RESUMO
The developmental origins of handedness remain elusive, though very early emergence suggests individual differences manifesting in utero could play an important role. Prenatal testosterone and Vitamin D exposure are considered, yet findings and interpretations remain equivocal. We examined n = 767 offspring from a population-based pregnancy cohort (The Raine Study) for whom early biological data and childhood/adolescent handedness data were available. We tested whether 18-week maternal circulatory Vitamin D (25[OH]D), and testosterone and estradiol from umbilical cord blood sampled at birth predicted variance in direction of hand preference (right/left), along with right- and left-hand speed, and the strength and direction of relative hand skill as measured by a finger-tapping task completed at 10 (Y10) and/or 16 (Y16) years. Although higher concentrations of Vitamin D predicted more leftward and less lateralized (regardless of direction) relative hand skill profiles, taken as a whole, statistically significant findings typically did not replicate across time-point (Y10/Y16) or sex (male/female) and were rarely detected across different (bivariate/multivariate) levels of analysis. Considering the number of statistical tests and generally inconsistent findings, our results suggest that perinatal testosterone and estradiol contribute minimally, if at all, to subsequent variance in handedness. Vitamin D, however, may be of interest in future studies.
Assuntos
Lateralidade Funcional , Testosterona , Gravidez , Recém-Nascido , Humanos , Adolescente , Masculino , Feminino , Estradiol , Vitamina D , MãosRESUMO
Competing theories have posited roles for foetal androgen exposure in the development of human handedness. However, due to practical and ethical considerations, few studies have used hormonal measures to examine this possibility. The current paper reviews this literature and reveals a generally inconsistent pattern of results. We also present data from a longitudinal study of prenatal sex hormone exposure and subsequent handedness. More specifically, we examine correlations between testosterone and estradiol measured from second trimester amniotic fluid and hand preference (Dutch language version of the Edinburgh Handedness Inventory) and hand skill asymmetry (pegboard task) measured at 15 years of age. Prenatal sex hormone exposure was not associated with the direction of hand preference in either males or females. However, in females, high levels of prenatal testosterone were associated with weaker lateralisation of hand skill, and high levels of prenatal estradiol were associated with weaker hand preference. In addition, high levels of prenatal testosterone were associated with increased task duration (i.e., slow hand speed) for the right and left hands of males. The pattern of results observed here is not entirely consistent with any of the main theories linking sex hormones with handedness, suggesting that an association between these variables may be more complex than initially thought.
Assuntos
Líquido Amniótico , Lateralidade Funcional , Feminino , Mãos , Humanos , Estudos Longitudinais , Masculino , Gravidez , TestosteronaRESUMO
While paying attention to the recommendations of Ocklenburg, Berretz, Packheiser, and Friedrich (2020) in the target article, researchers in the field of laterality should attempt to: (1) solve the long-standing puzzle of the relationship between handedness and language lateralization; (2) further explore the genetic bases of manual and cerebral asymmetry and of their associations with psychiatric and neurodevelopmental conditions; (3) explore the adaptive significance of laterality for humans and non-humans and elucidate the relationships of asymmetry across species; and (4) embrace developing technologies to investigate the interaction between the hemispheres during the performance of everyday tasks.
Assuntos
Lateralidade Funcional , IdiomaRESUMO
The Geschwind-Behan-Galaburda and sexual differentiation models predict an association between elevated foetal androgen exposure and left-handedness whereas the callosal hypothesis predicts the opposite. We present a meta-analysis of correlations between handedness and digit ratio (2D:4D), a putative marker of prenatal testosterone. Left-handedness predicted low (male-typical) right-hand digit ratio (R2D:4D), high (female-typical) left-hand digit ratio (L2D:4D), and low R2D:4D-L2D:4D directional asymmetry (D[R-L]). Effect sizes were extremely small and not moderated by sex or method of measuring handedness or 2D:4D. The same general pattern was observed after excluding the very large study (110,329 males, 90,412 females) of Manning and Peters ([2009]. Digit ratio (2D:4D) and hand preference for writing in the BBC Internet Study. Laterality: Asymmetries of Body, Brain and Cognition, 14(5), 528-540. doi:10.1080/13576500802637872); however, no significant effects for R2D:4D were observed once these samples were removed. The results do not confirm any theory linking prenatal androgens with handedness, so we speculate they instead reflect the mechanical action of writing causing subtle changes in the musculature and/or fat pads of the fingers. Gripping a pen/pencil might cause an increase in 2D relative to 4D (and/or decrease in 4D relative to 2D) resulting in higher ratios on the writing-hand; furthermore, this could differ between left- and right-handers due to writing in the left-to-right direction (as in English) having asymmetrical effects depending on which hand is used.
