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cursory
This word has appeared in 55 articles on NYTimes.com in the past year. Can you use it in a sentence?
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cursory \ ˈkər- sə -rē \ adjective
: hasty and without attention to detail; not thorough
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The word cursory has appeared in 55 articles on NYTimes.com in the past year, including on Sept. 21 in “What Hemingway Left in Sloppy Joe’s Bar 80 Years Ago” by Robert K. Elder:
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Ralph Lewis M.D.
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ATTENTION
Mind-Body Problem: How Consciousness Emerges from Matter
Subjective experience is built from physically encoded internal representations.
Posted January 18, 2023
Reviewed by Tyler Woods
KEY POINTS
The mind is the brain’s internal model of the body and environment. It is a physically encoded web of representations—a correlational map.
Internal representations are key to understanding how sensory perceptions of stimuli from the physical world are turned into mental phenomena.
Representations have valence. This forms the basis for affect and emotion. Affect infuses self-representations with feeling and agency.
The brain forms prediction models. When incoming stimuli match expectations, a state of resonance occurs, which generates conscious experience.
yesdoubleyes | AdobeStock
Source: yesdoubleyes | AdobeStock
“Conscious experience is at once the most familiar thing in the world and the most mysterious. There is nothing we know about more directly than consciousness, but it is far from clear how to reconcile it with everything else we know. Why does it exist? What does it do? How could it possibly arise from lumpy gray matter?” -David J. Chalmers, The Conscious Mind: In Search of a Fundamental Theory (1996)
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yesdoubleyes | AdobeStock
Source: yesdoubleyes | AdobeStock
The mystery of subjective experience, also known as the "hard problem of consciousness," refers to the question of how and why we have subjective experiences at all. The subjective, first-person experiences of sensory and mental phenomena, such as the redness of a rose or the taste of a lemon, are referred to as "qualia". The ultimate quest of neuroscience is to explain how qualia are produced by the brain, to explain how it is that our brain produces a distinct sense of self—an entity experiencing those qualia, possessing also agency, a coherent sense of stability and continuity, and a personal narrative.
Key to understanding the link between the physical and mental worlds are internal representations—also referred to as mental representations or cognitive representations. Subjective experience is built from internal representations.
Internal representations
Internal representations are images or models of the body and the world. They have a relational nature to the reality they map—they are built from and characterized by direct correlations to physical things. They are the way that sensory perceptions of the physical world get turned into mental phenomena, which in turn have causal power on the physical world. Internal representations begin with an animal’s sense organs receiving physical signals from its environment. Those signals may be visual (photons), auditory (air vibrations), touch (mechanical stimuli), smell (chemicals), etc. Figure 1 illustrates in simplified form how internal representations are formed from sensory perceptions, according to a theory elaborated by psychiatrist-neurologist Todd Feinberg and evolutionary biologist Jon Mallatt.
Illustration by Jill K Gregory. Used with permission of ©Mount Sinai Health System
Source: Illustration by Jill K Gregory. Used with permission of ©Mount Sinai Health System
Figure 1. Mapped isomorphic organization of the exteroceptive sensory pathways. Each sensory pathway of several neurons (right) is a hierarchy that carries signals up to the brain, keeping a point-by-point mapping (A, B, or C) of a body surface, a body structure, or the outside world. This mapping leads to the mapped mental images that are drawn around the brain. The touch map of the body (upper left) includes a cut section through the folded cerebral cortex. The bar code associated with the flower at left shows that each complex odor has its own, coded scent signature. [1]
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Because of their physical correspondence with what they are mapping, the representations may be referred to as isomorphic maps, or (in the case of vision) topographic images. Signals are also received from the animal’s own body, such as its spatial positioning. Thus, the brain forms models of the world and of itself in relation to the world.[2]
The process by which sense organs transduce and transmit stimuli into neuronal signals and internal representations is entirely physical and mechanistic at the molecular level.
The ability of an animal to form internal representations is just one of the things needed for that animal to have simple consciousness, but it is a key element. [See Footnote #3 for links elaborating on this point, and for an important point about how subjectivity is built into the very nature of life].
THE BASICS
Understanding Attention
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Memory
Brains evolved the ability to store salient mental representations (through short-term and long-term changes in neuronal connections), then access that information after intervals of time (short-term and long-term memory), integrate that information with other relevant information, and update those memories as new information becomes available.
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Cognition and behavior
The neuroscientist Joseph LeDoux defines cognition as the ability to form internal representations and to use these to guide behavior. Internal representations enable an animal to react to stimuli even when the stimuli are not present. For example, there may be stored representations of a cue that has previously been associated with food, danger, or sex. Those representations can then guide behavior independent of the presence of the actual stimulus. Thus, it is the mental representation that is now guiding behavior, rather than the stimulus.[4]
Mammals have a much more complex kind of cognitive representation than do simpler animals,[5] with some deliberative capacity—the ability, as LeDoux puts it, to form mental models that can be predictive of potential things that do not yet exist—this is a much more complex cognitive capacity than simply having a kind of static memory of what's there. It enables the ability to weigh, plan, and calculate behavioral options, imagining scenarios.
