scholarly journals Mouth asymmetry in the textbook example of scale-eating cichlid fish is not a discrete dimorphism after all

2012 ◽  
Vol 279 (1748) ◽  
pp. 4715-4723 ◽  
Author(s):  
Henrik Kusche ◽  
Hyuk Je Lee ◽  
Axel Meyer
Keyword(s):  
Lake Tanganyika ◽  
Juvenile Fish ◽  
Cichlid Fish ◽  
Ecological Specialization ◽  
Field Sampling ◽  
Left Hand ◽  
Extensive Field ◽  
Negative Frequency Dependent Selection ◽  
Left And Right ◽  
The Right

Individuals of the scale-eating cichlid fish, Perissodus microlepis , from Lake Tanganyika tend to have remarkably asymmetric heads that are either left-bending or right-bending. The ‘left’ morph opens its mouth markedly towards the left and preferentially feeds on the scales from the right-hand side of its victim fish, and the ‘right’ morph bites scales from the victims’ left-hand side. This striking dimorphism made these fish a textbook example of their astonishing degree of ecological specialization and as one of the few known incidences of negative frequency-dependent selection acting on an asymmetric morphological trait, where left and right forms are equally frequent within a species. We investigated the degree and the shape of the frequency distribution of head asymmetry in P. microlepis to test whether the variation conforms to a discrete dimorphism, as generally assumed. In both adult and juvenile fish, mouth asymmetry appeared to be continuously and unimodally distributed with no clear evidence for a discrete dimorphism. Mixture analyses did not reveal evidence of a discrete or even strong dimorphism. These results raise doubts about previous claims, as reported in textbooks, that head variation in P. microlepis represents a discrete dimorphism of left- and right-bending forms. Based on extensive field sampling that excluded ambiguous (i.e. symmetric or weakly asymmetric) individual adults, we found that left and right morphs occur in equal abundance in five populations. Moreover, mate pairing for 51 wild-caught pairs was random with regard to head laterality, calling into question reports that this laterality is maintained through disassortative mating.

Bilateral Writing Ability, Cerebral Organization, and Hand Posture

1979 ◽  
Vol 49 (3) ◽  
pp. 867-870
Author(s):  
Allan L. Combs ◽  
Dana A. Beezley ◽  
Gary M. Prater ◽  
Gerald F. Henning ◽  
Rhonda F. Cottrell
Keyword(s):  
Hand Position ◽  
Hand Posture ◽  
Writing Ability ◽  
Left Hand ◽  
Left And Right ◽  
The Right

Among a group of 12 persons selected for the ability to write with ease with either hand, none were found to write using a hooked hand posture with either the right or left hand. Tests of verbal and manipulospatial ability indicated a normal balance of these two types of abilities, usually associated with the left and right hemispheres. Findings are discussed in terms of implications for cerebral organization and hand position in writing.

Stimulus–Response Compatibility for Vertically Oriented Stimuli and Horizontally Oriented Responses: Evidence for Spatial Coding

1995 ◽  
Vol 48 (2) ◽  
pp. 367-383 ◽  
Author(s):  
Daniel J. Weeks ◽  
Robert W. Proctor ◽  
Brad Beyak
Keyword(s):  
Spatial Coding ◽  
Left Hand ◽  
Response Location ◽  
Stimulus Response ◽  
Response Sets ◽  
Response Switch ◽  
Oriented Stimulus ◽  
Left And Right ◽  
Active Switch ◽  
The Right

It has previously been shown that, when stimuli positioned above or below a central fixation point (“up” and “down” stimuli) are assigned to left and right responses, the stimulus–response mapping up-left/down-right is more compatible than the mapping up-right/down-left for responses executed by the left hand in the left hemispace, but this relation is reversed for responses executed by the right hand in the right hemispace. In Experiment 1, each hand responded at locations in both hemispaces to dissociate the influence of hand identity from response location, and response location was found to be the determinant of relative compatibility. In Experiment 2 responses were made at the sagittal midline, and an inactive response switch was placed to the left or right to induce coding of the active switch as right or left, respectively. This manipulation of relative location had an effect similar to, although of lesser magnitude than, that produced by physically changing location of the response switch in Experiment 1. It is argued that these results are counter to predictions of a movement-preference account and consistent with the view that spatial coding underlies compatibility effects for orthogonally oriented stimulus and response sets.

