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

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

Montgomery, Stephen, et al. Brain Evolution and Development. Proceedings of the Royal Society B. Vol. 283, Iss. 1838, 2016. Montgomery, a University College London geneticist, with Nicholas Mundy, Cambridge University zoology, and Robert Barton, Durham University anthropology, post a mid 2010s review from their angle, of how brains employ a either a more “concerted” mode whence modular areas evolve together, or a “mosaic” manner where they develop at different rates. Barton has long favored the latter, in contrast to Barbara Finlay and Richard Darlington (search) who proposed the former. See Principles of Brain Evolution by Georg Striedter herein for a balanced treatment.

Phenotypic traits are products of two processes: evolution and development. But how do these processes combine to produce integrated phenotypes? Comparative studies identify consistent patterns of covariation, or allometries, between brain and body size, and between brain components, indicating the presence of significant constraints limiting independent evolution of separate parts. These constraints are poorly understood, but in principle could be either developmental or functional. The developmental constraints hypothesis suggests that individual components (brain and body size, or individual brain components) tend to evolve together because natural selection operates on relatively simple developmental mechanisms that affect the growth of all parts in a concerted manner. The functional constraints hypothesis suggests that correlated change reflects the action of selection on distributed functional systems connecting the different sub-components, predicting more complex patterns of mosaic change at the level of the functional systems and more complex genetic and developmental mechanisms. These hypotheses are not mutually exclusive but make different predictions. We review recent genetic and neurodevelopmental evidence, concluding that functional rather than developmental constraints are the main cause of the observed patterns. (Abstract)

Montiel, Juan and Francisco Aboitiz. Homology in Amniote Brain Evolution. Brain, Behavior and Evolution. 91/2, 2018. From our late global vantage, Chilean neuroscientists can survey past years and decades of neural anatomy studies in a wide context of their embryo-forming mammal, avian, and reptilian occasion. As a result, a shared, repetitive ancestry in kind of genomic circuitry can be seen to persist across this evolutionary heritage. A closing paragraph alludes to a recapitulation of phylogeny and ontogeny. See also From Sauropsids to Mammals and Back: New Approaches to Comparative Cortical Development by Juan Montiel, et al in the Journal of Comparative Neurology (524/3, 2016).

The cerebral hemispheres are the most expanded brain region in most vertebrate lineages, which are generally associated with increases in behavioral complexity. In association with these expansions, the dorsal component of the hemispheres (the pallium) develops diverging morphologies in the various vertebrate classes, making it very difficult to establish correspondences between groups. The best-studied vertebrates in this sense are birds and mammals, which have both developed large brains and elaborate cognitive abilities. Comparing these two types of pallial organizations and establishing homologies between them has been a major challenge for evolutionary neuroanatomy for about a century. Recently, high-throughput analyses of all active transcripts have become a powerful method for comparing brain regions among species and for inferring homologies. (Abstract excerpt)

Moore, Brian. The Evolution of Learning. Biological Reviews. 79/2, 2004. An attempt to draw an “evolutionary cladogram” of pathways for the many modes of animal cerebration such as mimicry, imprinting and imitation. Moore then states that by this scheme, a recapitulation is evident for learning sequences between the ontogeny of an individual organism and the phylogeny of its species.

Morhardt, Ashley. From Fossils to Function: Integrative and Taxonomically Inclusive Approaches to Vertebrate Evolutionary Neuroscience. Brain, Behavior and Evolution. 91/3, 2018. A Washington University neuroscientist introduces this special issue from a 2017 Karger Workshop in Maryland with this title. Among the select papers are Human Paleoneurology and the Evolution of the Parietal Cortex by Emiliano Bruner, Development and Evolution of Cerebral and Cerebellar Cortex by D. Van Essen, et al, and Comparative Primate Connectomics by J. K. Rilling and M. van den Heuvel.

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)

Noorman, Marcella, et al. Maintaining and updating accurate internal representations of continuous variables with a handful of neurons.. Nature Neuroscience.. 27/2207, 2024. As a whole scale reconstruction of life’s evolutionary neural-like faculties and cognitive stirrings becomes filled in and quantified, Janelia Research Campus, Howard Hughes Medical Institute neuroresearchers including Ann Hermundstad begin to realize the actual presence of intelligent behaviors from its insect rudiments. One could record that into 2025, a retrospective observation has been achieved which sets aside an old gradual course from dim brute senses. By our Earthuman discovery, an original high level of mental performance, regardless of nervous system size or type, seems to be in place from the earliest onset. A further notice in a personal ecosmos might even allow a common, independent repertoire which is then accessible to any creaturely organism and group.

Many animals rely on persistent internal representations for working memory, navigation, and motor control. Existing theories assume that large networks of neurons are required to achieve this. We show analytically that even very small networks can be tuned to maintain continuous representations. This work expands the computational repertoire of small networks, and raises the possibility that larger networks could represent more and higher-dimensional variables than previously thought. (Excerpt)

While these results were interpreted in the context of Drosophila, they generalize to other scenarios. Our results suggest that such acuity could be maintained using few neurons, thereby broadening the classes of computations that could be performed by small circuits. More broadly, the ability to represent variables using small numbers of neurons could enable large systems to perceive multiple continuous variables, such as observed in the rodent hippocampus. (10)

The ability of small brains to perform tasks thought to require larger systems reveals a fundamental adaptability in neural computation. These findings underscore the efficiency of evolution, showing that even tiny networks can achieve extraordinary feats. Ultimately, the fruit fly’s internal compass demonstrates that size is no limitation to complexity. The lessons learned from these small networks may illuminate the universal principles of computation that underlie all brain functions from simple organisms to humans. (Brighter Side of News review)

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)

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