For all our daily technology stories go to www.NewScientist.com/section/tech

A “LIVING doll” made from human liver cells could allow new drugs to be tested in conditions closer to those inside the body. It was built using a technique that moulds tissue into any desired structure.

The structure was grown using about 100,000 beads of the connective protein collagen, seeded with liver cells and tipped into a body-shaped mould. On the surface of each bead are cells that secrete proteins and collagen that bind all the cells together. As a result, the final product is much closer to living tissue than a collection of cells grown in a dish.

Shoji Takeuchi , who led the team that developed the technique at the University of Tokyo, Japan, plans to use it to grow structures containing multiple cell types. These could even function as whole test organs, he says.

How a brain wires up for actionBEFORE a fetus is born, its brain

undergoes the complex process of

refining the connections between

its different regions. Now a computer

model is showing us how.

Although our genes provide an

initial blueprint for the way different

neurons connect together , the

developing brain must still refine the

wiring and prune out any redundant

connections. “It’s a big challenge to

have a system that is ready by the

time of birth so that newborns can

begin experiencing the world right

away,” says Jean-Philippe Thivierge

from Indiana University, Bloomington.

Neuroscientists suspect the brain

achieves this by sending out waves of

spontaneous electrical activity that

cascade across groups of neurons,

helping it to scout out the relative

positions of neurons and forge the

most efficient network.

PR

OF

ST

UA

RT

CA

MP

BE

LL

/RE

X F

EA

TU

RE

S

TECHNOLOGY

Human tissue, moulded to order

To investigate the exact nature

of this process, Thivierge created

a computer model of 1000 neurons

that simulates the way the retina

connects to the region of the mid-

brain that controls eye movements,

called the superior colliculus.

The model revealed that weak

waves of activity over a small number

of neurons were the most efficient at

forging new connections, rather than

big waves that sweep across the

whole region. Timing also proved to

be critical, with fluctuations as short

as a millisecond instrumental in the

wiring process (Neural Networks,

DOI: 10.1016/j.neunet.2009.01.001).

WHEN data gets stolen, there’s an unexpected suspect in the frame.

To protect their networks from viruses and hacker attacks, most companies insist their computers are “locked down” so they can’t run unauthorised software or CD and DVD content. “But woe betide the lowly IT director that would inconvenience the CEO with such restrictions,” says Glenn Zimmerman, a technology expert with the Pentagon’s cyberspace task force. “Most senior leaders’ computers are often wide open to threats,” and it is often the CEO who holds the most critical data,

Data theft? Blame the head honcho

he warned a London conference on Cyber Warfare last week.

The way to counter this threat from within is to hack their computers and show them what you find, says cyberwar analyst Yael Shahar of the International Institute for Counter-Terrorism in Herzliya, Israel. “They may close the door and show you out, but their security awareness will have gone up a notch,” she says.

Zimmerman says the solution is to use less onerous security measures. Locking down PCs leads savvy users to find workarounds – which introduce vulnerabilities. “The only totally secure computer is one that is switched off, filled with concrete and dropped to the bottom of the Mariana trench.”

–Busy making connections–

The estimated price of a laptop being developed in India. The computer will draw just 2 watts of electrical power

$10

The message displayed alongside every Google search result for nearly an hour on 31 January,

when an error at Google led to the whole internet being labelled a virus-ridden threat, rather

than just the sites on stopbadware.org’s list of malicious sites (Chicago Tribune, 1 February)

“This site may harm your computer”

“The developing brain must refine its wiring and prune out any redundant connections before birth”

7 February 2009 | NewScientist | 19