U.S. scientists said Wednesday they have found a way to decode how the brain hears words, in what researchers described as a major step toward one day helping people communicate after paralysis or stroke.

By placing electrodes on the brains of research subjects and then having them listen to conversations, scientists were able to analyze the sound frequencies registered and figure out which words they were hearing.

A new U.S. study has found that Alzheimer's disease spreads from one part of the brain to another like an infection, a discovery that could aid the development of treatments to slow its progress.

The Columbia University Medical Center (CUMC) study on transgenic mice found that the abnormal tau protein linked to the disease travels along brain circuits, "jumping" from neuron to neuron.

The U.S. Navy has announced that it assisted an Iranian fishing vessel in distress in the Gulf, the fourth such incident this year in an area marked by tension between Washington and Tehran.

The Bahrain-based U.S. Fifth Fleet said in a statement late Tuesday that forces from the USS Abraham Lincoln Carrier Strike Group responded to a "distressed Iranian fishing dhow" that had nine crew members on board.

Syrian President Bashar al-Assad's regime will inevitably collapse in the face of mounting protests, the U.S. spy chief said Tuesday.

"I do not see how he can sustain his rule of Syria," the director of national intelligence, James Clapper, told senators. "I personally believe it's a question of time but that's the issue, it could be a long time."

Iran could develop a nuclear bomb in about a year and create the means for delivery in a further two to three years, the U.S. defense chief said Sunday, reiterating President Barack Obama's determination to halt the effort.

"The United States -- and the president's made this clear -- does not want Iran to develop a nuclear weapon," Defense Secretary Leon Panetta told the CBS program "60 Minutes."

U.S. Defense Secretary Leon Panetta still believes someone in authority in Pakistan knew where Osama bin Laden was hiding before U.S. forces went in to find him, he said in a TV interview to air Sunday.

Intelligence reports found Pakistani military helicopters had passed over the compound in Abbottabad, Pakistan where U.S. Navy SEALs discovered and killed bin Laden last year, according to excerpts of an interview Panetta gave to CBS News.

The United States moved Thursday to deny any U.S. financing or material support to alleged Islamic extremists operating in Afghanistan, Europe and Lebanon.

The State Department targeted brothers Yassin and Mounir Chouka, who it said are recruiters, facilitators and propagandists for the Islamic Movement of Uzbekistan (IMU) and stage operations along the Afghanistan-Pakistan border.

The Pentagon on Thursday proposed trimming the Army's size by 13 percent as the debt-ridden United States winds down a decade of war but vowed new investments to exert power in Asia and the Middle East.

With pressure mounting to balance the U.S. books, President Barack Obama's administration sought a nine percent cut in the 2013 budget compared with last year's request by retiring older ships and planes and pulling back two brigades from Europe.

Republican White House hopefuls Mitt Romney and Newt Gingrich traded barbs Thursday on immigration and character ahead of a final debate showdown before Florida's ultra-competitive and all-important primary.

The frontrunners -- locked in a virtual tie in the polls -- spent Wednesday courting Latino voters and sniping at each other as they battled for the chance to take on Democratic President Barack Obama in the November election.

A U.S. drone fired missiles into a vehicle, killing four militants in Pakistan's Taliban and al-Qaida hub of North Waziristan on Monday that hugs the Afghan border, security officials said.

It was only the third such U.S. attack reported in the nuclear-armed state so far this year, following a moratorium after U.S. firepower inadvertently killed 24 Pakistani soldiers in November, plunging relations to an all-time low.