Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Chimpanzee brains are asymmetrical in key areas and their handedness reflects it

06.12.2004


The hippocampus skews ’right,’ especially in males, plus the righty-lefty distinction may go back 5 million years

New MRI-based studies present more evidence that the brains of chimpanzees are human-like in terms of the relationships among brain asymmetry, handedness and language, according to research undertaken at the Yerkes National Primate Research Center in Atlanta. Understanding our evolutionary cousins helps us to understand what makes us human. Two related reports appear in the December issue of Behavioral Neuroscience, which is published by the American Psychological Association (APA).

In the first study, Hani Freeman, BA, Claudio Catalupo, PhD (also with Georgia State University), and William Hopkins, PhD (also with Berry College), took magnetic resonance images of 60 chimpanzees to measure the anatomy of two key structures in their brains’ limbic systems, an early-evolving central region that includes the hippocampus and amygdala. In the MRI pictures, the hippocampus (which regulates learning and consolidation of spatial memory, mood, appetite and sleep) was asymmetrical, its right half significantly larger than its left. This asymmetry was bigger in males. These findings are consistent with studies of human hippocampi, which are also asymmetrical. At the same time, just as in humans, the amygdalas of the chimps were symmetrical.



Studies such as this confirm that human and chimp brains are not only asymmetrical, but asymmetrical in the same way. The findings echo previous looks at the non-limbic parts of chimpanzee brains, which also appear human-like in their patterns of asymmetry. This fact, especially if studied in the context of functional behaviors that reflect asymmetries, may help scientists get a better fix on the evolution of the limbic system in all primates, including humans.

Says Hopkins, "The limbic system asymmetries advance the position that asymmetries are fundamental aspects of the nervous system of all primates, and apply to more primitive systems in the brain." The asymmetries influence behavior. Given the new findings about chimps and previous findings that the limbic system affects human facial expression and emotions, it now seems more clear why across primates, says Hopkins, the left half of the face – controlled by the right side of the brain -- is more emotionally expressive. In addition, a right-dominant hippocampus would explain apes’ well-developed spatial memory. Again, that parallels how the right hippocampus in humans is involved in spatial memory.

In a second study, Hopkins and Cantalupo report the first-ever evidence of an association between hand preference and asymmetries in three areas of the brain cortex in chimps. Observing 66 chimps, they correlated asymmetries in brain anatomy with three measures of handedness: Simple reaching (which hand chimps used to pick up a raisin thrown into the cage), two-handed feeding (which hand chimps used to feed themselves chunks of fruit while holding the whole piece, such as a banana, in the other hand), and a measure of coordinated bimanual actions (which hand chimps used to fish peanut butter from a plastic tube with a finger).

Left-handed and right-handed chimps differed relative to the asymmetries in two primary motor areas, the planum temporale and the precentral gyrus. Say the authors, the results "challenge the long-held belief that the neurobiological substrates for handedness are unique to humans." Just as in humans, neuroanatomy governs whether a chimp becomes a lefty or a righty. Hopkins points out that chimps are also strongly right-handed for manual gestures and throwing, a clue to the origins of more general right-hand dominance in both chimps and humans.

This second study also confirms that handedness goes way back. Its findings, say the authors, "suggest that the neurobiological basis for handedness evolved as early as five million years ago and emerged independent of systems associated with language and speech."
The findings mesh with other recent human evidence that handedness has nothing to do with asymmetry in language-related cortical areas. The Yerkes chimps showed no links between handedness and the classic left-side "language" areas. Hopkins says, "Many studies document a correlation between handedness and lateralization, but these are only correlations. It doesn’t mean that being right-handed causes a person to be left-hemisphere dominant for language, or vice versa. Rather, these two abilities might be assigned to the same sides but independently of each other." The findings about chimps support the hypothesis that a third, undiscovered "sidedness" factor may account for both handedness and language-related dominance.

To further understand language functions relative to brain asymmetries, the Yerkes team will soon begin using another brain-imaging technology, PET scans (positron emission tomography), to evaluate brain regions that are active when chimpanzees manually gesture and/or vocally communicate.

Pam Willenz | EurekAlert!
Further information:
http://www.apa.org

More articles from Life Sciences:

nachricht Flow of cerebrospinal fluid regulates neural stem cell division
21.05.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Chemists at FAU successfully demonstrate imine hydrogenation with inexpensive main group metal
21.05.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

Im Focus: Computer-Designed Customized Regenerative Heart Valves

Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.

Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...

Im Focus: Light-induced superconductivity under high pressure

A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.

Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Supersonic waves may help electronics beat the heat

18.05.2018 | Power and Electrical Engineering

Keeping a Close Eye on Ice Loss

18.05.2018 | Information Technology

CrowdWater: An App for Flood Research

18.05.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>