David LaBerge      

Simon's Rock College


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   J. Neuroscience


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Making Waves and Pulses

With the Brain's Neurons

Neurons cluster in minicolumns.  Shown here are 3 of the approximately 100 neurons in one of the 3 hundred million minicolumns that make up the human cerebral cortex.

Close-up view of a single neuron, with its long vertical fiber (apical dendrite), its bush-like group of short fibers (basal dendrites), and its thread-like fiber (axon). Many of these apical dendrites have lengths that are 600 times their diameters (imagine a plastic tube, 6 inches in diameter, the length of a football field). A series of signals arriving near one end would not be faithfully transmitted to the other end.

Animation of pulses being processed through the neuron. (Animation may be temporarily slow while loading)   Pulses that arrive at a basal dendrite fiber produce a surge of electric current that travels the short distance to the pyramid-shaped cell body, which converts the electric current into another pulse that travels along the axon fiber to another neuron. Typically many pulses arrive simultaneously on several dendrite fibers, and sum their currents at the cell body, and the cell body then sends out a train  of pulses along the axon fiber to other neurons.

Animation of the wave. (Animation may be temporarily slow while loading)   A series of pulses arrives at the long apical dendrite in a regular, repeating rhythm, and produces surge after surge of current. These rhythmic surges of current make up a wave. When waves are synchronized in thousands of long apical dendrites which are clustered closely together and aligned in the same direction, the intensity of the combined wave produces an electric field that spreads to the surface of the brain and can be measured on the scalp as the well-known electroencephalogram(EEG). Electric current surges in the long apical dendrites may not reach the cell body to produce output pulses in the axon in the way current surges in the basal dendrites do. However, waves in the apical dendrite may influence the input-throughput-output processing of pulses that takes place via the short basal dendrites. The rhythmic surges of current that make up the wave on the long apical dendrite are believed to produce the subjective experiences of sustained attention and consciousness.

Spacing image


  31 Jan 01 -Wave animations posted to the site.

  18 Oct 02 -Pulse animations added to the site.

Recent publications that describe the wave basis of subjective experiences of consciousness and sustained attention:

 LaBerge, D. (2001). Attention, consciousness, and electrical wave activity within the cortical column. International Journal of Psychophysiology, Vol 43, pp 5-24.

 LaBerge, D. (2002). Attentional control: brief and prolonged. Psychological Research (Psychologische Forschung). (Online, Sept 6, 2002; to appear in print in Dec. 2002).

2000, David LaBerge, all rights reserved.