Does emotional state influence motor lateralization in California sea lions (<Emphasis Type="Italic">Zalophus californianus</Emphasis>)?

Motor lateralization is a behavioural asymmetry between the left and the right side of an individual due to hemispheric specialization. The right hemisphere controls the left side of the body and the left hemisphere the right side. The right hemisphere processes negative emotions such as fear and frustration, and on the contrary, the left hemisphere processes positive emotions such as happiness. This study, conducted at Parc Asterix Delphinarium (Plailly, France), tested the influence of supposedly positive, negative and neutral emotional situations on four California sea lions’ (Zalophus californianus) motor lateralization while performing a known exercise, here climbing on a stool. Latency between the caretakers’ command and the animals’ response was recorded. The results showed an interindividual variability in the effect of the supposed emotional situations on their motor lateralization and their response latency. The nature and the strength of this effect require deeper investigation by further studies, on a larger number of individuals and contexts.     

Cognitive alterations in motor imagery process after left hemispheric ischemic stroke

Background

Motor imagery training is a promising rehabilitation strategy for stroke patients. However, few studies had focused on the neural mechanisms in time course of its cognitive process. This study investigated the cognitive alterations after left hemispheric ischemic stroke during motor imagery task.

Methodology/Principal Findings

Eleven patients with ischemic stroke in left hemisphere and eleven age-matched control subjects participated in mental rotation task (MRT) of hand pictures. Behavior performance, event-related potential (ERP) and event-related (de)synchronization (ERD/ERS) in beta band were analyzed to investigate the cortical activation. We found that: (1) The response time increased with orientation angles in both groups, called “angle effect”, however, stoke patients’ responses were impaired with significantly longer response time and lower accuracy rate; (2) In early visual perceptual cognitive process, stroke patients showed hypo-activations in frontal and central brain areas in aspects of both P200 and ERD; (3) During mental rotation process, P300 amplitude in control subjects decreased while angle increased, called “amplitude modulation effect”, which was not observed in stroke patients. Spatially, patients showed significant lateralization of P300 with activation only in contralesional (right) parietal cortex while control subjects showed P300 in both parietal lobes. Stroke patients also showed an overall cortical hypo-activation of ERD during this sub-stage; (4) In the response sub-stage, control subjects showed higher ERD values with more activated cortical areas particularly in the right hemisphere while angle increased, named “angle effect”, which was not observed in stroke patients. In addition, stroke patients showed significant lower ERD for affected hand (right) response than that for unaffected hand.

Conclusions/Significance

Cortical activation was altered differently in each cognitive sub-stage of motor imagery after left hemispheric ischemic stroke. These results will help to understand the underlying neural mechanisms of mental rotation following stroke and may shed light on rehabilitation based on motor imagery training.     

The costs of hemispheric specialization in a fish

Laboratory and field studies have documented better cognitive performance associated with marked hemispheric specialization in organisms as diverse as chimpanzees, domestic chicks and topminnows. While providing an evolutionary explanation for the emergence of cerebral lateralization, this evidence represents a paradox because a large proportion of non-lateralized (NL) individuals is commonly observed in animal populations. Hemispheric specialization often determines large left–right differences in perceiving and responding to stimuli. Using topminnows selected for a high or low degree of lateralization, we tested the hypothesis that individuals with greater functional asymmetry pay a higher performance cost in situations requiring matching information from the two eyes. When trained to use the middle door in a row of a nine, NL fish correctly chose the central door in most cases, while lateralized fish showed systematic leftward or rightward biases. When choosing between two shoals, each seen with a different eye, NL fish chose the high-quality shoal significantly more often than the lateralized fish, whose performance was affected by eye preference for analysing social stimuli. These findings suggest the existence of a trade-off between computational advantages of hemispheric specialization and the ecological cost of making suboptimal decisions whenever relevant information is located on both sides of the body.     

Schizophrenia as Failure of Left Hemispheric Dominance for the Phonological Component of Language

Background

T. J. Crow suggested that the genetic variance associated with the evolution in Homo sapiens of hemispheric dominance for language carries with it the hazard of the symptoms of schizophrenia. Individuals lacking the typical left hemisphere advantage for language, in particular for phonological components, would be at increased risk of the typical symptoms such as auditory hallucinations and delusions.

