"Electrophysiology of the central nervous system indicates in brief that the brain is continuously active, in all its parts, and an afferent excitation must be superimposed on an already existent excitation. It is therefore impossible that the consequence of a sensory event should often be uninfluenced by the pre-existent activity." p7
"There are two radical modifications of earlier ideas: transmission is not simply linear but apparently always involves some closed or recurrent circuits; and a single impulse cannot ordinarily cross a synapse-two or more must act simultaneously, and two or more afferent fibres must therefore be active in order to excite a third to which they lead." p10
"In a single system, and with a constant set of connections between neurons in the system, the direction in whicy an entering excitation will be conducted may be completely dependent on the timing of other excitations. Connections are necessary but may not be decisive in themselves; in a complex system, especially, time factors must always influence the direction of conduction." p10-11
"When an axon of cell A is near enough to excite a cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A's efficiency, as one of the cells firing B, is increased." p62
"<p>Also under control are the fibers that lead from the sensory areas into the association areas. According to the schema of perception, this control is extended gradually, synapse by synapse. Considering the association areas as made up of a population of transmission units, two factors must affect the length of time needed to bring all these units under control. One is the number of controlling fibers leading from sensory areas into association areas. The second is the number of transmission units in the association areas themselves.
<i>With cortex of a given size</i>, these two factors may be considered to be roughly proportional to the size of the total sensory cortex, and the total association cortex. It then follows that the length of the primary learning period will be roughly proportional to the ratio
total association cortex / total sensory cortex
"<p>There is considerable variety in the make-up of central neural cells and their reaction to changes of blood content...
Now it has been seen that neural integration is fundamentally a question of timing, quite apart from the particular theory of integration that has been developed on these pages. Metabolic changes, by altering time relations in neural firing, must tend to disrupt behaviour-not merely slow it up, but disorganize it.
In the present theory, timing has its effect in the functioning of the cell-assembly and the interrelation of assemblies: diffuse, anatomically irregular structures that function briefly as closed systems, and do so only by virtue of the time relations in the firing of constituent cells. Synaptic changes are necessary to the setting up of an assembly, but these act by coordinating the action of two or more cells. The firing of one cell immediately after another is not determined by synaptic knobs alone but also by what is going on in some other cell or cells. Synaptic knobs alone cannot determine that a particular system will function as such.
Furthermore, an individual cell or transmission unit may enter into more than one assembly, at different times. Which is will form part of, at any moment, depends on timing in other cells; and to enter into any assembly requires that its frequency accord with the time properties of the active system.