Sleep and sleep cycles

Although we view sleep as an escape from the activity of the day, sleep is a fairly active process itself. Throughout a healthy night's sleep, structures in the hypothalamus and brain stem cycle repeatedly through five stages characterized by different brain waves produced during the cycles. The five cycles can be broken up into two main categories: REM (rapid eye movement) and non-REM (slow wave) sleep cycles (Waxman, 2003). This web page will focus on REM and non-REM sleep, but for more information on the specifics of the four sleep cycles, visit http://www.medicinenet.com/sleep/article.htm.
REM sleep, the most crucial part of the sleep cycle (studies have shown that rats deprived of REM sleep have prolonged learning and memory difficulties (Kim et al., 2005), occurs 70 to 90 minutes after falling asleep. REM sleep is initiated by dorsal midbrain and pontine tegmentum neurons. During the REM cycle, sometimes referred to paradoxical sleep, the locus ceruleus releases norepinephrene, a neurotransmitter in the brain that affects food intake, levels of arousal, and mood (Kalat, 2004). The brain then produces delta waves, waves nearly identical to ones observed when a person is awake (Figure 2). Along with a shift in brain waves, often heart rate and blood pressure increase, intense visual imageries (dreams) occur, and muscles can often become temporarily paralyzed. Narcoleptics still experience REM sleep, but instead of entering sleep at stage one and progressing to REM sleep, they often instantly enter REM sleep upon falling asleep. This sudden loss of consciousness and muscle control endangers narcoleptics and sometimes those around them (MedicineNet, 2005).
Figure 2. Brain waves collected by an electroencephalograph (EEG). Notice the similarity between the awake, alert waves and REM sleep waves. Permission pending, http://sun.science.wayne.edu/~bio340/StudentPages/Soliman/physweb.html
As stated previously, the hypothalamus is a structure in the brain that regulates the onset of sleep stages. Within the hypothalamus, hypocretins reside in cells and possibly aid in regulating the neurons involved in REM sleep. Some researchers believe that when Hcrtr2 is stimulated in humans with normal sleep patterns, hypocretins promote wakefulness and repress REM sleep. However, in narcoleptics, a mutation in Hcrtr2 disables this pathway, allowing the sudden onset of REM sleep (http://www.healthgene.com/canine/C110.asp).
Wednesday, February 18, 2009 | | 2 Comments
Scans

Magnetic Resonance Imaging (MRI) is a special type of procedure that allows a doctor to see what is happening inside your child's body. Unlike X-rays, the MRI scanner uses a magnetic field and radio waves to produce very clear and detailed pictures of parts of the body, such as the head, heart, chest, abdomen, pelvis, spine and extremities. MRI gathers soft tissue images and is used to evaluate function and structure of organs and to distinguish normal, healthy tissue from tissues that may need to be studied for disease.
Position Emission Tomography (PET) measures emissions from radioactively-labeled chemicals that have been injected into the bloodstream, and uses the data to produce images of the distribution of the chemicals in the body.
In drug abuse research, PET is being used for a variety of reasons including: to identify the brain sites where drugs and naturally occurring neurotransmitters act; to show how quickly drugs reach and activate receptors; to determine how long drugs occupy these receptors; and to find out how long they take to leave the brain. PET is also being used to show brain changes following chronic drug abuse, during withdrawal from drug use, and during the experience of drug craving. In addition, PET can be used to assess the effects of pharmacological and behavioral therapies for drug addiction on the brain.
What is MEG?
Marker coils placed on volunteer's head
Magnetoencephalography (MEG) is a non-invasive neurophysiological technique that measures the magnetic fields generated by neuronal activity of the brain. The spatial distributions of the magnetic fields are analyzed to localize the sources of the activity within the brain, and the locations of the sources are superimposed on anatomical images, such as those obtained through MRI, to provide information about both the structure and function of the brain.
Wednesday, February 18, 2009 | | 0 Comments
'Clear smoking link' to cot death
The Bristol University team said the risk also increased with every hour babies were exposed to passive smoke after birth.
The number of cot deaths has fallen, but those linked to smoking have risen.
The report, to be published in the journal Early Human Development, suggests public smoking bans will make people more likely to smoke at home.
