How the evolution of air breathing shaped hippocampal function

To make maps from airborne odours requires dynamic respiratory patterns. I propose that this constraint explains the modulation of memory by nasal respiration in mammals, including murine rodents (e.g. laboratory mouse, laboratory rat) and humans. My prior theories of limbic system evolution offer a framework to understand why this occurs. The answer begins with the evolution of nasal respiration in Devonian lobe-finned fishes. This evolutionary innovation led to adaptive radiations in chemosensory systems, including the emergence of the vomeronasal system and a specialization of the main olfactory system for spatial orientation. As mammals continued to radiate into environments hostile to spatial olfaction (air, water), there was a loss of hippocampal structure and function in lineages that evolved sensory modalities adapted to these new environments. Hence the independent evolution of echolocation in bats and toothed whales was accompanied by a loss of hippocampal structure (whales) and an absence of hippocampal theta oscillations during navigation (bats). In conclusion, models of hippocampal function that are divorced from considerations of ecology and evolution fall short of explaining hippocampal diversity across mammals and even hippocampal function in humans. This article is part of the theme issue ‘Systems neuroscience through the lens of evolutionary theory’.

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Strong links between genomic and anatomical diversity in both mammalian olfactory chemosensory systems

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2013.2828 ◽

2014 ◽

Vol 281 (1783) ◽

pp. 20132828 ◽

Cited By ~ 18

Author(s):

Eva C. Garrett ◽

Michael E. Steiper

Keyword(s):

Olfactory System ◽

Anatomical Variation ◽

Relative Proportion ◽

Genomic Evolution ◽

Vomeronasal System ◽

Qualitative Evidence ◽

Signature Of Selection ◽

Olfactory Systems ◽

Main Olfactory System ◽

Chemosensory Systems

Mammalian olfaction comprises two chemosensory systems: the odorant-detecting main olfactory system (MOS) and the pheromone-detecting vomeronasal system (VNS). Mammals are diverse in their anatomical and genomic emphases on olfactory chemosensation, including the loss or reduction of these systems in some orders. Despite qualitative evidence linking the genomic evolution of the olfactory systems to specific functions and phenotypes, little work has quantitatively tested whether the genomic aspects of the mammalian olfactory chemosensory systems are correlated to anatomical diversity. We show that the genomic and anatomical variation in these systems is tightly linked in both the VNS and the MOS, though the signature of selection is different in each system. Specifically, the MOS appears to vary based on absolute organ and gene family size while the VNS appears to vary according to the relative proportion of functional genes and relative anatomical size and complexity. Furthermore, there is little evidence that these two systems are evolving in a linked fashion. The relationships between genomic and anatomical diversity strongly support a role for natural selection in shaping both the anatomical and genomic evolution of the olfactory chemosensory systems in mammals.

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The Organization and Function of the Vomeronasal System

Annual Review of Neuroscience ◽

10.1146/annurev.ne.10.030187.001545 ◽

1987 ◽

Vol 10 (1) ◽

pp. 325-362 ◽

Cited By ~ 496

Author(s):

M Halpern

Keyword(s):

Vomeronasal System ◽

And Function

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Environmental–biomechanical reciprocity and the evolution of plant material properties

Journal of Experimental Botany ◽

10.1093/jxb/erab411 ◽

2021 ◽

Author(s):

Karl J Niklas ◽

Frank W Telewski

Keyword(s):

Physical Environment ◽

Structural Changes ◽

Abiotic Factors ◽

Biotic Interactions ◽

Cellular Solids ◽

Form And Function ◽

Evolutionary Innovation ◽

Plant Form ◽

And Function ◽

Abiotic Environmental Factors

Abstract Abiotic–biotic interactions have shaped organic evolution since life first began. Abiotic factors influence growth, survival, and reproductive success, whereas biotic responses to abiotic factors have changed the physical environment (and indeed created new environments). This reciprocity is well illustrated by land plants who begin and end their existence in the same location while growing in size over the course of years or even millennia, during which environment factors change over many orders of magnitude. A biomechanical, ecological, and evolutionary perspective reveals that plants are (i) composed of materials (cells and tissues) that function as cellular solids (i.e. materials composed of one or more solid and fluid phases); (ii) that have evolved greater rigidity (as a consequence of chemical and structural changes in their solid phases); (iii) allowing for increases in body size and (iv) permitting acclimation to more physiologically and ecologically diverse and challenging habitats; which (v) have profoundly altered biotic as well as abiotic environmental factors (e.g. the creation of soils, carbon sequestration, and water cycles). A critical component of this evolutionary innovation is the extent to which mechanical perturbations have shaped plant form and function and how form and function have shaped ecological dynamics over the course of evolution.

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Effects of Glucocorticoids on Age-Related Impairments of Hippocampal Structure and Function in Mice

Cellular and Molecular Neurobiology ◽

10.1007/s10571-007-9180-y ◽

2007 ◽

Vol 28 (2) ◽

pp. 277-291 ◽

Cited By ~ 22

Author(s):

Wen-Bin He ◽

Jun-Long Zhang ◽

Jin-Feng Hu ◽

Yun Zhang ◽

Takeo Machida ◽

...

