Dream Research and PET Scans

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Dream Research and PET Scans

 

There has been a lot of research done on dreams and dreaming. The

research I focused on was the work done with the PET scan. The

Positron Emissions Tornography have been used to measure various

rates of blood flow through the brain.(1)

 

There is basically two major Phases in Sleep. NREM - non rapid eye

movement and REM - rapid eye movement. NREM sleep is the beginning

of the sleep cycle. In NREM, the average brain activity decreases -

proportionately the rate of blood flow decreases.

So areas such as the Reticular Activating System which is the area

involved in arousal and wakening, shuts down. Areas involved in

muscle movement shut down. But, regions involved in the

consolidation and retrieval of memory did not decrease in blood flow,

but the pathways that bring information to and from this region did

shut down, therefore isolating them metabolically.

 

About 90 minutes into our sleep pattern we experience REM sleep. REM

sleep is produced by the excretion of Acetylcholine in the Pons. (2)

Suddenly, the Brain Stem begins firing electrical impulses through

the brain. Heightening breath, heart rate and sexual arousal and

sends impulses through the cortical and subcortical regions. Some

regions of the brain's metabolic rates wind up being higher than when

we are awake.

 

An area of gray matter, located at the Occipito-Temporo-Parital

junction is activated. This is where the brain performs the highest

level of processing of perceptual information.

 

Our emotional brain - The Limbic System increases with blood flow and

our memory and sensory processes connected to simple vision and

hearing in the Diencephelon and Medulla increase but the Primary

Visual Cortex region in the Occipital Lobe did not show much of an

increase in blood flow. Normally, an increase in activity in the

lower areas cannot occur without an increase in the Primary Visual

Cortex.

 

But, in REM sleep, the brain will activate the lower areas and begin

integration of visual patterns. This is what is speculated to be

the make-up of imagery and symbols in our dreams. (3)

 

The Prefrontal Cortex, which is divided into four regions, plays a

central role in our self-discipline, gratification restrainment and

controlling one's impulses. This region is typically inactive during

REM sleep, except for one of the four regions. This is the deep

white matter of the frontal lobe with large fiber pathways which

transmit the chemical Neurotransmitter Dopamine from the Mid Brain to

the Frontal Cortex.

 

So with the Limbic emotional brain extremely active and the self-

disciplinary Prefrontal Cortex mostly inactive, it is believed to be

the reason why we have such disinhibiting dreams (4) such as flying,

falling and fantasies.

 

 

Footnotes

 

1. National Institute of Health - Allen Braun, PET Scan Research

2. Sleep, Dream and Dreaming - William J. Cromie Harvard Gazzette

3. Wild Dreams- Robert Sapolsky Discover Magazine April 2001

4. Wild Dreams- Robert Sapolsky Discover Magazine April 2001

 

 

Andrew Pacholyk, MS, L.Ac.

Peacefulmind.com

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