Methodology/Principal Findings

Twelve schizophrenic patients treated with low levels of neuroleptics and twelve matched healthy controls participated in an event-related potential experiment. Subjects matched word-pairs in three tasks: rhyming/phonological, semantic judgment and word recognition. Slow evoked potentials were recorded from 26 scalp electrodes, and a laterality index was computed for anterior and posterior regions during the inter stimulus interval. During phonological processing individuals with schizophrenia failed to achieve the left hemispheric dominance consistently observed in healthy controls. The effect involved anterior (fronto-temporal) brain regions and was specific for the Phonological task; group differences were small or absent when subjects processed the same stimulus material in a Semantic task or during Word Recognition, i.e. during tasks that typically activate more widespread areas in both hemispheres.

Conclusions/Significance

We show for the first time how the deficit of lateralization in the schizophrenic brain is specific for the phonological component of language. This loss of hemispheric dominance would explain typical symptoms, e.g. when an individual''s own thoughts are perceived as an external intruding voice. The change can be interpreted as a consequence of “hemispheric indecision”, a failure to segregate phonological engrams in one hemisphere.     

Lateralization in Escape Behaviour at Different Hierarchical Levels in a Gecko: Tarentola angustimentalis from Eastern Canary Islands

At the individual level, to be behaviourally lateralized avoids costly duplication of neural circuitry and decreases possible contradictory order from the two brain hemispheres. However, being prey behaviour lateralized at higher hierarchical levels could generate different negative implications, especially if predators are able to make predictions after multiple encounters. These conflicting pressures, namely between the advantages for individuals and the disadvantages for populations could be concealed if higher-level lateralization would arise from the combination of lateralized behaviours of individuals which are mutually dependent. Here, we investigated the lateralization patterns in the escape behaviour of the gecko Tarentola angustimentalis undergoing a predatory attack simulation in a “T” maze experiment. Results showed that gecko populations displayed different degrees of lateralization, with an overall dominance of right-biased individuals. This trend is similar to that observed in the Podarcis wall lizards, which share predators with Tarentola. In addition, different morphological parameters plausible to affect refuge selection were explored in order to link directional asymmetries at morphological level with lateralization during refuge selection.     

Motivation and motor control: hemispheric specialization for approach motivation reverses with handedness

Background

According to decades of research on affective motivation in the human brain, approach motivational states are supported primarily by the left hemisphere and avoidance states by the right hemisphere. The underlying cause of this specialization, however, has remained unknown. Here we conducted a first test of the Sword and Shield Hypothesis (SSH), according to which the hemispheric laterality of affective motivation depends on the laterality of motor control for the dominant hand (i.e., the “sword hand," used preferentially to perform approach actions) and the nondominant hand (i.e., the “shield hand," used preferentially to perform avoidance actions).

Methodology/Principal Findings

To determine whether the laterality of approach motivation varies with handedness, we measured alpha-band power (an inverse index of neural activity) in right- and left-handers during resting-state electroencephalography and analyzed hemispheric alpha-power asymmetries as a function of the participants'' trait approach motivational tendencies. Stronger approach motivation was associated with more left-hemisphere activity in right-handers, but with more right-hemisphere activity in left-handers.

Conclusions

The hemispheric correlates of approach motivation reversed between right- and left-handers, consistent with the way they typically use their dominant and nondominant hands to perform approach and avoidance actions. In both right- and left-handers, approach motivation was lateralized to the same hemisphere that controls the dominant hand. This covariation between neural systems for action and emotion provides initial support for the SSH.     

Hemispheric Asymmetry for Affective Stimulus Processing in Healthy Subjects–A fMRI Study

Background

While hemispheric specialization of language processing is well established, lateralization of emotion processing is still under debate. Several conflicting hypotheses have been proposed, including right hemisphere hypothesis, valence asymmetry hypothesis and region-specific lateralization hypothesis. However, experimental evidence for these hypotheses remains inconclusive, partly because direct comparisons between hemispheres are scarce.

Methods

The present fMRI study systematically investigated functional lateralization during affective stimulus processing in 36 healthy participants. We normalized our functional data on a symmetrical template to avoid confounding effects of anatomical asymmetries. Direct comparison of BOLD responses between hemispheres was accomplished taking two approaches: a hypothesis-driven region of interest analysis focusing on brain areas most frequently reported in earlier neuroimaging studies of emotion; and an exploratory whole volume analysis contrasting non-flipped with flipped functional data using paired t-test.

