Dissertations / Theses on the topic 'Brain lateralization'

Research in neuropsychology has found depression to be related to impaired right hemisphere (RH) functioning. How clinical depression affects brain lateralized functioning for each sex, however, is not clear. The main aim of this thesis was to investigate how clinical depression impacts brain lateralized functioning for each sex. Additionally, this thesis investigates brain lateralization for emotional processing in a non-depressed group, as well as sex differences in brain lateralization for spatial, verbal, and emotional processing in a non-depressed group. In order to examine each of these research areas, sixty non-depressed participants, and thirty-nine dilnically depressed patients were recnjited to complete a set of neuropsychological tasks that measure brain lateralized spatial, verbal, and emotional functioning. The neuropsychological tasks that were selected also measure the brain regions known to be involved with depression (frontal lobe and right parietal lobe). The tasks were: the mental rotation task (MRT) to measure RH spatial functioning; the verbal fluency task (phonemic and semantic) to measure left hemisphere (LH) verbal functioning; and the chimeric faces task to measure frontal lobe emotional functioning. The data from these tasks were reported as two separate experiments. Experiment One examined sex differences in brain lateralization for spatial and verbal processing in a non-depressed group. Experiment One also investigates brain lateralization for emotional processing in a non-depressed group, in particular to determine whether there is a sex difference in brain lateralization for emotional processing. The aim of Experiment One was to replicate the male advantage in spatial processing and the female advantage in verbal processing, which have previously been interpreted as reflecting sex differences in brain lateralization for these functions. It was also the aim to differentiate between the competing RH and valence hypotheses of brain lateralization for emotional processing and further investigate sex differences in brain lateralization for emotional processing. Sex differences in brain lateralization for spatial, verbal, and emotional processing were examined by comparing the performance of thirty non-depressed males and thirty non-depressed females on the MRT, verbal fluency task, and chimeric faces task respectively. The hypothesis that males would mentally rotate the stimuli of the MRT faster than the females was not supported, as no significant sex differences in performance were observed on the MRT. Failure to replicate the male advantage in spatial functioning was attributed to a possible sex difference in level of spatial ability, which has been found to mediate hemispheric functioning. The hypothesis that the females would generate significantly more words than the males on the verbal fluency task was supported, thus replicating the female advantage in verbal processing. For the chimeric faces task, the group findings supported the RH hypothesis for brain lateralization for emotional processing, with responses being significanfly faster and more accurate to happy and sad expressions shown in the LVF than in the RVF. No consistent sex differences in performance were observed between the RT and accuracy rate analyses of the chimeric faces task. Reaction times to the chimeric faces showed a LVF advantage in emotional processing for the males, and no hemispheric bias for emotional processing for the females. In contrast, recognition accuracy of the chimeric faces showed a LVF advantage for emotional processing for both the males and the females. The inconsistent sex differences on the chimeric faces task suggests that there is not a strong sex difference in brain lateralization for emotional processing. Expertment Two investigated brain lateralization for spatial, verbal, and emotional functioning in a clinically depressed group. It was the aim of Experiment Two to determine whether clinical depression is associated with impaired RH functioning, as suggested by the literature. It was also the aim of Experiment Two to examine more specifically, how clinical depression affects brain lateralized functioning for each sex separately. To examine the effect of clinical depression on brain lateralized functioning, the performance of thirty-six (fifteen males, twenty-one females) clinically