Scientific Understanding of Consciousness
Consciousness as an Emergent Property of Thalamocortical Activity

Hierarchical Neural Network Processing



Cortical processing takes place through a hierarchy of cortical stages. Convergence and competition are key aspects of the processing. (Rolls & Deco; Noisy Brain, 26)

Representational networks or cognits of the two cortical regions, posterior and frontal, are hierarchically organized by development and connectivity. (Fuster; Prefrontal Cortex, 380)

Cortical connectivity apparatus of the perception-action cycle is completed in both directions at every hierarchical level. (Fuster; Prefrontal Cortex, 360)

In most brain systems information processing is organized hierarchically. (Kandel; Principles of Neural Science, 324)

In the brain's hierarchical system, each higher level carries out more sophisticated tasks, but there is an enormous amount of feedback and crosstalk. (Ramachandran; Tell-Tale Brain, 95)

Patterns of interconnectivity between visual cortical areas had been classified in a hierarchical organization of ten levels. (LaBerge; Attentional Processing, 105)

According to spreading activation theory, semantic memory is organized on the basis of semantic relatedness or semantic distance. (Baddeley,; Memory, 119)

The spreading activation model has generally proved more successful than the hierarchical network model. (Baddeley,; Memory, 121)


"Grandmother Cells"

The assumptions captured in the notion of a "grandmother cell," a neuron (or small ensemble of neurons) near the top of the processing cascade (e.g. the anterior temporal lobe) whose activity would comprehensively represent our grandmother when we perceive her. (Damasio; Self Comes to Mind, 137)

Reactivated grandmother cells would allow the playback of the same perceived contents in their entirety. The prediction of a grandmother cell is not borne out in the reality of neurophysiological findings. (Damasio; Self Comes to Mind, 138)

In regard to grandmother cells, patients with damage to the anterior brain regions -- frontal and temporal -- report normal perception and display only selected deficits in the recall and recognition of unique objects and events.(Damasio; Self Comes to Mind, 138)

Dispositional space can be considered to contain "grandmother cells," defined liberally as neurons whose activity correlates with the presence of the specific object but not as neurons whose activity permits, in and of themselves, explicit mental images of objects and events. (Damasio; Self Comes to Mind, 151)

To recognize or remember our 'grandmother,' we must reinstate a substantial part of the collection of explicit maps that, in their entirety, represent her meaning. (Damasio; Self Comes to Mind, 151)

Like mirror neurons, so-called 'grandmother neurons' are CDZs. They enable time-locked multiregional retroactivation of explicit maps in early sensorimotor cortices. (Damasio; Self Comes to Mind, 151)



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