scholarly journals Lateral comparisons using Fishman's skeletal maturation assessment

2014 ◽  
Vol 85 (3) ◽  
pp. 408-412 ◽  
Author(s):  
Abraham N. Safer ◽  
Peter Homel ◽  
David D. Chung
Keyword(s):  
Bone Development ◽  
Surgical Patients ◽  
Skeletal Maturation ◽  
Age And Gender ◽  
Left Hand ◽  
Right Hand ◽  
Significant Difference ◽  
Left And Right ◽  
And Gender ◽  
The Right

ABSTRACT Objective:  To assess lateral differences between ossification events and stages of bone development in the hands and wrists utilizing Fishman's skeletal maturation indicators (SMIs). Materials and Methods:  The skeletal ages of 125 subjects, aged 8 to 20 years, were determined with left and right hand-wrist radiographs using Fishman's SMI assessment. Each subject was also given the Edinburgh Handedness Questionnaire to assess handedness. The skeletal ages of both hand-wrist radiographs were analyzed against each other, handedness, chronologic age, and gender. Results:  There were no significant differences overall in right and left SMI scores (P  =  .70); 79% of all patients showed no difference in right and left SMI scores, regardless of handedness, gender, or age. However, when patients were categorized based on clinical levels of SMI score for the right hand-wrist, there was a significant difference (P  =  .01) between the SMI 1-3 group and the SMI 11 group. Subjects in the SMI 1-3 group were more likely to show a left > right SMI score, while subjects in the SMI 11 group were likely to show a right > left SMI score. Conclusion:  Although no significant overall lateral differences in SMI scores were noted, it may be advisable to obtain a left hand-wrist radiograph and/or additional diagnostic information to estimate completion of growth in young surgical patients.

scholarly journals Drawing with the Non-dominant Hand: Implications for the Study of Construction

1998 ◽  
Vol 25 (4) ◽  
pp. 306-309 ◽  
Author(s):  
Sherma Zacharias ◽  
Andrew Kirk
Keyword(s):  
Neurological Disease ◽  
Right Hemisphere ◽  
Normal Subjects ◽  
Elderly Subjects ◽  
Dominant Hand ◽  
Left Hand ◽  
Right Hand ◽  
Left And Right ◽  
The Right ◽  
Right And Left Hand

ABSTRACT:Background:Constructional impairment following left vs. right hemisphere damage has been extensively studied using drawing tasks. A confounding factor in these studies is that right-handed patients with left hemisphere damage (LHD) are often forced by weakness to use their non-dominant (left) hand or hemiparetic dominant hand. Qualitative differences in the drawing characteristics of left and right hand drawings by normal subjects have not previously been characterized. The present study was undertaken to determine the qualitative differences between left and right hand drawings of normal subjects.Methods:Thirty right-handed, elderly subjects without a history of neurological disease were asked to draw, from memory, seven objects using the right and left hand. Half of the subjects were randomly assigned to draw with the left hand first, and half the right hand first. Right and left hand drawings were compared using a standardized scoring system utilized in several previous studies of drawing in focal and diffuse neurological disease. Each drawing was scored on eighteen criteria. Right and left hand drawing scores were then compared using the t-test for paired samples or the Wilcoxon matched-pairs testResults:Drawings made using the left hand were found to be significantly simpler, more tremulous and of poorer overall quality than drawings made by the same subjects using the right hand.Conclusions:The deficits found in left versus right hand drawings of normals are similar to those found in patients with LHD, suggesting that much of the drawing impairment seen following LHD is due to an elementary motor disturbance related to use of the non-dominant hand.

scholarly journals Effects of tDCS Dose and Electrode Montage on regional cerebral blood flow and motor behavior

2021 ◽  
Author(s):  
Anant Shinde ◽  
Karl Lerud ◽  
Fanny Munsch ◽  
David C Alsop ◽  
Gottfried Schlaug
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Regional Cerebral Blood Flow ◽  
Brain Regions ◽  
Regional Cerebral Blood ◽  
Left Hand ◽  
Motor Region ◽  
Left And Right ◽  
The Right ◽  
Sequence Performance