depressed patients (three excluded from the recruited thirty-nine) and thirty-six (eighteen males, eighteen females) non-depressed control participants was compared on the MRT, verbal fluency task, and chimeric faces task. The hypothesis that clinical depression would be associated with impaired RH functioning was partially supported by the results of Experiment Two. The depressed group performed signiflcantiy poorer than the control group on both the RH task (the MRT intercept and overall R and the LH task (semantic verbal fluency). Therefore, impaired RH and LH functioning on the spatial and verbal task was evidenced for the clinically depressed group in Experiment Two. A RH impairment in emotional functioning with clinical depression could not be clearly ascertained from the results of the chimeric faces task. The RT analyses of the chimeric faces task showed a LVF advantage for emotional processing for both the control and depressed groups. In contrast to the RT analyses, the accuracy rate analyses of the chimeric faces task showed a LVF advantage in emotional processing for the control group, and no hemispheric bias for emotional processing for the depressed group, As the depressed group were significantly impaired for both RH and LH functioning in Experiment Two, it is possible that the findings of Experiment Two are reflective of a generalised performance deficit associated with clinical depression, rather than to a disturbance in brain lateralized functioning. The depressed group was also found to respond significantly slower than the control group in overall RT on the MRT and chimeric faces task. The significant group difference on the intercept of the FART implicates impaired information encoding for the clinically depressed group. The slowed Ris of the depressed group may also reflect impaired pre-motor organization with clinical depression, thus resulting in delayed motor responses. In relation to the affect of clinical depression on brain lateralizaflon for each sex, it was hypothesised that the depressed males would perform significantly poorer than the depressed females on tasks measuring functions lateralized to the cerebral hemisphere impaired due to clinical depression. The premise for this hypothesis lies in the evidence from past unilateral brain lesion research, which suggests that the stronger brain ateralization of males restricts assistance from the unimpaired hemisphere to perform the task of the impalred hemisphere. The bilateralization of females however, allows greater assistance of the unimpaired hemisphere to perform the task at hand. In contrast to the hypothesis however, there was no evidence from the results of Experiment Two that clinical depression had a greater impact on the brain lateralized functioning of males than females. No significant sex differences in performance on the FART were observed for either the non-depressed control group or clinical depressed group. For the verbal fluency task, a female advantage in word generation was observed for both phonemic and semantic fluency, regardless of group. Also regardless of group, the RT analyses of the chimeric faces task showed that the males responded significantly faster to emotional expressions shown in the LVF than in the RVF. For the females however, there was no hemispheric bias in RT for emotional processing. The accuracy rate analyses from the chimeric faces task also showed no sex differences for either group. The similar findings of sex differences between the control and depressed groups across each task suggests that clinical depression had a similar impact on both the males and the females, regardless of brain late ralization. The results of Experiment Two could be indicative of impaired LH and RH functioning with clinical depression, or of a generalised performance deficit with clinical depression. A generalised performance deficit for the clinically depressed group in Experiment Two may explain why a sex difference in the effects of clinical depression on brain lateralized functioning was not observed. Future research observing a RH impairment with clinical depression is encouraged to further examine the affect of clinical depression on brain lateralization for each sex separately. Further understanding of the affect of clinical depression on brain lateralization for each sex could provide addiional information on sex difference in the prevalence of clinical depression.

