Hemispheric asymmetry in the processing of an emotional working memory task.

Emotion and working memory are key components in daily life experiences. Previous research has already established a connection between these processes but the neural substrates of this relationship remain an open discussion. The present study aimed to investigate the effects of the use of pictures with emotional valence on the performance of a working memory task as well as the neuronal response during the task. For this purpose, 32 participants performed a 2-back task with negative, positive, and neutral images selected from the International Affective Pictures System (IAPS). No significant difference was found in the performance or in the response time related to the valence of the images. Repeated-measures ANOVA with hemisphere and valence as factors revealed an increase of the activity in the right hemisphere for the amplitude of the ERP P3 component and for the time-locked theta power for all the images. The P3 component in the right hemisphere additionally showed greater mean amplitude for the negative images as compared to the neutral and positive ones. Together, these results suggest a predominant role of the right hemisphere for the processing of both working memory and emotional information, as well as a higher neuronal resource allocation to the processing of negative valence images which enabled a proper performance of the working memory task for the negative images.

Cerebral localization of higher functions: The period between Thomas Willis and Paul Broca.

The age-old debates about the localization of the mind (higher functions) took a new course when Willis located a higher nervous function (memory) in the brain parenchyma, and supposedly, in the cerebral cortex. About two centuries later, Broca, founded on solid scientific reasoning, localized a circumscribed area of the 3rd frontal circumvolution of the left hemisphere as the seat of articulate language, a higher function (speech - language domain). He (and Dax) also defined the functional asymmetry (specialization) of the hemispheres, with left dominance (for language). The period between the findings of these individuals was not quiescent, as numerous authors contributed with their theoretical and clinicopathological research toward creating a conducive scientific atmosphere for this accomplishment, and should be regarded as important. Further studies, in the decades that followed, revealed the localization of additional aspects of language and of other higher functions (cognitive domains).

Os debates milenares sobre a localização da mente (funções superiores) chegaram a um novo caminho quando Willis localizou uma função nervosa superior (memória) no parênquima cerebral, e supostamente, no córtex cerebral. Cerca de dois séculos depois, Broca, baseado em sólido pensamento científico, localizou uma área circunscrita da 3ª circunvolução frontal do hemisfério esquerdo como o sítio da linguagem articulada, uma função superior (fala - domínio da linguagem). Ele (e Dax) também definiu a assimetria funcional (especialização) dos hemisférios, com dominância esquerda (para linguagem). O período entre os achados dessas duas personalidades não ficou quiescente, considerando que numerosos autores contribuíram, com suas pesquisas teóricas e clinicopatológicas, para criar uma atmosfera científica adequada para tal realização, devendo ser vistos como importantes. Mais estudos, nas décadas seguintes, revelaram a localização de aspectos adicionais da linguagem e de outras funções superiores (domínios cognitivos).

Cerebral localization of higher functions: The period between Thomas Willis and Paul Broca / Localização cerebral de funções superiores: o período entre Thomas Willis e Paul Broca

ABSTRACT. The age-old debates about the localization of the mind (higher functions) took a new course when Willis located a higher nervous function (memory) in the brain parenchyma, and supposedly, in the cerebral cortex. About two centuries later, Broca, founded on solid scientific reasoning, localized a circumscribed area of the 3rd frontal circumvolution of the left hemisphere as the seat of articulate language, a higher function (speech - language domain). He (and Dax) also defined the functional asymmetry (specialization) of the hemispheres, with left dominance (for language). The period between the findings of these individuals was not quiescent, as numerous authors contributed with their theoretical and clinicopathological research toward creating a conducive scientific atmosphere for this accomplishment, and should be regarded as important. Further studies, in the decades that followed, revealed the localization of additional aspects of language and of other higher functions (cognitive domains).

RESUMO. Os debates milenares sobre a localização da mente (funções superiores) chegaram a um novo caminho quando Willis localizou uma função nervosa superior (memória) no parênquima cerebral, e supostamente, no córtex cerebral. Cerca de dois séculos depois, Broca, baseado em sólido pensamento científico, localizou uma área circunscrita da 3ª circunvolução frontal do hemisfério esquerdo como o sítio da linguagem articulada, uma função superior (fala - domínio da linguagem). Ele (e Dax) também definiu a assimetria funcional (especialização) dos hemisférios, com dominância esquerda (para linguagem). O período entre os achados dessas duas personalidades não ficou quiescente, considerando que numerosos autores contribuíram, com suas pesquisas teóricas e clinicopatológicas, para criar uma atmosfera científica adequada para tal realização, devendo ser vistos como importantes. Mais estudos, nas décadas seguintes, revelaram a localização de aspectos adicionais da linguagem e de outras funções superiores (domínios cognitivos).

Gender and Hemispheric Asymmetries in Acquired Sociopathy.

