How brain processes speech

A review of human and non-human primate studies suggests that scientists are very close to forming a conclusive theory about the brain processes speech and language.
Dr Josef Rauschecker, Georgetown University, and his co-author Sophie Scott, University College, London, say that both human and animal studies have confirmed that speech is processed in the brain along two parallel pathways, each of which run from lower- to higher-functioning neural regions.
The authors describe these pathways as the ‘what’ and ‘where’ streams, which are similar to how the brain processes sight, but are located in different regions.
Both pathways begin with the processing of signals in the auditory cortex, located inside a deep fissure on the side of the brain underneath the temples.
Information processed by the ‘what’ pathway then flows forward along the outside of the temporal lobe, and the job of that pathway is to recognise complex auditory signals, which include communication sounds and their meaning.
The ‘where’ pathway is mostly in the parietal lobe, above the temporal lobe, and it processes spatial aspects of a sound but is also involved in providing feedback during the act of speaking.
Rauschecker says that auditory perception is tied to anatomical structures.

Window for stroke treatment widens

After a stroke, a patient gets very little time to get treatment. Now, a new study has shown that stroke medications can benefit patients up to 4.5 hours after they experience first symptom.
It is believed that if a patient arrives at the emergency room within three hours of experiencing stroke symptoms, doctors can administer a potent clot-busting medication and often save critical brain tissue.
But if more than three hours have passed, current clinical guidelines say the medication should not be used.
However, by combining data from multiple clinical trials, Dr Maarten Lansberg, Stanford University School of Medicine, showed that treatment can benefit patients up to 4.5 hours after they experience their first symptom.
A stroke, or brain attack occurs due to a sudden drop in blood flow to the brain. Most strokes are ischemic, meaning they’re caused by a blocked artery. For these strokes, a medication called tissue plasminogen activator, or tPA, can open blocked blood vessels and help restore blood flow to the brain.

New targets for HIV drugs

A new study suggests that HIV drug development should be focused on immune cells called macrophages, whose job is to ‘eat’ invading disease agents, instead of traditionally targeted T cells because that may take scientists a step closer to eradicating the disease.
The study showed that in HIV-infected diseased cells, such as cancer cells, almost all the virus was packed into macrophages.
The researchers observed that up to half of those macrophages were hybrids, formed when pieces of genetic material from several parent HIV viruses combined to form new strains.
They say that such ‘recombination’ is responsible for formation of mutants that easily elude immune system surveillance and escape from anti-HIV drugs.
“Macrophages are these little factories producing new hybrid particles of the virus, making the virus probably even more aggressive over time. If we want to eradicate HIV we need to find a way to actually target the virus specifically infecting the macrophages,” said study co-author Dr Marco Salemi, University of Florida.

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