Thesis (PhD) - Swinburne University of Technology, Brain Sciences Institute, 2006.
Typescript. [A thesis submitted for requirements of the degree of Doctorate of Philosophy, Faculty of Life and Social Sciences, Brain Sciences Institute, Swinburne University of Technology - 2006]. Includes bibliographical references (p. 234-270).

Since the face forms over the brain in the course of embryonic development, facial anthropometry may reflect brain structure. The motor functions of each side are controlled by the side of the brain opposite the body side. The purpose of this study was to establish whether a correlation exists between handedness and the location of the external auditory meatuses, as a possible consequence of brain asymmetry. Facial photographs were taken of 78 volunteers. Straws, placed in the external ear canals, were used to mark the external auditory meatuses. The level of the top of each meatus was measured from each volunteer's visual plane, as established by connecting the center of a point of reflected light in each pupil. Each volunteer was also given the Edinburgh Laterality Inventory (Durden-Smith and DeSimone, 1984:53) to determine "true" handedness (50 right-handers and 28 left-handers). Right-handers, as determined by either writing hand or laterality inventory, were found to exhibit a greater tendency for the left auditory meatus to be lower. Specifically, 68% of the right-handers, as opposed to 39% of the left-handers, exhibited a left external auditory meatus located at a lower position on the skull than the right meatus. This was significant at the 0.05 level. The differences in external auditory meatal distances from the visual plane were greater on the left in right-handers 68% of the time, equal 10%, and greater on the right 22% of the time. A reverse correlation for the right asymmetry for left-handers was not found. Instead, for the left-handed sample a nearly even distribution for meatal location was found: 39% left asymmetry, 29% symmetry, and 32% right asymmetry.The study strongly supported the hypothesis that right-handers have a significant tendency for left asymmetry in location of the external auditory meatuses. The study did not support the hypothesis that the meatal asymmetry correlates to the side opposite the handedness of the individual. Of-perhaps greater significance is the finding that the percentages of left asymmetry of both groups match the brain asymmetry percentages found by Galaburda (1984:15) for the planum temporale, an extension on the upper surface of the temporal lobe of the brain. The level of the external auditory meatuses, as a reflection of brain asymmetry, may serve as an external measurement of the location of Wernicke's area which is located near the planum temporale and has a major role in speaking and comprehension of the spoken word and in reading and writing. Simple techniques for locating the language centers of the brain would be an advantage in developing education plans and teaching strategies for students with each of the possible hemispheric dominance patterns.
Department of Anthropology

The current study utilized a priming paradigm in conjunction with a visual halffield presentation to determine if the right hemisphere contributes to pragmatic processing. Primes included conversational dialogues that either performed a speech act or did not. The targets identified the speech act and were presented to one of the two visual fields (lvf-RH or rvf-LH). It was hypothesized that the right visual field-left hemisphere (rvf-LH) would be more accurate and faster at identifying targets regardless of the script type that preceded it and the left visual field-right hemisphere (lvf-RH) would be significantly more accurate and faster at identifying targets when preceded by a script that performed the identified speech act. Results indicated that the lvf-RH was more accurate and faster at identifying a target regardless of the type of script that preceded it, while the rvf-LH was differentially affected by the type of script.
Department of Psychological Science

Hemispheric lateralization in speech perception in infants and adults was studied by means of brain activation patterns via EEGmeasurement. Overall activation and ERPs in response to IDS-stimuli in Swedish, Portuguese and rotated Swedish were tested in 9 4-monthold infants and 13 adults with EEG head-nets. Left-hemispheric activation was expected in adults at least for intelligible speech stimuli, whereas non-specific activation in both hemispheres was expected in infants. The results showed a right-hemispheric lateralization tendency in adults. The infants showed no lateralization pattern. Further research on 9-month-old infants is the next step to understand lateralization development in infants.
Hemisfärisk lateralisering vid talperception hos spädbarn och vuxna studerades genom hjärnaktiveringsmönster via EEG mätningar. Allmän aktivering och ERP som respons på barnriktat tal på svenska, portugisiska och roterad svenska testades på 9 stycken 4 månader gamla spädbarn och 13 stycken vuxna med EEG-nät. Vänster hjärnhalva förväntades aktiveras hos de vuxna åtminstone för förståeligt talstimuli, medan en icke-specifik aktivering i båda hemisfärerna förväntades hos spädbarnen. Resultaten visade en tendens mot högerhemisfärisk lateralisering hos vuxna. Spädbarnen visade inget lateraliseringsmönster. Ytterligare undersökningar på 9 månader gamla spädbarn är nästa steg för att nå kunskap angående lateraliseringsutvecklingen hos spädbarn.
The influence of attention to phonetic detail in speech perception on vocabulary development: Early prevention of developmental language delay

