Tag Archives: Executive functions

Nighttime Sleep Boosts Infant Skills

At ages 1 and 1-1/2, children who get most of their sleep at night (as opposed to during the day) do better in a variety of skill areas than children who don’t sleep as much at night.

That’s the finding of a new longitudinal study conducted by researchers at the University of Montreal and the University of Minnesota. The research appears in the November/December 2010 issue of the journal Child Development.

The study, of 60 Canadian children at ages 1, 1-1/2, and 2, looked at the effects of infants‘ sleep on executive functioning. Among children, executive functioning includes the ability to control impulses, remember things, and show mental flexibility. Executive functioning develops rapidly between ages 1 and 6, but little is known about why certain children are better than others at acquiring these skills.

“We found that infants’ sleep is associated with cognitive functions that depend on brain structures that develop rapidly in the first two years of life,” explains Annie Bernier, professor of psychology at the University of Montreal, who led the study. “This may imply that good nighttime sleep in infancy sets in motion a cascade of neural effects that has implications for later executive skills.”

When the infants were 1 year old and 1-1/2 years old, their mothers filled out three-day sleep diaries that included hour-by-hour patterns, daytime naps, and nighttime wakings. When the children were 1-1/2 and 2, the researchers measured how the children did on the skills involved with executive functioning.

Children who got most of their sleep during the night did better on the tasks, especially those involving impulse control. The link between sleep and the skills remained, even after the researchers took into consideration such factors as parents’ education and income and the children’s general cognitive skills. The number of times infants woke at night and the total time spent sleeping were not found to relate to the infants’ executive functioning skills.

“These findings add to previous research with school-age children, which has shown that sleep plays a role in the development of higher-order cognitive functions that involve the brain’s prefrontal cortex,” according to Bernier.

Source : Elements4Health

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Mind Power Moves Paralysed Limbs

Scientists have shown it is possible to harness brain signals and redirect them to make paralysed limbs move.

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The technology bypasses injuries that stop nerve signals travelling from the brain to the muscles, offering hope for people with spinal damage.

So far the US team from the University of Washington have only tested their “brain-machine interfaces” in monkeys.

The hope is to develop implantable circuits for humans without the need for robotic limbs, Nature reports.

Wired up
Spinal cord injuries impair the nerve pathways between the brain and the limbs but spare both the limb muscles and the part of the brain that controls movement – the motor cortex.

“Similar techniques could be applied to stimulate the lower limb muscles during walking” Says Lead researcher Dr Chet Moritz

Recent studies have shown that quadriplegic patients – people who have paralysis in all four limbs – can consciously control the activity of nerve cells or neurons in the motor cortex that command hand movements, even after several years of paralysis.

Using a gadget called a brain-machine interface, Dr Chet Moritz and colleagues re-routed motor cortex control signals from the brains of temporarily paralysed monkeys directly to their arm muscles.

The gadget, which is the size of a mobile phone, interprets the brain signals and converts them into electrical impulses that can then stimulate muscle to contract.

By wiring up artificial pathways for the signals to pass down, muscles that lacked natural stimulation after paralysis with a local anaesthetic regained a flow of electrical signals from the brain.

Life-changing
The monkeys were then able to tense the muscles in the paralysed arm, a first step towards producing more complicated goal-directed movements, such as grasping a cup or pushing buttons, say the researchers.

Lead researcher Dr Chet Moritz said: “This could be scaled to include more muscles or stimulate sites in the spinal cord that could activate muscles in a coordinated action.”

“Similar techniques could be applied to stimulate the lower limb muscles during walking.”

The scientists found the monkeys could learn to use virtually any motor cortex nerve cell to control muscle stimulation – it did not have to be one that would normally controlled arm movement. And their control over the muscles improved with practice.

The researchers say they need to do trials in humans, meaning a treatment could be decades away.

Dr Mark Bacon, head of research at the UK charity Spinal Research, said: “This is clearly a step in the right direction and proves the principle that artificially transducing the will to move generated in the brain with relevant motor activity can be achieved.

“However, these results have been produced in experimental models where there is no injury per se.”

