We’re used to thinking of neglect as a lack of appropriate care, but to a neuroscientist, it has a very different meaning. “Spatial neglect” is a neurological condition caused by damage to one half of the brain (usually the right), where patients find it difficult to pay attention to one half of their visual space (usually the left).
This bias can affect their mental images too. If neglect patients are asked to draw clocks, many only include the numbers from 12 to 6, while some shunt all the numbers to the right side. When two famous neglect patients were asked to describe a familiar square in Milan, the city they grew up in, the landmarks they reported shifted depending on where they pictured themselves standing in the square. They would only report buildings to the right of their imagined position – swap the location and new buildings would suddenly come into mental view.
Patients tend to be particularly unaware of things on the left if other objects on the right are vying for their attention – this phenomenon, where only one of two simultaneously presented objects is seen, is called “visual extinction“.
Neglect is clearly a fascinating condition but also a debilitating and underappreciated one. It affects up to 60% of patients who suffer strokes on the right side of their brain, and it can hamper recovery and deny patients their independence. As such, there are plenty of researchers interested in finding ways of improving its symptoms. David Soto from Imperial College London is one of them, and he has discovered a deceptively simple way of helping neglect patients to regain their lost awareness – listen to their favourite music.
Soto was encouraged by a recent study, which found that stroke victims showed greater improvements in both memory and attention when they tuned into music than when they listened to audiobooks or worked in silence. And other studies have suggested that emotional faces are less likely to fall prey to visual extinction than less compelling images. But Soto wanted to see if the patient’s own emotional state had anything to do with their awareness. Would it be possible to reduce the symptoms of neglect simply by making patients feel happier through the medium of pleasant melodies?
The wiping of unwanted memories is a common staple of science-fiction and if you believe this weekend’s headlines, you might think that the prospect has just become a reality. The Press Association said that a “drug helps erase fearful memories“, while the ever-hyperbolic Daily Mail talked about a “pill to erase bad memories“. The comparisons to The Eternal Sunshine of the Spotless Mind were inevitable, but the actual study, while fascinating and important, isn’t quite the mind-wiper these headlines might have you believe.
The drug in question is propranolol, commonly used to treat high blood pressure and prevent migraines in children. But Merel Kindt and colleagues from the University of Amsterdam have found that it can do much more. By giving it to people before they recalled a scary memory about a spider, they could erase the fearful response it triggered.
The critical thing about the study is that the entire memory hadn’t been erased in a typical sci-fi way. Kindt had trained the volunteers to be fearful of spidery images by pairing them with electric shocks. Even after they’d been given propranolol, they still expected to receive a shock when they saw a picture of a spider – they just weren’t afraid of the prospect. The drug hadn’t so much erased their memories, as dulled their emotional sting. It’s more like removing all the formatting from a Word document than deleting the entire file. Congatulations to Forbes and Science News who actually got it right.
Kindt’s work hinges on the fact that memories of past fears aren’t as fixed as previously thought. When they are brought back to mind, proteins at the synapses – the junctions between two nerve cells – are broken down and have to be created from scratch. This process is called “reconsolidation” and scientists believe that it helps to incorporate new information into existing memories. The upshot is that when we recall old memories, they have to be rebuilt on some level, which creates an opportunity for changing them.
A few years ago, two American scientists managed to use propranolol to banish fearful responses in rats. They injected the animals in their amygdalae, a part of their brains involved in processing emotional memories. The drug didn’t stop a fearful memory from forming in the first place, but it did impair the memory when the rats tried to retrieve it. Now, Kindt has shown that the chemical has the same effect in humans.