The aims of the thesis were to examine i) whether the endogenous opioid system (EOS) is lateralized in human brain areas involved in processing of emotions and pain; ii) whether EOS responses to unilateral brain injury depend on side of lesion, and iii) whether in human alcoholics, this system is involved in molecular adaptations in brain areas relevant for cognitive control of addictive behavior and habit formation. The main findings were that (1) opioid peptides but not opioid receptors and classic neurotransmitters are markedly lateralized in the anterior cingulate cortex involved in processing of  positive and negative emotions and affective component of pain. The region-specific lateralization of neuronal networks expressing opioid peptides may underlie in part lateralization of higher functions in the human brain including emotions and pain. (2) Analysis of the effects of traumatic brain injury (TBI) demonstrated predominant alteration of dynorphin levels in the hippocampus ipsilateral to the injury, while injury to the right hemisphere affected dynorphin levels in the striatum and frontal cortex to a greater extent than that to the left hemisphere. Thus, trauma reveals a lateralization in the mechanisms mediating the response of dynorphin expressing neuronal networks in the brain. These networks may differentially mediate effects of left or right brain injury on lateralized brain functions. (3) In human alcoholics, the enkephalin and dynorphin systems were found to be downregulated in the caudate nucleus and / or putamen that may underlie in part changes in goal directed behavior and formation of a compulsive habit in alcoholics. In contrast to downregulation in these areas, PDYN mRNA and dynorphins in dorsolateral prefrontal cortex, k-opioid receptor mRNA in orbitofrontal cortex, and dynorphins in hippocampus were upregulated in alcoholics. Activation of the k-opioid receptor by upregulated dynorphins may underlie in part neurocognitive dysfunctions relevant for addiction and disrupted inhibitory control. We conclude that the EOS exhibits region-specific lateralization in human brain and brain-area specific lateralized response after unilateral TBI in mice; and that the EOS is involved in adaptive processes associated with specific aspects of alcohol dependence.

This doctoral work consists of several studies that investigated the relationship between language lateralization and structural asymmetries found in auditory and language-related regions of the human brain. Language lateralization was determined via the intracarotid Sodium Amytal procedure in epilepsy patients. In study 1, three groups of patients were investigated: a left speech group (LSG); a right speech group (RSG); and a bilateral speech group (BSG). Two auditory cortex regions: Heschl's gyrus (HG) and the planum temporale (PT) were labelled on the magnetic resonance imaging scan of each subject. Additionally, an automatic voxel-based morphometry (VBM) analysis was performed. The overall findings suggested that the structural asymmetries found in the auditory regions did not clearly and directly relate to language lateralization. The VBM analysis, however, revealed a grey matter concentration difference in the region of Broca's area favoring the left hemisphere (LH) in the LSG, and the right hemisphere (RH) in the RSG. That structural difference did relate to language lateralization and was further investigated in studies 2 and 3. Previously collected positron emission tomography data were examined in these two studies. Three regions of interest (ROI) analyses and one group average analysis were performed. Activation related to various speech tasks was examined. The ROI analyses revealed a significant activation difference favoring the LH for two targeted speech-task subtractions but only for the LSG. The group analysis, in contrast, revealed that the LSG showed a functional asymmetry favoring the LH, and that the RSG showed a functional asymmetry favoring the RH. Overall, the present results provided only partial evidence for a relationship existing between structural asymmetry in Broca's area and language lateralization. The structural asymmetries found in HG and the PT, in contrast, did not clearly and directly relate to language

The database on hand preferences in non-human primates provides inconsistent and inconclusive findings, and is plagued by gaps and methodological issues. I studied hand preferences in the bonobo, which is a very interesting model for investigating evolutionary hypotheses on human handedness. There are few previous data on bonobos and they are from small samples and for relatively simple tasks. I studied a large sample of 94 bonobos in three zoos and one sanctuary, on a variety of actions. Five studies were performed to record: 1. hand use for spontaneous daily actions (non-social). 2. hand use for the tube task , a task that requires a manipulative bimanual coordinated precise action. 3. hand use for using a stick as a probe ( termite fishing ). 4. hand use for spontaneous social actions and gestures, recorded during their social interactions (intra-specific) and during interactions with humans (inter-specific). 5. hand use for induced begging gestures (begging for food from the observer). The results show significant manual laterality in almost all the behaviours studied. The hand preferences were present on an individual basis. The numbers of right-handed and left-handed individuals were similar, indicating no group-level bias, for any of the actions studied. There was no significant effect of the settings, rearing history, sex and age (except in study 2 where adults were more right-handed than younger subjects). I examined different factors that have been proposed as selective pressures for the emergence of handedness. Laterality was influenced by: postural demands (posture, activity of the other hand), precision, grip type, manipulation or bimanual coordination, tool-use, throwing, communication. Notably, the laterality was very marked for the tube task , the termite fishing task and the begging experiment, which suggests that the factors involved in these tasks could be important factors regarding laterality.

