A study by Miami University researchers Loren Hoffmann, graduate student in psychology, and Stephen Berry, professor of psychology, has shown that learning is enhanced in rabbits with the use of a brain-computer interface to control oscillatory potentials in the hippocampus, an important structure for memory formation.
This technology provides a useful means of observing and manipulating clearly different functional brain states, without lesions or drugs, that could be adapted in the future to other species, brain structures, or oscillatory frequencies, say the researchers.
Their study, “Cerebellar theta-oscillations are synchronized during hippocampal theta-contingent trace conditioning” is published in the Dec. 15, 2009, Proceedings of the National Academy of Sciences (PNAS).
The hippocampus has been strongly associated with memory processes in animals and humans and is characterized by the prevalence of neurobiological oscillations in the theta bandwidth, according to the researchers. They have shown that the presence of naturally occurring theta in rabbits is positively correlated with the rate at which an animal learns eyeblink conditioning, a simple learning task.
They used a brain-computer interface to select periods of time when an animal was naturally exhibiting hippocampal theta (high theta group) and, conversely, selected periods of time when an animal was explicitly not displaying hippocampal theta (low theta group). The rabbits in each group then received trace eyeblink classical conditioning trials. For the high theta group, learning rate increased.
“The difference in behavioral learning for these two groups is striking,” Hoffmann said, “often a doubling of learning rate and up to four times faster in older animals.”
Also, there was a corresponding synchronization between hippocampal and cerebellar oscillatory frequencies.
“This is interesting not only because both of these brain regions are essential for normal learning of the task, but because the mechanisms underlying hippocampal-cerebellar interactions during the learning process hadn’t been shown before,” Hoffmann said.
“Generalizing across species, studies have shown theta oscillations to be implicated in human cognitive processing. If tasks could be acquired and performed when there are periods of maximal theta, cognitive processes might be enhanced.”
Researchers are beginning to develop non-invasive recording techniques in humans that can mimic our cognition-enhancing interface, with encouraging results, according to the researchers.
“If successful, the substantial benefit and lack of side effects could result in widespread use for cognitive enhancement technologies,” Hoffman said.
Hoffmann received her master’s degree in December 2009 and is currently in the doctoral program in brain and cognitive psychology at Miami, with adviser Berry. Their research was noted as a “Hot Topic” by the Society for Neuroscience at its annual meeting last fall.