Results

The region of interest analysis revealed lateralization towards the left in the medial prefrontal cortex (BA 10) during positive stimulus processing; while negative stimulus processing was lateralized towards the right in the dorsolateral prefrontal cortex (BA 9 & 46) and towards the left in the amygdala and uncus. The whole brain analysis yielded similar results and, in addition, revealed lateralization towards the right in the premotor cortex (BA 6) and the temporo-occipital junction (BA 19 & 37) during positive stimulus processing; while negative stimulus processing showed lateralization towards the right in the temporo-parietal junction (BA 37,39,42) and towards the left in the middle temporal gyrus (BA 21).

Conclusion

Our data suggests region-specific functional lateralization of emotion processing. Findings show valence asymmetry for prefrontal cortical areas and left-lateralized negative stimulus processing in subcortical areas, in particular, amygdala and uncus.     

From decision to action: Detailed modelling of frog tadpoles reveals neuronal mechanisms of decision-making and reproduces unpredictable swimming movements in response to sensory signals

How does the brain process sensory stimuli, and decide whether to initiate locomotor behaviour? To investigate this question we develop two whole body computer models of a tadpole. The “Central Nervous System” (CNS) model uses evidence from whole-cell recording to define 2300 neurons in 12 classes to study how sensory signals from the skin initiate and stop swimming. In response to skin stimulation, it generates realistic sensory pathway spiking and shows how hindbrain sensory memory populations on each side can compete to initiate reticulospinal neuron firing and start swimming. The 3-D “Virtual Tadpole” (VT) biomechanical model with realistic muscle innervation, body flexion, body-water interaction, and movement is then used to evaluate if motor nerve outputs from the CNS model can produce swimming-like movements in a volume of “water”. We find that the whole tadpole VT model generates reliable and realistic swimming. Combining these two models opens new perspectives for experiments.     

Floral phenology of an Andean bellflower and pollination by buff‐tailed sicklebill hummingbird

The Andean bellflowers comprise an explosive radiation correlated with shifts to specialized pollination. One diverse clade has evolved with extremely curved floral tubes and is predicted to be pollinated exclusively by one of two parapatric species of sicklebill hummingbirds (Eutoxeres). In this study, we focused on the floral biology of Centropogon granulosus, a bellflower thought to be specialized for pollination by Eutoxeres condamini, in a montane cloud forest site in southeastern Peru. Using camera traps and a pollination exclusion experiment, we documented E. condamini as the sole pollinator of C. granulosus. Visitation by E. condamini was necessary for fruit development. Flowering rates were unequivocally linear and conformed to the “steady‐state” phenological type. Over the course of >1800 h of monitoring, we recorded 12 E. condamini visits totaling 42 s, indicating traplining behavior. As predicted by its curved flowers, C. granulosus is exclusively pollinated by buff‐tailed sicklebill within our study area. We present evidence for the congruence of phenology and visitation as a driver of specialization in this highly diverse clade of Andean bellflowers.     

Potassium Channels in Motor Cells of Samanea saman: A Patch-Clamp Study

Leaflet movements in Samanea saman are driven by the shrinking and swelling of cells in opposing (extensor and flexor) regions of the motor organ (pulvinus). Changes in cell volume, in turn, depend upon large changes in motor cell content of K⁺, Cl⁻ and other ions. We performed patch-clamp experiments on extensor and flexor protoplasts, to determine whether their plasma membranes contain channels capable of carrying the large K⁺ currents that flow during leaflet movement. Recordings in the “whole-cell” mode reveal depolarization-activated K⁺ currents in extensor and flexor cells that increase slowly (t_½ = ca. 2 seconds) and remain active for minutes. Recordings from excised patches reveal a single channel conductance of ca. 20 picosiemens in both cell types. The magnitude of the K⁺ currents is adequate to account quantitatively for K⁺ loss, previously measured in vivo during cell shrinkage. The K⁺ channel blockers tetraethylammonium (5 millimolar) or quinine (1 millimolar) blocked channel opening and decreased light- and dark-promoted movements of excised leaflets. These results provide evidence for the role of potassium channels in leaflet movement.     

Limb use and preferences in wild orang-utans during feeding and locomotor behavior

Limited data are available on hemispheric lateralization in wild orang-utans. There has been only one previous investigation of limb preferences in wild orang-utans [Yeager, 1991]. We examined the lateralization of limb use in wild Bornean orang-utans (Pongo pygmaeus pygmaeus) with the aim of providing more insight into possible hemispheric specialization in wild nonhuman primates. Here, we report in detail on limb use and preference during arboreal locomotion between trees (N=6) and on feeding involving one limb (N=8) and two limbs (N=6). We distinguished between locomotion between overlapping trees (Type I) and locomotion involving gap crossing (Types II and III). For locomotion Type I, the six orang-utans showed no leading hand preference, however for locomotion Types II and III, all six showed significant right-hand preferences. All eight orang-utans showed individual hand preferences for reaching for food, but no significant group bias was found. Limb preferences for feeding involving two limbs (hand-hand or hand-foot) differed between juveniles (right hand-right foot), adult females (left hand-right hand) and adult males (right hand-left hand). Although not present for all tasks, the results indicate that orang-utans do show evidence of hemispheric specialization, but the use of the hands is not under a strong lateralized hemispheric control and is adaptable.     

