Chapter 16: Motivation

Motivated Behavior

def 3 motivated beh

1. food
2. thirst
3. temperature

def 2 types of beh

1. Unconscious reflexes


2. voluntary movements

def motivation

the need or desire to do something

def 4 theories for motivation

1. evolutionary perspective
2. drive-reduction theory
3. optimal arousal
4. Maslow’s hierarchy of needs

analogy for motivation

ionic driving force - motivation depends on many factors

what 2 things vary with the driving force needed to perform the behavior

probability, direction

def Homeostasis

Maintains internal environment within a narrow physiological range

which part of the brain regulates homeostasis

hypothalamus

def 3 components of neuronal response

1. Humoral response
2. Visceromotor response
3. Somatic motor response

def humoral response

stimulating/inhibiting release of pituitary hormones

def visceromotor response

a reflex response to noxious stimulation of a visceral organ (the soft internal organs of the body)

def somatic motor response

voluntary muscle movement.

def 2 energy balance states

Prandial state—anabolism

Postabsorptive state—catabolism

funct: anabolism v catabolism

storing energy v using (breaking down) energy

Loading and Emptying the Body’s Energy Reserves

anabolism v catabolism

what hormone regulates body mass by decreasing what and increasing what

Leptin: Decreases appetite, Increases energy expenditure

what incites adaptive responses to fight starvation

leptin

what do experiments with parabiosis show (Lipostatic hypothesis)

our body has a set point of weight, we can adjust it with food, but usually regression to mean

what disorder arises from lateral hypothalamic syndrome

anorexia

what disorder arises from ventromedial hypothalamic syndrome

obesity

what part of the hypothalamus controls feeding

Arcuate nucleus of hypothalamus

def 3 phases of regulation of Feeding

1. cephalic
2. gastric
3. substrate

def cephalic

hunger

what happens to Ghrelin during _____ phase

cephalic, it is released when the stomach is empty

what does ghrelin do once it is released in the cephalic phase

Activates **NPY/AgRP**-containing neurons in arcuate nucleus

Removal of ghrelin-secreting cells of stomach thought to cause…

loss of appetite

def gastric

feeling full

Gastric distension signals brain via during _____ phase

gastric, vagus nerve

Gastric distension works synergistically with ____ release

CCK

what peaks during eating a meal

insulin levels

insulin is released from β cells of the… and is important for…

pancreas, anabolism

both insulin and serotonin levels are highest during what phase

substrate phase

serotonin levels rise in… spike during… and are low during the… in what period of eating

* Rise in **anticipation of food**
* Spike **during meal**
* Low during the **postabsorptive period**

what NT is correlated with drive to eat

dopamine

* effective sites for self-stimulation: dopaminergic axons in the ventral tegmental area projecting to the forebrain


* drugs that block dopamine receptors: reduce self-stimulation
* Stimulation of the dopamine axons: Produces craving for food without increasing the hedonic impact

eating: liking v wanting

hedonic v drive reduction

how do we identify brain sites of reinforcement

electrical self-stimulation experiments

Former belief of Role of Dopamine in Motivation

dopamine projection served **hedonic** (liking) reward

New understanding of Role of Dopamine in Motivation

* Dopamine-depleted animals “like” food but **do not “want” food.**
* **Lack motivation** to seek food but enjoy it when available

Disorders in which NT regulation results in anorexia nervosa or bulimia nervosa

serotonin

what is the automatic beh response when body is cold

mobilize: Body shivers, blood shunted away from the body surface, urine production inhibited, body fat reserves—mobilized

def Hypovolemia

pathway that decreases blood volume

what leads to volumetric drinking

hypovolemia

def hypertonicity

pathway that increased concentration of dissolved

substances in blood (solutes)

what leads to osmotic drinking

hypertonicity

what hormone acts on the kidneys and increases water retention and inhibits urine production

vasopressin

vasopressin causes an inc or dec in drinking motivation

inc

when the temperature falls, what hormone is released

TSH

TSH is released by…

anterior pituitary

TSH stimulates release of…

thyroxin (from thyroid gland)

TSH leads to an inc in…

cellular metabolism

Food - Fat: location, blood leptin levels, aMSH/CART neurons, NYP/AgRP neurons, TSH/ACTH, sympathetic, parasympathetic, eat

hypothalamus arcuate nucleus, +, +, -, +, +, -, -

Drink - thirsty: humoral, visceromotor, somatic motor

inc vasopressin, inc sympathetic, drink

Temp - Cold: location, humoral, visceromotor, somatic motor

medial preoptic area, inc TSH, inc sympathetic (constricted blood vessels in the skin), shivering/seeking warmth