VI. Life’s Cerebral Cognizance Becomes More Complex, Smarter, Informed, Proactive, Self-Aware

B. A Neural Encephalization from Minimal Stirrings to an Earthuman Cognizance

Moroz, Leonid. Biodiversity Meets Neuroscience: From the Sequencing Ship to Deciphering Parallel Evolution of Neural Systems in Omic’s Era. Integrative & Comparative Biology. 55/6, 2015. The University of Florida marine biologist and neuroscientist introduces an Origins of Neurons and Parallel Evolution of Nervous Systems: The Dawn of Neuronal Organization section. As the Abstract notes, by way of research vessel studies of rudimentary nautical life forms, along with laboratory genome sequencings, it is now possible to robustly reconstruct the earliest cerebral-cognitive structures. From this vantage, it is revealed that constant forms were in place from cellular life’s beginnings. As a result, a recurrent convergence in separate lineages and phyla, especially of visual systems, becomes quite evident.

The origins of neural systems and centralized brains are one of the major transitions in evolution. These events might occur more than once over 570–600 million years. The convergent evolution of neural circuits is evident from a diversity of unique adaptive strategies implemented by ctenophores, cnidarians, acoels, molluscs, and basal deuterostomes. But, further integration of biodiversity research and neuroscience is required to decipher critical events leading to development of complex integrative and cognitive functions. Here, we outline reference species and interdisciplinary approaches in reconstructing the evolution of nervous systems. In the “omic” era, it is now possible to establish fully functional genomics laboratories aboard of oceanic ships and perform sequencing and real-time analyses of data at any oceanic location. In doing so, fragile, rare, cryptic, and planktonic organisms, or even entire marine ecosystems, are becoming accessible directly to experimental and physiological analyses by modern analytical tools. Thus, we are now in a position to take full advantages from countless “experiments” Nature performed for us in the course of 3.5 billion years of biological evolution. Together with progress in computational and comparative genomics, evolutionary neuroscience, proteomic and developmental biology, a new surprising picture is emerging that reveals many ways of how nervous systems evolved. (Abstract)

Murray, Elizabeth, et al. The Evolution of Memory Systems. New York: Oxford University Press, 2017. The authors Elizabeth Murray (physiology and psychology) and Steven Wise (neurobiology) are at the National Institute of Mental Health, and Kim Graham is a cognitive neuroscientist at Cambridge University. They accomplish a 500 page treatise on how Earth life came to possess neural capacities to remember and retrieve so as to better survive, evolve and flourish. Five sections are Foundations of Memory systems, Architecture of Vertebrate Memory, Primate Augmentations, Hominin Adaptations, and Deconstructing and Reconstructing Memory Systems. One may add that as this homologous creaturely course reaches our sapient retrospective it quite appears as a long embryonic gestation.

Current theories about human memory have been shaped by clinical observations and animal experiments. This doctrine holds that the medial temporal lobe subserves one memory system for explicit or declarative memories, while the basal ganglia subserves a separate memory system for implicit or procedural memories, including habits. Cortical areas outside the medial temporal lobe are said to function in perception, motor control, attention, or other aspects of executive function, but not in memory. 'The Evolution of Memory Systems' proposes that several memory systems arose during evolution and that they did so for the same general reason: to transcend problems and exploit opportunities encountered by specific ancestors at particular times and places in the distant past. Instead of classifying cortical areas in terms of mutually exclusive perception, executive, or memory functions, the authors show that all cortical areas contribute to memory and that they do so in their own ways-using specialized neural representations.

The book also presents a proposal on the evolution of explicit memory. According to this idea, explicit (declarative) memory depends on interactions between a phylogenetically ancient navigation system and a representational system that evolved in humans to represent one's self and others. As a result, people embed representations of themselves into the events they experience and the facts they learn, which leads to the perception of participating in events and knowing facts. (Publisher)

Negyessy, Laszlo, et al. Convergence and Divergence are Mostly Reciprocated Properties of the Connections in the Network of Cortical Areas. Proceedings of the Royal Society B. 275/2403, 2008. A team of Hungarian neuroscientists report on a systemic complementarity which distinguishes these cortical phenomena, along with a hierarchical division of labor. These findings, if one may reflect, evince once more that a universal dynamics is instantiated in our brains and thought as everywhere else from galaxies to Gaia.

