Long-term depression, or LTD, is one of the ways by which synaptic plasticity—changes in the strength of chemical synapses—can occur in the brain. LTD is the process of synaptic weakening that occurs over time between pre and postsynaptic neuronal connections. The synaptic weakening of LTD works in opposition to synaptic strengthening by long-term potentiation (LTP) and together are the main mechanisms that underlie learning and memory.

The need for affiliation is a fundamental human motive that drives individuals to form and maintain interpersonal relationships. This universal drive varies in intensity among individuals due to genetic predispositions and life experiences, shaping it into a relatively stable personality trait. Social inclusion enhances emotional well-being by fulfilling the need for affiliation, whereas social exclusion leads to distress, negative emotions, and cognitive impairments.Psychological and Emotional...

The discussion of bullying highlights the problem of witnesses not intervening to help a victim. This is a common occurrence, as the following well-publicized event demonstrates. In 1964, in Queens, New York, a 19-year-old woman named Kitty Genovese was attacked by a person with a knife near the back entrance to her apartment building and again in the hallway inside her apartment building. When the attack occurred, she screamed for help numerous times and eventually died from her stab wounds.