A Brain Rhythm Underlying Detachment from Reality

Post by D. Chloe Chung

What's the science?

Dissociation is an altered mental state in which a person feels disconnected from their body and the physical world. Dissociation can happen not only with the use of dissociative drugs like ketamine, but also with certain neuropsychiatric conditions such as epilepsy and trauma. While the underlying neural mechanisms of this subjective experience have been largely unknown previously, advanced imaging technologies allow for scanning the whole brain for neural activity with high spatial and temporal resolution. This week in Nature, Vesuna, Kauvar, and colleagues utilized such technologies to identify oscillations in the specific locations of the brain that underlie dissociation.

How did they do it?

The authors used a mouse model that is genetically modified so that neuronal activity in the cortex can be visualized under the green light. These mice were injected with a low dosage of ketamine or other drugs (dissociative or non-dissociative), and their whole brains were monitored to identify the location of neuronal activity. The firing patterns of hundreds of neurons were also recorded using probes throughout the brain to investigate oscillations in brain regions that were not accessed by imaging. Since mice cannot report their subjective mental state, the authors indirectly determined whether ketamine-injected mice were experiencing something similar to dissociation by placing them on a moderately hot plate. Paw-flicking indicated that mice can feel the heat from the plate and reflexively react to it, while paw-licking indicated instead that mice were “emotionally” behaving to protect their paws from heat. To test whether rhythm in a specific brain location can cause a dissociation-like state and related behaviors in mice, the authors used an optogenetics approach to rhythmically activate the brain region of interest and observed changes in their behaviors during the hot plate test. For clinical relevance, the authors examined the neural activity of an epilepsy patient who received electrode implantation in the brain after experiencing seizure and dissociation.

What did they find?

After being injected with ketamine, mice showed an oscillation of 1-3 Hz (1-3 cycles per second) localized to the retrosplenial cortex (RSP). This brain rhythm appeared to be specifically induced by dissociative drugs as it was not observed when mice received drugs without dissociative properties. Further examination of the whole brain revealed that, among thalamic nuclei neighboring the RSP, the ones connected to the RSP entered a similar oscillation phase with the RSP while the others went out of phase, defining a brain circuitry responsive to dissociative drugs. Also, ketamine-injected mice on the hot plate were found to be able to detect the stimulus (heat) but fail to have an emotional response to it, as they flicked their paws but did not lick them to cool off. The authors interpreted these behaviors to mean that mice were having dissociation-like experiences under the influence of ketamine. Importantly, optogenetic stimulation of RSP similarly reduced paw-licking responses in mice, suggesting that oscillation in the RSP is responsible for a dissociation-like state. The authors expanded upon this observation in humans by confirming that, when an epilepsy patient experiences seizure-related dissociation, oscillations similar to those that occurred in the mouse RSP-equivalent brain region were present. Electrode stimulation in this brain region also induced a dissociative experience in the patient, which further emphasized the causal link between this brain rhythm and dissociation, mirroring that found in mouse experiments.

What’s the impact?

Our understanding of the biological basis of dissociation has been rather poor, as it is highly challenging to investigate a dissociative state of mind given its subjective and complex nature. This work is the first study to reveal that oscillations in a specific brain region can be responsible for dissociation. From this study, we can now better understand how drugs like ketamine work to exert dissociative effects. Also, findings from this study may help the development of clinical strategies that can effectively modulate neurological conditions accompanied by dissociation.

Vesuna, Kauvar et al. Deep posteromedial cortical rhythm in dissociation. Nature (2020). Access the original scientific publication here.

The Role of Group Identity in Social Influence

Post by Lincoln Tracy

What's the science?

Social influence refers to the change in behavior (either intentionally or unintentionally) a source (e.g. a person) causes in a target (e.g. another person). This is a broad notion that covers a range of phenomena, one aspect of which is group influence. Individual influence frequently contrasts with group influence. Such topics are normally addressed separately in introductory textbooks. Furthermore, earlier reviews have not fully explored the group identity approach to influence. This week in Annual Reviews of Psychology, Spears summarizes recent research about group identity while also reappraising classical research, aiming to provide an integrated overview of group identity in social influence.

What do we already know?

Group influence research has been heavily influenced by Deutsch and Gerard’s dual-process model, first proposed in 1955. This model identifies the two psychological needs that lead humans to conform: informational influence (the need to be right) and normative social influence (the need to be liked). While normative influence is a form of group influence, personal identity and interpersonal dynamics are implicated in normative influence. Deutsch and Gerard’s model is one of many early theories to distinguish different forms of influence. The concept of group identity had not been developed at this point. Consequently, group influence retained an element of external pressure as there was no concept of group identity to internalize this process. A theoretical shift was required to see the group as part of the self. Such a shift would allow for the possibility that true group influence may lead to private acceptance. Using network approaches to account for the spread of influence throughout a group offers some potential. But one challenge with many network models is that the process of how influence operates is not always clear, even if we can model and predict the spread of influence.