He said injury-induced changes to the nerve circuits might hinder the technology’s application in real life.

Also, brain-machine interfaces communicate in only one direction – in this case from the brain to the muscle.

“Sensory feedback, so important for fine control of movements and dexterity, is still some way away,
” he said.

Sources: BBC NEWS:15 October 2008

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The Vulnerable Lobes

Medical students have always been fascinated by the story of Phineas Gage, a normal, hard working 26-year-old labourer. He became famous in 1848, when an iron rod pierced his skull and brain and exited on the opposite side. He survived this extensive trauma and was physically normal. His life aroused scientific curiosity as physicians suddenly realised that, contrary to popular opinion at that time, all parts of the brain where not essential for life.

The brain controls the physical functions of the body, determines our intelligence, memory, personality and ability to respond to change. It has four paired lobes. Of these, the parietal, temporal and occipital lobes have well elucidated mapped areas for functions like sight, speech, hearing and movement. The frontal lobes (through which the rod pierced Gage), situated just behind the forehead, are responsible for subtle psychological functions like mental maturity, recognition of social norms of behaviour, emotional development and appropriate responses to society.

English: Four brain lobes frontal lobe(red) pa...

English: Four brain lobes frontal lobe(red) parietal lobe(orange) temporal lobe(green) occipital lobe(yellow) and insula(purple) is also shown. others are Brain stem(black) Cerebellum(sky blue). Polygon data are from BodyParts3D maintained by Database Center for Life Science(DBCLS). ???: ????? ???(??) ???(?????) ???(??) ???(??) ??? ?????? ? ??(??) ??(??) ????????Database Center for Life Science(DBCLS)???????BodyParts3D??? (Photo credit: Wikipedia)

The frontal area of the brain is protected to some extent by the skull bones. However, damage to the frontal lobes can occur as a result of accidents. Surgery may be performed on the frontal lobes to remove cysts or tumours, to treat intractable epilepsy, or very rarely for psychiatric disorders. The effects of injury to the frontal lobes are often subtle and difficult to pinpoint as the IQ (intelligence quotient) may remain normal. There may be weakness without actual paralysis, inability to perform sequential movement (like dressing for work), lack of flexibility and spontaneity, poor attention and difficulty in expressing thoughts lucidly despite increased talking. Sexual habits may change with promiscuity or disinterest or socially inappropriate behaviour. The entire personality of the individual may change, making him or her unpleasant, obnoxious and intolerable.

The brain fibres in the frontal lobes mature as we grow older and develop fully around the age of 25. Genetic defects or injury in the uterus, during birth or within this time frame, can result in faulty connections, inadequate development and poor release of brain chemicals like dopamine. This can cause learning disabilities, antisocial personalities and sometimes even major psychiatric illnesses like schizophrenia. Also the size of our brain, particularly of the frontal lobes, shrinks over time. This affects important human abilities such as planning, reasoning and problem solving.

Not all brains age or deteriorate at the same rate. Part of this process is genetic and the degeneration sets in at a certain chronological age triggered by an in-built biological alarm. This apparently inevitable mental decline is further influenced by environmental factors, which can be modified favourably.

The concept of retraining ageing brain circuits has been gaining popularity. There are DVDs and books available on brain exercises. The numbers game Sudoku is in almost every newspaper. Retraining the frontal lobes can also be done quite simply by memorising passages or poetry from books. Repetition of a task makes performance rapid and more efficient with less room for error, as the cascading chemical reactions in the brain then occur on accustomed pathways. Older adults who regularly participate in cognitive activity improve their memory, speed of thought and attention span. This helps them to efficiently manage their day-to-day activities and their finances. The benefits of brain training can be enhanced by regular physical activity.

Look after your brain as it is the only one you have.

* Protect it from injury by wearing seat belts and using helmets.

* Do not hit anyone on the head (this particularly includes corporal punishment).

* If anyone has had an accident or brain surgery, tolerate their idiosyncrasies, changes in personality, unreasonable anger and emotional outbursts.

Sources: The Telegraph (Kolkata, India)