The emergence of enduring antisocial personality changes in previously normal individuals, or "acquired sociopathy," has consistently been reported in patients with bilateral injuries of the ventromedial prefrontal cortex. Over the past three decades, cases of acquired sociopathy with (a) bilateral or (b) unilateral sparing of the ventromedial prefrontal cortex have been reported. These cases indicate that at least in a few individuals (a') neural structures beyond the ventromedial prefrontal cortex are also critical for normal social behavior, and (b') the neural underpinnings of social cognition may be lateralized to one cerebral hemisphere. Moreover, researchers have presented evidence that lesion laterality and gender may interact in the production of acquired sociopathy. In the present review, we carried out a comprehensive literature survey seeking possible interactions between gender and hemispheric asymmetry in acquired sociopathy. We found 85 cases of acquired sociopathy due to bilateral (N = 48) and unilateral (N = 37) hemispheric injuries. A significant association between acquired sociopathy and right hemisphere damage was found in men, whereas lesions were bilateral in most women with acquired sociopathy. The present survey shows that: (i) the number of well-documented single-cases of acquired sociopathy is surprisingly small given the length of the historical record; (ii) acquired sociopathy was significantly more frequent in men after an injury of the right or of both cerebral hemispheres; and (iii) in most women who developed acquired sociopathy the injuries affected both cerebral hemispheres. These findings may be especially valuable to neuroscientists and to functional neurosurgeons in particular for the planning of tumor resections as well as for the choice of the best targets for therapeutic neuromodulation.

Right cerebral hemisphere specialization for quiet and perturbed body balance control: Evidence from unilateral stroke.

Our aim in this investigation was to assess the relative importance of each cerebral hemisphere in quiet and perturbed balance, based on uni-hemispheric lesions by stroke. We tested the hypothesis of right cerebral hemisphere specialization for balance control. Groups of damage either to the right (RHD, n=9) or the left (LHD, n=7) cerebral hemisphere were compared across tasks requiring quiet balance or body balance recovery following a mechanical perturbation, comparing them to age-matched nondisabled individuals (controls, n=24). They were evaluated in conditions of full and occluded vision. In Experiment 1, the groups were compared in the task of quiet standing on (A) rigid and (B) malleable surfaces, having as outcome measures center of pressure (CoP) amplitude and velocity sway. In Experiment 2, we evaluated the recovery of body balance following a perturbation inducing forward body oscillation, having as outcome measures CoP displacement, peak hip and ankle rotations and muscular activation of both legs. Results from Experiment 1 showed higher values of CoP sway velocity for RHD in comparison to LHD and controls in the anteroposterior (rigid surface) and mediolateral (malleable surface) directions, while LHD had lower balance stability than the controls only in the mediolateral direction when supported on the rigid surface. In Experiment 2 results showed that RHD led to increased values in comparison to LHD and controls for anteroposterior CoP displacement and velocity, time to CoP direction reversion, hip rotation, and magnitude of muscular activation in the paretic leg, while LHD was found to differ in comparison to controls in magnitude of muscular activation of the paretic leg and amplitude of mediolateral sway only. These results suggest that damage to the right as compared to the left cerebral hemisphere by stroke leads to poorer postural responses both in quiet and perturbed balance. That effect was not altered by manipulation of sensory information. Our findings suggest that the right cerebral hemisphere plays a more prominent role in efferent processes responsible for balance control.

Normative study of tympanic infrared thermometry: a non-invasive index of asymmetric cerebral activity

Human and primate studies have demonstrated that performance of tasks that induce asymmetrical physiological activation of the cerebral hemispheres leads to a reduction of tympanic temperature (TT) ipsilateral to the most active hemisphere. It is possible that diseases that interfere in an asymmetrical fashion with the degree of cerebral activity cause similar TT changes. There are not, however, normative studies of the acceptable interaural difference in TT in normal subjects at rest. This study was done to establish normative values for interaural TT values measured by means of infrared tympanic thermometry in resting normal subjects not engaged in any specific task. TT values were measured in 47 normal volunteers (20 men and 27 women, aged 39.38±12.57 years old) at rest; mean interaural differences of TT were calculated. Mean right ear TT was 36.85±0.50ºC and mean left ear TT was 36.74±0.57ºC; these values are in agreement with those already reported in the literature. Mean interaural TT difference was 0.25ºC (SD 0.21ºC). These findings indicate that maximal normal values for interaural TT differences, with confidence levels of 99 percent and 95 percent, are, respectively, 0.88 and 0.67ºC. The value of interaural differences of TT as a marker of asymmetrical hemispheric activity in neurological patients will have to be established by additional studies.

Estudos em humanos e outros primatas demonstraram que a realização de tarefas que causam ativação assimétrica fisiológica dos hemisférios cerebrais resulta em redução da temperatura timpânica (TT) ipsilateral ao hemisfério cerebral mais ativo. É possível que patologias que interfiram de modo assimétrico com o grau de atividade cerebral causem alterações similares da TT. Não existem, entretanto, estudos normativos da diferença normal aceitável de TT entre os tímpanos de um mesmo indivíduo em repouso. Este estudo teve como objetivo estabelecer uma normatização dos valores bilaterais da TT, e principalmente das diferenças interauriculares desse parâmetro, obtidas por termometria timpânica por infravermelho, em indivíduos normais, na ausência de execução de tarefas específicas. Foram obtidas medidas da TT em 47 voluntários normais (20 homens e 27 mulheres, com média de idade de 39,38±12,57 anos) em repouso e calculadas as diferenças interauriculares, sua média e desvio-padrão. A TT média foi de 36,85±0,50ºC à direita e de 36,74± 0,57ºC à esquerda, o que está de acordo com dados da literatura. A média das diferenças de TT encontrada foi de 0,25ºC e o desvio padrão (DP) 0,21ºC. Com base nesses achados, os valores máximos considerados normais para a diferença interauricular da TT, com níveis de confiança de 99 por cento e de 95 por cento, são de 0,88ºC e 0,67ºC, respectivamente. A utilidade da medida da diferença interauricular da TT como marcador de assimetria da atividade cerebral em pacientes com patologias neurológicas deverá ser avaliada em estudos adicionais.