Research Highlights

Area deep in the brain generates activity related to consciousness and dreaming.

Background
When we are awake with our eyes closed, electrodes on the scalp measure waves of human brain activity at 10 Hertz, or 10 per second. If we fall asleep, these waves slow to 6-8 Hertz during drowsiness and light sleep, and then to 2-4 Hertz in deep sleep. When we open our eyes, are alerted and pay attention, our brains begin to fire at 20-40 Hertz. These waves are called ‘gamma band activity’, and are present during consciousness and learning, and also during dreaming. Dogma was that ‘gamma band activity’ was only present in the cerebral cortex, the thin, convoluted surface of the brain. Recently, others found ‘gamma band activity’ in other parts of the brain, such as the hippocampus and cerebellum. Scientists at the COBRE Center for Translational Neuroscience at UAMS have discovered that parts of the reticular activating system, the part of the brain that controls sleep, dreaming and waking, exhibit ‘gamma band activity’. In fact, nerve cells in this area prefer to fire at ~40 Hertz when stimulated. This means that the reticular activating system activates the rest of the brain when we are alerted, and it does so, not by triggering such activity in other regions, but by itself inducing ‘gamma band activity’. This process thus recruits waking or dreaming. This novel mechanism may allow the development of new stimulants and anesthetics that can modulate this brain rhythm.

Advance
We discovered that parts of the reticular activating system, the part of the brain that controls sleep, dreaming and waking, exhibit ‘gamma band activity’. In fact, nerve cells in this area prefer to fire at ~40 Hertz when stimulated. This means that the reticular activating system activates the rest of the brain when we are alerted, and it does so, not by triggering such activity in other regions, but by itself inducing ‘gamma band activity’.

Grant Support
Supported by Core Facilities of the COBRE P20 RR20146, and individual grant support R01 NS20246.

Public Health Impact/Significance
This novel mechanism may allow the development of new stimulants and anesthetics that can modulate this brain rhythm.

Link to article
http://www.ncbi.nlm.nih.gov/pubmed/20463196

Gamma band unit activity and population responses in the pedunculopontine nucleus. Simon C, Kezunovic N, Ye M, Hyde J, Hayar A, Williams DK, Garcia-Rill E. J Neurophysiol. 2010 Jul;104(1):463-74. Epub 2010 May 12. PMID: 20463196 [PubMed – in process]

Institution and State
University of Arkansas for Medical Sciences, Arkansas COBRE Center for Translational Neuroscience.