Earlier research has found that preterm birth with low gestational age (GA) and low birth weight (BW) is associated with an increased risk of long-term effects such as atypical lateralization, cognitive deficits and smaller brain volume. Similar consequences have been found in twins. This study compares twins born preterm (n=22, Mean GA=32.1, Mean BW=1781) with GA and BW matched singletons (n=24) and singletons born full term (n=22) on functional laterality, cognition (WISC-IV) and brain volume (SyMRI) at early school ages (M=7.8 years). The result showed that twins had a higher prevalence of left-handedness than both singleton groups. The preterm (PT) singletons show less right ear preference on the Dichotic Listening test than full term (FT) singletons. It was found that the FT-group performed higher than both PT-groups on cognition. Smaller brain volumes were associated with lower performances on WISC-IV in the group of twins. Furthermore it was found that the PT-singletons had smaller Total Brain volume as well as smaller Grey Matter than FT-singletons. No differences were found between the twins and the PT-singletons on intra pair comparisons. Combined with the associations found between GA, BW and cognitive performance and brain volumes the results indicate that low GA and BW are greater risk factors for long-term effects on development than twin-ship per se.

Earlier research has found that preterm birth with low gestational age (GA) and low birth weight (BW) is associated with an increased risk of long-term effects such as atypical lateralization, cognitive deficits and smaller brain volume. Similar consequences have been found in twins. This study compares twins born preterm (n=22, Mean GA=32.1, Mean BW=1781) with GA and BW matched singletons (n=24) and singletons born full term (n=22) on functional laterality, cognition (WISC-IV) and brain volume (SyMRI) at early school ages (M=7.8 years). The result showed that twins had a higher prevalence of left-handedness than both singleton groups. The preterm (PT) singletons show less right ear preference on the Dichotic Listening test than full term (FT) singletons. It was found that the FT-group performed higher than both PT-groups on cognition. Smaller brain volumes were associated with lower performances on WISC-IV in the group of twins. Furthermore it was found that the PT-singletons had smaller Total Brain volume as well as smaller Grey Matter than FT-singletons. No differences were found between the twins and the PT-singletons on intra pair comparisons. Combined with the associations found between GA, BW and cognitive performance and brain volumes the results indicate that low GA and BW are greater risk factors for long-term effects on development than twin-ship per se.

Musicians comprise a unique population whereby persistent musical practice involving complex cognitive and motor tasks dates back to childhood when the potential for neural plasticity is at its highest. Accordingly, it has been speculated that musical training results in neural structural and functional differences between musicians and non-musicians. In particular, there is evidence to indicate parietal regions are more equally lateralized in musicians, but research investigating visuospatial abilities and lateralization in musicians is scarce. Studies 1 and 2 aimed to assess the visuospatial ability and cognitive processing speed of adult musicians versus ‪demographically and educationally matched non-musicians. ‪Musicians performed more quickly and more accurately than non-musicians in two tasks of visuospatial ability, and completed more items than non-musicians in three tasks of processing speed, suggesting ‪musicians had better ‪visuospatial ability and a faster speed of processing. Studies 3 and 4 aimed to investigate ‪visuospatial attention in ‪these groups using a line-bisection task and a visual discrimination task. On both tasks musicians demonstrated more balanced visuospatial attention with a slight bias to the right hemispace, which was in contrast to the non-musicians’ bias to the left hemispace, a natural phenomenon known as ‘right pseudoneglect’. In Study 5, the laterality of visual processing in musicians and non-musicians was further investigated by comparing electrophysiological interhemispheric transfer time (IHTT) of lateralized visual stimuli across the corpus callosum. Non-musicians had faster right-to-left than left-to-right IHTT consistent with previous research, whilst musicians had more balanced IHTT in both directions and faster left-to-right transfer than non-musicians. Absolute latency patterns revealed similar results and consistently demonstrated more balanced visual processing in musicians. The behavioural data, analysed in Study 6, revealed a tendency (n.s.) for the ‪musician group to respond more quickly to stimuli presented in the right visual field than to stimuli presented in the left visual field, whilst ‪non-musicians did not show this pattern. Overall, the results indicate that musicians have enhanced visuospatial ability and are less lateralized for visuospatial attention and perception than non-musicians. The results are discussed in relation to plastic developmental changes that may be caused by extended musical training from childhood. Specifically, it is proposed that musical training in early life may elicit a process of myelination that is more bilaterally distributed than myelination in non-musicians.

