The evolutionary origins of human handedness are still unknown. The study of lateralized behaviour in our closest relatives, the nonhuman primates, is useful to clarify how this trait appeared and evolved in our species. In the present study, lateralized behaviour was assessed in a population of 32 free-ranging Mexican mantled howler monkeys (Alouatta palliata mexicana) for thirteen spontaneous motor patterns, at individual and group levels, as well as the effect that age, sex and posture have on its strength and direction. The studied population of howler monkeys displayed only few significant lateral biases at the individual level with single motor patterns (Binomial tests, p≤0.05). No biases towards the use of a particular limb or side of the body were found at a population level. Therefore, even though some individuals showed significant limb/side preference with single motor patterns, no signs of task specialization, side specialization, or true handedness were found. Similarly, no effects of sex, age or posture were found on the direction or strength of lateralized behaviour. The general absence of limb/side preferences found in this population may be due to the constraints imposed by the arboreal life and/or the type of diet. Possible causal agents of the few significant individual biases found here may be the presence of handicaps and/or experience. Further research is needed in order to assess whether the lack of human-like handedness reported in this study is only specific to the studied population, a general phenomenon of the genus Alouatta or perhaps of all the Platyrrhini.

The evolutionary origins of human handedness are not yet fully understood as evidence of lateralized behavior in nonhuman primates is inconclusive. In the present study, lateralized behavior in both spontaneously occurring motor patterns and a tube task was examined in 15 white-handed gibbons (Hylobates lar). Significant side preferences at the individual level were found within all 15 studied motor patterns. However, no population-level side bias was found for any of the spontaneously occurring or task-related motor patterns and none of the gibbons were consistent in their hand preference across all motor patterns. When only considering the individuals with a significant preference, a significant majority was left-preferent for resting foot. Strength of side preference was significantly higher for the tube task than for all spontaneously occurring motor patterns. Side preferences for manipulation and resting position were significantly stronger than those for supporting hand. Additionally, the preferences for manipulation were significantly stronger than those for leading limb. In the bimanual tube task, females displayed a tendency towards a left-side bias, while males tended to display a bias to the right. Furthermore, females had a significantly stronger hand preference for supporting hand than males. No other sex differences were found. Age, posture, and kinship had no significant effect on lateralized behavior for any of the motor patterns. As in other nonhuman primates, the white-handed gibbons were only consistent in their hand preference across tasks that required similar movements. Altogether, these findings support the notion that population-level handedness may be restricted to human subjects.

After an intelligence test battery, the sixty right-handed subjects (30 males, 30 females) performed two visual field (VF) reaction time (RT) tasks requiring odd-even judgments concerning the whole numbers 1 through 8. Numbers were presented as words, a right VF left-hemisphere (LH) advantage task, or as bargraphs, a left, VF right-hemisphere (RH) advantage task, the height of the bargraphs indicating the number.

No description available.