Assuntos
Lateralidade Funcional , Testosterona , Androgênios , Encéfalo , Feminino , Dedos , Humanos , Masculino , Gravidez , Caracteres SexuaisRESUMO
The Annett Hand Preference Questionnaire (AHPQ), as modified by Briggs and Nebes [(1975). Patterns of hand preference in a student population. Cortex, 11(3), 230-238. doi: 10.1016/s0010-9452(75)80005-0] , was administered to a sample of 177 participants alongside the Reinforcement Sensitivity Theory of Personality Questionnaire [RST-PQ; Corr, P. J., & Cooper, A. (2016). The Reinforcement Sensitivity Theory of Personality Questionnaire (RST-PQ): Development and validation. Psychological Assessment. doi: 10.1037/pas000 ], which measures two factors of defensive negative emotion, motivation and affectivity-the Behavioural Inhibition System (BIS) and the Fight-Flight-Freeze System (FFFS)-and one positive-approach dimension related to reward sensitivity, persistence and reactivity-the Behavioural Approach System. We sought to clarify the nature of negative, and positive, affectivity in relation to handedness. ANOVAs and multiple regression analyses converged on the following conclusions: left-handers were higher on the BIS, not the FFFS, than right-handers; in right-handers only, strength of hand preference was positively correlated with the FFFS, not the BIS. The original assessment method proposed by Annett was also used to assess handedness, but associations with RST-PQ factors were not found. These findings help us to clarify existing issues in the literature and raise new ones for future research.
Assuntos
Afeto/fisiologia , Lateralidade Funcional/fisiologia , Personalidade , Teoria Psicológica , Reforço Psicológico , Adolescente , Adulto , Fatores Etários , Análise de Variância , Feminino , Humanos , Inibição Psicológica , Masculino , Análise de Regressão , Fatores Sexuais , Inquéritos e Questionários , Adulto JovemRESUMO
The Annett Hand Preference Questionnaire (AHPQ) as modified by Briggs and Nebes was administered along with Carver and White's behavioural inhibition system (BIS) and behavioural activation system (BAS) scale and a shortened form of the Big Five personality questionnaire to 92 university students. After eliminating the data from five respondents who reported having changed handedness and one outlier, there was a significant sex difference in mean BIS scores, with females (n = 43) scoring higher than males (n = 43). Replicating the results of Wright, Hardie and Wilson, non-right-handers (n = 36) had significantly higher mean BIS score than right-handers (n = 50). Controlling for sex of participant, neuroticism and BAS sub-scale scores in hierarchical regression analyses left this BIS effect substantially unaffected. There was no handedness or sex difference on any of the three BAS sub-scales. Further analyses revealed no association between strength, as distinct from direction, of handedness and BIS (or BAS) scores. The findings are discussed with reference to recent developments in reinforcement sensitivity theory on which BIS/BAS variables are based.
