Brain Size and Visual Environment Predict Species Differences in Paper Wasp Sensory Processing Brain Regions (Hymenoptera: Vespidae, Polistinae)

The extent to which size constrains the evolution of brain organization and the genesis of complex behaviour is a central, unanswered question in evolutionary neuroscience. Advanced cognition has long been linked to the expansion of specific brain compartments, such as the neocortex in vertebrates and the mushroom bodies in insects. Scaling constraints that limit the size of these brain regions in small animals may therefore be particularly significant to behavioural evolution. Recent findings from studies of paper wasps suggest miniaturization constrains the size of central sensory processing brain centres (mushroom body calyces) in favour of peripheral, sensory input centres (antennal and optic lobes). We tested the generality of this hypothesis in diverse eusocial hymenopteran species (ants, bees and wasps) exhibiting striking variation in body size and thus brain size. Combining multiple neuroanatomical datasets from these three taxa, we found no universal size constraint on brain organization within or among species. In fact, small-bodied ants with miniscule brains had mushroom body calyces proportionally as large as or larger than those of wasps and bees with brains orders of magnitude larger. Our comparative analyses suggest that brain organization in ants is shaped more by natural selection imposed by visual demands than intrinsic design limitations.

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Allometry unleashed: an adaptationist approach of brain scaling in mammalian evolution

10.7287/peerj.preprints.27872 ◽

2019 ◽

Cited By ~ 1

Author(s):

Romain Willemet

Keyword(s):

Body Size ◽

Allometric Scaling ◽

Species Differences ◽

Brain Size ◽

Brain Evolution ◽

Neural Systems ◽

Selection Pressures ◽

Number Of Factors ◽

Functional Consequences ◽

Main Factor

The idea that allometry in the context of brain evolution mainly result from constraints channelling the scaling of brain components is deeply embedded in the field of comparative neurobiology. Constraints, however, only prevent or limit changes, and cannot explain why these changes happen in the first place. In fact, considering allometry as a lack of change may be one of the reasons why, after more than a century of research, there is still no satisfactory explanatory framework for the understanding of species differences in brain size and composition in mammals. The present paper attempts to tackle this issue by adopting an adaptationist approach to examine the factors behind the evolution of brain components. In particular, the model presented here aims to explain the presence of patterns of covariation among brain components found within major taxa, and the differences between taxa. The key determinant of these patterns of covariation within a taxon-cerebrotype (groups of species whose brains present a number of similarities at the physiological and anatomical levels) seems to be the presence of taxon-specific patterns of selection pressures targeting the functional and structural properties of neural components or systems. Species within a taxon share most of the selection pressures, but their levels scale with a number of factors that are often related to body size. The size and composition of neural systems respond to these selection pressures via a number of evolutionary scenarios, which are discussed here. Adaptation, rather than, as generally assumed, developmental or functional constraints, thus appears to be the main factor behind the allometric scaling of brain components. The fact that the selection pressures acting on the size of brain components form a pattern that is specific to each taxon accounts for the peculiar relationship between body size, brain size and composition, and behavioural capabilities characterizing each taxon. While it is important to avoid repeating the errors of the “Panglossian paradigm”, the elements presented here suggests that an adaptationist approach may shed a new light on the factors underlying, and the functional consequences of, species differences in brain size and composition.

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Going beyond rote auditory learning: Neural patterns of generalized auditory learning

10.1101/2020.12.30.424903 ◽

2021 ◽

Author(s):

Shannon L.M. Heald ◽

Stephen C. Van Hedger ◽

John Veillette ◽

Katherine Reis ◽

Joel S. Snyder ◽

...

