A review of cell assemblies

Abstract

Since the cell assembly (CA) was hypothesised, it has gained substantial support and is believed to be the neural basis of psychological concepts. A CA is a relatively small set of connected neurons, that through neural firing can sustain activation without stimulus from outside the CA, and is formed by learning. Extensive evidence from multiple single unit recording and other techniques provides support for the existence of CAs that have these properties, and that their neurons also spike with some degree of synchrony. Since the evidence is so broad and deep, the review concludes that CAs are all but certain. A model of CAs is introduced that is informal, but is broad enough to include, e.g. synfire chains, without including, e.g. holographic reduced representation. CAs are found in most cortical areas and in some sub-cortical areas, they are involved in psychological tasks including categorisation, short-term memory and long-term memory, and are central to other tasks including working memory. There is currently insufficient evidence to conclude that CAs are the neural basis of all concepts. A range of models have been used to simulate CA behaviour including associative memory and more process- oriented tasks such as natural language parsing. Questions involving CAs, e.g. memory persistence, CAs' complex interactions with brain waves and learning, remain unanswered. CA research involves a wide range of disciplines including biology and psychology, and this paper reviews literature directly related to the CA, providing a basis of discussion for this interdisciplinary community on this important topic. Hopefully, this discussion will lead to more formal and accurate models of CAs that are better linked to neuropsychological data.

A psychoengineering paradigm for the neurocognitive mechanisms of biofeedback and neurofeedback

“…Through progressive abstraction due to synaptic homeostasis, a new assembly of neurons could be gathered into abstract schemata combining elements of these memories. Despite the likelihood that other biological mechanisms may also underlie the formation of schemata, such mechanisms have not yet been described (Huyck & Passmore, 2013), so the iOtA model is the most complete available.…”

“…Schemata correspond closely to biological networks of neurons usually termed "neural assemblies." A neural assembly is a small set of interconnected neurons that can persist without external stimulus, connected by learning and supported by synchronous firing behavior (Huyck & Passmore, 2013). The "information overlap to abstract" (iOtA) model of Lewis and Durant (Lewis & Durrant, 2011) theorizes that schemata are created through reinforcement of synaptic connections of overlapping memories: when a group of neural assemblies are activated simultaneously, their common overlapping networks are reinforced.…”

Towards neuro-inspired symbolic models of cognition: linking neural dynamics to behaviors through asynchronous communications

“…A possible solution is to consider group of neurons, or neural assemblies . Following a tradition going back to D. Hebb (1949) and further illustrated by numerous authors (see e.g., Palm 1982; Edelman 1987; Bienenstock 1994; Knoblauch and Palm 2002; Izhikevich 2006), neural (or Hebbian cell) assemblies can be described informally as groups of strongly interconnected neurons that support specific functions (for a review, see Huyck and Passmore 2013; Pulvermüller et al 2014). This approach has already led to the design of artifacts relating behaviors and brain processes by mapping neural assemblies onto the topology of brain regions (Seth et al 2004; Knoblauch et al 2005).…”

A comparison of simple agents implemented in simulated neurons

“…The Cell Assembly (CA), initially proposed in 1949 (Hebb, 1949;Huyck and Passmore, 2013), is a key component in brain function linking neural behaviour to psychological behaviour. A CA is a set of neurons that are able to support firing amongst themselves; when activated, the firing CA becomes a short-term memory that persists while many of the neurons continue to fire at a rate much higher than the background base neural firing rate.…”