Welcome to the Nexus of Ethics, Psychology, Morality, Philosophy and Health Care

Welcome to the nexus of ethics, psychology, morality, technology, health care, and philosophy
Showing posts with label Brain Functioning. Show all posts
Showing posts with label Brain Functioning. Show all posts

Monday, December 5, 2022

Social isolation and the brain in the pandemic era

Bzdok, D., and Dunbar, R.
Nat Hum Behav 6, 1333–1343 (2022).
https://doi.org/10.1038/s41562-022-01453-0

Abstract

Intense sociality has been a catalyst for human culture and civilization, and our social relationships at a personal level play a pivotal role in our health and well-being. These relationships are, however, sensitive to the time we invest in them. To understand how and why this should be, we first outline the evolutionary background in primate sociality from which our human social world has emerged. We then review defining features of that human sociality, putting forward a framework within which one can understand the consequences of mass social isolation during the COVID-19 pandemic, including mental health deterioration, stress, sleep disturbance and substance misuse. We outline recent research on the neural basis of prolonged social isolation, highlighting especially higher-order neural circuits such as the default mode network. Our survey of studies covers the negative effects of prolonged social deprivation and the multifaceted drivers of day-to-day pandemic experiences.

Conclusion

The human social world is deeply rooted in our primate ancestry. This social world is, however, extremely sensitive to the time we invest in it. Enforced social isolation can easily destabilize its delicate equilibrium. Many of the psychological sequalae of COVID-19 lockdowns are readily understood as resulting from the dislocation of these deeply rooted social processes. Indeed, many of these findings could have been anticipated long before the COVID-19 pandemic. For example, almost one in ten Europeans admitted never meeting friends or family outside of their own household in the course of an entire year, with direct consequences for their psychological and physical health. Solitary living made up >50% of households in a growing number of metropolitan cities worldwide and has long been thought to be the cause of increasing levels of depression and psychological dystopia. Indeed, aversive feelings of social isolation probably serve as a biological warning signal that alerts individuals to improve their social relationships.

Three key points emerge from our present assessment. One is that COVID-19 and associated public health restrictions to curb the spread of the virus are likely to have demonstrable mental health and psychosocial ramifications for years to come. This will inevitably place a significant burden on our health systems and societies. The impact may, however, be largely restricted to specific population strata. Older people, for example, are likely to face disproportionately adverse consequences. Worryingly, prolonged social isolation seems to invoke changes in the capacity to visualize internally centred thoughts, especially in younger sub-population. This may presage a switch from an outward to an inward focus that may exacerbate the experience of social isolation in susceptible individuals. The longer-term implications of this are, however, yet to be determined. Second, the experience of undergoing social isolation is known to have significant effects on the structure and function of the hippocampus and default network, long recognized as a primary neural pathway implicated in the pathophysiology of dementia and other major neurodegenerative diseases as well as in effective social function. The fact that these same brain regions turn up in the neuroanatomical consequences of COVID-19 infection is concerning. Our third key point is that social determinants that condition inequality in our societies have strong impacts on lived day-to-day pandemic experiences. This is highlighted by the negative outcomes from COVID-19 for families of lower socio-economic status, single-parent households, and those with racial and ethnic minority backgrounds.

As a note of caution, in our judgement, few datasets or methodological tools exist today to definitively establish causal directionality in many of the population effects we have surveyed in this review. For example, many of the correlative links do not allow us to infer whether loneliness directly causes depression and anxiety, as opposed to already depressed, anxious individuals being more prone to developing loneliness in times of adversity. Similarly, none of the reviewed findings can be used to tease apart whether changes in psychopathology during periods of mass social isolation are the chicken or the egg of the many biological manifestations. To fill knowledge gaps on mediating mechanisms for theoretical models, future research requires carefully designed and controlled longitudinal before-versus-after COVID-19 population investigations.

Monday, April 11, 2022

Distinct neurocomputational mechanisms support informational and socially normative conformity

Mahmoodi A, Nili H, et al.
(2022) PLoS Biol 20(3): e3001565. 
https://doi.org/10.1371/journal.pbio.3001565

Abstract

A change of mind in response to social influence could be driven by informational conformity to increase accuracy, or by normative conformity to comply with social norms such as reciprocity. Disentangling the behavioural, cognitive, and neurobiological underpinnings of informational and normative conformity have proven elusive. Here, participants underwent fMRI while performing a perceptual task that involved both advice-taking and advice-giving to human and computer partners. The concurrent inclusion of 2 different social roles and 2 different social partners revealed distinct behavioural and neural markers for informational and normative conformity. Dorsal anterior cingulate cortex (dACC) BOLD response tracked informational conformity towards both human and computer but tracked normative conformity only when interacting with humans. A network of brain areas (dorsomedial prefrontal cortex (dmPFC) and temporoparietal junction (TPJ)) that tracked normative conformity increased their functional coupling with the dACC when interacting with humans. These findings enable differentiating the neural mechanisms by which different types of conformity shape social changes of mind.

