Stress affects theta activity in limbic networks and impairs novelty-induced exploration and familiarization

Exposure to a novel environment triggers the response of several brain areas that regulate emotional behaviors. Here, we studied theta oscillations within the hippocampus (HPC)-amygdala (AMY)-medial prefrontal cortex (mPFC) network in exploration of a novel environment and subsequent familiarization through repeated exposures to that same environment; in addition, we assessed how concomitant stress exposure could disrupt this activity and impair both behavioral processes. Local field potentials were simultaneously recorded from dorsal and ventral hippocampus (dHPC and vHPC respectively), basolateral amygdala (BLA) and mPFC in freely behaving rats while they were exposed to a novel environment, then repeatedly re-exposed over the course of 3 weeks to that same environment and, finally, on re-exposure to a novel unfamiliar environment. A longitudinal analysis of theta activity within this circuit revealed a reduction of vHPC and BLA theta power and vHPC-BLA theta coherence through familiarization which was correlated with a return to normal exploratory behavior in control rats. In contrast, a persistent over-activation of the same brain regions was observed in stressed rats that displayed impairments in novel exploration and familiarization processes. Importantly, we show that stress also affected intra-hippocampal synchrony and heightened the coherence between vHPC and BLA. In summary, we demonstrate that modulatory theta activity in the aforementioned circuit, namely in the vHPC and BLA, is correlated with the expression of anxiety in novelty-induced exploration and familiarization in both normal and pathological conditions.

Chronic stress disrupts neural coherence between cortico-limbic structures

Chronic stress impairs cognitive function, namely on tasks that rely on the integrity of cortico-limbic networks. To unravel the functional impact of progressive stress in cortico-limbic networks we measured neural activity and spectral coherences between the ventral hippocampus (vHIP) and the medial prefrontal cortex (mPFC) in rats subjected to short term stress (STS) and chronic unpredictable stress (CUS). CUS exposure consistently disrupted the spectral coherence between both areas for a wide range of frequencies, whereas STS exposure failed to trigger such effect. The chronic stress-induced coherence decrease correlated inversely with the vHIP power spectrum, but not with the mPFC power spectrum, which supports the view that hippocampal dysfunction is the primary event after stress exposure. Importantly, we additionally show that the variations in vHIP-to-mPFC coherence and power spectrum in the vHIP correlated with stress-induced behavioral deficits in a spatial reference memory task. Altogether, these findings result in an innovative readout to measure, and follow, the functional events that underlie the stress-induced reference memory impairments.

A HIPÓTESE INTEGRADORA DA GOVERNANÇA CORPORATIVA E DA RESPONSABILIDADE SOCIAL CORPORATIVA SOB O ENFOQUE DOS DIREITOS HUMANOS

A governança corporativa e a responsabilidade social corporativa são dois instrumentos que têm o caráter de atingir a excelência da organização empresarial. Por sua vez, os mesmos foram instrumentalizados como meio de proteção dos interesses dos agentes privados com vista à potencialização da sociedade empresarial, motivados pela desconfiança dos processos decisórios dos administradores societários. Posteriormente, evoluiram sob a forma de códigos de condutas, ditados pelos organismos de controle empresarial, sempre conservando o caráter voluntário de sua aceitação. Alguns objetivos sequer foram incluídos nos seus processos internos de excelência, como por exemplo os direitos humanos de determinados stakeholders. Esse ponto é o objeto principal desta investigação, que busca evidenciar a hipótese de integração da governança corporativa e da responsabilidade social corporativa sob o enfoque dos direitos humanos. § The Corporate governance and corporate social responsibility are two instruments that have the character to achieve excellence in business organization. On the other hand, they have been exploited as a way of protecting the interests of private agents for enhancement of corporate society, motivated by the distrust of the decision-making process of corporate managers. Later, it evolved in the form of codes of conduct, dictated by the bodies of corporate control, always preserving the voluntary nature of their acceptance. Some objectives were not even included in its internal process of excellence, such as the human rights of certain stakeholders. This point is the main object of this research, which seeks to demonstrate the possibility of integration of corporate governance and corporate social responsibility in the human rights perspective.