Nat Neurosci: Selfish or selfless? Scientists reveal the cortical-amygdala neural circuit, which regulates altruistic decision-making behavior

Most decisions are made in the context of social behavior, and these decisions require the integration of different cognitive processes and behaviors to enable individuals to understand and interact
with others.
The psychological conflict between self-interest and the interests of others is a key factor in
social decision-making.
From an evolutionary perspective, altruism may promote survival
through behaviors such as parental care and mutual help.

In nonhuman primates, prefrontal cortex-amygdala network activity contributes to social decision-making behavior (SDM).

The basolateral amygdala (BLA) encodes self-reward and others' reward information
.

On October 24, 2022, the research team of Francesco Papaleo of the Italian Institute of Technology found that mice are more willing to make altruistic choices, which are related
to gender, social status, emotional state, etc.
Mice with high social status were more willing to make altruistic choices
.

1

Mice prefer altruistic decision-making

The researchers designed an interesting "selfish-altruistic" experiment: the experimental setup contained two cubicles, one side for the actor mice to receive the double-choice decision-making mode, the nose tentacle 1 only provided food rewards for themselves (selfish choice), and after the nose touches 2, both themselves and the familiar recipient mice could receive food rewards (altruistic choice); On the other side is the recipient mouse, which, as a passive participant, has access to food
from the actor mouse.

During 5 days of training, actor mice had more nostral tentacles2 and more trials of making altruistic choices, and actor mice had an equal number of nostral touches 1 and 2 when recipient mice were absent
.
Among the 52 mice, the proportion of female mice making selfless choices was 46.
7%, and the proportion of selfish mice was 53.
3%.
The proportion of male mice who made the choice of altruistic person was 75.
7%, and the proportion of selfish people was 24.
3%.

Figure 1: Mice are more willing to make altruistic decision-making behaviors with familiar peers

2

Selfless decision-making is related to social status, not to paying a price

The researchers further increased the cost of altruistic choice (it takes two nasal touches for both themselves and recipient mice to get food at the same time, and only they have food for nasal touches of any hole), and male mice also make altruistic choices, even if they need to touch 4 or 6 times, they will make altruistic choices
.
This shows that even at great cost, mice are willing to choose
altruistically.

However, the actor mice showed more selfish choices
when confronted by unfamiliar recipient mice.
In addition, by screening out mice with a dominant position and a disadvantageous position, the researchers found that mice in a dominant position were more willing to make selfless choices, and mice in a disadvantaged position were more likely to make selfish choices
.

Figure 2: High/low social status influences altruistic/selfish decision-making behaviors

3

The cortex-amygdala circuit regulates altruistic decision-making behavior

Immunofluorescence experiments showed that the activity of neurons in the BLA region of actor mice increased in the presence of recipient mice
compared with the absence of recipient mice.
Mice after chemical chronic inhibition of neurons in the BLA region did not exhibit more altruistic selection
.
Fiber calcium imaging found that neuronal activity in the BLA region was stronger
than selfish selection when making nostalgic selection.

The anterior marginal cortex (PL) of the prefrontal cortex subregion regulates goal-directed behavior, and there is mutual projection
between BLA and PL regions.
The researchers significantly reduced the mice to make altruistic choices after inhibiting the BLA → PL neural circuit through chemogenetics, and significantly promoted the mice to make selfish choices
after inhibiting the PL→BLA neural circuit.
These results suggest that BLA-PL interactive projection plays different roles
in selfish and altruistic choices.

Figure 3: Neural circuits that regulate selfish, altruistic decision-making behavior

summary

In this paper, it is found that social reward-driven mice are more willing to make altruistic choices by designing a selfish-altruistic dual-choice decision-making model, which is regulated
by the prefrontal cortex and basolateral amygdala circuit.

Original source:

Scheggia， D.
， La Greca， F.
， Maltese， F.
et al.
Reciprocal cortico-amygdala connections regulate prosocial and selfish choices in mice.
Nat Neurosci (2022).
https：//doi.
org/10.
1038/s41593-022-01179-2.