Nern, Aljoscha, et al. Connectome-driven neural inventory of a complete visual system.. bioRxiv.. Some sixty Janelia Research Campus, Howard Hughes Medical Institute neuroscientists achieve a first overall quantification of this cerebral faculty with both detail and expanse. A surmise is then made that although performed on an archetypal insect model its generic format seems extend through life’s evolutionary procession to our curious selves.

Vision provides animals with detailed information such as color, form, and movement across the visual scene. Computing these spatial features requires a large, diverse network of neurons, such that in animals as distant as flies and humans, these regions comprise half the brain’s volume. Here, we report a new connectome mapping of the right optic lobe from a male Drosophila central nervous system. Altogether, this comprehensive set of tools and data unlock new possibilities for systematic investigations of vision in Drosophila, a foundation for a deeper understanding of sensory processing. (Excerpt)

Ng, Renny, et al. Neuronal Compartmentalization: A Means to Integrate Sensory Input at the Earliest Stage of Information Processing. BioEssays. July, 2020. UC San Diego neurobiologists graphically demonstrate how life’s developmental propensity to form functional modules persists from initial rudiments across the span of invertebrate and mammalian species. From the get-go, neural operations are performed by bounded cellular whole units.

In peripheral sense organs, external stimuli are detected by sensory neurons compartmentalized within structures of cuticular or epithelial tissue. Beyond developmental constraints, such compartmentalization allows grouped neurons to functionally interact. Here, we review the prevalence of these units, describe compartmentalized neurons, and consider interactions between cells. Particular attention is paid to insect olfaction with well‐characterized mechanisms of functional, cross‐neuronal interactions. (Abstract excerpt)

Nomura, Tadashi, et al. Reptiles: A New Model for Brain Evo-Devo Research? Journal of Experimental Zoology B. Online January, 2013. Kyoto Prefectural University of Medicine, Ehime University, and National Institute of Neuroscience, Toyko, investigators contend that in the lineage of amniotic, egg laying or bearing, organisms, this ancient Reptilia Class can provide a revealing array of iconic forebears. Telencephalon, diencephalon, optic tectum, cerebellum, and medulla each appear in rudimentary forms. Lizard neurogenesis, for example, can be seen to presage avian and mammalian cerebral plans. Might one then ask, whom as if a similar, nascent global brain/mind is now proceeding altogether to reconstruct this? What kind of an abiding universe tries to learn and achieve, billions of years on, its own self-observation, witness, comprehension, so as to actively, decisively, select itself?

Vertebrate brains exhibit vast amounts of anatomical diversity. In particular, the elaborate and complex nervous system of amniotes is correlated with the size of their behavioral repertoire. However, the evolutionary mechanisms underlying species-specific brain morphogenesis remain elusive. In this review we introduce reptiles as a new model organism for understanding brain evolution. These animal groups inherited ancestral traits of brain architectures. We will describe several unique aspects of the reptilian nervous system with a special focus on the telencephalon, and discuss the genetic mechanisms underlying reptile-specific brain morphology. The establishment of experimental evo-devo approaches to studying reptiles will help to shed light on the origin of the amniote brains. (Abstract)

O’Connell, Lauren. Evolutionary Development of Neural Systems in Vertebrates and Beyond. Journal of Neurogenetics. 27/3, 2013. For this Harvard University, Center for Systems Biology, researcher such a comprehensive reconstruction of how creaturely neurological systems came to be and evolve is now possible. With a full scenario from urchins to us now in view, a consistent, ramifying image as an embryonic development becomes evident. The second quote notes its affinity to the popular “deep homology” model to inform this realization.

The emerging field of “neuro-evo-devo” is beginning to reveal how the molecular and neural substrates that underlie brain function are based on variations in evolutionarily ancient and conserved neurochemical and neural circuit themes. Comparative work across bilaterians is reviewed to highlight how early neural patterning specifies modularity of the embryonic brain, which lays a foundation on which manipulation of neurogenesis creates adjustments in brain size. Small variation within these developmental mechanisms contributes to the evolution of brain diversity. Comparing the specification and spatial distribution of neural phenotypes across bilaterians has also suggested some major brain evolution trends, although much more work on profiling neural connections with neurochemical specificity across a wide diversity of organisms is needed. These comparative approaches investigating the evolution of brain form and function hold great promise for facilitating a mechanistic understanding of how variation in brain morphology, neural phenotypes, and neural networks influences brain function and behavioral diversity across organisms. (Abstract)