Multifunctional Setup for Studying Human Motor Control Using Transcranial Magnetic Stimulation,Electromyography, Motion Capture,and Virtual Reality

The study of neuromuscular control of movement in humans is accomplished with numerous technologies. Non-invasive methods for investigating neuromuscular function include transcranial magnetic stimulation, electromyography, and three-dimensional motion capture. The advent of readily available and cost-effective virtual reality solutions has expanded the capabilities of researchers in recreating “real-world” environments and movements in a laboratory setting. Naturalistic movement analysis will not only garner a greater understanding of motor control in healthy individuals, but also permit the design of experiments and rehabilitation strategies that target specific motor impairments (e.g. stroke). The combined use of these tools will lead to increasingly deeper understanding of neural mechanisms of motor control. A key requirement when combining these data acquisition systems is fine temporal correspondence between the various data streams. This protocol describes a multifunctional system’s overall connectivity, intersystem signaling, and the temporal synchronization of recorded data. Synchronization of the component systems is primarily accomplished through the use of a customizable circuit, readily made with off the shelf components and minimal electronics assembly skills.     

<Emphasis Type="Italic">PLP1</Emphasis> Gene Variation Modulates Leftward and Rightward Functional Hemispheric Asymmetries

Molecular neurobiological factors determining corpus callosum physiology and anatomy have been suggested to be one of the major factors determining functional hemispheric asymmetries. Recently, it was shown that allelic variations in two myelin-related genes, the proteolipid protein 1 gene PLP1 and the contactin 1 gene CNTN1, are associated with differences in interhemispheric integration. Here, we investigated whether three single nucleotide polymorphisms that were associated with interhemispheric integration via the corpus callosum in a previous study also are relevant for functional hemispheric asymmetries. To this end, we tested more than 900 healthy adults with the forced attention dichotic listening task, a paradigm to assess language lateralization and its modulation by cognitive control processes. Moreover, we used the line bisection task, a paradigm to assess functional hemispheric asymmetries in spatial attention. We found that a polymorphism in PLP1, but not CNTN1, was associated with performance differences in both tasks. Both functional hemispheric asymmetries and their modulation by cognitive control processes were affected. These findings suggest that both left and right hemisphere dominant cognitive functions can be modulated by allelic variation in genes affecting corpus callosum structure. Moreover, higher order cognitive processes may be relevant parameters when investigating the molecular basis of hemispheric asymmetries.     

The effect of eye movement on the control of arm movement to a target

Abstract

The purpose of this study was to investigate the effect of eye movement on the control of arm movement to a target. Healthy humans flexed the elbow to a stationary target in response to a start tone. Simultaneously, the subject moved the eyes to the target (saccade eye movement), visually tracked a laser point moving with the arm (smooth pursuit eye movement), or gazed at a stationary start point at the midline of the horizontal visual angle (non-eye movement—NEM). Arm movement onset was delayed when saccade eye movement accompanied it. The onset of an electromyographic burst in the biceps muscle and the onset of saccade eye movement were almost simultaneous when both the arm and the eyes moved to the target. Arm movement duration during smooth pursuit eye movement was significantly longer than that during saccade eye movement or NEM. In spite of these findings, amplitudes of motor-evoked potential in the biceps and triceps brachii muscles were not significantly different among the eye movement conditions. These findings indicate that eye movement certainly affects the temporal control of arm movement, but may not affect corticospinal excitability in the arm muscles during arm movement.     

