Parkinson’s disease has experienced a substantial improvement in his ability to walk after being fitted with a device that electrically stimulates his spinal cord. The findings, although based on one person’s experience, suggest this technique could be used widely to treat movement deficits in people with the condition.

Around 90 per cent of people with Parkinson’s experience some kind of movement difficulty, says at the Swiss Federal Institute of Technology in Lausanne. Existing treatments include drugs that target parts of the brain affected by a loss of the chemical dopamine, which regulates movement, as well as deep-brain stimulation, which similarly focuses on these brain areas and changes some of the abnormal electrical signals that cause symptoms.

However, many people with Parkinson’s disease don’t respond to these treatments, particularly if their condition is advanced, says Courtine. He and his colleagues wanted to find out whether directly stimulating the spinal cord in a person with severe Parkinson’s could alleviate their gait-related problems.

They focused on epidural electrical stimulation (EES), which can modulate the activity of neurons behind locomotor movements. Previous studies showed that .

The team devised a form of EES that specifically targets neurons in the spine that are activated when legs walk, which . To test it in a person, the researchers recruited a 62-year-old man called Marc, who has experienced Parkinson’s symptoms for around 30 years. These included severe motor issues, particularly gait freezing – sudden, short and temporary episodes of an inability to move despite the intention to walk.

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For the method to be effective, the researchers had to first map the neurons in Marc’s spine. This helped to guide the implantation of the electrical stimulators so they would only target his legs’ neurons.

They then placed sensors on Marc’s legs and shoes to monitor the electrical activity of the neurons that activate the muscles in these limbs and his feet. When these sensors detected this electrical activity, they activated the stimulators.

After three months of rehabilitative training using the stimulators, Marc more or less stopped experiencing gait freezing, says Courtine. Marc says that passing through narrow paths or turning as he walked had previously caused gait freezing, which led to him falling five or six times a day. Marc has now been using the stimulator for two years and says he hardly falls at all any more, allowing him to walk several kilometres at a time without a cane or helper.

The stimulation is personalised to Marc, who found it particularly difficult to move one leg, says Courtine, prompting the researchers to apply more stimulation to that limb. Nevertheless, they think a similar technique could help many people with severe Parkinson’s.

“In response to the precise stimulation of the lumbar spinal cord, [we’ve] observed for the first time the remarkable improvement of gait deficits due to Parkinson’s disease,” says team member . “I really believe that these results open realistic perspectives to develop treatments that alleviate gait deficits due to Parkinson’s disease.”

The researchers hope to test this method in more people with the condition, says Bloch. There are at least five more years of development and testing of the technology before the treatment will reach people outside a trial, says Courtine.

Sperm change how they swim in response to different conditions in the vaginal tract. The ability to adjust to these conditions could be a measure of sperm health. If this is shown in future research, the most adaptable sperm could one day be selected for fertility treatments to maximise the chance of conceiving.

“The female reproductive tract is a complex environment that plays a critical role in influencing sperm migration behaviour to ultimately select high-quality sperm for natural fertilisation,” says at Monash University in Melbourne, Australia.

After vaginal intercourse, mucus secretion into the fallopian tubes intensifies, she says. This stimulates fluid movement in the vaginal tract, making it more viscous.

separately considered factors such as the sperm’s shape and the viscosity and flow of the fluid they swam through, says Yazdan Parast. To better understand the collective conditions sperm face, she and her colleagues wanted to study these factors together.

The researchers filled a container with a mucus-like liquid, similar to that in the vagina, which they could manipulate to be more or less viscous.

They then attached a bull sperm cell to a tiny chamber in the container to observe how it changed the way it moved its tail as the team altered the viscosity of the liquid. Bull sperm have a similar structure and swimming pattern to human sperm, but it is easier to gain regulatory approval to study them, says Yazdan Parast. The experiment was repeated for nine other bull sperm cells.

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The team imaged the sperm’s movements using a technique called high-resolution dark-field microscopy, finding that the more viscous the liquid was, the larger the up and down motions made by the sperm’s tails.

The tails beat fastest when the environment around them most resembled the area upstream of the vaginal tract, when sperm start to approach an egg. Sperm that can’t adapt to these conditions are probably less likely to fertilise an egg, says Yazdan Parast.

With further research, the findings could help to improve fertility treatments in people. “By replicating the relevant conditions in sperm selection processes, we may have the potential to identify and isolate sperm that display optimal swimming behaviour under conditions similar to those encountered within the female reproductive tract,” she says.

Several devices already exist to sort sperm according to their quality, says at the University of Birmingham, UK. Before making a new, improved one, we need to “properly understand what characteristics make a ‘good’ sperm, and studies like these are important steps”, he says.