Le stress prénatal est un sujet d'intérêt éthologique croissant en raison de ses effets sur la santé humaine et le bien-être des animaux. Cette thése de doctorat s’intéresse à la seiche Sepia officinalis, un modèle pratique dans lequel la progéniture en développement peut être séparée de leurs mères pour examiner diverses sources potentielles de stress en isolement expérimental. Plusieurs catégories de facteurs de stress ont été appliquées aux embryons et aux juvéniles et la progéniture résultante a été testée dans une série d'épreuves physiologiques et comportementales. L'objectif était de déterminer si différents types de stress prénatal affectent la seiche et, dans l'affirmative, comment ces effets se transmettent. Les données présentées démontrent que les stresseurs appliqués aux femelles reproductrices (stress maternel), ainsi que les stresseurs appliqués directement aux embryons (stress embryonnaire), affectent le comportement postnatal (y compris la structuration corporelle, la latéralisation cérébrale, la prédation et les schémas d'activité) la mémoire et / ou la neurobiologie (y compris les concentrations et le renouvellement de la monoamine, la taille des différents lobes cérébraux et la division cellulaire). Les résultats mettent en évidence la présence de trois voies par lesquelles le stress peut exercer des effets: sur le nombre de descendants produits par la femelle, la transmission de la femelle à sa progéniture et directement sur la progéniture elle-même. Les expériences ont également démontré qu'un facteur de stress complètement artificiel (lumière forte) affectait un éventail plus large de comportements chez la progéniture qu’un stress naturel (odeur de prédateur). Enfin, les données ont montré que l'environnement d'incubation et d’élevage peuvent également affecter la progéniture et méritent donc une attention particulière dans la formulation et l'interprétation des expériences avec cette espèce. Ces découvertes informent à la fois les pratiques de bien-être des seiches et d'autres céphalopodes (par exemple, réduisent la manipulation pour maximiser la reproduction) et élucident et renforcent les principes éthologiques qui s'appliquent au stress animal en général (par exemple la transmission des effets de stress de la mère à la progéniture). Compte tenu des informations fournies ici et dans de nombreuses autres études, la seiche et d'autres céphalopodes devraient continuer à servir de modèles comportementaux en éthologie et en biologie en général
Prenatal stress is a subject of growing ethological interest due to its effects on human health and animal welfare. This Ph.D. thesis utilizes the cuttlefish Sepia officinalis, a convenient model in which developing offspring can be separated from their mothers to examine various potential sources of stress in experimental isolation. Several categories of stressors were applied to cuttlefish and cuttlefish eggs and the resulting offspring were tested in a range of physiological and behavioral tests. The goal was to determine if various types of prenatal stress affect cuttlefish, and if so, how these effects are transmitted. The data presented demonstrate that both stressors applied to reproducing females (maternal stress), as well as stressors applied directly to embryos (embryonic stress), affected post-natal behavior (including body patterning, brain lateralization, predation and activity patterns), learning, memory and/or neurobiology (including monoamine concentrations and turnover, the size of various brain lobes and cell division). The results highlight the presence of three pathways by which stress can exert effects: on the number of offspring produced by the female, transmission from the female to her offspring and directly on the offspring themselves. The experiments also demonstrated that a completely artificial stressor (bright light) affected a wider range of behaviors in offspring than a natural-occurring one (predator odor). Finally, the data showed that incubation and spawning environment can also affect offspring, and thus deserve attention in the formulation and interpretation of experiments with this species. These findings inform both welfare practices for cuttlefish and other cephalopods (e.g. reduce handling to maximize reproduction) as well as elucidating and reinforcing ethological principles that apply to animal stress in general (e.g. the transmission of stress effects from mother to offspring). Given the insight provided here and in numerous other studies, cuttlefish and other cephalopods should continue to serve as behavioral models in ethology and biology in general

