Parents’ voices become less important through adolescence Daniel Pain, Science Editor, explains what changes in adolescent brains when listening to the world

FOR many, the sound of a parent’s voice changes from being one of authority, that must be obeyed at all costs, to one that should be ignored — at least for as long as possible. This well-known feeling of annoyance and desire to rebel is one that many adolescents feel more strongly as they grow up. It turns out that this isn’t just a feeling either. Pathways in the brain which alter how teenagers respond to the sound of their parents change as they age.

A study conducted on children aged seven to 16 compared the brain activity of children listening to either their mother, or the voice of an unknown woman. The words spoken were gibberish so as not to sway participants by their meaning. The result of the study found that children aged seven to 12 were more likely to respond the sound of their mother than a stranger. The ar- eas in the brain responsible for detecting rewards and paying attention were turned on in this case. In a slightly older group (13 to 14) teenagers were found to have the complete opposite reaction.

The areas responsible for [...] paying attention were turned on

This doesn’t come as a surprise to many who have lived through this transition themselves either as parents or teenagers. The phenomenon of teenagers rebelling and exploring the world for themselves is universal and important to social development. The increase in attention to new voices outside of parental influence plays a large factor in this period of life. As teenagers grow into mature adults, they

Plant leaves fold up like a book

need to be able to listen to a variety of perspectives in order to put their own opinion of the world forward.

So, if and when the day comes that you find yourself hopelessly lost as to how to control a teenager of your own, just remember that it isn’t really their fault they won’t listen to you. It’s simply the neurons in their heads telling them not to.

Daniel Pain, Science Editor, opens the door to the fascinating phenomena of plant movement

PLANTS are one of the most diverse and incredible forms of life on planet Earth. From flowers that smell like rotting corpses to plants that completely lack chlorophyll and look as white as ghosts. Even among these incredible specimens, plants which appear to have the abil - ity to move are somewhat of a novelty.

The Mimosa pudica is a species of plant which can fold its two sets of leaflets inwards when it experiences physical stimulation, much like the folding of a book along its spine. This is done by the movement of ions and subsequently water, resulting in the inflation and deflation of the two leaf halves, controlling this distinctive movement. Scientists have known about the Mimosa pudica plant and the underlying chemistry which controls the movements of its leaves for a long time. However, what has recently been uncovered is the tiny structures within the ‘muscle’ cells of these unique plants, known as pulvinus cells. These cells are reinforced with microscopic fibrils, which control the expansion of the cell as water floods in to cause cell expansion to occur in very specific sites. Rather than bulging in all directions, as would be the case in your average plant cell, the swelling is only along the axis of the leaf fold. As well as this, these cells contain extremely porous areas, known as pit fields. The development of these structures is believed to occur in order to allow large volumes of water to move quickly through cells, therefore in essence functioning as miniature sluices. In turn, this aids in the rapid movement of water which allows the plant to ‘close’ its leaves when physically stimulated.

[The plants] in essence [are] functioning as miniature sluices

Combined, these microscopic structures help the plant open and close its leaves in the most efficient and energy-conserving way possible. The reason behind why the M. pudica can close its leaves like a book still remains a mystery. Since this unique and rapid movement makes the plant seem more ‘animal-like’, one hypothesis has suggested that it could be useful to dissuade grazers from eating the plant’s leaves. Others theorise that it is to protect against the cold.

The reason behind why M. pudica can close its leaves [...] still remains a mystery

Whatever the real reason, this plant will still remain a remarkable and unique specimen and possibly the closest thing to animal movement ever found in the plant kingdom.