Quick: commit this to memory. There will be a quiz.
Neuroscientists implanted artificial memories into slices of rat brain, they reported in Nature Neuroscience online. By jolting the rodent brain cells with electrical current, the researchers produced memory-like patterns of neuron activity that survived for around 10 seconds. This is the first time that researchers have created memory without a brain.
The researchers performed these memory experiments on slices from the hippocampus, a brain region involved in short-term, declarative memory—the kind of memory humans rely on when recalling things like an address or what color tie your boss is wearing today. The researchers shocked the brain slice at four different positions and then recorded the electrical outputs from three different cells in the slice. Each kind of stimulation produced a unique and consistent response. The neurons could also take on more complicated stimuli, giving different responses to the four stimuli when they came in different orders.
These artificial memories are very short-term. As time passed, the different responses to the four stimuli started to look alike; they were indistinguishable after 15 seconds.
“This is the first time anyone has found a way to store information over seconds about both temporal sequences and stimulus patterns directly in brain tissue,” said neuroscientist Ben Strowbridge, one of the study’s authors, in a press release. “This paves the way for future research to identify the specific brain circuits that allow us to form short-term memories.”
Picking apart how short-term memories form in isolated tissue is an early step toward understanding how memories play out in the larger, more chaotic networks of a living brain, the researchers hope, and towards understanding how memory malfunctions in neurodegenerative diseases.
Reference: Robert A Hyde, Ben W Strowbridge. Mnemonic representations of transient stimuli and temporal sequences in the rodent hippocampus in vitro. Nature Neuroscience, 2012
Image from Gray’s Anatomy/Wikimedia Commons