Assuntos
Lateralidade Funcional/fisiologia , Testes Neuropsicológicos , Personalidade , Reforço Psicológico , Adolescente , Adulto , Feminino , Humanos , Inibição Psicológica , Masculino , Psicometria , Análise de Regressão , Inquéritos e Questionários , Adulto JovemRESUMO
In less than three decades, the concept "cerebellar neurocognition" has evolved from a mere afterthought to an entirely new and multifaceted area of neuroscientific research. A close interplay between three main strands of contemporary neuroscience induced a substantial modification of the traditional view of the cerebellum as a mere coordinator of autonomic and somatic motor functions. Indeed, the wealth of current evidence derived from detailed neuroanatomical investigations, functional neuroimaging studies with healthy subjects and patients and in-depth neuropsychological assessment of patients with cerebellar disorders shows that the cerebellum has a cardinal role to play in affective regulation, cognitive processing, and linguistic function. Although considerable progress has been made in models of cerebellar function, controversy remains regarding the exact role of the "linguistic cerebellum" in a broad variety of nonmotor language processes. This consensus paper brings together a range of different viewpoints and opinions regarding the contribution of the cerebellum to language function. Recent developments and insights in the nonmotor modulatory role of the cerebellum in language and some related disorders will be discussed. The role of the cerebellum in speech and language perception, in motor speech planning including apraxia of speech, in verbal working memory, in phonological and semantic verbal fluency, in syntax processing, in the dynamics of language production, in reading and in writing will be addressed. In addition, the functional topography of the linguistic cerebellum and the contribution of the deep nuclei to linguistic function will be briefly discussed. As such, a framework for debate and discussion will be offered in this consensus paper.
Assuntos
Cerebelo/fisiologia , Cognição/fisiologia , Idioma , Memória/fisiologia , Fala , Animais , HumanosRESUMO
The ability to recall a dream upon waking up in the morning has been linked to a broad variety of factors such as personality, creativity, sleep behaviour and cognitive function. There have been conflicting findings as to whether dream recall is related more to the right or to the left hemisphere, and conflicting findings regarding the relationship of dream-recall frequency to handedness. We have found previously that right- and mixed-handers report having more dreams than left-handers, a finding more pronounced among adolescents than adults. In the present sample of 3535 participants aged from 6 to 18 years, right-handedness and mixed/inconsistent handedness were associated with higher dream-recall frequency compared to that of left-handed persons, again especially in adolescents compared with children. Further research is required to uncover the reason for the lower frequency of dream recall by left-handers.
Assuntos
Sonhos , Lateralidade Funcional/fisiologia , Rememoração Mental/fisiologia , Adolescente , Criatividade , Feminino , Humanos , Modelos Logísticos , Masculino , Inquéritos e QuestionáriosRESUMO
The right cerebral hemisphere is preferentially involved in recognising at least some facial expressions of emotion. We investigated whether there is a laterality effect in judging emotions from the eyes. In one task a pair of emotionally expressive eyes presented in central vision had to be physically matched to a subsequently presented set of eyes in one or other visual hemifield (eyes condition). In the second task a word was presented centrally followed by a set of eyes to left or right hemifield and the participant had to decide whether the word correctly described the emotion portrayed by the laterally presented set of eyes (word condition). Participants were a group of undergraduate students and a group of older volunteers (> 50). There was no visual hemifield difference in accuracy or raw response times in either task for either group, but log-transformed times showed an overall left hemifield advantage. Contrary to the right hemisphere ageing hypothesis, older participants showed no evidence of a relative right hemisphere decline in performance on the tasks. In the younger group mean peak amplitude of the N170 component of the EEG at lateral posterior electrode sites was significantly greater over the right hemisphere (T6/PO2) than the left (T5/PO1) in both the perceptual recognition task and the emotional judgement task. It was significantly greater for the task of judging emotion than in the eyes-matching task. In future it would be useful to combine electrophysiological techniques with lateralised visual input in studying lateralisation of emotion with older as well as younger participants.
Assuntos
Emoções/fisiologia , Potenciais Evocados Visuais/fisiologia , Expressão Facial , Lateralidade Funcional/fisiologia , Campos Visuais/fisiologia , Idoso , Envelhecimento/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estimulação Luminosa/métodos , Desempenho Psicomotor/fisiologia , Tempo de Reação/fisiologia , Reconhecimento Psicológico/fisiologia , Percepção Visual/fisiologia , Adulto JovemRESUMO
Androstenol has been reported to influence judgements of attractiveness and to affect participants' mood. In the present study, participants were asked to sniff androstenol or a control odour (pure ethanol) unilaterally with the left or right nostril. Subsequently, they rated the attractiveness of photographs of the opposite sex and their own feelings on four mood scales. Participants rated the photographs as significantly more attractive after sniffing androstenol compared with the control odour. This did not depend upon androstenol being perceived as pleasant. Androstenol made male participants feel more lively, and both male and female participants more sexy, when sniffed through the right compared with the left nostril. Participants rated themselves as more irritable and aggressive when exposed to androstenol through the left nostril. The findings are discussed in relation to the effects of arousal on attraction and in the context of current theories of hemispheric differences in emotion.
