Avaliação da imobilidade tônica em codornas de corte via análise de sobrevivência' / Tonic immobility evaluation in meat quail via survival analysis

Tonic immobility (TI) is a way to measure fear, as characterized by the reduced capacity to respond to external stimuli. The time spent in TI indicates the level of fear. Since TI is measured as the time until event occurrence, survival analysis stands out as a suitable statistical method to treat these data. We aimed to investigate the influence of possible factors (lines, sex and age) on fear behavior in meat quail (Coturnix coturnix) measured through TI by using survival analysis (non parametric Kaplan-Meyer method via logrank test). The dataset was composed by TI information provided by 50 animals from each line (UFV1 and UFV2) in each age (14 and 28 days of age), totalizing 200 records. Despite the slight difference between the two evaluated ages, there was no significance for this factor between each studied line, UFV1 (P= 0.1493) and UFV2 (P= 0.2583). The logrank test indicated significant difference (P= 0.0407) between levels of line/sex groups at 14 days of age. We noted that males from UFV2 line presented higher fear behavior in relation to males from UFV1 line. No significant differences were observed for this factor when considering 28 days of age.(AU)

Peritraumatic tonic immobility is associated with posttraumatic stress symptoms in undergraduate Brazilian students / A imobilidade tônica peritraumática está associada aos sintomas do transtorno de estresse pós-traumático em estudantes brasileiros de graduação

OBJECTIVE: Tonic immobility is a defensive reaction occurring under extreme life threats. Patients with posttraumatic stress disorder (PTSD) reporting peritraumatic tonic immobility show the most severe symptoms and a poorer response to treatment. This study investigated the predictive falue of tonic immobility for posttraumatic stress symptoms in a non-clinical sample. METHODS: One hundred and ninety-eight college students exposed to various life threatening events were selected to participate. The Posttraumatic Stress Disorder Checklist - Civilian Version (PCL-C) and tonic immobility questions were used. Linear regression models were fitted to investigate the association between peritraumatic tonic immobility and PCL-C scores. Peritraumatic dissociation, peritraumatic panic reactions, negative affect, gender, type of trauma, and time since trauma were considered as confounding variables. RESULTS: We found significant association between peritraumatic tonic immobility and PTSD symptoms in a non-clinical sample exposed to various traumas, even after regression controlled for confounding variables (β = 1.99, p = 0.017). CONCLUSIONS: This automatic reaction under extreme life threatening stress, although adaptive for defense, may have pathological consequences as implied by its association with PTSD symptoms.

OBJETIVO: A imobilidade tônica é uma resposta defensiva que ocorre sob ameaça extrema à vida. Pacientes com transtorno de estresse pós-traumático (TEPT) que relatam imobilidade tônica peritraumática são os que apresentam os sintomas mais graves e a pior resposta ao tratamento. Este estudo investigou o valor preditivo da imobilidade tônica para os sintomas de TEPT em uma amostra não clínica. MÉTODOS: Os participantes da pesquisa foram 198 estudantes universitários expostos a traumas diversos. A versão brasileira do Post-Traumatic Stress Disorder Checklist Civilian Version (PCL-C) e questões referentes à imobilidade tônica foram empregadas. Modelos de regressão linear foram utilizados para investigar a associação dos sintomas de estresse pós-traumático com a imobilidade tônica peritraumática. Foram consideradas como variáveis de confusão a dissociação peritraumática, as reações físicas de pânico peritraumática, o traço de afeto negativo, o gênero, o tipo de trauma e o tempo de trauma. RESULTADOS: Encontrou-se uma associação significativa entre a imobilidade tônica peritraumática e os sintomas de TEPT em uma amostra não clínica exposta a traumas diversos mesmo quando controlada por variáveis de confusão (β = 1,99; p = 0,017). CONCLUSÕES: Esta reação defensiva que ocorre sob intensa ameaça, apesar de adaptativa para a defesa, pode ter consequências patológicas como sugere sua associação aos sintomas de TEPT.

Defensive responses to threat scenarios in Brazilians reproduce the pattern of Hawaiian Americans and non-human mammals

A former study with scenarios conducted in Hawaii has suggested that humans share with non-human mammals the same basic defensive strategies - risk assessment, freezing, defensive threat, defensive attack, and flight. The selection of the most adaptive strategy is strongly influenced by features of the threat stimulus - magnitude, escapability, distance, ambiguity, and availability of a hiding place. Aiming at verifying if these strategies would be consistent in a different culture, 12 defensive scenarios were translated into Portuguese and adapted to the Brazilian culture. The sample consisted of male and female undergraduate students divided into two groups: 76 students, who evaluated the five dimensions of each scenario and 248 medical students, who chose the most likely response for each scenario. In agreement with the findings from studies of non-human mammal species, the scenarios were able to elicit different defensive behavioral responses, depending on features of the threat. "Flight" was chosen as the most likely response in scenarios evaluated as an unambiguous and intense threat, but with an available route of escape, whereas "attack" was chosen in an unambiguous, intense and close dangerous situation without an escape route. Less urgent behaviors, such as "check out", were chosen in scenarios evaluated as less intense, more distant and more ambiguous. Moreover, the results from the Brazilian sample were similar to the results obtained in the original study with Hawaiian students. These data suggest that a basic repertoire of defensive strategies is conserved along the mammalian evolution because they share similar functional benefits in maintaining fitness.

Estímulos emocionais: processamento sensorial e respostas motoras / Emotional stimuli: sensory processing and motor responses

A emoçäo pode ser funcionalmente considerada como uma disposiçäo à açäo que prepara o organismo para comportamentos relacionados à aproximaçäo e esquiva. Para preparar uma saída motora apropriada, o organismo tem que ser eficiente na codificaçäo de estímulos relevantes. Neste trabalho, apresentamos evidências a partir de estudos de neuroimagem que revelam que a visualizaçäo de imagens emocionais promove uma maior ativaçäo do córtex visual do que a observaçäo de figuras neutras. Além desta facilitaçäo do processamento sensorial, os estímulos emocionais desencadeiam reaçöes somáticas e vegetativas. Registros da dinâmica postural e da freqüência cardíaca enquanto voluntários assistiam a um bloco de figuras desagradáveis revelou uma reduçäo significativa na oscilaçäo corporal e bradicardia. Uma investigaçäo paralela mostrou que o tempo de reaçäo também lentifica após a visualizaçäo de figuras negativas. Este conjunto de respostas - imobilidade, bradicardia e tempo de reaçäo mais lento - pode refletir o engajamento do sistema defensivo, similar às reaçöes defensivas desencadeadas em ambiente natural por estímulos ameaçadores distantes. Em resumo, o sistema afetivo influencia um nível precoce de codificaçäo sensorial e a saída motora favorecendo, portanto, disposiçöes para as açöes apropriadas