How young mice phone home: Study gives clue to how mothers' brains screen for baby calls

Jun 10, 2009
How young mice phone home: Study gives clue to how mothers' brains screen for baby calls
A new study gives a clue to how mother mice' brains screen for baby calls. Credit: The Liu lab

Emory University researchers have identified a surprising mechanism in the brains of mother mice that focuses their awareness on the calls of baby mice. Their study, published June 11 in Neuron, found that the high-frequency sounds of mice pups stand out in a mother's auditory cortex by inhibiting the activity of neurons more attuned to lower frequency sounds.

"Previous research has focused on how the excitation of can detect or interpret sounds, but this study shows the key role that inhibition may play in real situations," said Robert Liu, assistant professor of biology and senior author of the study.

In 2007, Liu and colleagues were the first to demonstrate that the behavioral context in which communication sounds are heard affects the brain's ability to detect, discriminate and respond to them. Specifically, the researchers found that the auditory neurons of female mice that had given birth were better at detecting and discriminating vocalizations from mice pups than auditory neurons in virgin females.

Experiments on awake mice

While that experiment was done with anesthetized mice, the current study by Liu's lab is the first to record the activity of neurons in the auditory cortex of awake mice. Both female mice that had given birth and virgin female mice with no experience caring for mice pups were used in the study.

When exposed to the high-frequency whistles of mice pups, which fall into the 60 to 80 kilohertz range, a large area of neurons in the auditory cortex of the mother mice was more strongly inhibited than in the virgin mice. The pattern of excitation of neurons was similar, however, for both the mothers and virgins.

"Something different is happening in the mothers' brains when they are processing the same sound, and this difference is consistent," Liu said. "The inhibition of neurons appears to be enhancing the contrast in the sound of mice pups, so they stand out more in the acoustic environment."

Showing neural plasticity

Liu's research focuses on how the brain evolves to process sounds in the natural environment. "By understanding normal functioning of the auditory processes in the brain, then we can begin to understand what is breaking down in disease situations, such as following a stroke or brain lesion," he said.

Until recently, it had been widely assumed that the auditory cortex acted simply as a static filter, and that areas downstream in the brain did the complex task of learning to parse meaning from sounds.

"What our experiments help demonstrate is that even at this relatively early stage of cortical sound processing, responses are dynamic," Liu said. "The auditory cortex has plasticity, so that sounds that become behaviorally relevant to us can get optimized."

More research is needed, he added, to determine whether the changes in the brains of mother is due to hormonal shifts, the behavioral experience of caring for pups, or both.

Source: Emory University (news : web)

Explore further: Tackling neurotransmission precision

add to favorites email to friend print save as pdf

Related Stories

Call of the Child

Jun 12, 2007

Like a student in a foreign country or a young mother trying to decipher her baby’s cries, we all encounter initially meaningless sounds that in fact carry meaning. With experience, we become better at detecting and discriminating ...

Lend me your ears -- and the world will sound very different

Jan 14, 2008

Recognising people, objects or animals by the sound they make is an important survival skill and something most of us take for granted. But very similar objects can physically make very dissimilar sounds and we are able to ...

Recommended for you

Researchers unlock mystery of skin's sensory abilities

2 hours ago

Humans' ability to detect the direction of movement of stimuli in their sensory world is critical to survival. Much of this stimuli detection comes from sight and sound, but little is known about how the ...

Tackling neurotransmission precision

21 hours ago

Behind all motor, sensory and memory functions, calcium ions are in the brain, making those functions possible. Yet neuroscientists do not entirely understand how fast calcium ions reach their targets inside ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.