Assuntos
Identidade de Gênero , Comportamento Sexual , Afeto , Nível de Alerta , Feminino , Humanos , Julgamento , MasculinoRESUMO
The length of the index finger relative to that of the ring finger, the 2D:4D ratio, has been taken to be a marker of the amount of testosterone (T) that was present in the foetal environment (Manning, Scutt, Wilson, & Lewis-Jones, 1998). It has also been suggested (Geschwind & Galaburda, 1987) that elevated levels of foetal T are associated with left-handedness and that adult levels of circulating T might relate to foetal levels (Jamison, Meier, & Campbell, 1993). We used multiple regression analyses to investigate whether there is any relationship between either left or right hand 2D:4D ratio and handedness. We also examined whether adult levels of salivary T (or cortisol, used as a control hormone) predict digit ratio and/or handedness. Although the 2D:4D ratio of neither the left nor the right hand was related to handedness, the difference between the digit ratios of the right and left hands, D(R-L), was a significant predictor of handedness and of the performance difference between the hands on a peg-moving task, supporting previous findings (Manning & Peters, 2009; Manning et al., 1998; Manning, Trivers, Thornhill, & Singh, 2000; Stoyanov, Marinov, & Pashalieva, 2009). Adult circulating T levels did not predict the digit ratio of the left or right hand; nor was there a significant relationship between concentrations of salivary T (or cortisol) and either hand preference or asymmetry in manual skill. We suggest that the association between D(R-L) and hand preference arises because D(R-L) is a correlate of sensitivity to T in the developing foetus.
Assuntos
Padronização Corporal/fisiologia , Dedos/embriologia , Lateralidade Funcional/fisiologia , Saliva/metabolismo , Caracteres Sexuais , Testosterona/metabolismo , Adolescente , Adulto , Idoso , Feminino , Dedos/crescimento & desenvolvimento , Humanos , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
Semantic errors of oral reading by aphasic patients are said to be comparatively rare in languages with a shallow orthography. The present report concerns three bilingual brain-damaged patients who prior to their stroke were fluent in both English, an orthographically deep language, and Welsh, an orthographically shallow language. On a picture-naming task, each patient made a similar proportion of semantic errors in the two languages. Similarly, in oral reading of the corresponding words, no patient produced proportionally more semantic paralexias in English than in Welsh. The findings are discussed in relation to the summation hypothesis as invoked by Miceli, Capasso, and Caramazza (1994) to explain apparent differences in frequency of semantic errors of reading in languages differing in orthographic depth.
Assuntos
Encéfalo/diagnóstico por imagem , Dislexia/etiologia , Multilinguismo , Semântica , Idoso , Afasia/diagnóstico , Afasia/etiologia , Infarto Cerebral/complicações , Infarto Cerebral/diagnóstico por imagem , Dislexia/diagnóstico , Inglaterra , Feminino , Lateralidade Funcional , Humanos , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Lobo Parietal/diagnóstico por imagem , Índice de Gravidade de Doença , Tomografia Computadorizada por Raios X , País de GalesRESUMO
Two experiments on finger localization are reported. Experiment 1 compared children who were poor readers with two groups of children matched to poor readers for sex and either age (CA controls) or reading age (RA controls). The participant's hands were kept out of his or her sight in a semi-open box while the fingers of one hand were lightly touched by the experimenter. The participant's task was to indicate, using the thumb of either the same hand (within-hand condition) or the opposite hand (across-hands condition) to respond, the finger(s) which had been touched by the experimenter. Performance was significantly impaired in the across-hands condition compared with the within-hand condition. Experiment 2 was carried out with dyslexic adults and a control group of normal readers. Using the same method of responding as in Experiment 1, a significant deficit in the across-hands condition compared to the within-hand condition was found for both groups. The effect was also obtained for both groups when participants were required to point to the relevant fingers on a photograph of a hand rather than use the thumb of the opposite hand to respond. The results are discussed in relation to the hypothesis of a deficit in inter-hemispheric transfer of tactile information in dyslexia.
