Even the world's most powerful supercomputers cannot replicate basic aspects of the human mind.
The machines cannot imagine a wall painted a different colour, for instance, or picture a person's face and connect that to an emotion.
If researchers can make computers operate more like a brain thinks - by reasoning and dealing with abstractions, among other things - they could unleash tremendous insights in such diverse fields as medicine and economics.
A computer with the power of a human brain is not yet near. But last week, researchers from IBM Corp were reporting that they have simulated a cat's cerebral cortex, the thinking part of the brain, using a massive supercomputer.
processors
The computer has 147,456 processors (most modern PCs have just one or two processors) and 144 terabytes of main memory - 100,000 times as much as your computer has.
The scientists had previously simulated 40 per cent of a mouse's brain in 2006, a rat's full brain in 2007, and one per cent of a human's cerebral cortex this year, using progressively bigger supercomputers.
The latest feat, being presented at a supercomputing conference in Portland, Oregon, does not mean the computer thinks like a cat, or that it is the progenitor of a race of robo-cats.
The simulation, which runs 100 times slower than an actual cat's brain, is more about watching how thoughts are formed in the brain and how the roughly one billion neurons and 10 trillion synapses in a cat's brain work together.
The researchers created a programme that told the supercomputer, which is in the Lawrence Livermore National Laboratory, to behave how a brain is believed to behave. The computer was shown images of corporate logos, including IBM's, and scientists watched as different parts of the simulated brain worked together to figure out what the image was.
Dharmendra Modha, manager of cognitive computing for IBM Research and senior author of the paper, called it a "truly unprecedented scale of simulation". Researchers at Stanford University and Lawrence Berkeley National Laboratory were also part of the project.
'structured' data
Modha says the research could lead to computers that rely less on 'structured' data, such as the input 2 plus 2 equals 4, and can handle ambiguity better, like identifying the corporate logo even if the image is blurry. Or such computers could incorporate senses like sight, touch and hearing into the decisions they make.
One reason that development would be significant to IBM: The company is selling "smarter planet" services that use digital sensors to monitor things like weather and traffic and feed that data into computers that are asked to do something with the information, like predicting a tsunami or detecting freeway accidents. Other companies could use "cognitive computing" to make better sense of large volumes of information.