Differential cortical network engagement during states of un/consciousness in humans

Zelmann, R., Paulk, A., et al. (2023).

Neuron. Volume 111, (21)

https://doi.org/10.1016/j.neuron.2023.08.007

Summary

What happens in the human brain when we are unconscious? Despite substantial work, we are still unsure which brain regions are involved and how they are impacted when consciousness is disrupted. Using intracranial recordings and direct electrical stimulation, we mapped global, network, and regional involvement during wake vs. arousable unconsciousness (sleep) vs. non-arousable unconsciousness (propofol-induced general anesthesia). Information integration and complex processing we`re reduced, while variability increased in any type of unconscious state. These changes were more pronounced during anesthesia than sleep and involved different cortical engagement. During sleep, changes were mostly uniformly distributed across the brain, whereas during anesthesia, the prefrontal cortex was the most disrupted, suggesting that the lack of arousability during anesthesia results not from just altered overall physiology but from a disconnection between the prefrontal and other brain areas. These findings provide direct evidence for different neural dynamics during loss of consciousness compared with loss of arousability.

Highlights

• Decreased complexity and connectivity, with increased variability when unconscious

• Changes were more pronounced during propofol-induced general anesthesia than sleep

• During sleep, changes were homogeneously distributed across the human brain

• During anesthesia, substantial prefrontal disconnection is related to lack of arousability

A pdf is here.

Here is my summary:

State-Dependent Cortical Network Engagement

The human brain undergoes significant changes in its functional organization during different states of consciousness, including wakefulness, sleep, and general anesthesia. This study investigated the neural underpinnings of these state-dependent changes by comparing cortical network engagement during wakefulness, sleep, and propofol-induced general anesthesia.

Prefrontal Cortex Disruption during Anesthesia

The findings revealed that loss of consciousness, whether due to sleep or anesthesia, resulted in reduced information integration and increased response variability compared to wakefulness. However, these changes were more pronounced during anesthesia than sleep. Notably, anesthesia was associated with a specific disruption of the prefrontal cortex (PFC), a brain region crucial for higher-order cognitive functions such as decision-making and self-awareness.

Implications for Understanding Consciousness

These findings suggest that the PFC plays a critical role in maintaining consciousness and that its disruption contributes to the loss of consciousness during anesthesia. The study also highlights the distinct neural mechanisms underlying sleep and anesthesia, suggesting that these states involve different modes of brain function.

The Neuroscience of Trust

Paul J. Zak

Harvard Business Review

Originally posted January-February 2017

Here is an excerpt:

The Return on Trust

After identifying and measuring the managerial behaviors that sustain trust in organizations, my team and I tested the impact of trust on business performance. We did this in several ways. First, we gathered evidence from a dozen companies that have launched policy changes to raise trust (most were motivated by a slump in their profits or market share). Second, we conducted the field experiments mentioned earlier: In two businesses where trust varies by department, my team gave groups of employees specific tasks, gauged their productivity and innovation in those tasks, and gathered very detailed data—including direct measures of brain activity—showing that trust improves performance. And third, with the help of an independent survey firm, we collected data in February 2016 from a nationally representative sample of 1,095 working adults in the U.S. The findings from all three sources were similar, but I will focus on what we learned from the national data since itʼs generalizable.

By surveying the employees about the extent to which firms practiced the eight behaviors, we were able to calculate the level of trust for each organization. (To avoid priming respondents, we never used the word “trust” in surveys.) The U.S. average for organizational trust was 70% (out of a possible 100%). Fully 47% of respondents worked in organizations where trust was below the average, with one firm scoring an abysmally low 15%. Overall, companies scored lowest on recognizing excellence and sharing information (67% and 68%, respectively). So the data suggests that the average U.S. company could enhance trust by

improving in these two areas—even if it didnʼt improve in the other six.

The effect of trust on self-reported work performance was powerful.  Respondents whose companies were in the top quartile indicated they had 106% more energy and were 76% more engaged at work than respondents whose firms were in the bottom quartile. They also reported being 50% more productive

—which is consistent with our objective measures of productivity from studies we have done with employees at work. Trust had a major impact on employee loyalty as well: Compared with employees at low-trust companies, 50% more of those working at high-trust organizations planned to stay with their employer over the next year, and 88% more said they would recommend their company to family and friends as a place to work.

The info is here.

Here is a summary of the key points from the article:

• Trust is crucial for social interactions and has implications for economic, political, and healthcare outcomes. There are two main types of trust - emotional trust and cognitive trust.

• Emotional trust develops early in life through attachments and is more implicit, while cognitive trust relies on reasoning and develops later. Both rely on brain regions involved in reward, emotion regulation, understanding others' mental states, and decision making.

• Oxytocin and vasopressin play key roles in emotional trust by facilitating social bonding and attachment. Disruptions to these systems are linked to social disorders like autism.

• The prefrontal cortex, amygdala, and striatum are involved in cognitive trust judgments and updating trustworthiness based on new evidence. Damage to prefrontal regions impairs updating of trustworthiness.

• Trust engages the brain's reward circuitry. Betrayals of trust activate pain and emotion regulation circuits. Trustworthiness cues engage the mentalizing network for inferring others' intentions.

• Neuroimaging studies show trust engage brain regions involved in reward, emotion regulation, understanding mental states, and decision making. Oxytocin administration increases trusting behavior.

• Understanding the neuroscience of trust can inform efforts to build trust in healthcare, economic, political, and other social domains. More research is needed on how trust develops over the lifespan.

Arrested development: early prefrontal lesions impair the maturation of moral judgement

By Bradley Taber-Thomas, Erik Asp, Michael Koenings, Matthew Sutterer, Steven Anderson, and Daniel Tranel
Brain (2014) 137 (4): 1254-1261 first published online February 11, 2014
doi: 10.1093/brain/awt377

Summary

Learning to make moral judgements based on considerations beyond self-interest is a fundamental aspect of moral development. A deficit in such learning is associated with poor socialization and criminal behaviour. The neural systems required for the acquisition and maturation of moral competency are not well understood. Here we show in a unique sample of neurological patients that focal lesions involving ventromedial prefrontal cortex, acquired during development, result in an abnormally egocentric pattern of moral judgement. In response to simple hypothetical moral scenarios, the patients were more likely than comparison participants to endorse self-interested actions that involved breaking moral rules or physically harming others in order to benefit themselves. This pattern (which we also found in subjects with psychopathy) differs from that of patients with adult-onset ventromedial prefrontal cortex lesions—the latter group showed normal rejection of egocentric rule violations. This novel contrast of patients with ventromedial prefrontal cortex lesions acquired during development versus during adulthood yields new evidence suggesting that the ventromedial prefrontal cortex is a critical neural substrate for the acquisition and maturation of moral competency that goes beyond self-interest to consider the welfare of others. Disruption to this affective neural system early in life interrupts moral development.

The article can be found here, behind a paywall.

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