Think you’re good at multi-tasking? Here’s how your brain compensates – and how this changes with age

Arlington Research/Unsplash Peter Wilson, Australian Catholic UniversityWe’re all time-poor, so multi-tasking is seen as a necessity of modern living. We answer work emails while watching TV, make shopping lists in meetings and listen to podcasts when doing the dishes. We attempt to split our attention countless times a day when juggling both mundane and important tasks.

But doing two things at the same time isn’t always as productive or safe as focusing on one thing at a time.

The dilemma with multi-tasking is that when tasks become complex or energy-demanding, like driving a car while talking on the phone, our performance often drops on one or both.

Here’s why – and how our ability to multi-task changes as we age.

Doing more things, but less effectively

The issue with multi-tasking at a brain level, is that two tasks performed at the same time often compete for common neural pathways – like two intersecting streams of traffic on a road.

In particular, the brain’s planning centres in the frontal cortex (and connections to parieto-cerebellar system, among others) are needed for both motor and cognitive tasks. The more tasks rely on the same sensory system, like vision, the greater the interference.

The brain’s action planning centres are in the frontal cortex (blue), with reciprocal connections to parietal cortex (yellow) and the cerebellum (grey), among others. grayjay/Shutterstock

This is why multi-tasking, such as talking on the phone, while driving can be risky. It takes longer to react to critical events, such as a car braking suddenly, and you have a higher risk of missing critical signals, such as a red light.

The more involved the phone conversation, the higher the accident risk, even when talking “hands-free”.

Having a conversation while driving slows your reaction time. GBJSTOCK/Shutterstock

Generally, the more skilled you are on a primary motor task, the better able you are to juggle another task at the same time. Skilled surgeons, for example, can multitask more effectively than residents, which is reassuring in a busy operating suite.

Highly automated skills and efficient brain processes mean greater flexibility when multi-tasking.

Adults are better at multi-tasking than kids

Both brain capacity and experience endow adults with a greater capacity for multi-tasking compared with children.

You may have noticed that when you start thinking about a problem, you walk more slowly, and sometimes to a standstill if deep in thought. The ability to walk and think at the same time gets better over childhood and adolescence, as do other types of multi-tasking.

When children do these two things at once, their walking speed and smoothness both wane, particularly when also doing a memory task (like recalling a sequence of numbers), verbal fluency task (like naming animals) or a fine-motor task (like buttoning up a shirt). Alternately, outside the lab, the cognitive task might fall by wayside as the motor goal takes precedence.

Brain maturation has a lot to do with these age differences. A larger prefrontal cortex helps share cognitive resources between tasks, thereby reducing the costs. This means better capacity to maintain performance at or near single-task levels.

The white matter tract that connects our two hemispheres (the corpus callosum) also takes a long time to fully mature, placing limits on how well children can walk around and do manual tasks (like texting on a phone) together.

For a child or adult with motor skill difficulties, or developmental coordination disorder, multi-tastking errors are more common. Simply standing still while solving a visual task (like judging which of two lines is longer) is hard. When walking, it takes much longer to complete a path if it also involves cognitive effort along the way. So you can imagine how difficult walking to school could be.

What about as we approach older age?

Older adults are more prone to multi-tasking errors. When walking, for example, adding another task generally means older adults walk much slower and with less fluid movement than younger adults.

These age differences are even more pronounced when obstacles must be avoided or the path is winding or uneven.

Our ability to multi-task reduces with age. Shutterstock/Grizanda

Older adults tend to enlist more of their prefrontal cortex when walking and, especially, when multi-tasking. This creates more interference when the same brain networks are also enlisted to perform a cognitive task.

These age differences in performance of multi-tasking might be more “compensatory” than anything else, allowing older adults more time and safety when negotiating events around them.

Older people can practise and improve

Testing multi-tasking capabilities can tell clinicians about an older patient’s risk of future falls better than an assessment of walking alone, even for healthy people living in the community.

Testing can be as simple as asking someone to walk a path while either mentally subtracting by sevens, carrying a cup and saucer, or balancing a ball on a tray.

Patients can then practise and improve these abilities by, for example, pedalling an exercise bike or walking on a treadmill while composing a poem, making a shopping list, or playing a word game.

The goal is for patients to be able to divide their attention more efficiently across two tasks and to ignore distractions, improving speed and balance.

There are times when we do think better when moving

Let’s not forget that a good walk can help unclutter our mind and promote creative thought. And, some research shows walking can improve our ability to search and respond to visual events in the environment.

But often, it’s better to focus on one thing at a time

We often overlook the emotional and energy costs of multi-tasking when time-pressured. In many areas of life – home, work and school – we think it will save us time and energy. But the reality can be different.