Keyword(s):

Speech Perception ◽

Sensory Processing ◽

Auditory Processing ◽

Auditory Evoked Potentials ◽

Brain Regions ◽

Auditory Evoked Potential ◽

Cortical Processing ◽

Rote Learning ◽

Neural Responses ◽

Auditory Learning

AbstractThe ability to generalize rapidly across specific experiences is vital for robust recognition of new patterns, especially in speech perception considering acoustic-phonetic pattern variability. Behavioral research has demonstrated that listeners are rapidly able to generalize their experience with a talker’s speech and quickly improve understanding of a difficult-to-understand talker without prolonged practice, e.g., even after a single training session. Here, we examine the differences in neural responses to generalized versus rote learning in auditory cortical processing by training listeners to understand a novel synthetic talker using a Pretest-Posttest design with electroencephalography (EEG). Participants were trained using either (1) a large inventory of words where no words repeated across the experiment (generalized learning) or (2) a small inventory of words where words repeated (rote learning). Analysis of long-latency auditory evoked potentials at Pretest and Posttest revealed that while rote and generalized learning both produce rapid changes in auditory processing, the nature of these changes differed. In the context of adapting to a talker, generalized learning is marked by an amplitude reduction in the N1-P2 complex and by the presence of a late-negative (LN) wave in the auditory evoked potential following training. Rote learning, however, is marked only by temporally later source configuration changes. The early N1-P2 change, found only for generalized learning, suggests that generalized learning relies on the attentional system to reorganize the way acoustic features are selectively processed. This change in relatively early sensory processing (i.e. during the first 250ms) is consistent with an active processing account of speech perception, which proposes that the ability to rapidly adjust to the specific vocal characteristics of a new talker (for which rote learning is rare) relies on attentional mechanisms to adaptively tune early auditory processing sensitivity.Statement of SignificancePrevious research on perceptual learning has typically examined neural responses during rote learning: training and testing is carried out with the same stimuli. As a result, it is not clear that findings from these studies can explain learning that generalizes to novel patterns, which is critical in speech perception. Are neural responses to generalized learning in auditory processing different from neural responses to rote learning? Results indicate rote learning of a particular talker’s speech involves brain regions focused on the memory encoding and retrieving of specific learned patterns, whereas generalized learning involves brain regions involved in reorganizing attention during early sensory processing. In learning speech from a novel talker, only generalized learning is marked by changes in the N1-P2 complex (reflective of secondary auditory cortical processing). The results are consistent with the view that robust speech perception relies on the fast adjustment of attention mechanisms to adaptively tune auditory sensitivity to cope with acoustic variability.

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Convergent mosaic brain evolution is associated with the evolution of novel electrosensory systems in teleost fishes

10.1101/2021.09.29.462233 ◽

2021 ◽

Author(s):

Erika L. Schumacher ◽

Bruce A. Carlson

Keyword(s):

Brain Region ◽

Brain Size ◽

Brain Evolution ◽

Brain Regions ◽

Torus Semicircularis ◽

Micro Computed Tomography ◽

Electrosensory System ◽

Electric Fishes ◽

Weakly Electric ◽

Region Size

AbstractBrain region size generally scales allometrically with total brain size, but mosaic shifts in brain region size independent of brain size have been found in several lineages and may be related to the evolution of behavioral novelty. African weakly electric fishes (Mormyroidea) evolved a mosaically enlarged cerebellum and hindbrain, yet the relationship to their behaviorally novel electrosensory system remains unclear. We addressed this by studying South American weakly electric fishes (Gymnotiformes) and weakly electric catfishes (Synodontis spp.), which evolved varying aspects of electrosensory systems, independent of mormyroids. If the mormyroid mosaic increases are related to evolving an electrosensory system, we should find similar mosaic shifts in gymnotiforms and Synodontis. Using micro-computed tomography scans, we quantified brain region scaling for multiple electrogenic, electroreceptive, and non-electrosensing species. We found mosaic increases in cerebellum in all three electrogenic lineages relative to non-electric lineages and mosaic increases in torus semicircularis and hindbrain associated with the evolution of electrogenesis and electroreceptor type. These results show that evolving novel electrosensory systems is repeatedly and independently associated with changes in the sizes of individual brain regions independent of brain size, which suggests that selection can impact structural brain composition to favor specific regions involved in novel behaviors.