AbstractWe used three dose levels (Sham, 2mA and 4mA) and two different electrode montages (unihemispheric or bihemispheric) to examine DOSE and MONTAGE effects on regional cerebral blood flow (rCBF) as a surrogate marker of neural activity, and on a finger sequence task, as a surrogate behavioral measure drawing on brain regions targeted by transcranial direct current stimulation (tDCS). We placed the anodal electrode over the right motor region (C4) while the cathodal or return electrode was placed either over a left supraorbital region (unihemispheric montage) or over the left motor region (C3 in the bihemispheric montage). Performance changes in the finger sequence task for both hands (left hand: p = 0.0026, and right hand: p = 0.0002) showed a linear tDCS dose response, but no effect of montage. rCBF in the the right hemispheric perirolandic area increased with dose under the anodal electrode (p = 0.027), while in the perirolandic ROI in the left hemisphere, rCBF showed a trend to increase with dose (p = 0.053), and significant effect of montage (p = 0.00004). The bihemispheric montage showed additional rCBF increases in frontomesial regions in the 4mA condition but not in the 2mA condition. Furthermore, we found correlations between rCBF changes in the right perirolandic region and improvements in the finger sequence task performance (FSP) for left and right hand. Our data support not only a strong direct tDCS dose effect for rCBF and FSP as surrogate measures of targeted brain regions, but also indirect effects on rCBF in functionally connected regions (e.g., frontomesial regions), particularly in the higher dose condition, and on FSP of the ipsilateral hand (to the anodal electrode). At higher dose and irrespective of polarity, a wider network of sensorimotor regions is positively affected by tDCS.Graphical AbstractHighlightstDCS-DOSE had linear effect on finger sequence performance for both handsrCBF changes in both perirolandic ROIs demonstrated tDCS-DOSE effects and left perirolandic ROI demonstrated tDCS-MONTAGE effects.Simulated current intensity in the left and right perirolandic ROI strongly correlated with the contralateral hand’s finger sequence performance.tDCS-Tolerability scores did not correlate with change in rCBF or finger sequence performance of the left hand.

scholarly journals Are left- and right-eye pupil sizes always equal?

2019 ◽  
Vol 12 (2) ◽  
Author(s):  
Gonca Gokce Menekse Dalveren ◽  
Nergiz Ercil Cagiltay
Keyword(s):  
Cognitive Load ◽  
Movement Analysis ◽  
Difficulty Level ◽  
Human Beings ◽  
Left Hand ◽  
Surgical Residents ◽  
Right Hand ◽  
Significant Difference ◽  
Left And Right ◽  
The Right

Eye movements provide very critical information about the cognitive load and behaviors of human beings. Earlier studies report that under normal conditions, the left- and right-eye pupil sizes are equal. For this reason, most studies undertaking eye-movement analysis are conducted by only considering the pupil size of a single eye or taking the average size of both eye pupils. This study attempts to offer a better understanding concerning whether there are any differences between the left- and right-eye pupil sizes of the right-handed surgical residents while performing surgical tasks in a computer-based simulation environment under different conditions (left hand, right hand and both hands). According to the results, in many cases, the right-eye pupil sizes of the participants were larger than their left-eye pupil sizes while performing the tasks under right-hand and both-hands conditions. However, no significant difference was found in relation to the tasks performed under left-hand condition in all scenarios. These results are very critical to shed further light on the cognitive load of the surgical residents by analyzing their left-eye and right-eye pupil sizes. Further research is required to investigate the effect of the difficulty level of each scenario, its appropriateness with the skill level of the participants, and handedness on the differences between the left- and right-eye pupil sizes.

