A collaborative study by researchers from New York University and Israel's Weizmann Institute of Science has revealed patterns of brain activation that are linked to the formation of long-term memories.
Published in the journal Neuron, the study also presents an innovative and more comprehensive method for gauging memories.
The researchers asked the study participants to recall the content of a television sitcom that more accurately simulated real-life experiences. The idea was to make the subjects to retrieve material that occurs in more complex settings than typically exist in a laboratory environment.
For the purpose, the subjects were made to view a 27-minute episode of the HBO sitcom 'Curb Your Enthusiasm'. The researchers used functional magnetic resonance imaging (fMRI) to examine the subject's brain function as they watched the programme.
Three weeks after they watched the programme, the subjects were asked several questions about its content. The researchers then used the memory performance of subjects to analyse their brain activity during movie viewing.
A novel technique called inter-subject correlation analysis (ISC) was used for the purpose, which revealed brain regions for which this correlation is greater during successful, or accurate, as compared to unsuccessful memory formation.
The new technique allowed the researchers to identify brain networks whose activation waxes and wanes in a similar way across participants during memory formation as well as other regions where activation was important for memory formation but which showed individual variability.
Such different patterns might help discern why people can share aspects of memory for an event that they experience together, but those memories also have an individual flavour or personal tone, said the researchers.
Traditional experiments, which relied on simple words or still images, have consistently revealed that the brain's medial temporal lobes (MTL) and inferior frontal gyrus (IFG) are active during memory formation and retrieval. The same regions were also found to be active in the present study.
However, the researchers also found activity in new areas—namely the brain's temporal pole, superior temporal gyrus (STG), medial prefrontal cortex (mPFC), and temporal parietal junction (TPJ).
They say that such regions have all been implicated in various aspects of social cognition—such as understanding the intentions of others, simulating experiences, language comprehension, and even person perception.