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Quantitative genetic analysis of brain size variation in sticklebacks: support for the mosaic model of brain evolution

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2015.1008 ◽

2015 ◽

Vol 282 (1810) ◽

pp. 20151008 ◽

Cited By ~ 25

Author(s):

Kristina Noreikiene ◽

Gábor Herczeg ◽

Abigél Gonda ◽

Gergely Balázs ◽

Arild Husby ◽

...

Keyword(s):

Body Size ◽

Brain Size ◽

Additive Genetic Variance ◽

Genetic Correlations ◽

Relative Size ◽

Strong Support ◽

Brain Evolution ◽

Brain Regions ◽

Independent Evolution ◽

Mosaic Model

The mosaic model of brain evolution postulates that different brain regions are relatively free to evolve independently from each other. Such independent evolution is possible only if genetic correlations among the different brain regions are less than unity. We estimated heritabilities, evolvabilities and genetic correlations of relative size of the brain, and its different regions in the three-spined stickleback ( Gasterosteus aculeatus ). We found that heritabilities were low (average h 2 = 0.24), suggesting a large plastic component to brain architecture. However, evolvabilities of different brain parts were moderate, suggesting the presence of additive genetic variance to sustain a response to selection in the long term. Genetic correlations among different brain regions were low (average r G = 0.40) and significantly less than unity. These results, along with those from analyses of phenotypic and genetic integration, indicate a high degree of independence between different brain regions, suggesting that responses to selection are unlikely to be severely constrained by genetic and phenotypic correlations. Hence, the results give strong support for the mosaic model of brain evolution. However, the genetic correlation between brain and body size was high ( r G = 0.89), suggesting a constraint for independent evolution of brain and body size in sticklebacks.

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Brain regions associated with visual cues are important for bird migration

Biology Letters ◽

10.1098/rsbl.2015.0678 ◽

2015 ◽

Vol 11 (11) ◽

pp. 20150678 ◽

Cited By ~ 11

Author(s):

Orsolya Vincze ◽

Csongor I. Vágási ◽

Péter L. Pap ◽

Gergely Osváth ◽

Anders Pape Møller

Keyword(s):

Visual Cues ◽

Optic Lobe ◽

Brain Size ◽

Relative Size ◽

Bird Species ◽

Interspecific Variation ◽

Brain Regions ◽

Long Distance ◽

Migration Distance ◽

Whole Brain

Long-distance migratory birds have relatively smaller brains than short-distance migrants or residents. Here, we test whether reduction in brain size with migration distance can be generalized across the different brain regions suggested to play key roles in orientation during migration. Based on 152 bird species, belonging to 61 avian families from six continents, we show that the sizes of both the telencephalon and the whole brain decrease, and the relative size of the optic lobe increases, while cerebellum size does not change with increasing migration distance. Body mass, whole brain size, optic lobe size and wing aspect ratio together account for a remarkable 46% of interspecific variation in average migration distance across bird species. These results indicate that visual acuity might be a primary neural adaptation to the ecological challenge of migration.

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Synthesis

Brains Through Time ◽

10.1093/oso/9780195125689.003.0007 ◽

2019 ◽

pp. 423-472

Author(s):

Georg F. Striedter ◽

R. Glenn Northcutt

Keyword(s):

Functional Organization ◽

Brain Size ◽

Brain Regions ◽

Brain Areas ◽

Nervous Systems ◽

Internal Organization ◽

Vertebrate Brain ◽

Relative Brain Size

After summarizing the earlier chapters, which focused on the evolution of specific lineages, this chapter examines general patterns in the evolution of vertebrate nervous systems. Most conspicuous is that relative brain size and complexity increased independently in many lineages. The proportional size of individual brain regions tends to change predictably with absolute brain size (and neurogenesis timing), but the scaling rules vary across lineages. Attempts to link variation in the size of individual brain areas (or entire brains) to behavior are complicated in part because the connections, internal organization, and functions of individual brain regions also vary across phylogeny. In addition, major changes in the functional organization of vertebrate brains were caused by the emergence of novel brain regions (e.g., neocortex in mammals and area dorsalis centralis in teleosts) and novel circuits. These innovations significantly modified the “vertebrate brain Bauplan,” but their mechanistic origins and implications require further investigation.