Deep homology is a concept born of evo-devo and refers to homologous molecular mechanisms or gene modules involved in homologous phenotypes that are conserved across wide evolutionary distances (Figure 4A). A classic example is eye development across metazoans, where pax genes (especially pax6) are frequently involved in the development of the eye (Shubin et al., 2009). The concept of deep homology has also recently been discussed in the context of brain function (Scharff & Petri, 2011). In the case of deep homology, behaviors that are shared across animals, such as aggression, reproductive behavior, or vocal communication, rely on ancient gene modules that are highly conserved and promote similar behaviors. (11)

O’Connell, Lauren and Hans Hofmann. Evolution of a Vertebrate Social Decision-Making Network. Science. 336/6085, 2012. University of Texas, Austin, neuroscientists offer further insights into a “remarkable conservation” of neural substrates for animal behaviors from life’s earliest multicellular appearance. For a further survey of Decision Theory views see Genes, Hormones, and Circuits by the authors in Frontiers in Neuroendocrinology (32/320, 2011), Evolutionary Themes in the Neurobiology of Social Cognition by Hofmann and Chelsea Weitekamp in Current Opinion in Neurobiology (28/1, 2014), Decision Making: The Neuroethological Turn by John Pearson, et al, in Neuron (82/5, 2014), and a special issue The Principles of Goal-Directed Decision-Making of the Philosophical Transactions of the Royal Society B (3699/1655, 2014).

Animals evaluate and respond to their social environment with adaptive decisions. Revealing the neural mechanisms of such decisions is a major goal in biology. We analyzed expression profiles for 10 neurochemical genes across 12 brain regions important for decision-making in 88 species representing five vertebrate lineages. We found that behaviorally relevant brain regions are remarkably conserved over 450 million years of evolution. We also find evidence that different brain regions have experienced different selection pressures, because spatial distribution of neuroendocrine ligands are more flexible than their receptors across vertebrates. Our analysis suggests that the diversity of social behavior in vertebrates can be explained, in part, by variations on a theme of conserved neural and gene expression networks. (O’Connell Abstract)

Neuroeconomics applies models from economics and psychology to inform neurobiological studies of choice. Such observations have led theorists to hypothesize a single, unified decision process that mediates choice behavior via a common neural currency. In parallel, recent neuroethological studies of decision making have focused on natural behaviors like foraging, mate choice, and social interactions. These decisions strongly impact evolutionary fitness and thus are likely to have played a key role in shaping the neural circuits that mediate decision making. This approach has revealed a suite of computational motifs that appear to be shared across a wide variety of organisms. We argue that the existence of deep homologies in the neural circuits mediating choice may have profound implications for understanding human decision making in health and disease. (Pearson Abstract)

Phelps, Steven. Like Minds: Evolutionary Convergence in Nervous Systems. Trends in Ecology & Evolution. 17/4, 2002. A conference summary of how both somatic and mental development employ common solutions.

Premack, David. Human and Animal Cognition. Proceedings of the National Academy of Sciences. 104/13861, 2007. The University of Pennsylvania primatologist argues that although an evolutionary continuity exists with our chimpanzee ancestors, human brains possess a greatly enhanced inter-connectivity. As a result, eight domains are cited that set us quite apart: teaching, short-term memory, causal reasoning, planning, deception, transitive inference, theory of mind, and language.

Reader, Simon and Kevin Laland. Social Intelligence, Innovation and Enhanced Brain Size in Primates. Procedings of the National Academy of Sciences. 99/4436, 2002. An extensive literature search on social learning, invention, and tool use reveals a close correlation between brain size and cognitive capacity.

Redies, Christoph and Luis Puelles. Modularity in Vertebrate Brain Development and Evolution. BioEssays. 23/12, 2001. Semi-autonomous, diverse modules are at work in both the embryonic and functional phases of cerebral formation. Here is another example of the constant modularity throughout the biological kingdom.

It is thought that modularity plays an important role in the evolutionary divergence of species, because modularity allows for adaptive modification of form and function of individual body parts while, at the same time, keeping the general developmental basic plan (Bauplan) of the organism the same. (1100)

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