At Toronto Western Hospital in Ontario, neurosurgeons seem to have stumbled on a surprising discovery when a patient receiving deep-brain hypothalamus stimulation therapy had clear memory recalls of things he long forgot.
A limited clinical study being conducted to follow up on that finding is so far pointing to similar results.
The accidental breakthrough came during an experiment originally intended to suppress the obese man’s appetite, using the increasingly successful technique of deep-brain stimulation. Electrodes were pushed into the man’s brain and stimulated with an electric current. Instead of losing appetite, the patient instead had an intense experience of déjà vu. He recalled, in intricate detail, a scene from 30 years earlier. More tests showed his ability to learn was dramatically improved when the current was switched on and his brain stimulated.
Scientists are now applying the technique in the first trial of the treatment in patients with Alzheimer’s disease. If successful, it could offer hope to sufferers from the degenerative condition, which affects 450,000 people in Britain alone, by providing a "pacemaker" for the brain.
Three patients have been treated and initial results are promising, according to Andres Lozano, a professor of neurosurgery at the Toronto Western Hospital, Ontario, who is leading the research.
Professor Lozano said: "This is the first time that anyone has had electrodes implanted in the brain which have been shown to improve memory. We are driving the activity of the brain by increasing its sensitivity – turning up the volume of the memory circuits. Any event that involves the memory circuits is more likely to be stored and retained…"
The man, who has not been identified, was also tested on his ability to learn lists of paired objects. After three weeks of continuous hypothalamic stimulation, his performance on two learning tests was significantly improved. He was also much more likely to remember a list of unrelated paired objects with the electrodes turned on than when turned off.
Speaking to The Independent yesterday, Professor Lozano said: "His performance improved dramatically. As we turned the current up, we first drove his memory circuits and improved his learning. As we increased the intensity of the current, we got spontaneous memories of discrete events. At a certain intensity, he would slash to the scene [in the park]. When the intensity was increased further, he got more detail but, when the current was turned off, it rapidly decayed."
The discovery surprised the scientists as the hypothalamus has not usually been identified as a seat of memory. The contacts that most readily produced the memories were located close to a structure called the fornix, an arched bundle of fibres that carries signals within the limbic system, which is involved in memory and emotions and is situated next to the hypothalamus.
More at The Independent…