Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Monkey talk, human speech share left-brain processing


Scans have pinpointed circuits in the monkey brain that could be precursors of those in humans for speech and language. As in humans, an area specialized for processing species-specific vocalizations is on the left side of the brain, report Drs. Amy Poremba, Mortimer Mishkin, and colleagues in NIH’s National Institute of Mental Health (NIMH), Warren G. Magnuson Clinical Center (CC), components of the National Institutes of Health (NIH), and the University of Iowa. An area near the left temple responded significantly more than the same area on the right only to monkey calls, not to other animal calls, human voices or various other sounds. The researchers published their findings in the January 29, 2004 Nature.

Area 5 (left dorsal temporal pole) at the front of the brain’s temporal lobe in the left hemisphere, activated significantly more than it’s counterpart in the right hemisphere only when monkeys heard monkey calls. A right hemisphere area activated more for a variety of other sounds. This suggests that the left hemisphere site is specialized for species-specific vocalizations and may hold clues to the evolution of human speech and language. Front of brain is at right.
Source: NIMH Laboratory of Neuropsychology

PET scan of monkey brain cross-section, showing greater activity in left dorsal temporal pole than in same area of right hemisphere (arrows) while animal listens to monkey vocalizations.
Source: NIMH Laboratory of Neuropsychology

"Since it’s in the left temporal lobe and specialized for vocalizations only, it bears intriguing similarities to human language," noted Mishkin. "Assuming this is an adaptive mechanism, it suggests that vocalizations can be deciphered better if they are processed by only one temporal pole rather than by both."

Scientists have known for years that the human brain processes speech on the left side of the brain, but they only had hints that this is also the case for non-human primates. For example, when a monkey hears a call from behind, it characteristically turns its head to the right, suggesting that the primitive vocalizations are being processed in the left hemisphere, which receives greater input from the right ear than from the left. Also, a monkey’s ability to perceive such calls is impaired if it lacks the left auditory cortex, but not the right.

To find out how this works, the researchers used PET (positron emission tomography) scanning. A radioactive tracer visualized the parts of the brain that were active while different types of sounds were being processed. After eight healthy monkeys heard a series of monkey calls, an area just below the left temple, at the front of the left temporal lobe (left dorsal temporal pole), activated significantly more than its mate on the right. Yet, this area failed to similarly activate when the animals heard a variety of other sounds – bells, tones, dog barks, bird tweets, a human voice, scrambled monkey calls, etc. Instead, significant activation was seen in a different temporal lobe area on the right side of the brain, which seems to process virtually every sound.

To gain insight into how the brain achieves this hemispheric specialization, three monkeys surgically-altered to lack connecting links between the hemispheres were also scanned after listening to the sounds. With communication between the hemispheres thusly severed, the asymmetrical pattern vanished. Conspicuously, no significant difference in activation was seen in the two temporal poles when the animals heard monkey calls.

This suggests that monkey calls normally stimulate interactions between brain hemispheres that suppress the corresponding right temporal lobe area, focusing auditory processing within the left area. "Our results open up the possibility of characterizing such neuronal responses in a cortical region of the monkey that is not only a higher-order auditory processing area, but also one that could be a precursor for an acoustic language area in humans," note the researchers.

"This study provides neuroscientists with new biological clues for studying how communication evolved," said Poremba, who left NIMH a few years ago and is now at the University of Iowa.

In addition to NIMH, the research was supported, in part, by the University of Iowa.

Also participating in the study were Megan Malloy, NIMH, Dr. Richard Saunders, NIMH, Dr. Richard Carson, CC, Dr. Peter Herscovitch, CC.

The National Institute of Mental Health (NIMH) and the Warren G. Magnuson Clinical Center are parts of the National Institutes of Health (NIH), the Federal Government’s primary agency for biomedical and behavioral research. NIH is a component of the U.S. Department of Health and Human Services.

Jules Asher | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht How the African clawed frog got an extra pair of genes: Whole genome sequence reveals evolutionary history of Xenopus laevis
27.10.2016 | Hokkaido University

nachricht Mitochondria control stem cell fate
27.10.2016 | Technische Universität München

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

How a fungus inhibits the immune system of plants

27.10.2016 | Life Sciences

Mitochondria control stem cell fate

27.10.2016 | Life Sciences

The gene of autumn colours

27.10.2016 | Life Sciences

More VideoLinks >>>