Norman Geschwind, Albert M. Galaburda.
"A Bradford book." "Much of this book appeared as a three-part article in the 'Archives of neurology' volume 42, May, June, and July, 1985"--T.p. verso. Includes index.
Bibliography: p. [241]-273.

碩士
國立臺灣師範大學
生命科學研究所
96
By the proving of molecular biological technology, zebrafish has been widely used in transgenic experiments. Recently, results showed that brain lateralization exists both in the small fish’s and human’s brain. In the present study, we use modified T-maze apparatus which is symmetry and able to control opening way to examine the possible direction preference of zebrafish in the spatial memory task. In addition, we give animal irreversible surgical lesion and observe its effect on the spatial memory task. There are three experiments in this study. In experiment-1 we use naïve animals to develop the standard training procedure. Briefly, there are two training procedure which named right-side learning and left-side learning. Animals were taught to swim direct to the right side and left side respectively. We found that only the right side learning group shows the learning curve, but similar pattern was not found in the left side learning group. Animals of the left side learning group just swam in a randomly manner and kept the speed while enter the target area. In experiment 2, we train the animals which has been bilateral telencephalic ablation on the protocol of T-maze we has made in experiment 1. We found animals in sham group show almost the same pattern and performance with the naïve groups in experiment 1. However, animals in the lesion group, the right side learning group didn’t show the learning curve. The speed of left side group was faster than the right side group, but animal didn’t choose the left side when animals first arrived the connect area of T-maze. In experiment 3 animals were given one-side telencephalic ablation and saw the learning performance in T-maze. The results showed that the right side telencephalon played an important role in the T-maze task of right side learning, and the left side was more important in emotional progressing. Recent results showed that there were lateralize in zebrafish brain. The right eye system (RES) made decision to bite and the familiar objects. The left eye system (LES) was to use to observe the strange environment or identify new objects. And our results showed that the direction of the target reservoir will confound the learning response. Zebrafish expressed an accumulative learning response when the target reservoir settled on the right hand side. We suggest that the differential learning responses of zebrafish was resulted in the lateralization of zebrafish brain. And the right telecephalon may be play the more important on the spatial learning progress.

Cerebral lateralization was once thought to be unique to humans, but is now known to be widespread among the vertebrates. Lateralization appears to confer cognitive advantages upon those that possess it. Despite the taxonomic ubiquity and described advantages of lateralization, substantial individual variation exists in all species. Individual variation in cerebral lateralization may be tied to individual variation in behaviour and the selective forces that act to maintain variation in behaviour may also act to maintain variation in lateralization. Sex differences may also be an important source of variation in lateralization, as differences between males and females are often observed. Here, I present three papers that collectively deal with the interrelationships between sex, behaviour and cerebral lateralization in the convict cichlid. My results illustrate that lateralization is related to personality-like characteristics in the convict cichlid, and that there are important differences between the sexes in their pattern of lateralization.

