Zador's
team trained rats to associate specific tones with a reward. Changes in the
tone signaled the animal to look for a reward either on the left or right side
of a training box.The team later deciphered the neural code with which the
animals encoded memories of these decisions. Even after the animals had died,
the scientists could "read the minds of these rats."
Credit:
Image courtesy of Cold Spring Harbor Laboratory
It
sounds like the stuff of science fiction: researchers slice a brain into thin
little sections and, just by measuring the properties of specific neurons, they
can determine what an organism learned before it died. In fact, this sort of
mind reading has become a reality. In work published in Nature,
researchers at Cold Spring Harbor Laboratory (CSHL) describe how postmortem
brain slices can be "read" to determine how a rat was trained to
behave in response to specific sounds. The work provides one of the first
examples of how specific changes in the activity of individual neurons encode
particular acts of learning and memory in the brain.
"Neuroscientists
have previously identified brain areas involved in learning something,"
says CSHL Professor Anthony Zador, who led the team of researchers on this
current work. "But we wanted to drill down further and identify how
changes at specific connections encode a particular behavioral response."
To
do this, the team focused on how rats translate sound cues into behavior. The
researchers trained rats to associate a specific tone with a reward. Changes in
the tone -- like the difference between a tuba and a flute -- signaled the
animal to look for the reward either on the left or right side of a training
box.
In
previous work, the team discovered that activity in a specific population of
neurons was crucial for animals to perform the task. This neuronal population
transmitted information from one auditory brain region (the auditory cortex) to
another (the auditory striatum).
In
the current work, the team measured the strength of the connections between
these two populations of neurons, as animals learned the task. "We found
that there was a gradient in activity across the auditory striatum that
corresponded to whether the animal was trained to go left or right for their
reward." explains Zador.
Based
upon this information, the team reasoned that they might be able to use
postmortem brain slices to "predict" (obviously, in retrospect) how
these or other rats had been trained. As Zador describes, "We were amazed
that in all cases, our predictions -- left or right -- were correct. We had
deciphered a tiny piece of the neural code with which the animal encoded these
memories. In essence, we could read the minds of these rats."
"For
decades scientists have been trying to map memories in the brain," said
James Gnadt, Ph.D., a program director at the NIH's National Institute of
Neurological Disorders and Stroke (NINDS). "This study shows that
scientists can precisely pinpoint the synapses where certain memories are
expressed."
According
to Zador, the results are likely to be broadly applicable to other senses and
parts of the brain. "We are excited to apply this method to more complex
forms of learning, and to other sensory systems, like vision."
Story Source:
The
above story is based on materials
provided by Cold Spring
Harbor Laboratory. Note: Materials may be edited for content and
length.
Journal Reference:
1.
Qiaojie Xiong, Petr Znamenskiy, and Anthony Zador. Selective
corticostriatal plasticity during acquisition of an auditory discrimination
task. Nature, March 2015 DOI: 10.1038/nature14225
Associate with: ile bağlantılı olmak
Broadly: açık olarak, ayrıntılı olarak, en sonunda
Correspond to: uymak, uyumlu olmak, karşılık gelmek
Crucial : çok önemli, can alıcı
Encode: şifrelemek
Gradient: meyil, eğim
In essence: esas itibarıyle
Pinpoint: tam yerini belirlemek, nokta atışı yapmak
Postmortem: otopsi, ölüm sonrası
Transmit : iletmek, yayınlamak
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