ATTENTION ESSENTIAL READS
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Notice how mental activity is not just caused by input from the physical world, but routinely acts back on it.[6]
Learning
As we've noted, internal representations are correlational maps. Most learning is based on establishing correlations between things—correspondences or associations. Behavioral conditioning occurs through rewards and consequences reinforcing or weakening those associations.
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According to an elegant theory by neuroscientist Simona Ginsburg and evolutionary biologist Eva Jablonka, which I have reviewed elsewhere, learning may actually be the fundamental driver of the evolution of consciousness. As Ginsburg and Jablonka state: “The evolution of learning and the evolution of consciousness are intimately linked, even entangled. “[7] Their theory proposes that a form of associative learning/conditioning that they call "unlimited associative learning" is an evolutionary marker of simple consciousness.[8]
Value
Positive and negative reinforcement obtained in the process of learning by association confers valence or affect to experience. Thus, brains assign value to stimuli—"good"-ness or "bad"-ness. This forms the basis for the evolution of feeling and emotion, and the fuel for motivation and goal-directedness.[9]
All this, of course, occurs entirely physically and mechanistically, at the molecular level—just like all the other processes we have discussed, and just like every aspect of brain functioning that produces the “mind.”
Self-representations and self-awareness
Self-representations (the brain's mapping of the body and its spatial positioning and actions) combine with affect (feeling) to provide a sense of ownership of the body and of perception, a feeling of presence and agency—the sense of being an entity that is doing the experiencing. A feedback loop of the brain’s modeling, predicting, and controlling of the body’s internal state and actions reinforces the sense of self.
Humans’ complex sense of self-awareness probably arises from recursive forms of self-representation—the brain modeling its models of itself, in what Douglas Hofstadter referred to as a “strange loop.”[10]
The self is a very stable illusion constructed at a high level of abstraction from layers of underlying mental activity. The self has no perceptual access to the underlying neural processes from which it is built. It has no need for such access from an evolutionary point of view, so it never evolved to understand its own building blocks. All that the brain “knows” is its simplified, non-physical model of its own attention processes.
Complex, abstract representations
At a basic level, internal representations are simply sensory images (as was illustrated by figure 1). Complex brains form representations of representations. Abstract mental concepts are constructed as higher-order representations from symbolic, analogous correspondences to physical things—they are still assembled, at bottom, from the building blocks of sensory images.[11, 12]
Predictions and expectations
Predictions are key to how the brain processes information and learns. The brain is a prediction machine: As the brain learns to recognize patterns of information, so it acquires the ability to predict the form that new information will take and to form expectations about sensory input. This improves efficiency of information processing by imposing top-down predictions on partial information as it is received bottom-up from the senses. This short-cutting reduces the amount of energy and resources required to process all that information. Mental representations are central to this process of making predictions.[13]
Resonance
When inputs match expectations, a neural state of resonance occurs, which, according to one influential theory, is the conscious experience. The neuroscientist Stephen Grossberg formulated a theory of how brains learn to attend, recognize, and predict objects and events in a changing world, called Adaptive Resonance Theory (ART). Following is a very summarized explanation of this complex and sophisticated theory:
When an active expectation matches attended critical features well enough, excitatory bottom-up and top-down signals mutually reinforce each other between the features and the active recognition category that is reading out the expectation. The result is a state of resonance in which the matched signals are synchronized, amplified, and prolonged long enough for us to consciously recognize the attended object or event.[14]
Resonance is the physical instantiation of subjective awareness: “It cannot be overemphasized that these resonances are not just correlates of consciousness. Rather, they embody the subjective properties of individual conscious experiences.”[15]
The computational neuroscientists Ogi Ogas and Sai Gaddam, in describing Stephen Grossberg's ART, note:
If a mind is not capable of resonance, it is not capable of consciousness. We can go one step further: because a pair of mental representations is an essential component of every resonant state, we know that a mind that lacks representational thinking cannot be conscious.[16]
Language and culture
Humans have the ability to share their internal mental states by employing shared attention and symbolic language,[17] and to mirror these to each other, thereby building a more sophisticated sense of self.[18] From language comes the ability to develop extremely abstract ideas, with almost unlimited complexity. And from language emerges the potential for practically limitless cultural evolution and the ratcheting up of collective learning.[19] Some neuroscientists, including Ogas and Gaddam,[20] consider language essential to higher forms of consciousness.[21]
Conclusion
Internal representations are, of course, just part of the answer to the question of how consciousness emerges from physical neuronal processes, but they are key to explaining how subjective mental experiences are fundamentally physical phenomena—how consciousness emerges from matter.