Keyword(s):

Structure And Function ◽

Age Related ◽

And Function ◽

Hippocampal Structure

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A Neural Model of Intrinsic and Extrinsic Hippocampal Theta Rhythms: Anatomy, Neurophysiology, and Function

Frontiers in Systems Neuroscience ◽

10.3389/fnsys.2021.665052 ◽

2021 ◽

Vol 15 ◽

Author(s):

Stephen Grossberg

Keyword(s):

Entorhinal Cortex ◽

Category Learning ◽

Neural Model ◽

Brain Regions ◽

Beta Oscillations ◽

Emotional Processes ◽

Theoretical Synthesis ◽

Multiple Species ◽

And Function ◽

Hippocampal Theta

This article describes a neural model of the anatomy, neurophysiology, and functions of intrinsic and extrinsic theta rhythms in the brains of multiple species. Topics include how theta rhythms were discovered; how theta rhythms organize brain information processing into temporal series of spatial patterns; how distinct theta rhythms occur within area CA1 of the hippocampus and between the septum and area CA3 of the hippocampus; what functions theta rhythms carry out in different brain regions, notably CA1-supported functions like learning, recognition, and memory that involve visual, cognitive, and emotional processes; how spatial navigation, adaptively timed learning, and category learning interact with hippocampal theta rhythms; how parallel cortical streams through the lateral entorhinal cortex (LEC) and the medial entorhinal cortex (MEC) represent the end-points of the What cortical stream for perception and cognition and the Where cortical stream for spatial representation and action; how the neuromodulator acetylcholine interacts with the septo-hippocampal theta rhythm and modulates category learning; what functions are carried out by other brain rhythms, such as gamma and beta oscillations; and how gamma and beta oscillations interact with theta rhythms. Multiple experimental facts about theta rhythms are unified and functionally explained by this theoretical synthesis.

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From Pheromones to Behavior

Physiological Reviews ◽

10.1152/physrev.00037.2008 ◽

2009 ◽

Vol 89 (3) ◽

pp. 921-956 ◽

Cited By ~ 195

Author(s):

Roberto Tirindelli ◽

Michele Dibattista ◽

Simone Pifferi ◽

Anna Menini

Keyword(s):

Current Knowledge ◽

Reproductive Physiology ◽

Vomeronasal System ◽

Standard View ◽

Functional Roles ◽

Pheromonal Communication ◽

Olfactory Systems ◽

Molecular Aspects ◽

Main Olfactory System ◽

And Behavior

In recent years, considerable progress has been achieved in the comprehension of the profound effects of pheromones on reproductive physiology and behavior. Pheromones have been classified as molecules released by individuals and responsible for the elicitation of specific behavioral expressions in members of the same species. These signaling molecules, often chemically unrelated, are contained in body fluids like urine, sweat, specialized exocrine glands, and mucous secretions of genitals. The standard view of pheromone sensing was based on the assumption that most mammals have two separated olfactory systems with different functional roles: the main olfactory system for recognizing conventional odorant molecules and the vomeronasal system specifically dedicated to the detection of pheromones. However, recent studies have reexamined this traditional interpretation showing that both the main olfactory and the vomeronasal systems are actively involved in pheromonal communication. The current knowledge on the behavioral, physiological, and molecular aspects of pheromone detection in mammals is discussed in this review.

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Centromeres under Pressure: Evolutionary Innovation in Conflict with Conserved Function

Genes ◽

10.3390/genes11080912 ◽

2020 ◽

Vol 11 (8) ◽

pp. 912 ◽

Cited By ~ 1

Author(s):

Elisa Balzano ◽

Simona Giunta

Keyword(s):

Genome Instability ◽

Dynamic Features ◽

Sequence Composition ◽

Evolutionary Innovation ◽

Microtubule Attachment ◽

Meiotic Transmission ◽

Secondary Dna Structures ◽

Dna 2 ◽

And Function ◽

Mitosis And Meiosis

Centromeres are essential genetic elements that enable spindle microtubule attachment for chromosome segregation during mitosis and meiosis. While this function is preserved across species, centromeres display an array of dynamic features, including: (1) rapidly evolving DNA; (2) wide evolutionary diversity in size, shape and organization; (3) evidence of mutational processes to generate homogenized repetitive arrays that characterize centromeres in several species; (4) tolerance to changes in position, as in the case of neocentromeres; and (5) intrinsic fragility derived by sequence composition and secondary DNA structures. Centromere drive underlies rapid centromere DNA evolution due to the “selfish” pursuit to bias meiotic transmission and promote the propagation of stronger centromeres. Yet, the origins of other dynamic features of centromeres remain unclear. Here, we review our current understanding of centromere evolution and plasticity. We also detail the mutagenic processes proposed to shape the divergent genetic nature of centromeres. Changes to centromeres are not simply evolutionary relics, but ongoing shifts that on one side promote centromere flexibility, but on the other can undermine centromere integrity and function with potential pathological implications such as genome instability.

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Epigenetic Regulation of the Hippocampus, with Special Reference to Radiation Exposure

International Journal of Molecular Sciences ◽

10.3390/ijms21249514 ◽

2020 ◽

Vol 21 (24) ◽

pp. 9514

Author(s):

Genevieve Saw ◽

Feng Ru Tang

Keyword(s):

Epigenetic Regulation ◽

Molecular Mechanisms ◽

Cell Types ◽

Epigenetic Changes ◽

Epigenetic Factors ◽

Hippocampal Function ◽

Neuropsychological Disorders ◽

Radiation Induced ◽

Non Coding Rnas ◽

And Function

The hippocampus is crucial in learning, memory and emotion processing, and is involved in the development of different neurological and neuropsychological disorders. Several epigenetic factors, including DNA methylation, histone modifications and non-coding RNAs, have been shown to regulate the development and function of the hippocampus, and the alteration of epigenetic regulation may play important roles in the development of neurocognitive and neurodegenerative diseases. This review summarizes the epigenetic modifications of various cell types and processes within the hippocampus and their resulting effects on cognition, memory and overall hippocampal function. In addition, the effects of exposure to radiation that may induce a myriad of epigenetic changes in the hippocampus are reviewed. By assessing and evaluating the current literature, we hope to prompt a more thorough understanding of the molecular mechanisms that underlie radiation-induced epigenetic changes, an area which can be further explored.

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