How does the brain handle speech?

Neuroscientists believe they have come closer to a general theory of brain processing of speech and language, according to Georgetown University Medical Center scientist, who built the The first concept a decade ago, and just published an article confirming that theory.

In the June issue of Nature Neuroscience, researcher Dr. Josef Rauschecker, and co-author Dr. Sophie Scott, neuroscience scientist at University College London, said in both humans and primates, the words , an important aspect of language, is processed in the brain in two parallel lines, each running from low-functioning neurological regions to higher functions.

These nerve pathways are called 'what' and 'where' lines, similar to brain imaging, but in different areas, Rauschecker, professor of physiology. studying and physics biology, and a lecturer at Georgetown Institute of Neuroscience and Computing, said.

Both nerve pathways begin with signal processing in the auditory region of the brain, located inside a deep gap on either side of the brain below the temples - called the temporal lobe.

Information processed by the 'what' nerve pathway then continues to move along the outer portion of the temporal lobe, and the task of this nerve pathway is to recognize complex sound signals, including sounds. Contact bar and their meaning. The 'where' nerve pathway lies mainly in the lobe, above the temporal lobe, and it handles the spatial aspects of a sound - the position of the sound as well as its movement in space - but also involved in feedback when speaking. Sound recognition - the process of processing and analyzing audio information - depends on the anatomical structure; The signal moves from the low to high brain region, Rauschekcer said: 'The whole sound enters the ear canal and is converted into a mono-frequency, then the higher neurons are only responding to more complex sounds. , including the sounds used in speech recognition '.

Studies on both humans and primates are analyzed in the article.

Scientists found that in both humans and primates, speech, an important aspect of language, is processed in the brain in two parallel lines, each of which runs around low-functioning neurological areas. to higher functions.(Photo: iStockphoto / Don Bayley)

In humans, researchers use magnetic resonance imaging (fMRI) technology to monitor activity between brain regions in experiments that test speech recognition. In primates, researchers use a technique called single cell recording, to measure changes in a single neuron. To do this, anesthetized animals and equipped with microelectrodes can recognize activity in certain brain areas.

Rauschecker said: 'In both humans and primates, we use specific communication sounds to stimulate, such as human voices and the call of brown monkeys. We found that the structure of these communication sounds is similar '.

Interestingly, although speech and language are thought to be unique in humans, the landscape picture of brain processing of language suggests ' in evolution, language forms from mechanisms Nervous, at least one part exists in animals'.

Rauschecker explains: 'The communication system in animals is the model of speech, or the initial process of language, and these studies are proof that the auditory region of the brain, in different species, has along the structural cycle, and functional nerve pathways. There seems to be conservation of neurological pathways processed through evolution in humans and primates'.

This study is the basic science that attempts to explain the basic question of the brain, while providing important insights into disorders that include problems with sound signal processing, including autoimmune disease. century and schizophrenia.

Rauschekcer commented: 'Difficulty in handling and understanding speech is a major problem of autism, and a person with schizophrenia hears a sound just like an illusion. This field of research will provide more effective treatments for these disorders. '

'The fact that humans have sophisticated feelings to distinguish very small differences in sound waves is amazing, and only until recently have we been able to model how the brain attaches its meaning to those sounds when we communicate, communicate '.

The research was funded by the National Science Foundation and the National Heart and Disorders Institute, as well as the British Wellcome Trust.

References:
Josef P Rauschecker, Sophie K Scott.Maps and streams in cortex auditory: nonhuman primates illuminate human speech processing.Nature Neuroscience, 2009;12 (6): 718 DOI: 10.1038 / nn.2331