Assuntos
Dislexia/fisiopatologia , Dedos/fisiologia , Lateralidade Funcional/fisiologia , Tempo de Reação/fisiologia , Tato/fisiologia , Adulto , Criança , Feminino , Humanos , Masculino , Análise por Pareamento , Reconhecimento Fisiológico de Modelo/fisiologia , Valores de ReferênciaRESUMO
Clinical case descriptions and experimental evidence dating back to the early part of the 19th century from time to time documented a range of nonmotor cognitive and affective impairments following cerebellar pathology. However, a causal relationship between disruption of nonmotor cognitive and affective skills and cerebellar disease was dismissed for several decades and the classical view of the cerebellum as a mere coordinator of autonomic and somatic sensorimotor function prevailed for more than two centuries in behavioural neuroscience. The ignorance of early clinical evidence suggesting a much richer and complex role for the cerebellum than a pure sensorimotor one is remarkable given that in addition: 1) the cerebellum contains more neurons than the rest of the combined cerebral cortex and 2) no other structure has as many connections with other parts of the brain as the cerebellum. During the past decades, the long-standing view of the cerebellum as pure coordinator of sensorimotor function has been substantially modified. From the late 1970s onwards, major advances were made in elucidating the many functional neuroanatomical connections of the cerebellum with the supratentorial association cortices that subserve nonmotor language, cognition and affect. Combined with evidence derived from experimental functional neuroimaging studies in healthy subjects and neurophysiological and neuropsychological research in patients, the role of the cerebellum has been substantially extended to include that of a crucial modulator of cognitive and affective processes. In addition to its long-established role in coordinating motor aspects of speech production, clinical and experimental studies with patients suffering from etiologically different cerebellar disorders have identified involvement of the cerebellum in a variety of nonmotor language functions, including motor speech planning, language dynamics and verbal fluency, phonological and semantic word retrieval, expressive and receptive syntax processing, various aspects of reading and writing and aphasia-like phenomena. Despite considerable efforts currently devoted to further refine typology and anatomoclinical configurations of nonmotor linguistic dysfunctions linked to cerebellar pathology, the exact underlying pathophysiological mechanisms of cerebellar involvement remain to be elucidated.
RESUMO
We recorded the direction of hair whorl rotation in samples of male right- and non-right-handers. The data corroborate those of Klar (2003) in showing equal numbers of clockwise and anti-clockwise whorls in non-right-handers but an excess of clockwise whorls in right-handers. The findings support the view that in some proportion of the population direction of coiling arises as a consequence of random events occurring during early (pre-natal) development of the nervous system, while in the remainder of the population there is a systematic bias towards a clockwise direction of rotation. The association with handedness implies that the latter is in a very large measure biologically rather than culturally determined.
Assuntos
Lateralidade Funcional , Cabelo/crescimento & desenvolvimento , Humanos , Masculino , Estatística como Assunto , País de GalesRESUMO
Using a tachistoscopic split-field paradigm, hemifield asymmetry for single word recognition was examined in monolingual English speakers and in fluent bilingual English-Welsh speakers. A robust right hemifield advantage was found for both groups and both languages. Among bilinguals, the laterality index was significantly greater for Welsh than for English, supporting previous findings. The magnitude of the laterality index was unaffected by which language was learned first (Welsh or English) and by the age of acquisition (before or after 5-6years old) of the second language. However, among bilinguals there was a significant difference in the laterality index for Welsh words compared with English words for those participants brought up in a predominantly Welsh-speaking environment, but not for those brought up in a predominantly English-speaking or dual-language environment. We attribute our results to the difference in orthographic depth between Welsh and English. and argue that the transparency of Welsh favours adoption of a left-hemisphere based phonological decoding strategy in reading. Such a strategy is not necessarily used exclusively by readers of Welsh, but is encouraged by regular exposure to the Welsh language on a day-to-day basis.