Page 115 - Biobehavioral Resilence to Stress

92 Biobehavioral Resilience to Stress

The human biobehavioral stress response consists of behavioral and physi-

ological reactions to “stressors” (events or situations) that are perceived as

difficult, threatening, challenging, or dangerous. Challenges that are exhila-

rating and manageable are sometimes described as “good” (i.e., motivating)
stress, whereas those that imply threat and danger, or are persistent and irri-

tating, are usually seen as “bad” (unhealthy) stress. The frequency and the

duration of stress may determine whether its ultimate effects are positive or
negative. Also important is whether and to what extent an individual feels a
sense of control or mastery over a challenging situation or its outcome.
Stress-related trauma may result from exposure to extreme stress or vio-
lence such as experience in combat or a natural disaster, or it may occur as the
result of physical or psychological abuse. Less extreme but more pervasive are
a variety of relatively ordinary and sometimes chronic stressors encountered

in the course of daily life. These might include persistent financial burdens and
everyday hassles at work and at home as well as less frequent but unavoidable
life events such as job loss, relocation, divorce, or the death of a loved one. Stress-
related health problems may result from chronic physical stress due to heat, cold,
hunger, injury, substance abuse, and vigorous physical activity beyond one’s
capacity. Quality and quantity of sleep, diet, and exercise also play an important
role in determining how the human body and brain will handle stress.
In this chapter, we consider the neurobiological basis for resilience to
stress in terms of brain structures, processes, and mechanisms associated
with the regulation of factors and phenomena related to resilience. It is
important to note that because these mechanisms are highly complex and
involve a host of neurotransmitters, peptides, and hormones that interact
with multiple neural circuits—including those involved in the regulation
of fear, reward, learning, and social behavior—they are not yet fully under-
stood. Nor is the psychological construct of resilience yet well-defi ned. Th us,
our consideration is constrained by limitations common to the discussion of
relationships between brain and behavior. Our observations are off ered as a
model to guide future theory and research in this area.

The Stress Response

Systemic stress mediators are produced by the autonomic, neuroendocrine,

and immune systems. These mediators interact in a nonlinear manner, as
illustrated in Figure 5.1. Regulated by endogenous biological clocks found
in each cell and coordinated by a central pacemaker located in the suprachi-
asmatic nucleus of the brain, these mediators also perform “housekeeping”
functions. In contrast to the notion of general adaptation syndrome (Selye,
1998), each type of mediator responds to different types of challenges in

somewhat diff erent ways.

12/17/2007 3:27:52 PM
CRC_71777_Ch005.indd 92 12/17/2007 3:27:52 PM
CRC_71777_Ch005.indd 92