Many other studies have shown a clear link between smoking and cot death, but the Bristol research tries to unravel more precisely the cost of smoking both before and after birth.
Smoking among pregnant women has fallen from 30% to 20% in the last 15 years.
Back sleeping
The experts found that the proportion of babies who went on to die from Sudden Infant Death Syndrome (SIDS) who were born to mothers who smoked during pregnancy had risen from 57% to 86%.
This, they say, is mostly due to the success of campaigns to lay babies on their backs to sleep, which is credited with preventing hundreds of cot deaths.
The remaining cot deaths are now much more likely to be due to smoking.
The report, from the university's Institute of Child Life and Health, said that fresh messages about the dangers of smoking while pregnant had to be given to women.
Lead author Professor Peter Fleming said: "What we have been trying to do is look at the whole impact of exposure, both before and after birth, to smoking and its adverse effects.
"After delivery, the mother can reduce the risk by protecting her baby and not smoking near it."
Hour by hour
He found that for every hour a newborn was exposed to tobacco smoke, the risk increased.
"We found a perfectly linear relationship," said Professor Fleming.
"The risk of death increased with each individual hour the baby was exposed to smoke.
"For example a baby exposed to smoke eight hours a day was eight times more likely to die from SIDS than a baby that was never exposed. These are startling statistics."
He said that although the recent introduction of smoking bans in public buildings led to a "potential increase" in smoking at home, the findings might send an "encouraging" message.
"What it is saying to parents as a positive message is 'even if you can't give up smoking, don't smoke around the baby'."
Professor George Haycock, from the Foundation for the Study of Infant Deaths said: "The figures show that maternal smoking is now the most important avoidable risk factor for Sudden Infant Death Syndrome (SIDS).
"If no women smoked in pregnancy, about 60% of cot deaths could be avoided. This means that in the UK the number of deaths could fall from around 300 a year to 120 a year."
Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/health/7045230.stm
Published: 2007/10/15 12:18:11 GMT
Tuesday, February 10, 2009 | | 2 Comments
Epilepsy
Epilepsy
Epilepsy is caused by surges of electrical activity
Epilepsy is a common neurological disorder which causes seizures.
One in 133 people in the UK has epilepsy, and at any one time 300,000 have an active form of the condition.
What causes epilepsy?
An epileptic seizure is caused by over-activity of the brain cells, which produces a surge of electricity.
This may be due to a variety of factors, such as brain damage from birth injuries, head injury, stroke, brain tumours and alcoholism.
There is some evidence to suggest the condition sometimes has a genetic basis - although it is rare for it to run in families.
In many instances, the cause of the condition is a mystery.
Are there different types of seizure?
Yes. Essentially, there are two types.
A partial seizure begins in one specific part of the brain, and may spread to other areas.
A generalised seizure can start in both sides of the brain at once.
Partial seizures:
Simple partial seizure - Confined to one particular area of the brain. The person retains consciousness, but may be fearful, and experience a strong sense of deja vu. Symptoms include jerking of an arm and an unpleasant taste in the mouth.
Complex partial seizure - The electrical disturbance spreads, disrupting consciousness. The person may interact with the surroundings, but be unaware of what they are doing and have no recollection of the event.
Symptoms may include repeatedly chewing, swallowing or scratching. Afterwards the person is likely to be confused for some minutes.
Generalised seizures:
Tonic clonic seizure - This leads to 'grand mal' convulsions in which the person loses consciousness, falls to the ground, becomes stiff and shakes.
In some instances a tonic clonic seizure may occur after an initial partial seizure - in which case the person may have some warning of what is about to occur.
Absence attack - A blank spell lasting a matter of seconds from which recovery is almost immediate.
Myoclonic seizures - Jerks caused by a sudden contraction of the muscles. Can affect the whole body usually restricted to one or both arms and sometimes the head.
Tonic seizures - All the muscles contract. The body stiffens and the person will fall over if unsupported.
Atonic seizures - All muscle tone is lost and the person simply drops to the ground.
How is epilepsy treated?
There are a wide range of anti-epileptic drugs to prevent seizures.
