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Mindscapes: The woman who gets lost in her own home
THIS WEEK
Spin me round and I know where I am of the street, so you should be heading left. You easily flip everything around in your mind to get back on track. But the disorientation in that split second before you do might come close to the sensation Sharon feels when her world flips around. Giuseppe Iaria at the University of Calgary in Alberta, Canada, and his colleagues have scanned the brains of hundreds of people with DTD to investigate our ability to form mental maps.
“I WAS 5 when I realised something was horribly wrong,” says Sharon. She was playing blind man’s buff in her garden. When the blindfold was removed, she didn’t recognise where she was. “My world seemed to have shifted. I saw my mum, and asked her ‘where am I? Why are you in this strange house?’ ” Although she didn’t know it at the time, Sharon has a condition called developmental topographical disorientation. People with DTD have difficulty orienting themselves – even in their own homes. Sharon can wake up and not know how to get from her bedroom to the kitchen. “It’s like someone has flipped the universe a quarter turn,” she says. But now, experiences like Sharon’s have brought researchers closer to locating the mental compass within our brains. Sharon says the best way to picture how she feels is to imagine coming out of a shop and turning right to get somewhere. You’re sure that you are going the correct way. Then you realise you thought the shop was on the opposite side
Wireless energy powers tiny pacemaker THERE’S electricity in the air. A rabbit’s beating heart has been regulated using a tiny pacemaker powered by energy beamed in from outside its body. In people, the ability to transfer energy wirelessly could shrink pacemakers and other medical devices, making them less invasive to implant. Being fitted with a pacemaker requires surgery, plus another 16 | NewScientist | 24 May 2014
SHARON ROSEMAN
Helen Thomson
operation when the battery eventually runs down. Ada Poon of Stanford University and her colleagues fitted a rabbit with a pacemaker that has no battery and is just 3 millimetres long. A batterypowered metal plate was then held a couple of centimetres above the rabbit’s chest. The plate transmitted 2000 microwatts to the pacemaker via electromagnetic waves, and was able to safely regulate the rabbit’s heartbeat (PNAS, doi.org/st4). Such “near-field energy transmission” was considered too weak to power devices placed deep in
Their as-yet-unpublished work shows that people with DTD have no problems with their memory, intelligence, or brain anatomy. But they do have impaired communication between two brain areas: the right hippocampus, involved in memory, and the prefrontal cortex, which is important for monitoring information, attention and working memory. Iaria thinks that these two areas work in tandem to help us form the mental maps we use to navigate. “When you move around, you do so by monitoring a lot of information, you look at landmarks and you try not to bump into walls,” Iaria says. “There is all this processing of
dynamic information. You use this to form and constantly update a cognitive map of where everything is around you.” People with DTD can’t keep track of spatial information or the relationship between landmarks while moving around, which makes it hard for them to form and update a mental map. More work is needed to gain a broader picture of why this is, says Iaria. For example, grid cells in the brain, which fire as we move about, were only recently found in humans. These cells and others like them send signals to the hippocampus, which collates all the information. Investigating this navigational network could lead to drugs or brain stimulation techniques to help people who have problems remembering their way, say researchers. For now, Iaria’s team are testing potential memory aids, such as a belt lined with vibrating pads that indicate which direction is north. Sharon has developed her own tricks. When she closes her eyes and spins around, she can usually flip her world back to normal – she calls it her Wonder Woman trick. Then there is the problem of remembering where she lives. “I bought a great big red lobster lawn ornament. I call him Louie. If I recognise Louie, I know I’m home. And I know I can go in and play Wonder Woman,” –Welcome home, Sharon– Sharon says. ■
the body. But Poon’s team designed the plate to emit radiation in a concentrated beam towards the implant. The waves are also of a high frequency, so they propagate very well in animal tissue, allowing energy to pass further into the body with little loss and no harm to the tissue. The team also delivered energy to devices implanted in samples of pig heart and brain tissue. They are now
“A metal plate transmitted energy to the pacemaker and safely regulated the rabbit’s heart”
launching a company to adapt the technology for use in humans. This will include exploring how to deliver energy via a skin patch, which is more practical than a metal plate. Robert Puers at the Catholic University of Leuven (KUL), Belgium, isn’t sure the technique makes sense for pacemakers. “These devices, being life-supporting, should not depend on an external powering device,” he says. Poon’s team also plans to adapt the technology for other types of implants, such as stimulators which sit in the brain to treat conditions such as Parkinson’s disease. Aviva Rutkin ■
Spin me round and I know where I am of the street, so you should be heading left. You easily flip everything around in your mind to get back on track. But the disorientation in that split second before you do might come close to the sensation Sharon feels when her world flips around. Giuseppe Iaria at the University of Calgary in Alberta, Canada, and his colleagues have scanned the brains of hundreds of people with DTD to investigate our ability to form mental maps.