Division of Labor Regulates Precision Rescue Behavior in Sand-Dwelling Cataglyphis cursor Ants: To Give Is to Receive

Division of labor, an adaptation in which individuals specialize in performing tasks necessary to the colony, such as nest defense and foraging, is believed key to eusocial insects'' remarkable ecological success. Here we report, for the first time, a completely novel specialization in a eusocial insect, namely the ability of Cataglyphis cursor ants to rescue a trapped nestmate using precisely targeted behavior. Labeled “precision rescue”, this behavior involves the ability of rescuers not only to detect what, exactly, holds the victim in place, but also to direct specific actions to this obstacle. Individual ants, sampled from each of C. cursor''s three castes, namely foragers, nurses and inactives, were experimentally ensnared (the “victim”) and exposed to a caste-specific group of potential “rescuers.” The data reveal that foragers were able to administer, and obtain, the most help while members of the youngest, inactive caste not only failed to respond to victims, but also received virtually no help from potential rescuers, regardless of caste. Nurses performed intermediate levels of aid, mirroring their intermediate caste status. Our results demonstrate that division of labor, which controls foraging, defense and brood care in C. cursor, also regulates a newly discovered behavior in this species, namely a sophisticated form of rescue, a highly adaptive specialization that is finely tuned to a caste member''s probability of becoming, or encountering, a victim in need of rescue.     

Common SNPs in FTO Gene Are Associated with Obesity Related Anthropometric Traits in an Island Population from the Eastern Adriatic Coast of Croatia

Background

Multiple studies have provided compelling evidence that the FTO gene variants are associated with obesity measures. The objective of the study was to investigate whether FTO variants are associated with a broad range of obesity related anthropometric traits in an island population.

Methodology/Principal Findings

We examined genetic association between 29 FTO SNPs and a comprehensive set of anthropometric traits in 843 unrelated individuals from an island population in the eastern Adriatic coast of Croatia. The traits include 11 anthropometrics (height, weight, waist circumference, hip circumference, bicondilar upper arm width, upper arm circumference, and biceps, triceps, subscapular, suprailiac and abdominal skin-fold thicknesses) and two derived measures (BMI and WHR). Using single locus score tests, 15 common SNPs were found to be significantly associated with “body fatness” measures such as weight, BMI, hip and waist circumferences with P-values ranging from 0.0004 to 0.01. Similar but less significant associations were also observed between these markers and bicondilar upper arm width and upper arm circumference. Most of these significant findings could be explained by a mediating effect of “body fatness”. However, one unique association signal between upper arm width and rs16952517 (P-value = 0.00156) could not be explained by this mediating effect. In addition, using a principle component analysis and conditional association tests adjusted for “body fatness”, two novel association signals were identified between upper arm circumference and rs11075986 (P-value = 0.00211) and rs16945088 (P-value = 0.00203).

Conclusions/Significance

The current study confirmed the association of common variants of FTO gene with “body fatness” measures in an isolated island population. We also observed evidence of pleiotropic effects of FTO gene on fat-free mass, such as frame size and muscle mass assessed by bicondilar upper arm width and upper arm circumference respectively and these pleiotropic effects might be influenced by variants that are different from the ones associated with “body fatness”.     

The gene vitellogenin has multiple coordinating effects on social organization

Temporal division of labor and foraging specialization are key characteristics of honeybee social organization. Worker honeybees (Apis mellifera) initiate foraging for food around their third week of life and often specialize in collecting pollen or nectar before they die. Variation in these fundamental social traits correlates with variation in worker reproductive physiology. However, the genetic and hormonal mechanisms that mediate the control of social organization are not understood and remain a central question in social insect biology. Here we demonstrate that a yolk precursor gene, vitellogenin, affects a complex suite of social traits. Vitellogenin is a major reproductive protein in insects in general and a proposed endocrine factor in honeybees. We show by use of RNA interference (RNAi) that vitellogenin gene activity paces onset of foraging behavior, primes bees for specialized foraging tasks, and influences worker longevity. These findings support the view that the worker specializations that characterize hymenopteran sociality evolved through co-option of reproductive regulatory pathways. Further, they demonstrate for the first time how coordinated control of multiple social life-history traits can originate via the pleiotropic effects of a single gene that affects multiple physiological processes.     

New data on morphology of the African scraping feeder Varicorhinus beso (Osteichthyes: Cyprinidae) with the special reference to specialized traits

Ten samples of Varicorhinus beso, the type species of the genus from East Africa were studied using a large set of morphological characters to evaluate the degree of specialization. It is found that V. beso is highly specialized scraping feeder that possesses many specialized trails: short and wide head, wide inferior mouth with keratinized scraping edge on the lower jaw, modified bones of mouth apparatus, high number of the gill rakers with papillae between rows of the rakers, strongly elongated intestine, and one pair of minute barbels (contrary to scraping trophic forms of barbs possessing two pairs). Despite specialization, V. beso is morphologically rather variable, and some divergence was detected between populations studied.