Which drug is prescribed will depend on the individual patient, and their particular form of epilepsy.
The drugs are effective, but can have side effects, including drowsiness and dizziness.
Some drugs may produce longer term side effects, such as acne and weight gain.
Anti-epileptic drugs should not be taken in tandem with some other medications. They may also slightly increase the risk of malformations if taken during pregnancy.
Is surgery an option?
Yes, for people who do not respond to drug treatment.
The most common form of surgical treatment is to remove the hippocampus - a part of the brain involved in memory which is particularly vulnerable to damage.
Other forms of surgery which may be considered include:
Temporal lobectomy - a larger part of the temporal lobe is removed.
Sub-pial resection - fine cuts are made in the motor areas of the brain.
Hemispherectomy - the removal of the whole of one side of the brain
Corpus callosotomy - cutting the fibres that connect the two halves of the brain.
An alternative to neurosurgery is a treatment called vagal nerve stimulation in which a pacemaker device is placed under the skin to stimulate the vagus nerve in the neck.
This form of treatment does not usually cure the epilepsy, but can reduce seizure frequency and severity.
Wednesday, January 21, 2009 | | 1 Comments
Drink and prematurity
'Drink link' to premature birth
Doctors say women who drink heavily early in a pregnancy - possibly before they know they are pregnant - may be raising the risk of premature delivery.
A study of 4,719 Australian women found almost an 80% higher risk for women who drank heavily in the first third of pregnancy, then stopped.
However, experts warned it was possible the results were a "statistical quirk".
The BJOG journal study found no evidence of problems for women who drank low levels throughout pregnancy.
The subject of alcohol and pregnancy has been controversial, with some guidelines advocating no alcohol intake, while other specialists believe that drinking small amounts is unlikely to harm the developing child.
The latest study suggests that the period during which binge or heavy drinking can have the greatest effect is during the first trimester.
With as many as 40% of pregnancies unplanned, this may include several weeks in which the woman is unaware she is carrying a child.
Unusually, the strongest link between alcohol use and early birth was for women who drank moderately or heavily - several units of alcohol or more a week - during the first trimester, but then stopped completely for the rest of the pregnancy.
The researchers suggested that it was possible that the sudden cessation of alcohol drinking might provoke inflammation which could harm the developing foetus in some way, although this idea was not tested during the study.
Caution urged
Dr Colleen O'Leary, from the University of Western Australia, who led the study, said: "The risk of pre-term birth is highest for women who drink heavily or at binge levels.
"Women should be advised that during pregnancy, drinking alcohol above low levels increases the risk to the baby and that the safest choice is not to drink alcohol during pregnancy."
The editor of the British Journal of Obstetrics and Gynaecology, Professor Phillip Steer, said the study represented a warning to women.
He said: "When you consider the number of pregnancies which are not planned, it is quite possible that by the time a woman realises she is pregnant, it is too late and the damage has been done."
However, Professor Andrew Shennan, representing baby charity Tommy's, said that the results needed to be interpreted cautiously.
"It is still possible that, given the relatively small number of women involved, this finding could be a statistical quirk.
"More research needs to be done to ascertain the true extent of the risk posed by drinking alcohol during pregnancy.
"This is a controversial area with many conflicting results and recommendations about what is deemed a 'safe' level of alcohol consumption."
However, he said that a precautionary approach was still sensible for women who might fall pregnant.
"Now that you can buy kits which can tell you whether you are pregnant before you have even missed a period, perhaps women who binge drink should take advantage of these."
Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/health/7839671.stm
Published: 2009/01/21 00:11:43 GMT
© BBC MMIX
Wednesday, January 21, 2009 | | 0 Comments
Autism some facts

Autistic traits 'spread widely'
Autism is more often diagnosed in boys
Many children have mild autistic "symptoms" without ever having enough problems to attract specialist attention, say UK researchers.
The Institute of Child Health team says diagnosed children have severe versions of character traits probably shared by millions of others.
The 8,000 child study found even these mild traits could impair development.
Boys - who make up the bulk of autism diagnoses - were most likely to be affected, the US journal study found.