Les troubles des tics, comme le syndrome de Gilles de la Tourette et le trouble de tics chroniques, sont des conditions neuropsychiatriques impliquant des tics moteurs et/ou phoniques. En plus de nombreuses comorbidités, les patients qui en sont atteints ont aussi des difficultés neuropsychologiques, notamment au niveau de l’inhibition et des fonctions motrices. La thérapie cognitivo-comportementale permet d’améliorer les tics et la condition générale de ces patients. Nous avons donc enregistré, durant une tâche de compatibilité stimulus-réponse, les potentiels évoqués cognitifs et les potentiels de latéralisation motrice (lateralized readiness potential; LRP) chez 20 patients atteints de trouble des tic avant et après une thérapie cognitivo-comportementale, et chez 20 participants contrôles. Chez les patients atteints de trouble des tics, nos résultats ont révélé une apparition plus tardive de l’amorce du LRP moyenné par rapport au stimulus, une amplitude plus élevée du LRP moyenné par rapport à la réponse, et une suractivation frontale liée aux processus d’inhibition. Suite à la thérapie, le retard au niveau de la latence de l’amorce du LRP moyenné par rapport à la réponse est comblé et l’amplitude du LRP moyenné par rapport à la réponse est normalisée, mais pas la suractivation frontale liée à l’inhibition. Cela suggère donc que la thérapie induit une modification des processus prémoteurs de sélection et de préparation de la réponse, ainsi que des processus d’exécution motrice, mais n’altère pas la suractivation frontale reliée aux fonctions inhibitrices. Étant donnés ces résultats, nous suggérons que la thérapie cognitivo-comportementale induit une modification du fonctionnement des aires motrices du cerveau. / Gilles de la Tourette syndrome and chronic tic disorder are two neuropsychiatric condition involving motor and/or phonic tics. In the DSM, these two conditions are characterized as “tic disorders”. Patients with such diagnoses face numerous comorbidities, and also show multiple neuropsychological impairments, especially concerning inhibition and motor processing. Tic symptoms, as well as general condition, can be improved with a cognitive-behavioural therapy (CBT). To this end, we recorded, during a stimulus-response compatibility task, event-related potentials and lateralized readiness potentials in 20 patients with tic disorder and 20 healthy controls. Patients and controls were paired on age, sex and hand dominance. Our result revealed a delay in stimulus-locked lateralized readiness potential (LRP) onset latency, higher response-locked LRP peak amplitude and a frontal overactivation related to stimulus inhibition in GTS and CTD patients. Following CBT, stimulus-locked LRP onset latency and response-locked LRP peak amplitude were normalized, but the frontal overactivation related to inhibition processing remained unchanged. These results suggest that CBT induces a modification of pre-motor processes such as response selection and preparation, as well as motor processes like response execution, but does not affect cortical activation related to stimulus inhibition. Since we found a reduction in tic symptoms, as well as a normalization of stimulus-locked LRP onset latency and response-locked LRP peak amplitude, and because LRPs are partly generated by the supplementary motor area, we suggest that CBT leads to a modification of this structure’s functioning.

Made available in DSpace on 2016-06-02T20:18:22Z (GMT). No. of bitstreams: 1 5877.pdf: 9914755 bytes, checksum: 449c8d0ab2defc77d6b0d5a4ea1b20bb (MD5) Previous issue date: 2014-06-11 / Universidade Federal de Minas Gerais / The effect of using the non-preferred hand on manual preference and motor performance was assessed in two experiments. Experiment 1 investigated the short-term effect of lateralized experience on manual preference and motor performance in infants reaching. Four- and seven-month-olds were induced to use the non-preferred hand through reaching for toys contralaterally to the preferred hand. Reassessment of manual preference in reaching at the central position revealed that infants used the nonpreferred hand more frequently. That behavior was similar between both age groups. Kinematic analysis of reaching did not indicate variations coherent with shift of manual preference. Experiment 2 tested the effect of practice with the non-preferred hand on manual preference and intermanual asymmetries of performance, comparing children and adults. Different tasks requiring reaching and manipulation were practiced. Manual preference was assessed through reaching toward cards at different positions on the right and left of the participant, and inserting the card into a slot. Results showed that use of the nonpreferred hand increased after practice in both age groups. There was no effect of practice on intermanual asymmetries of performance. Results indicate that manual preference is flexible and modulated by immediate lateralized experiences. / O efeito do uso da mão não-preferida sobre a preferência manual específica à tarefa e desempenho motor foi avaliado em dois experimentos. O experimento 1 objetivou investigar o efeito de curto-prazo de experiências lateralizadas sobre a preferência manual e o desempenho motor no alcance em bebês. Bebês aos 4 e 7 meses foram induzidos ao uso mais frequente da mão não-preferida por meio do oferecimento de brinquedos em posição contralateral à mão preferida. A reavaliação da preferência manual no alcance em posição medial revelou que os bebês passaram a usar mais frequentemente a mão não-preferida, sendo esse comportamento similar entre ambos os grupos etários. A análise cinemática dos alcances não indicou variações coerentes com a mudança de preferência manual. O objetivo do experimento 2 foi testar o efeito da prática com a mão não-preferida sobre preferência manual e assimetrias intermanuais de desempenho, comparando crianças e adultos. Foram praticadas tarefas que exigiam alcance e manipulação de objetos variados. A preferência manual foi avaliada no alcance de cartas em diferentes posições à direita e esquerda do participante e subsequente depósito em uma urna. Houve aumento no uso da mão não-preferida após a prática em ambos os grupos etários. Não foi encontrado nenhum efeito da prática lateralizada sobre as assimetrias intermanuais de desempenho. Os resultados indicam que a preferência manual é flexível e modulada por experiências lateralizadas imediatamente anteriores.