Discussion

A key feature of adaptive behavioural control is our ability to change our mind as new evidence comes to light. Previous research has identified dACC as a neural substrate for changes of mind in both nonsocial situations, such as when receiving additional evidence pertaining to a previously made decision, and social situations, such as when weighing up one’s own decision against the recommendation of an advisor. However, unlike the nonsocial case, the role of dACC in social changes of mind can be driven by different, and often competing, factors that are specific to the social nature of the interaction. In particular, a social change of mind may be driven by a motivation to be correct, i.e., informational influence. Alternatively, a social change of mind may be driven by reasons unrelated to accuracy—such as social acceptance—a process called normative influence. To date, studies on the neural basis of social changes of mind have not disentangled these processes. It has therefore been unclear how the brain tracks and combines informational and normative factors.

Here, we leveraged a recently developed experimental framework that separates humans’ trial-by-trial conformity into informational and normative components to unpack the neural basis of social changes of mind. On each trial, participants first made a perceptual estimate and reported their confidence in it. In support of our task rationale, we found that, while participants’ changes of mind were affected by confidence (i.e., informational) in both human and computer settings, they were only affected by the need to reciprocate influence (i.e., normative) specifically in the human–human setting. It should be noted that participants’ perception of their partners’ accuracy is also an important factor in social change of mind (we tend to change our mind towards the more accurate participants). 

Sunday, April 3, 2022

Enhanced Interplay of Neuronal Coherence and Coupling in the Dying Human Brain

R. Vicente, M. Rizzuto, et al. 
Front. Aging Neurosci., 22 February 2022

Abstract

The neurophysiological footprint of brain activity after cardiac arrest and during near-death experience (NDE) is not well understood. Although a hypoactive state of brain activity has been assumed, experimental animal studies have shown increased activity after cardiac arrest, particularly in the gamma-band, resulting from hypercapnia prior to and cessation of cerebral blood flow after cardiac arrest. No study has yet investigated this matter in humans. Here, we present continuous electroencephalography (EEG) recording from a dying human brain, obtained from an 87-year-old patient undergoing cardiac arrest after traumatic subdural hematoma. An increase of absolute power in gamma activity in the narrow and broad bands and a decrease in theta power is seen after suppression of bilateral hemispheric responses. After cardiac arrest, delta, beta, alpha and gamma power were decreased but a higher percentage of relative gamma power was observed when compared to the interictal interval. Cross-frequency coupling revealed modulation of left-hemispheric gamma activity by alpha and theta rhythms across all windows, even after cessation of cerebral blood flow. The strongest coupling is observed for narrow- and broad-band gamma activity by the alpha waves during left-sided suppression and after cardiac arrest. Albeit the influence of neuronal injury and swelling, our data provide the first evidence from the dying human brain in a non-experimental, real-life acute care clinical setting and advocate that the human brain may possess the capability to generate coordinated activity during the near-death period.


From the Discussion

The findings we report here are similar to the alterations in neuronal activity that have been observed in rodents, where an increase of low gamma band frequencies was observed 10–30 s after cardiac arrest (Borjigin et al., 2013). Our data reveals enhanced relative gamma power compared to other bands along with a decrease in theta. An interesting difference between the two studies can be observed when comparing phase-amplitude coupling (cross-frequency coupling): Post cardiac arrest, delta, theta, and alpha modulate low gamma activity in the rodent (Borjigin et al., 2013), whereas in the human brain, such modulation occurs in all gamma bands and is mostly mediated by alpha waves, to a lesser degree by theta rhythms. The alpha band is thought to critically interfere in cognitive processes by inhibiting networks that are irrelevant or disruptive (Klimesch, 2012). Given that cross-coupling between alpha and gamma activity is involved in cognitive processes and memory recall in healthy subjects, it is intriguing to speculate that such activity could support a last “recall of life” that may take place in the near-death state. Unlike previous reports, our study is the first to use full EEG placement, which allows a more complete neurophysiological analysis in a larger dimension. Further, the data was obtained from an acutely deteriorating patient. Previous human reports were limited to frontal cortex EEG signals that were analyzed by neuromonitoring devices, which may have captured artifacts and the focus was set on critically ill patients in chronic settings (Chawla et al., 2009, 2017). In line with our findings, electrical surges were also reported in these studies after cessation of blood circulation.