AS anyone who has suffered a hangover well knows, the human brain is a delicate instrument indeed. It is also a much under-used organ, a fact one Japanese company is looking to change. The Para Memory Co is about to launch the formidably named ''brain potentialiser'' in Hongkong - a machine the company claims reduces stress, improves memory and enhances concentration. Such is the reputation of Hongkong as a Mecca of electronic gadgets, the territory is the first market outside of Japan to see the product. There is so much that science is still endeavouring to learn about what makes the human brain tick, that consumer products which seek to improve it are generally scorned as bogus, snake-oil cure-alls. Mr Tony Chan, president of Para Memory, said the product had been an instant success in Japan, where it was launched last year and has apparently been used to improve the mental focus of Olympic athletes. The $2,500 machine looks like a Walkman music cassette player, and is worn in the same manner. There is no prescribed limit to how long the brain potentialiser is worn - it is used as a means of mental relaxation whenever required. Don't ask us, we haven't used it. But Mr Chan assured us it worked. The theory behind the Para Memory brain potentialiser was to stimulate the left and right sides of the brain so that they ''work together producing an optimum balanced condition'', Mr Chan said. ''The whole idea is that it makes people relax - and when you relax it makes people concentrate more in order to allow the left and the right sides of the brain to communicate and work in harmony. ''The machine reduces stress levels, and increases concentration in a very relaxed manner,'' Mr Chan said. ''As a result, you are able to considerably improve memory.'' Para Memory obviously puts a lot of stock in Hongkong's fascination for electronic gadgets - it expects to sell more than 75,000 brain potentialisers in its first year. Don't start looking for the product now, though. Mr Chan is still looking for an exclusive distributor for the item in Hongkong, before moving on to launch the machine in China and then Taiwan. Para Memory is not taking any chances on its target market. According to the company, the product is suitable for students at all levels, businessmen, company executives, sports men and women, and people who practice meditation.