New Delhi, Oct. 10: Neurobiologists in India have discovered through studies on rats a way to enhance memory after cramming, but they caution that they're nowhere close to generating a dream pill for students. Not yet.
The scientists at the National Brain Research Centre, Manesar, about 40km south of the capital, have shown that a chemical that modifies memory-linked proteins in the brain can enhance memory after quick cramming to the same levels as through slow, repeated learning.
"We think we've found a strategy to enhance memory after cramming - but is it practical, and can it ever be tailored for use in humans? We have absolutely no idea yet," said Shiv Kumar Sharma, a scientist at the NBRC, who led the study.
Scientists have known for decades that slow or repeated learning, also called spaced training with time intervals between training sessions, is better for long-lasting memory than massed training, or cramming, with short, or no time-intervals between training.
Hurried preparation just hours or even days ahead of examinations is an example of massed training. A 19th-century German psychologist, Hermann Ebbinghaus, was the first to describe the difference between spaced training and massed training in 1885.
Since then, scientists have consistently observed differences across vertebrates and invertebrates. In 1972, New York University biologist Thomas Carew had demonstrated the superior effect of spaced training in marine molluscs. About a decade ago, a team led by Indian neurobiologist Upinder Bhalla at the National Centre for Biological Sciences (NCBS), Bangalore, showed a similar effect of spaced learning at the level of neural circuitry.
In the new study, Sharma and his colleagues observed rats made to swim in a large laboratory tank filled with water. The experiments were designed to measure the memory capacity of rats after spaced training as well as after massed training, or cramming.
The rats had to "learn" how to find a near-submerged platform in the water that would allow them to stay out of the water. Coloured posters and other objects placed on the walls of the laboratory served as cues for the rats to "remember" the location of the platform.
Sharma and research scholars Kiran Pandey and Kaushik Sharma have described their study in the journal Learning and Memory. Their experiments have corroborated earlier findings that spaced training is better than cramming.
The rats that learnt to find the platform in the water through training sessions spaced by two hours when tested after a 24-hour gap found it in about 20 seconds, while the rats that learnt to find the platform through training sessions spaced by one-minute intervals took over 40 seconds.
In a second set of experiments, the scientists administered the rats that crammed the swimming routes an injection of sodium butyrate and observed that their memory capacity appeared to approach the level achieved by the rats that received spaced training.
The scientists also studied the effect of sodium butyrate at the level of neurons, or brain cells.
Using electrodes to stimulate cells of the hippocampus, a region in the brain involved in memory formation, the NBRC researchers observed that sodium butyrate enhanced a neuron-level feature called long-term potentiation, the cellular-basis of long-term memory.
The compound helps in a process that modifies proteins involved in memory formation. While it is unclear whether such work will pan out into memory-enhancing pills, Sharma said, the advantages of spaced training could be used by students and even advertisers.
"It would be better to present commercial advertisements in a spaced manner rather than presenting it repeatedly with hardly any time intervals," Sharma said. "Sometimes, ads on television are repeated with very short intervals."
Neuroscientists are viewing the study results as fresh evidence for differences between spaced learning and cramming. "Changes in the neural circuitry that is linked to memory rely on the mode of learning," said B.S. Shankaranarayana Rao, professor of neurophysiology at the National Institute of Mental Health and Neurosciences, Bangalore, who was not associated with the NBRC research.
"It is premature right now to expect that the effect they've observed with sodium can be translated into applications to enhance memory," Rao told The Telegraph. "But such studies will help improve our understanding of processes involved in memory."
Bhalla, a neurobiologist from the NCBS, said the findings suggest that the differences between the two kinds of learning may be related to how learning-triggered genes are activated. "The difference can be overcome using sodium butyrate," Bhalla said. "This extends the idea that one of the mechanisms for forming strong and long-lasting memories relies on changes to gene activation."