Clinicians and those involved in education need to aware that there are children who do not have autism but who nevertheless have somewhat elevated levels of autistic traits
Professor David Skuse
Institute for Child Health
Scientists have understood for some time that the "autistic spectrum" covers a wide range of children with differing levels of problems, from relatively mild cases to severely disabling problems.
However, a relatively small number of children - approximately 116 per 10,000 - are said to have an autistic disorder.
The UK research, published in the Journal of the American Academy of Child and Adolescent Psychiatry provides further evidence that the same traits do not begin and end there, but continue at into the whole population of children, just at a level which does not lead parents to seek medical help.
Seeing autism as a "distinct illness" was probably wrong, they said.
Even at this mild level, however, these characteristics - particularly problems communicating with peers and teachers - can be a disadvantage.
The findings confirmed that IQ was not an issue - the traits could be present regardless of levels of intelligence.
However, it cast some light on the differential in the numbers of boys and girls diagnosed with autism.
Girls with autistic traits appeared to be able to compensate for social communication problems if they had sufficient "verbal IQ" - a natural ability to use language well.
However, even boys with high "verbal IQ" seemed less able to overcome their communication problems.
Education awareness
Professor David Skuse, one of the researchers involved, said the results did not downplay the genuine impact of more severe autism.
However, he added: "What this does suggest is that drawing a dividing line between those with autism and the rest of the population involves taking an arbitrary decision."
"Clinicians and those involved in education need to aware that there are children who do not have autism but who nevertheless have somewhat elevated levels of autistic traits - our research suggests that these children are at slightly greater risk of developing behavioural and emotional problems."
In an accompanying editorial, Professor John Constantino, from Washington University, said that the idea that autism represented the "severe end" of a natural distribution of abilities could help scientists looking for the genetics underlying the condition, or for ways to treat it.
It could also help the development of children who were affected, but not to the level of an autism diagnosis.
He wrote: "The approach of teachers and family members to such children can vary dramatically on the basis of the perceived origins of the behaviour, and recognition of the contribution of subthreshold autistic impairments can result in far more appropriate and supportive responses than typically occur when antisocial motives are presumed."
Wednesday, January 21, 2009 | | 1 Comments
Reading is important
Take advantage of your holidays to promote reading
Parents urged to read to children
Children in England are not reading enough outside of school
Parents are being urged to make a New Year's resolution to spend more time reading to their children.
Schools Secretary Ed Balls is spearheading the initiative ahead of the National Year of Reading 2008, which officially starts in April.
Mr Balls said reading a child a bedtime story every night could have a huge impact on their development.
"Reading can bring fun to their lives, feed their imagination, and develop their curiosity about the world."
Too many children today are not reading for pleasure - and this is harming not just our children's reading skills, but also their imagination and general knowledge
Ed Balls, Children, Schools and Families Secretary
"As parents we need to make reading a part of everyday life for our children - whether that is reading stories to younger children or talking about books and magazines with older kids," he said.
A recent survey found the reading performance of children in England had fallen from third to 19th in the world.
The Progress in International Reading Literacy Study, published in November, highlighted significant increases in the proportion of English 10-year-olds with the "least positive" attitudes to reading and who said they very seldom read stories or novels outside school.
Mr Balls said it could make "all the difference" if parents set aside 10 minutes a day before bedtime to read with their children.
Reading tips
"Too many children today are not reading for pleasure - and this is harming not just our children's reading skills, but also their imagination and general knowledge," he said.
The National Year of Reading is being run by the National Literacy Trust, which has some ideas to encourage reading in different age groups.
These include:
For babies to 3-year-olds - make a scrapbook about your child full of pictures and words. Read the words with your child and get them to say what else should be in their story.
For three to five-year-olds - cut out pictures from catalogues or magazines of objects that all begin with the same letter, plus a few that do not. Write down the names of the objects and get your child to match the picture to the name.
For five to eight-year-olds. - find your family's top five reads. Ask everyone in your family to name their favourite reads - it could be a book, magazine, comic or newspaper. Involve grandparents, cousins etc. And see if the neighbours agree.
If you have read the newspaper you will see that on corrientes Avenue in Buenos Aires the bookshops were open at night in an effort to promote reading.
Thursday, December 11, 2008 | | 1 Comments




