Has science just given credence to the brain-bending sci-fi-romance Eternal Sunshine of The Spotless Mind?
In Philip Kaufman's 2004 film, a couple who have just broken up undergo a procedure to delete painful memories of each other.
Now, a new study has found that different types of memories stored in the same neuron of the marine snail Aplysia can be selectively erased.
The findings suggest that it may be possible to develop drugs to delete memories that trigger anxiety and post-traumatic stress disorder (PTSD) without affecting other important memories of past events.
During emotional or traumatic events, multiple memories can become encoded, including memories of any incidental information that is present when the event occurs.
In the case of a traumatic experience, the incidental, or neutral, information can trigger anxiety attacks long after the event has occurred, say the researchers.
"If you are walking in a high-crime area and you take a shortcut through a dark alley and get mugged, and then you happen to see a mailbox nearby, you might get really nervous when you want to mail something later on," explained study author Professor Samuel Schacher, of Columbia University Medical Centre in the US.
In his example, fear of dark alleys is an associative memory that provides important information based on a previous experience.
Fear of mailboxes, however, is an incidental, non-associative memory that is not directly related to the traumatic event.
"One focus of our current research is to develop strategies to eliminate problematic non-associative memories that may become stamped on the brain during a traumatic experience without harming associative memories, which can help people make informed decisions in the future - like not taking shortcuts through dark alleys in high-crime areas."
The study, published in the journal Current Biology, involved stimulating two sensory neurons connected to a single motor neuron of the marine snail Aplysia; one sensory neuron was stimulated to induce an associative memory and the other to induce a non-associative memory.
By measuring the strength of each connection, the researchers found that the increase in the strength of each connection produced by the different stimuli was maintained by a different form of a Protein Kinase M (PKM) molecule.
They found that each memory could be erased - without affecting the other - by blocking one of the PKM molecules.
Further, they found that specific synaptic memories may also be erased by blocking the function of distinct variants of other molecules that either help produce PKMs or protect them from breaking down.
Can puppies revive passion?
One of the well-known challenges of marriage is keeping the passion alive after years of partnership, as passions tend to cool even in very happy relationships.
In a new study, a team of psychological scientists has developed an unconventional intervention for helping a marriage maintain its spark: pictures of puppies and bunnies.
Previous research has shown that, in many instances, marriage satisfaction declines even when day-to-day behaviours stay the same.
This led Florida State University's Dr James McNulty and colleagues to hypothesise that an intervention focused on changing someone's thoughts about their spouse, as opposed to one that targets their behaviours, might improve relationship quality.
Specifically, the research team wanted to find out whether it was possible to improve marital satisfaction by subtly retraining the immediate, automatic associations that come to mind when people think about their spouses.
"One ultimate source of our feelings about our relationships can be reduced to how we associate our partners with positive affect, and those associations can come from our partners but also from unrelated things, like puppies and bunnies," McNulty explained.
In an experiment involving 144 married couples, images of a spouse were repeatedly paired with very positive words or images, like puppies and bunnies, while a control group were shown "neutral pairings", like an image of their spouse and objects like buttons.
Participants who were exposed to positive images paired with their partner's face showed more positive automatic reactions to their partner over the course of the intervention compared with those who saw neutral pairings.
More importantly, the intervention was associated with overall marriage quality: more positive automatic reactions to the partner predicted greater improvements in marital satisfaction over the course of the study.
"I was actually a little surprised that it worked," McNulty explained.
"All the theory I reviewed on evaluative conditioning suggested it should, but existing theories of relationships, and just the idea that something so simple and unrelated to marriage could affect how people feel about their marriage, made me sceptical."
Older Dads have 'geek' sons
New research suggests that sons of older fathers are more intelligent, more focused on their interests and less concerned about fitting in, all characteristics typically seen in "geeks".
While previous research has shown that children of older fathers are at a higher risk of some adverse outcomes, including autism and schizophrenia, a new study published in the journal Translational Psychiatry suggests that children of older fathers may also have certain advantages over their peers in educational and career settings.
The researchers from King's College London and US-based Seaver Autism Center for Research and Treatment collected behavioural and cognitive data from 15,000 UK-based twin pairs.
When the twins were 12, they completed online tests that measured "geek-like" traits, including non-verbal IQ, strong focus on the subject of interest and levels of social aloofness.
Parents were also asked whether their child cares about how they are perceived by their peers and if they have any interests that take up substantial majority of their time.
Using this information, the researchers computed a "geek index" for every child in the study.
Overall, higher geek index scores were reported in the sons of older fathers.
This effect persisted after controlling for parent's social-economic status, qualifications and employment.
Further, they found that "geekier" children do better in school exams, particularly in the STEM subjects, several years after their geek index was measured.
"Our study suggests that there may be some benefits associated with having an older father," study author Dr Magdalena Janecka said.
"We have known for a while about the negative consequences of advanced paternal age, but now we have shown that these children may also go on to have better educational and career prospects."
Although the study did not directly investigate the role of environmental factors, there were a number of potential reasons why older fathers may have geekier sons.
For example, older fathers were likely to have more established careers and a higher socioeconomic status than younger fathers, meaning that their children may be brought up in more enriched environments and have access to better schooling.