Frustration-aggression hypothesis reconsidered: The role of significance quest.

One of the oldest scientific theories of human aggression is the frustration-aggression hypothesis, advanced in 1939. Although this theory has received considerable empirical support and is alive and well today, its underlying mechanisms have not been adequately explored. In this article, we examine major findings and concepts from extant psychological research on hostile aggression and offer an integrative conception: aggression is a primordial means for establishing one's sense of significance and mattering, thus addressing a fundamental social-psychological need. Our functional portrayal of aggression as a means to significance yields four testable hypotheses: (1) frustration will elicit hostile aggression proportionately to the extent that the frustrated goal serves the individual's need for significance, (2) the impulse to aggress in response to significance loss will be enhanced in conditions that limit the individual's ability to reflect and engage in extensive information processing (that may bring up alternative, socially condoned means to significance), (3) significance-reducing frustration will elicit hostile aggression unless the impulse to aggress is substituted by a nonaggressive means of significance restoration, (4) apart from significance loss, an opportunity for significance gain can increase the impulse to aggress. These hypotheses are supported by extant data as well as novel research findings in real-world contexts. They have important implications for understanding human aggression and the conditions under which it is likely to be manifested and reduced.

Terrorism and conspiracy theories: A view from the 3N model of radicalization.

In this work, we discuss through lens of the 3N model of radicalization vulnerability to conspiracy beliefs and the factors, which contribute to acting upon such beliefs. After discussing the numerous empirically supported precursors to conspiracy beliefs, we integrate them within the 3N framework, positing that belief in conspiracy theories are particularly suited to satisfy the need for significance through the incitation to violence against an alleged enemy. Conspiracy theories highlight for believers their grievance and a culprit responsible for that grievance who needs to be defeated. They also isolate individuals from non-believing friends and family while bringing them closer to a community of other believers-a network which validates the narrative and rewards those who act upon it.

The comparative effects of mGlu5 receptor positive allosteric modulators VU0409551 and VU0360172 on cognitive deficits and signalling in the sub-chronic PCP rat model for schizophrenia.

In schizophrenia, mGlu5 receptor hypofunction has been linked with neuropathology and cognitive deficits, making it an attractive therapeutic target. The cognitive impairment associated with schizophrenia remains an unmet clinical need, with existing antipsychotics primarily targeting positive symptoms, with weaker and more variable effects on cognitive deficits. Using the sub-chronic phencyclidine rat model, widely shown to mimic the cognitive impairment and neuropathology of schizophrenia, we have investigated two mGlu5 receptor positive allosteric modulators (PAMs), VU0409551 and VU0360172. We compared the efficacy of these compounds in restoring cognitive deficits and, since these two PAMs have reportedly distinct signalling mechanisms, changes in mGlu5 receptor signalling molecules AKT and MAPK in the PFC. Although not effective at 0.05 and 1 mg/kg, cognitive deficits were significantly alleviated by both PAMs at 10 and 20 mg/kg. The compounds appeared to have differential effects on the scPCP-induced increases in AKT and MAPK phosphorylation: VU0409551 induced a significant decrease in expression of p-AKT, whereas VU0360172 had this effect on p-MAPK levels. Thus, the beneficial effects of PAMs on scPCP-induced cognitive impairment are accompanied by at least partial reversal of scPCP-induced elevated levels of p-MAPK and p-AKT, whose dysfunction is strongly implicated in schizophrenia pathology. These promising data imply an important role for mGlu5 receptor signalling pathways in improving cognition in the scPCP model and provide support for mGlu5 receptor PAMs as a possible therapeutic intervention for schizophrenia.

Group I metabotropic glutamate receptor-mediated long term depression is disrupted in the hippocampus of WAG/Rij rats modelling absence epilepsy.

Absence epilepsy is frequently associated with cognitive dysfunction, although the underlying mechanisms are not well understood. Here we report that some forms of hippocampal synaptic plasticity are abnormal in symptomatic Wistar Albino Glaxo/Rijswijk (WAG/Rij) rats. Metabotropic Glu 1/5 receptor-mediated long term depression (LTD) at Schaffer collateral CA1 synapses is significantly reduced in symptomatic, 5-6 months old WAG/Rij rats compared to age-matched non epileptic control rats. There were no significant changes in mGlu1/5-dependent LTD in pre-symptomatic, 4-6 weeks old WAG/Rij rats compared to age matched controls. The changes in LTD found in symptomatic WAG/Rij forms are not indicative of general deficits in all forms of synaptic plasticity as long term potentiation (LTP) was unchanged. Immunoblot analysis of hippocampal tissue showed a significant reduction in mGlu5 receptor expression, a trend to an increase in pan Homer protein levels and a decrease in GluA1 receptor expression in the hippocampus of symptomatic WAG/Rij rats vs non-epileptic control rats. There were no changes in mGlu1α receptor or GluA2 protein levels. These findings suggest that abnormalities in hippocampal mGlu5 receptor-dependent synaptic plasticity are associated with the pathological phenotype of WAG/Rij rats. This lays the groundwork for the study of mGlu5 receptors as a candidate drug target for the treatment of cognitive dysfunction linked to absence epilepsy.

In Vivo Non-radioactive Assessment of mGlu5 Receptor-Activated Polyphosphoinositide Hydrolysis in Response to Systemic Administration of a Positive Allosteric Modulator.

mGlu5 receptor-mediated polyphosphoinositide (PI) hydrolysis is classically measured by determining the amount of radioactivity incorporated in inositolmonophosphate (InsP) after labeling of membrane phospholipids with radioactive inositol. Although this method is historically linked to the study of mGlu receptors, it is inappropriate for the assessment of mGlu5 receptor signaling in vivo. Using a new ELISA kit we showed that systemic treatment with the selective positive allosteric modulator (PAM) of mGlu5 receptors VU0360172 enhanced InsP formation in different brain regions of CD1 or C57Black mice. The action of VU0360172 was sensitive to the mGlu5 receptor, negative allosteric modulator (NAM), MTEP, and was abolished in mice lacking mGlu5 receptors. In addition, we could demonstrate that endogenous activation of mGlu5 receptors largely accounted for the basal PI hydrolysis particularly in the prefrontal cortex. This method offers opportunity for investigation of mGlu5 receptor signaling in physiology and pathology, and could be used for the functional screening of mGlu5 receptor PAMs in living animals.