What’s new?

Research primarily focusing on the theoretical underpinnings of group identity-based influence has waned in recent times. Despite this decline, the principles underlying group identity-based influence are still sources of inspiration for not only more recent research, but also for reviewing classic findings. However, there has been an emergence of other research that has shifted focus somewhat and brings a different approach to considering social norms. A major theoretical development occurred following the differentiation of descriptive and injunctive norms (behaviours everyone else is doing and behaviours you feel you are supposed to do, respectively). These concepts have been widely adopted by the social norm literature, and research from theorists of morality have made the case that as group identity frames values and prescribes norms, group identity also implies group morality. This notion prefaces a wide-ranging discussion of the association between norms, motivation, and morality. This discussion confirms that there is no “generic” norm, but that the relevant group priority is flexible. This resonates with the argument that group identities are variable and contested, rather than dominant or assigned. Prototypicality, group identification, salience and identity threat, social isolation, and anonymity are identified as moderators of group identify-based influence.  

What’s the bottom line?

Spears provides a case for group identity-based social influence and argues that this may be more persuasive than first thought. Group identity can be distinguished from other forms of social and group influence. Group identity serves as the foundation for much of our being and behavior. Further exploration of the relationships between the personal self, the group self, and the outwards facing self is required.  

Spears. Social influence and group identity. Annual Reviews of Psychology. Access the original scientific publication here.

Tackling COVID-19: The Behavioural Consequences of Face Mask Policies

Post by Flora Moujaes 

What's the science?

Wearing face masks to curb local outbreaks of COVID-19 or reduce transmission in future waves of the pandemic has already become a contentious issue worldwide. For example, in the US in May 2020 an employee was shot after telling a customer her daughter was required to wear a face mask, while in France a bus driver was stabbed to death after asking three passengers to wear face masks. Despite its potential to generate conflict, wearing face masks is currently believed to be the most effective way to stop the transition of COVID-19. In addition, as mask wearing protects others from contracting the virus, but does not protect the wearers themselves as much, a high level of compliance is needed for the method to be effective. It is therefore imperative to explore the behavioural and social consequences of different types of mask wearing policies. This week in PNAS, Betsch and colleagues explored the social and behavioural consequences as well as compliance levels of voluntary vs. mandatory mask policies.

How did they do it?

To assess the behavioural consequences of mandatory vs. voluntary mask policies, the researchers first gathered data from 7000 German participants using an online weekly cross-sectional survey. They found that after mask wearing became mandatory in public shops and on transport in Germany in April 2020, mask wearing increased steeply from 30% to 80% over a two-week period. They also found that people who wore masks were much more likely to wash their hands, avoid handshakes, and keep their physical distance. This implies that mandatory mask wearing policies are (1) effective and (2) that individuals wearing masks exhibit other protective behaviours more often. 

In order to explore the social and behavioural consequences of mandatory and voluntary mask policies, the researchers then conducted an experiment in which 925 participants were asked to imagine that they were in the fruit section of their local supermarket with one other person. They were randomly assigned to a scenario involving either a mandatory or voluntary mask policy where the other person was either wearing a face mask or not wearing a face mask.   

What did they find?

Perception of Mask Wearers: Overall, regardless of whether the mask-wearing policy was mandatory or voluntary, others wearing masks were perceived as more prosocial. People who reported wearing a mask frequently themselves in everyday life perceived greater warmth toward others who also wore masks compared to those who didn’t. Mask wearing was therefore perceived as a social contract, as those who complied with it socially ‘rewarded’ each other but ‘punished’ others who did not wear a mask. Finally, both those who were low risk and high risk for contracting COVID-19 reported feeling more at risk when the other person did not wear a mask.

Voluntary vs. Mandatory Mask-Wearing Policies: Fewer people were likely to wear a mask themselves when the mask-wearing policy was voluntary (77% compliance under a voluntary policy vs. 96% under a mandatory policy). The mandatory mask policy was judged fairer than the voluntary policy, especially by participants belonging to a risk group. In addition, the voluntary mask policy resulted in stigmatization, as others wearing a mask were judged as belonging to a risk group, though they were not judged as more likely to be infected with COVID-19.

What's the impact?

Understanding the social and behavioural consequences of mask-wearing policies is important (1) to ensure high compliance for effectiveness  (2) to avoid it becoming a socially contentious issue. Overall, this study suggests that mandatory mask-wearing policies are necessary in order to ensure a sufficient number of people to wear masks. Furthermore, this study suggests that mandatory policies are preferable as voluntary policies may increase the amount of stigmatization associated with mask wearing, and increase the potential for polarization within society. This study also highlights the importance of communicating to the public not only the benefits of mask wearing (e.g. risk reduction, mutual protection, positive social signaling), but also the benefits of mandatory policies (e.g. fairness, less stigmatization, and higher effectiveness).

Betsch et al. Social and behavioral consequences of mask policies during the COVID-19 pandemic. PNAS (2020). Access the original scientific publication here.