Functional Asymmetry in the Motor Performances of Women: Neuropsychological Effects of Depression

1994 ◽  
Vol 78 (3_suppl) ◽  
pp. 1315-1322 ◽  
Author(s):  
W. David Crews ◽  
David W. Harrison
Keyword(s):  
Motor Functioning ◽  
Left Hand ◽  
Neuropsychological Effects ◽  
Hand Grip ◽  
Arousal Theory ◽  
Hand Dynamometer ◽  
Left And Right ◽  
State And Trait Anxiety ◽  
Standardized Measure ◽  
The Right

The influence of depression on the cerebral hemispheric motor functioning of 40 right-handed women, half of whom had been classified as depressed, the other half as nondepressed, was examined. The depressed women were also characterized by elevated state and trait anxiety, suggestive of an anxious-depressive state with heightened arousal. A hand dynamometer was used as a standardized measure of hemispheric motor functioning such as hand-grip strength, perseveration, and fatigue. Primary findings indicated that depressed women displayed significantly less perseveration at the left hand than did nondepressed women, but a nonsignificant trend only was noted for less perseveration at the right hand. These results suggest possible differential arousal of the left and right cerebral hemispheres in this sample of anxious-depressed women and are discussed in terms of arousal theory.

scholarly journals Genetic support for random mating between left and right-mouth morphs in the dimorphic scale-eating cichlid fish Perissodus microlepis from Lake Tanganyika

2010 ◽  
Vol 76 (8) ◽  
pp. 1940-1957 ◽  
Author(s):  
H. J. Lee ◽  
S. Pittlik ◽  
J. C. Jones ◽  
W. Salzburger ◽  
M. Barluenga ◽  
...  
Keyword(s):  
Lake Tanganyika ◽  
Random Mating ◽  
Cichlid Fish ◽  
Left And Right

scholarly journals Neural support of manual preference revealed by BOLD variations during right and left finger-tapping in a sample of 287 healthy adults balanced for handedness

2020 ◽  
Author(s):  
Nathalie Tzourio-Mazoyer ◽  
Loïc Labache ◽  
Laure Zago ◽  
Isabelle Hesling ◽  
Bernard Mazoyer
Keyword(s):  
Finger Tapping ◽  
Brain Areas ◽  
Left Hand ◽  
Left Handedness ◽  
Somatosensory Cortices ◽  
Hand Control ◽  
Left And Right ◽  
The Right ◽  
The Brain ◽  
Somatosensory Areas

AbstractWe have identified the brain areas involved in Manual Preference (MP) in 143 left-handers (LH) and 144 right-handers (RH)). First, we selected the pairs of homotopic regions of interest (hROIs) of the AICHA atlas with significant contralateral activation and asymmetry during the right-hand and the left-hand Finger-Tapping (FT) both in RH and LH. Thirteen hROIs were selected, including the primary and secondary sensorimotor, and premotor cortices, thalamus, dorsal putamen and cerebellar lobule IV. Both contralateral activations and ipsilateral deactivations (reversed for the cerebellum) were seen in primary motor and somatosensory areas, with stronger asymmetries when the preferred hand was used. Comparing the prediction of MP with different combinations of BOLD variations in these 13 hROIs, the differences between movement of the preferred hand versus that of the non-preferred hand within the contralateral and/or ipsilateral cortices of 11 hROIS performed best at explaining handedness distribution, Handedness is thus supported by: 1-between-hand variations of ipsilateral deactivations of hand primary sensorimotor and secondary somatosensory cortices and 2-variations in regions showing the same profile in left and right-handers during the right or left FT. The present study demonstrates that right and left-handedness are not based on mirrored organization of hand control areas.

Handedness and Hand Injuries

1994 ◽  
Vol 19 (2) ◽  
pp. 158-161 ◽  
Author(s):  
A. A. BEATON ◽  
L. WILLIAMS ◽  
L. G. MOSELEY
Keyword(s):  
Emergency Department ◽  
Hand Injuries ◽  
Medical Attention ◽  
Male And Female ◽  
Left Hand ◽  
Female Patients ◽  
Accident And Emergency ◽  
Left And Right ◽  
Accident And Emergency Department ◽  
The Right

Data are reported from a study of 1,003 patients attending with hand injuries at an Accident and Emergency Department. Among both left- and right-handers, injuries to the right hand were more common than to the left hand, except for accidents to right-handers at work. For this group there were more injuries to the left hand. Male and female patients differ in the frequency with which they present for medical attention but show similar types of injury.

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