Scientific Understanding of Consciousness
FAPs — Fixed Action Patterns
Action is the end product of brain activity. Action is mediated by a hierarchy of stereotyped, procedural-memory Fixed Action Patterns (FAPs).
Stereotyped movement control for ingrained motor behavior is known by a number of names, including ‘Fixed Action Patterns (FAPs)’ and ‘Central Pattern Generators (CPGs)’ and Damasio’s term, dispositions. At some time in the future, the nomenclature will likely converge to universally accepted terminology. For these current discussions I’ll use Llinás’s terminology of Fixed Action Patterns (FAPs).
Cell ensembles at the top levels of the processing hierarchies would not hold explicit representation of the maps for objects and events. Rather, the ensembles would hold know how, i.e. dispositions, for the eventual reconstruction of explicit representations when they become needed. (Damasio; Self Comes to Mind, 140)
Fixed action patterns (FAPs) are sets of well-defined motor patterns, that when invoked, produce well-defined and coordinated movements. These motor patterns are called fixed because they are stereotyped and relatively unchanging between individual people. The FAPs are aggregated into hierarchies of functionality for the execution of movement. For very simple spinal reflexes, the upper central nervous system is not required. (Llinás; I of the Vortex, 151)
FAPs are aggregated into hierarchies that group ever more complex FAPs into synergies for complex, goal-oriented behavior. The rhythm of our walking, having been initiated by the upper motor system, and with minor adjustments to the terrain we are walking on, is handled largely by the nervous circuitry in the spinal cord. Neuronal networks, which specify stereotypical, often rhythmic, and relatively unchanging movements of the body when activated, are known as Central pattern generators (CPG's). (Llinás; I of the Vortex, 151)
The central nervous system is required for FAPs more complicated than locomotion, which can be elicited by brain stem and spinal cord alone. More sophisticated processing capabilities of the central nervous system are needed for more elaborate motor events of the complicated finger articulations of a concert violinist. (Llinás; I of the Vortex, 136)
Language itself is a premotor FAP. A patient with a massive stroke having nothing functional left except the basal ganglia and Broca’s area of the cortex was in vegetative state and coma and yet could still occasionally utter words. The nervous system is organized in functional modules. Word generation is an intrinsic property of the brain. (Llinás; I of the Vortex, 151)
Complex FAPs are believed to be generated centrally by the basal ganglia, which represents some of the least understood areas of the brain. Scientists currently believe that the expression of FAPs is supported by the interplay among a number of vastly differing parts of the nervous system and the basal ganglia. The basal ganglia connect synaptically with the thalamus and receive input from both the cortex and the thalamus. As with the cerebellum, the majority of connections within the basal ganglia are inhibitory; there are many reciprocal contacts within the basal ganglia. Thus the basal ganglia generate very complicated inhibitory electrical patterns that in essence represent the negation of activity. The intrinsic reciprocal, inhibitory activity of the basal ganglia keeps all the potential FAPs from becoming expressed until they are supposed to be. When a FAPs is actually executed, it is said to have been "liberated" into action. The basal ganglia are the doors that when unlocked may released into action very large functions outside of the basal ganglia. (Llinás; I of the Vortex, 136-8)
Neuropathology of the basal ganglia may be viewed as either producing an excess of FAPs as in Tourette’s syndrome, or a deficit with the eventual loss of them, as seen in Parkinson's syndrome. In Tourette’s syndrome, there is a partial destruction of the basal ganglia with an abnormal continual liberation of very particular types of FAPs. Tourette's patients are compelled by the neuropathology to continue to act; they may do so through the generation of words, generally short, loud expletives, curse words. (Llinás; I of the Vortex, 141)
The neuropathy of Parkinson's syndrome is a selective degeneration of a portion of the substantia nigra, one of the nuclei of the basal ganglia. Parkinson's patients are characterized by immobile faces, dullness of thought, slow thinking, quite the opposite of Tourette's syndrome. In Parkinson's patients there is the lack of ability to release FAPs. (Llinás; I of the Vortex, 142)
The existence of Tourette's and Parkinson's syndrome's, along with other motor syndromes related to disorders of the basal ganglia, suggest that FAPs are most probably implemented at the level of the basal ganglia and put into context by the reentry of the basal ganglia output into the ever cycling thalamocortical system. (Llinás; I of the Vortex, 144)
The basal ganglia send to and receive information from the thalamus. In fact, the intralaminar complex of the thalamus projects with a veritable vengeance onto the basal ganglia, which suggests the idea of physiological interplay between the self and FAPs. (Llinás; I of the Vortex, 144)
FAPs are subject to modification; they can be learned, remembered, and perfected. (Llinás; I of the Vortex, 153)
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