“I WAS 5 when I realised something was horribly wrong,” says Sharon. She was playing blind man’s buff in her garden. When the blindfold was removed, she didn’t recognise where she was. “My world seemed to have shifted. I saw my mum, and asked her ‘where am I? Why are you in this strange house?’ ” Although she didn’t know it at the time, Sharon has a condition called developmental topographical disorientation. People with DTD have difficulty orienting themselves – even in their own homes. Sharon can wake up and not know how to get from her bedroom to the kitchen. “It’s like someone has flipped the universe a quarter turn,” she says. But now, experiences like Sharon’s have brought researchers closer to locating the mental compass within our brains. Sharon says the best way to picture how she feels is to imagine coming out of a shop and turning right to get somewhere. You’re sure that you are going the correct way. Then you realise you thought the shop was on the opposite side
Wireless energy powers tiny pacemaker THERE’S electricity in the air. A rabbit’s beating heart has been regulated using a tiny pacemaker powered by energy beamed in from outside its body. In people, the ability to transfer energy wirelessly could shrink pacemakers and other medical devices, making them less invasive to implant. Being fitted with a pacemaker requires surgery, plus another 16 | NewScientist | 24 May 2014
SHARON ROSEMAN
Helen Thomson
operation when the battery eventually runs down. Ada Poon of Stanford University and her colleagues fitted a rabbit with a pacemaker that has no battery and is just 3 millimetres long. A batterypowered metal plate was then held a couple of centimetres above the rabbit’s chest. The plate transmitted 2000 microwatts to the pacemaker via electromagnetic waves, and was able to safely regulate the rabbit’s heartbeat (PNAS, doi.org/st4). Such “near-field energy transmission” was considered too weak to power devices placed deep in
Their as-yet-unpublished work shows that people with DTD have no problems with their memory, intelligence, or brain anatomy. But they do have impaired communication between two brain areas: the right hippocampus, involved in memory, and the prefrontal cortex, which is important for monitoring information, attention and working memory. Iaria thinks that these two areas work in tandem to help us form the mental maps we use to navigate. “When you move around, you do so by monitoring a lot of information, you look at landmarks and you try not to bump into walls,” Iaria says. “There is all this processing of
dynamic information. You use this to form and constantly update a cognitive map of where everything is around you.” People with DTD can’t keep track of spatial information or the relationship between landmarks while moving around, which makes it hard for them to form and update a mental map. More work is needed to gain a broader picture of why this is, says Iaria. For example, grid cells in the brain, which fire as we move about, were only recently found in humans. These cells and others like them send signals to the hippocampus, which collates all the information. Investigating this navigational network could lead to drugs or brain stimulation techniques to help people who have problems remembering their way, say researchers. For now, Iaria’s team are testing potential memory aids, such as a belt lined with vibrating pads that indicate which direction is north. Sharon has developed her own tricks. When she closes her eyes and spins around, she can usually flip her world back to normal – she calls it her Wonder Woman trick. Then there is the problem of remembering where she lives. “I bought a great big red lobster lawn ornament. I call him Louie. If I recognise Louie, I know I’m home. And I know I can go in and play Wonder Woman,” –Welcome home, Sharon– Sharon says. ■
the body. But Poon’s team designed the plate to emit radiation in a concentrated beam towards the implant. The waves are also of a high frequency, so they propagate very well in animal tissue, allowing energy to pass further into the body with little loss and no harm to the tissue. The team also delivered energy to devices implanted in samples of pig heart and brain tissue. They are now
“A metal plate transmitted energy to the pacemaker and safely regulated the rabbit’s heart”
launching a company to adapt the technology for use in humans. This will include exploring how to deliver energy via a skin patch, which is more practical than a metal plate. Robert Puers at the Catholic University of Leuven (KUL), Belgium, isn’t sure the technique makes sense for pacemakers. “These devices, being life-supporting, should not depend on an external powering device,” he says. Poon’s team also plans to adapt the technology for other types of implants, such as stimulators which sit in the brain to treat conditions such as Parkinson’s disease. Aviva Rutkin ■