28 July 2007

Inteligenta sociala in creier

Poate cel mai importat lucru care ne distinge de celelalte maimute este inteligenta noastra sociala. Oamenii sunt capabili sa atribuie scopuri altor oameni (lucru pe care numai cimpanzeii il mai pot face) si sunt capabili sa colaboreze in vederea atingerii unui scop comun (lucru pe care cimpanzeii nu-l pot face). In ce anume a constat insa schimbarea din creier care a condus la aceste diferente? Se pare ca un factor important a fost restructurarea unei mici zone din creier numita amigdala (zona albastra din imagine) care actioneaza ca un fel de releu emotional intre alte zone din creier. Restructurarea a constat in marirea acelei portiuni care face legaturile cu zonele din creier legate de comportamentul social.
The amygdala, a small, almond-shaped area deep within our brains, appears to be essential in helping us read the emotions of others. Research shows that the structure is crucial for detecting fear, but scientists have also found evidence that it can help spot a wide variety of mental states (ScienceNOW, 7 April 2006). Last year, for example, scientists noted that the amygdalas of patients with autism, which is characterized by decreased social interaction and an inability to understanding the feelings of others, have fewer nerve cells, especially in a subdivision called the lateral nucleus. To see how the amygdala varies in different primate species, a team led by anthropologist Katerina Semendeferi of the University of California, San Diego, measured brain area in autopsy material from 12 ape and human specimens. The researchers found that although the human amygdala was much larger than those of the apes, it was actually the smallest when compared to overall brain size. In humans, however, the lateral nucleus occupied a bigger fraction of the amygdala, and was larger compared to overall brain size, than in the other species, the team reports online today in the American Journal of Physical Anthropology. Although the functions of the amygdala's subunits are unclear, the lateral nucleus makes more direct connections with the brain's temporal lobe--which is involved in social behavior and the processing of emotions--than other parts of the amygdala make, the researchers note. The team concludes that the amygdala's lateral nucleus has enlarged relative to the rest of the structure since the human line split from the apes, and that this enlargement might reflect the "social pressures" of living in large groups. For example, Semendeferi and her colleagues note that the orangutan, which has a relatively smaller amygdala and lateral nucleus than those of the other species, is solitary.