All things brain...

[Recusant]

Having a particularly active esprit de l'escalier I was amused to learn that it's a sort of resonance from the old amygdala, playing the strings of the more advanced regions that our conscious social mind inhabits. Figuratively (and no doubt somewhat inaccurately due to my lack of subject expertise) the lizard advises/dictates to the hominin.

"Overthinking what you said? It's your 'lizard brain' talking to newer, advanced parts of your brain" | EurekAlert!

We've all been there. Moments after leaving a party, your brain is suddenly filled with intrusive thoughts about what others were thinking. "Did they think I talked too much?" "Did my joke offend them?" "Were they having a good time?"

In a new Northwestern Medicine study, scientists sought to better understand how humans evolved to become so skilled at thinking about what's happening in other peoples' minds. The findings could have implications for one day treating psychiatric conditions such as anxiety and depression.

"We spend a lot of time wondering, 'What is that person feeling, thinking? Did I say something to upset them?'" said senior author Rodrigo Braga. "The parts of the brain that allow us to do this are in regions of the human brain that have expanded recently in our evolution, and that implies that it's a recently developed process. In essence, you're putting yourself in someone else's mind and making inferences about what that person is thinking when you cannot really know."

The study found the more recently evolved and advanced parts of the human brain that support social interactions — called the social cognitive network — are connected to and in constant communication with an ancient part of the brain called the amygdala.

Often referred to as our "lizard brain," the amygdala typically is associated with detecting threats and processing fear. A classic example of the amygdala in action is someone's physiological and emotional response to seeing a snake: startled body, racing heart, sweaty palms. But the amygdala also does other things, Braga said.

"For instance, the amygdala is responsible for social behaviors like parenting, mating, aggression and the navigation of social-dominance hierarchies," said Braga, an assistant professor of neurology at Northwestern University Feinberg School of Medicine. "Previous studies have found co-activation of the amygdala and social cognitive network, but our study is novel because it shows the communication is always happening."

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The paper is open access:

"The human social cognitive network contains multiple regions within the amygdala" | Science Advances

Abstract:

Reasoning about someone's thoughts and intentions—i.e., forming a "theory of mind"—is a core aspect of social cognition and relies on association areas of the brain that have expanded disproportionately in the human lineage. We recently showed that these association zones comprise parallel distributed networks that, despite occupying adjacent and interdigitated regions, serve dissociable functions.

One network is selectively recruited by social cognitive processes. What circuit properties differentiate these parallel networks? Here, we show that social cognitive association areas are intrinsically and selectively connected to anterior regions of the medial temporal lobe that are implicated in emotional learning and social behaviors, including the amygdala at or near the basolateral complex and medial nucleus.

The results suggest that social cognitive functions emerge through coordinated activity between internal circuits of the amygdala and a broader distributed association network, and indicate the medial nucleus may play an important role in social cognition in humans.

[Recusant]

How deep are your sulci? 

"Your Brain Wrinkles Are Way More Important Than We Ever Realized" | Science Alert

The folds and ridges of the human brain are more complex than any other in the animal kingdom, and a new study shows that this complexity may be linked to the brain's level of connectivity and our reasoning abilities.

Research led by a team from the University of California, Berkeley (UC Berkeley) looked at the brain shapes and neural activity of 43 young people, and in particular the lateral prefrontal cortex (LPFC) and lateral parietal cortex (LPC) – parts of the brain that handle reasoning and high-level cognition.

The grooves and folds on the brain are known as sulci, with the smallest grooves known as tertiary sulci. These are the last to form as the brain grows, and the research team wanted to see how these grooves related to cognition.

"The hypothesis is that the formation of sulci leads to shortened distances between connected brain regions, which could lead to increased neural efficiency, and then, in turn, individual differences in improved cognition with translational applications," says neuroscientist Kevin Weiner, from UC Berkeley.

The analysis revealed each sulci had its own distinct connectivity pattern, and that the physical structure of some of these grooves was linked to the level of communication between brain areas – and not just areas that were close to each other.

It adds to the findings of a 2021 study carried out by some of the same researchers, which found the depth of certain sulci are associated with cognitive reasoning. Now we have more data to help scientists understand why that might be.

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The paper is behind a paywall.

Abstract:

A salient neuroanatomical feature of the human brain is its pronounced cortical folding, and there is mounting evidence that sulcal morphology is relevant to functional brain architecture and cognition.

However, our understanding of the relationships between sulcal anatomy, brain activity, and behavior is still in its infancy. We previously found that the depth of three small, shallow sulci in lateral prefrontal cortex (LPFC) was linked to reasoning performance during development (Voorhies et al., 2021). These findings beg the question: what is the linking mechanism between sulcal morphology and cognition?

Here, we investigated functional connectivity among sulci in LPFC and lateral parietal cortex (LPC) in participants from the same sample as our previous study. We leveraged manual parcellations (21 sulci/hemisphere, total of 1806) and functional magnetic resonance (fMRI) data from a reasoning task from 43 participants aged 7–18 years (20 female). We conducted clustering and classification analyses of individual-level functional connectivity among sulci.

Broadly, we found that 1) the connectivity patterns of individual sulci could be differentiated – and more accurately than rotated sulcal labels equated for size and shape; 2) sulcal connectivity did not consistently correspond with that of probabilistic labels or large-scale networks; 3) sulci clustered together into groups with similar patterns, not dictated by spatial proximity; and 4) across individuals, greater depth was associated with higher network centrality for several sulci under investigation. These results illustrate how sulcal morphology can be relevant for functional connectivity, and provide proof of concept that using sulci to define an individual coordinate space for functional connectomes is a promising future direction.