Frontiers in Systems Neuroscience
January 1, 2022
Thurston Lacalli
9 citations
Conscious experience can be modeled as occupying a high-dimensional space (E-space) whose dimensions correspond to the degrees of freedom needed to specify sets of qualia. Phenomenal consciousness likely originated as one or more multidimensional ur-experiences that combined multiple forms of experience. Evolution then extracted the qualia best suited to each sensory modality through a process called dimensional sorting. This framework provides a systematic way to think about early stages in the evolution of consciousness, moving beyond narrative and conjecture alone.
Frontiers in Psychology
January 1, 2024
Thurston Lacalli
7 citations
Consciousness has two general evolutionary functions: expanding behavioral repertoires through neurocircuitry innovations that depend on consciousness, and shortening the time scale for altering preprogrammed behaviors from generations to real-time. However, these do not explain why consciousness is proximately adaptive. Consciousness likely first evolved to make motivational control more responsive to an individual's past experiences via memory, such as consciously inhibiting harmful appetitive behaviors. For amniote vertebrates, this memory role may have led to broader functions like global behavioral oversight or conferring meaning on sensory experience. Meaning here is valence embodied in genomic instructions for phenomenal contents, constituting species memory that stores adaptive information across evolutionary time.
Frontiers in Psychology
April 29, 2024
Thurston Lacalli
2 citations
Consciousness and individual agency can be decoupled in two hypothetical ways: reflex pathways that incorporate conscious sensations as an intrinsic component (InCs), and consciously conditioned reflexes dependent on synaptic plasticity but not memory (CCRs). Whether these exist is unclear, and InCs are limited to theories where consciousness depends on EM field effects. Consciousness with agency, as humans experience it, requires deliberate choice of alternative actions (DCs) that depend on explicit memory systems. CCRs provide a heuristic model for how conscious inputs could refine routine behaviors while evolution optimizes qualia without agency.
Frontiers in Psychology
January 1, 2025
Thurston Lacalli
1 citation
Consciousness likely evolved from simpler antecedents, raising the question of how unified experience arises from basic beginnings. This is simplified if conscious contents combine constitutively, allowing natural selection to adjust their balance incrementally. The text contrasts two models: a conventional non-modular, fully integrated consciousness, and a modular, local, constitutive model where integration occurs non-consciously. In the modular model, a broadcast signal's amplitude at its source matters more than propagation distance, though it fails to explain how localized signals become globally perceived. Integrative models risk misdirecting attention to structures and processes unrelated to conscious sensation production.
Frontiers in Psychology
June 22, 2026
Thurston Lacalli
Conscious vision presents a challenge for theories of consciousness because it involves a 2-dimensional perceptual display. A modular/constitutive model requires that awareness of visual stimuli has position-dependence, meaning the physical location of each module contributing to visual experience has perceptual consequences. Conscious gaze control registers salient visual features in a way that has no preconscious counterpart and helps visual experience acquire meaning. The analysis justifies Merker's ideas on vision and gaze control as core functions of consciousness, where postnatal refinement of visual skills equates to learning agency. It provides a framework for the hard problem and suggests conscious experience for non-visual species may incorporate position-dependent components based on something other than light perception. The adaptive advantage of consciousness depends on both position-dependent contents and valence to assign meaning to experience.
Frontiers in Psychology
January 1, 2023
Thurston Lacalli
Many theories of consciousness are silent about evolution, making it hard to assess their applicability across species and evolutionary time. A conceptual "consciousness machine" helps examine how ontology and evolution produce consciousness with distinct contents. A key divide is whether consciousness requires electromagnetic field effects, as in neurophysical theories, or whether neural connectivity and information flow suffice, as in algorithmic theories. For consciousness to evolve non-randomly, a link to behavior is needed. An EM field scenario can produce distinct contents without agency, suggesting agency is a developmental, not evolutionary, issue requiring real-time feedback and learning each generation. This splits the problem of evolved consciousness into two: explaining conscious experience and explaining agency.
Philosophical transactions of the Royal Society of London. Series B, Biological sciences
February 14, 2022
Thurston Lacalli
The amphioxus brain serves as a benchmark for understanding vertebrate brain evolution because of similarities in regional subdivision, cell types, and circuitry. While basal chordates already had well-developed locomotory control systems, they lacked complex sense organs. Vertebrate evolution involved progressive improvements to sensory organs and brain centers processing their output, alongside the emergence of primary consciousness (sentience). A bottom-up evolutionary perspective focuses on obstacles to sentience's emergence, the sequence of new conscious contents, and homology between them. Future investigation should explore how subjective experience is optimized for each sensory modality.
Frontiers in Systems Neuroscience
January 1, 2021
Thurston Lacalli
Conscious experience likely evolved from simple beginnings, gaining complexity over time as new categories of subjective experience were added. The simplest, most fundamental contents—qualia—resist further analysis and can be represented as points, lines, or curves on a topological experience space, distinct from more complex experiences called formats (e.g., vision, language) that depend on algorithmic processes or memory. Qualia correspond to domains in a configuration space representing a subset of neural correlates of consciousness called selector circuits (SCs), which ensure a particular experience is evoked.
Frontiers in Behavioral Neuroscience
January 1, 2020
Thurston Lacalli
The evolution of consciousness from a pre-conscious state presents conceptual difficulties analogous to biological pattern formation, as described by Alan Turing. Just as molecular-level statistical variations can seed biological patterns, the microstructure of synaptic networks and their activity patterns can vary, with some variants serving as neural correlates of consciousness (NCCs). If NCCs must be precisely ordered to evoke specific experiences, Turing's framework helps explain how such order arises developmentally and how neural changes correlate with conscious experience. The analysis does not address the ultimate nature of consciousness but shows that once sentience emerges, evolution can elaborate and shape that experience.
Consciousness and Cognition
July 1, 2018
Thurston Lacalli
Gene expression studies have identified in amphioxus a brain region homologous to the combined caudal diencephalon and midbrain of vertebrates, areas involved in locomotory control and some forms of primary consciousness. Electron-microscope reconstructions of the larval amphioxus brain show that inputs for light and physical contact converge on the same synaptic zone. This neural circuitry offers a basis for understanding the evolution of locomotory control and arousal in vertebrates. The findings suggest that one early task of midbrain-based consciousness in vertebrates was to distinguish light from physical contact—likely sharp pain—by assigning different qualia to each. Further study of midbrain circuitry may clarify the neural basis of certain sensory experiences.