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Neural Connectivity Subtypes Predict Discrete Attentional-Bias Profiles Among Heterogeneous Anxiety Patients

Clinical Psychological Science ◽

10.1177/2167702620906149 ◽

2020 ◽

Vol 8 (3) ◽

pp. 491-505 ◽

Cited By ~ 2

Author(s):

Rebecca B. Price ◽

Adriene M. Beltz ◽

Mary L. Woody ◽

Logan Cummings ◽

Danielle Gilchrist ◽

...

Keyword(s):

Functional Connectivity ◽

Selective Attention ◽

Attentional Bias ◽

Sensory Processing ◽

Brain Regions ◽

Data Driven ◽

Neural Connectivity ◽

Group Level ◽

Behavioral Measures ◽

Substantial Heterogeneity

On average, anxious patients show altered attention to threat—including early vigilance toward threat and later avoidance of threat—accompanied by altered functional connectivity across brain regions. However, substantial heterogeneity within clinical, neural, and attentional features of anxiety is overlooked in typical group-level comparisons. We used a well-validated method for data-driven parsing of neural connectivity to reveal connectivity-based subgroups among 60 adults with transdiagnostic anxiety. Subgroups were externally compared on attentional patterns derived from independent behavioral measures. Two subgroups emerged. Subgroup A (68% of patients) showed stronger executive network influences on sensory processing regions and a paradigmatic “vigilance–avoidance” pattern on external behavioral measures. Subgroup B was defined by a larger number of limbic influences on sensory regions and exhibited a more atypical and inconsistent attentional profile. Neural connectivity-based categorization revealed an atypical, limbic-driven pattern of connectivity in a subset of anxious patients that generalized to atypical patterns of selective attention.

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Shifts in brain regions with brain size

Science ◽

10.1126/science.360.6394.1198-o ◽

2018 ◽

Vol 360 (6394) ◽

pp. 1198.15-1200

Author(s):

Pamela J. Hines

Keyword(s):

Brain Size ◽

Brain Regions

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Selection for reduced fear in red junglefowl changes brain composition and affects fear memory

Royal Society Open Science ◽

10.1098/rsos.200628 ◽

2020 ◽

Vol 7 (8) ◽

pp. 200628

Author(s):

Rebecca Katajamaa ◽

Per Jensen

Keyword(s):

Body Size ◽

Brain Size ◽

Prior Experience ◽

Fear Memory ◽

Brain Regions ◽

Preference Learning ◽

Response To Selection ◽

Red Junglefowl ◽

Selection For ◽

Region Size

Brain size reduction is a common trait in domesticated species when compared to wild conspecifics. This reduction can happen through changes in individual brain regions as a response to selection on specific behaviours. We selected red junglefowl for 10 generations for diverging levels of fear towards humans and measured brain size and composition as well as habituation learning and conditioned place preference learning in young chicks. Brain size relative to body size as well as brainstem region size relative to whole brain size were significantly smaller in chicks selected for low fear of humans compared to chicks selected for high fear of humans. However, when including allometric effects in the model, these differences disappear but a tendency towards larger cerebra in low-fear chickens remains. Low-fear line chicks habituated more effectively to a fearful stimulus with prior experience of that same stimulus, whereas high-fear line chicks with previous experience of the stimulus had a response similar to naive chicks. The phenotypical changes are in line with previously described effects of domestication.

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