Trabalho Final do Mestrado Integrado em Medicina apresentado à Faculdade de Medicina
O cérebro tem dois hemisférios assimétricos. Desde o século XIX que se sabe que as funções por eles desempenhadas são diferentes. Procurámos clarificar a relação entre lesões do hemisfério direito e manifestações psiquiátricas. Pesquisámos a base de dados Google Académico em busca de relatos de casos de danos unilaterais direitos com algum tipo de manifestação psiquiátrica. Encontrámos casos de alucinações, delírios e alterações do humor que ocorreram na sequência de lesão do hemisfério direito. Os resultados vêm ao encontro de evidência no sentido da existência de uma relação entre patologia psiquiátrica, em particular delirante, e lesão do hemisfério direito, e de hipóteses que localizam funções do self e atribuição de significado neste hemisfério cerebral.
The brain has two asymmetrical hemispheres. It is known since the nineteenth century that they have different functions. We tried to clarify the relationship between right brain damage and psychiatric manifestations. We searched the Google Scholar database for case reports of unilateral right brain damaged patients displaying some kind of psychiatric symptoms. We found cases of hallucinations, delusions and humor changes that happened following a lesion on the right hemisphere. The results are convergent with evidence pointing towards a relationship between psychiatric disease, particularly of the delusional type, and right brain damage, and with hypothesis that localize self and meaning attribution functions in this brain hemisphere.<© Corona 2015>

Thesis presented at ISPA – Instituto Universitário as to obtain a Master’s degree in the specialty of Cognitive and Behavioural Neuroscience
Recent evidence in the animal kingdom, specifically in the Phylum Chordata, has revealed a variety of asymmetries regarding social and non-social behaviours. These preferences for side use can be translated into a lateralized processing of information in the brain. Studies performed with domestic horses show several behavioural asymmetries, however, domestic horses have a lot of interaction with caretakers and tend to lack real threats. This study investigated lateralization in frequency and duration of social interactions (affiliative and agonistic) and in resting behaviours on feral horses (Equus ferus caballus). While a small skewness of the data for a left-side preference was found for agonistic behaviours, statistical analyses revealed no significant bias. Horses were more prone to display grooming interactions using the right side and this behaviour lasted longer on this side, but no bias was found for cross-resting (although a skewness was visible for the left side). As for resting, although no bias was found for frequency of side use, a marginal (albeit non-significant) difference was present for the duration, resting tends to last longer when performed on the left side. These results do not entirely support a right-hemisphere dominance for social interactions nor a valence-specific assumption (left-hemisphere dominance for positive affect and right-hemisphere dominance for negative affect). Our findings on the right-side bias for grooming may eventually be interpreted as a role of the environment (ecological pressures) that shapes lateralization in different behaviours.
Novas evidências no Reino Animal, em específico no Filo Chordata, mostram frequências diferentes na direção de comportamentos sociais e não sociais. A propensão pelo uso de um lado revela um processamento de informação lateralizado no encéfalo. Estudos com cavalos domésticos revelam assimetrias comportamentais, porém, cavalos domésticos podem estar sujeitos a treino, para além de uma ausência de perigos como predação. Este estudo investiga a lateralização em cavalos assilvestrados (Equus ferus caballus) na frequência e duração de comportamentos sociais (afiliativos e agonísticos) e no comportamento de repouso. A tendência para o uso do lado esquerdo em comportamentos agonísticos não revelou nenhum enviesamento significativo. Contudo, uma preferência estatisticamente significativa pelo uso do lado direito foi encontrada para o comportamento de grooming e a duração do mesmo era maior com o uso desse lado. O comportamento de repouso cruzado não apresentou diferenças significativas a nível da frequência ou duração, todavia apesar do repouso não ter exibido diferença na frequência, a duração aparenta (apesar de não significativamente) ser mais longa com o uso do lado esquerdo. Estes resultados não apoiam inteiramente a hipótese de um controlo do hemisfério direito para comportamentos sociais nem são inteiramente congruentes com a ideia de especificidade de valência (dominância do hemisfério esquerdo para comportamentos com valência positiva e do hemisfério direito para comportamentos com valência negativa). Contudo, a lateralização para o lado direito no grooming poderá vir a ser interpretada como o resultado de pressões seletivas que moldam a lateralização de diferentes comportamentos.