Die Studie hat zum Ziel, im Rahmen des Äußerungsproduktionsmodells die Annahme thinking for speaking (Slobin, 1996) experimentell zu überprüfen. Ansatzpunkt ist der Unterschied in der Stellung der Markierung einer Entscheidungsfrage zwischen drei Sprachen. Während der Fragemodus im Deutschen/Polnischen vor dem Frageinhalt markiert wird, geschieht die Modusmarkierung im Chinesischen nach dem Inhalt. Um die entsprechende Satzstruktur aufzubauen, sollte der Fragemodus beim syntaktischen Kodierungsprozess (speaking) im Deutschen/Polnischen vor, im Chinesischen nach dem Inhalt verarbeitet werden. Unter Zugrundelegung der inkrementellen Äußerungsproduktion gehen wir davon aus, dass die Verarbeitungsreihenfolge beim vorangehenden Konzeptualisierungsprozess (thinking) mit der syntaktischen Kodierungsabfolge übereinstimmt: Der Fragemodus wird im Deutschen/ Polnischen vor, im Chinesischen hingegen nach dem Inhalt konzeptualisiert. Um den zeitlichen Ablauf der zwei Konzeptualisierungsprozess zu ermitteln, bedienten wir uns des lateralisierten Bereitschaftspotenzials (lateralized readiness potential, LRP) im binären Wahlreaktions-Go/Nogo-Paradigma. Im Versuch reagierten deutsche, chinesische und polnische Muttersprachler auf dargebotene Bilder mit Tastendrücken und Sprechen. Zu beobachten war das Auftreten eines LRP bei Nogo, das signalisierte, in welcher Reihenfolge sich die Handwahl und die Nogo-Entscheidung realisierten Ein Nogo-LRP trat bei allen drei Sprechergruppen auf. Zudem wurde festgestellt, dass die Nogo-Entscheidung, die erwartungsgemäß mit der sprachlichen Verarbeitung des Fragemodus verbunden wurde, bei den drei Sprechergruppen ungefähr zeitgleich getroffen wurde. Die Befunde legen nahe, dass der Fragemodus in den drei Sprachen zeitlich nicht unterschiedlich, sondern einheitlich geplant wurde. Die Schlussfolgerung wird im Rahmen von thinking for speaking sowie dem Äußerungsproduktionsmodell diskutiert. / Languages differ in the marking of the sentence mood of a polar interrogative (yes/no question). For instance, the interrogative mood is marked at the beginning of the surface structure in Polish, whereas the marker appears at the end in Chinese. In order to generate the corresponding sentence frame, the syntactic specification of the interrogative mood is early in Polish and late in Chinese. In this respect, German belongs to an interesting intermediate class. The yes/no-question is expressed by a shift of the finite verb from its final position in the underlying structure into the utterance initial position, a move affecting, hence, both the sentence final and the sentence initial constituents. The present study aimed to investigate whether during generation of the semantic structure of a polar interrogative, i.e. the processing preceding the grammatical formulation, the interrogative mood is encoded according to its position in the syntactic structure at distinctive time points in Chinese, German, and Polish. In a two-choice go/nogo experimental design, native speakers of the three languages responded to pictures by pressing buttons and producing utterances in their native language while their brain potentials were recorded. The emergence and latency of lateralized readiness potentials (LRP) in nogo conditions, in which speakers asked a yes/no question, should indicate the time point of processing the interrogative mood. The results revealed that Chinese, German, and Polish native speakers did not differ from each other in the electrophysiological indicator. The findings suggest that the semantic encoding of the interrogative mood is temporally consistent across languages despite its disparate syntactic specification. The consistent encoding may be ascribed to economic processing of interrogative moods at various sentential positions of the syntactic structures in languages or, more generally, to the overarching status of sentence mood in the semantic structure.