Chunking and consolidation: A theoretical synthesis of semantic networks, configuring in conditioning, S-R versus cognitive learning, normal forgetting, the amnesic syndrome, and the hippocampal arousal system.

TLDR

Horizontal and vertical associative memory concepts differ, with vertical memory relying on chunking to create new nodes that combine existing bound nodes, forming the basis of semantic memory, conditioning, and cognitive learning. The cortex performs chunking while the hippocampal arousal system primes free neurons and, upon binding, suppresses their connections to the arousal system, thereby consolidating the memory and slowing forgetting. Disrupting the hippocampal arousal system leads to anterograde and retrograde amnesia by preventing new chunking and retrieval of recently formed chunks.

Abstract

Horizontal versus vertical associative memory concepts are denned. Vertical associative memory involves chunking: the specification of new (previously free) nodes to represent combinations of old (bound) nodes. Chunking is the basis of semantic memory, configuring in conditioning, and cognitive (as opposed to stimulus-response) learning. The cortex has the capacity for chunking, but the hippocampal (limbic) arousal system plays a critical role in this chunking process by differentiall y priming (partially activating) free, as opposed to bound, neurons. Binding a neuron produces negatively accelerated repression of its connections to the hippocampal arousal system, consolidating the memory by protecting the newly bound neuron from diffuse hippocampal input and thus retarding forgetting. Disruption of the hippocampal arousal system produces the amnesic syndrome of an inability to do new chunking (cognitive learning)—anterograde amnesia—and an inability to retrieve recently specified chunks—retrograde amnesia.