Multi-tasking can sometimes sap our reserves and create stress, raising our cortisol levels, especially when we’re time-pressured. If such performance is sustained over long periods, it can leave you feeling fatigued or just plain empty.

Deep thinking is energy demanding by itself and so caution is sometimes warranted when acting at the same time – such as being immersed in deep thought while crossing a busy road, descending steep stairs, using power tools, or climbing a ladder.

So, pick a good time to ask someone a vexed question – perhaps not while they’re cutting vegetables with a sharp knife. Sometimes, it’s better to focus on one thing at a time.

Peter Wilson, Professor of Developmental Psychology, Australian Catholic University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→January 02, 2024

Pigs with human brain cells and biological chips: how lab-grown hybrid lifeforms bamboozle scientific ethics

 

Shutterstock Julian Koplin, Monash University

Earlier this month, scientists at the Guangzhou Institutes of Biomedicine and Health announced they had successfully grown “humanised” kidneys inside pig embryos.

The scientists genetically altered the embryos to remove their ability to grow a kidney, then injected them with human stem cells. The embryos were then implanted into a sow and allowed to develop for up to 28 days.

The resulting embryos were made up mostly of pig cells (although some human cells were found throughout their bodies, including in the brain). However, the embryonic kidneys were largely human.

This breakthrough suggests it may soon be possible to generate human organs inside part-human “chimeric” animals. Such animals could be used for medical research or to grow organs for transplant, which could save many human lives.

But the research is ethically fraught. We might want to do things to these creatures we would never do to a human, like kill them for body parts. The problem is, these chimeric pigs aren’t just pigs – they are also partly human.

If a human–pig chimera were brought to term, should we treat it like a pig, like a human, or like something else altogether?

Maybe this question seems too easy. But what about the idea of creating monkeys with humanised brains?

Chimeras are only one challenge among many

Other areas of stem cell science raise similarly difficult questions.

In June, scientists created “synthetic embryos” – lab-grown embryo models that closely resemble normal human embryos. Despite the similarities, they fell outside the scope of legal definitions of a human embryo in the United Kingdom (where the study took place).

Like human–pig chimeras, synthetic embryos straddle two distinct categories: in this case, stem cell model and human embryo. It is not obvious how they should be treated.

In the past decade, we have also seen the development of increasingly sophisticated human cerebral organoids (or “lab-grown mini-brains”).

Unlike synthetic embryos, cerebral organoids don’t mimic the development of a whole person. But they do mimic the development of the part that stores our memories, thinks our thoughts, and makes conscious experience possible.

A network of neural cells grown on an array of electrodes to produce a ‘biological computer chip’. Cortical Labs

Most scientists think current “mini-brains” are not conscious, but the field is developing rapidly. It is not far-fetched to think a cerebral organoid will one day “wake up”.

Complicating the picture even further are entities that combine human neurons with technology – like DishBrain, a biological computer chip made by Cortical Labs in Melbourne.

How should we treat these in vitro brains? Like any other human tissue culture, or like a human person? Or perhaps something in between, like a research animal?

A new moral framework

It might be tempting to think we should settle these questions by slotting these entities into one category or another: human or animal, embryo or model, human person or mere human tissue.

This approach would be a mistake. The confusion sparked by chimeras, embryo models, and in vitro brains shows these underlying categories no longer make sense.

We are creating entities that are neither one thing nor the other. We cannot solve the problem by pretending otherwise.

We would also need good reasons to classify an entity one way or another.

Should we count the proportion of human cells to determine whether a chimera counts as an animal or a human? Or should it matter where the cells are located? What matters more, brain or buttocks? And how can we work this out?

Moral status

Philosophers would say these are questions about “moral status”, and they have spent decades deliberating on what kinds of creatures we have moral duties to, and how strong these duties are. Their work can help us here.

For example, utilitarian philosophers see moral status as a matter of whether a creature has any interests (in which case it has moral status), and how strong those interests are (stronger interests matter more than weaker ones).

On this view, so long as an embryo model or brain organoid lacks consciousness, it will lack moral status. But if it develops interests, we need to take these into account.

Similarly, if a chimeric animal develops new cognitive abilities, we need to reconsider our treatment of it. If a neurological chimera comes to care about its life as much as a typical human does, then we should hesitate to kill it just as much as we would hesitate to kill a human.

This is just the beginning of a bigger discussion. There are other accounts of moral status, and other ways of applying them to the entities stem cell scientists are creating.

But thinking about moral status sets us down the right path. It fixes our minds on what is ethically significant, and can begin a conversation we badly need to have.

Julian Koplin, Lecturer in Bioethics, Monash University & Honorary fellow, Melbourne Law School, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→September 27, 2023