Figure 3.

When the cue stimulus activates synapse A-B, the previously formed functional LINK between postsynapses B and D is re-activated. Lateral entry of activity activating postsynapse D without receiving activity from presynaptic terminal C evokes a cellular semblance of an action potential reaching from its presynaptic terminal C, which is called synaptic semblance. The nature of the semblance is derived as follows. Postsynapse D experiences the cellular semblance that it is receiving inputs from the set of neurons {Y} that synapse to the neuron Z of its presynapse C. The set of neurons {Y} is activated by the set of neurons {X}, which in turn is activated by the set of neurons {W}. Continuing this extrapolation toward the sensory level identifies a set of sensory receptors {SR}. The nature of the semblance depends on the sensory stimuli that would activate the receptor set {SR}. The stimulation of subsets of sensory receptor sets {sr1}, {sr2}, and {sr3} of the set {SR} may be capable of independently activating neuron Z. The dimensions of hypothetical packets of sensory stimuli capable of activating the sensory receptor subsets {sr1}, {sr2}, and {sr3} are called semblions 1, 2, and 3 respectively and are viewed as the basic building blocks of the virtual internal sensations of memory. The identities of the cue-activated semblances from different postsynapses at each order of neurons (by combination) and the temporal formation of semblances (due to synaptic delay) at different orders of neurons (by permutation) can become integrated to provide the virtual sensation of a sensory stimulus during memory retrieval. Neuronal oscillations and the background sensory inputs result in the summation of EPSPs to only sub-threshold levels in many neurons, short of eliciting action potentials (neuron N2 before the arrival of the cue stimulus). Arrival of the cue stimulus re-activates the functional LINK and activates postsynapse D. When this potential is added to the sub-threshold EPSPs, some neurons (for example, neuron N2) trigger action potential. Thus, the formation of semblances at the functionally LINKed postsynapses may explain the concurrent activation of certain neurons (Reijmers et al., 2007; Gelbard-Sagiv et al., 2008; Tye et al., 2008) by specific cue stimuli during memory retrieval that are likely the neurons that are currently thought to represent memories [Figure was used after modification (Vadakkan, 2011)].