Sunday, 24 August 2008

Memory research roundup - More Sleep

Following my last post, I received a comment from njtom as follows:

"Brain scans of humans and animals have indicated that bursts of information pass between the neocortex and the hippocampus during the first hours of sleep, known as slow wave sleep. It is during slow wave sleep that the brain remembers declarative or episodic memory – precise facts a person can access consciously."

If this is correct than how can the current medical advice to prevent Slow-wave sleep in infants be safe? Slow-wave sleep is when infants die of SIDS. So, doctors no longer allow infants to get slow-wave sleep. Is this safe?

This led me to read a couple of fascinating detailed research posts on the njtom's Tummy Sleep Central blog. The latest post covers Post-natal Slow Wave Sleep Inhibition and the SIDS "Back to Sleep" Campaign. Essentially the current advice to change an infant's sleeping position from tummy (prone) to back (supine) may be having a long term negative effect on their cognitive development while having a negligible effect on the reduction of SIDS deaths. Particularly resonant with my post is the following excerpt:

Since 1998 there have been three studies published which show that infants placed to sleep in the supine position lag in motor skills, social skills, and cognitive ability development when compared to infants who sleep in the prone position [35-37]. None of these three studies analyzed children older than 18 months of age and the authors of all three studies considered the lags at less than 18 months of age to be temporary and do not think that the supine sleep recommendations should be changed. Placing infants in the prone position while they are awake has been recommended to offset the motor skills delays associated with the supine sleep position [38] but positioning the infant prone while awake will not impact the amount of slow wave sleep [39-43].

These studies are covered in more detail in an earlier post and lead to further research that suggests supine sleep position increases apnea episodes and decreases sleep duration in infants. This nocturnal respiratory disturbance is associated with a decrease in learning in children who were otherwise healthy. Sleep fragmentation has an adverse impact on memory and learning (as indicated in my previous post), and that hypoxemia (a condition in which there is an inadequate supply of oxygen in the blood) has an adverse influence on nonverbal skills.

I don't know the answer to the question posed by njtom but it emphasises the importance of further research in how the quality of our sleep affects our cognitive development at all ages.

Sunday, 3 August 2008

Memory research roundup - Sleep

I've previously posted on the effect of sleep on our learning and memory effectiveness in Snooze and Learn Faster and Six minute nap may boost memory.

Here's yet another study supporting the need for sleep to consolidate a new experience.

To sleep, perchance to remember
(Nice title, not mine but a similar Shakespearian steal as Learning As You Like It)

Neuroscientists at Geneva University have discovered that sleep can produce a lasting impact on how the brain processes and stores newly learnt information. The research, conducted by Sophie Schwartz of the Neurology and Imaging of Cognition laboratory at Geneva University, involved subjects being exposed to new visual stimuli, such as a face or tasks like tracing a moving dot with a joystick. They were then allowed to sleep normally - or not.

Scientists compared a whole night of normal sleep with a whole night of sleep deprivation, naps versus no naps, and eight hours of night sleep compared with eight hours of being awake during the day. The brain changes were highly localised and relevant to the task the volunteer had been set.

Brain scans of humans and animals have indicated that bursts of information pass between the neocortex and the hippocampus during the first hours of sleep, known as slow wave sleep. It is during slow wave sleep that the brain remembers declarative or episodic memory – precise facts a person can access consciously. Our skills – or procedural memory – are encoded during the rapid eye movement sleep, which is more abundant during the latter hours of the night.

Right, I'd better get off to bed myself now for a bit of my own consolidation...

Saturday, 2 August 2008

Memory research roundup - Blueberries

In the last post, HDL cholesterol levels appear to have a positive effect on memory recall (or at least arrest its decline). On a similar dietary theme:

Scientists Find Blueberries Reverse Age Related Memory Deficits

Researchers (from the Schools of Food Biosciences and Psychology in Reading and the Institute of Biomedical and Clinical Sciences at the Peninsula Medical School in Exeter) supplemented a regular diet with blueberries over a three month period. Within three weeks, they discovered improvements in spatial working tasks and the improvements continued throughout the course of the study.


The scientists were able to pinpoint the ability of flavonoids to activate signaling proteins in a specific area of the hippocampus, the learning and memory-controlling part of the brain.

Friday, 1 August 2008

Memory research round up - Cholesterol

Over the past month I've managed to collect an interesting range of research snippets relating to memory and cognition. There's definitely a sense of acceleration of activity in this area, which unfortunately also brings with it its own hype and hysterical headlines.

Over the next few posts I'll summarise the ones that most caught my eye:

Cholesterol and Memory

People with high levels of cholesterol of the HDL variety (high-density lipoprotein) did better on memory tests than those with lower levels. The UK research checked the levels of 3,600 British civil servants and gave them memory tests at an average age of 55 and then again at 61. The tests involved reading a list of 20 words and then asked to write down as many as they could remember within 2 minutes (I'm guessing they didn't use Brain Training on the Nintendo DS for this task).

Apparently, not only did those with higher HDL do better, but those whose HDL levels declined between tests also saw a decline in their performance.

This research is part of a long term "Whitehall II" study that started in 1985 and has been following over 10,000 male and female London-based members of the British Civil Service. The participants have regular clinical exams and periodically fill in questionnaires.