Emotion and Motivation

Pleasure, elation, ecstasy, sadness, depression, fear, anger and calm imbue our action with passion and character

Emotion, like perception and action is controlled by distinct neuronal circuits within the brain

What parts of the brain are involved in emotion?

A: Emotional states Chapter 32

A theory of emotion must explain the relationship of cognitive and physiological states

How is the emotion represented in the cortex ?

How do subcortical structures regulate the autonomic and endocrine systems?

Hypothalamus communicates reciprocally with areas of the cerebral cortex, information about the conscious and peripheral aspects of emotion affect each other

The hypothalamus is a critical subcortical structure in the regulation of emotion

- homeostatic mechanism

Hypothalamus regulates the vital functions that vary with emotional states : temperature, heart rate, blood pressure, and water and food intake (autonomic system).

Hypothalamus also controls the endocrine system.

The autonomic nervous system participates in emotional states

- Sympathetic: fight or flight - parasympathetic: rest and digest- enteric

The autonomic nervous system is controlled by many region of the brain, the cerebral cortex, the amygdale that influence the

autonomic system through the hypothalamus.

NucleusOf the

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Hypothalamicnuclei

Targetorgans

Autonomicoutput

Hormonaloutput

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Visceralafferents

The hypothalamus controlsthe endocrine system

- directly by secretion of neuroendocrine products in to the general circulation from the pituitary

- indirectly by secretion of regulating hormones in to the pituitary

Manifestations of emotional states can be selectively elicited by stimulating the hypothalamus

hypothalamus is the coordinating center that integrates various inputs into a well organized set of autonomic and somatic responses

The search for cortical and subcrotical representation of emotions has led to the amygdala

The amygdala is the part of limbic system most specifically concerned with emotion

The amygdala mediates both inborn and acquired emotional responses

Emotional memories are not stored in the amygdala directly but are stored in the cingulate and parahippocampal cortices, with which the amygdala is interconnected

Motivation is the area of biology concerned with internal needs rather than with the processing of sensory information

Motivational state is thought to be controlled by homeostatic process

Motivation varies as a function of deprivation

B: Motivation Chapter 33

Motivational states serve three functions

1- Directing function

2- Activating function

3- Organizing function

Attainment of a goal decreases the intensity of the motivational states

Curiosity and sexual arousal do not appear to be based on any well-defined physiological deprivation

Motivation intensity and direction of behaviors

Homeostatic mechanisms - Hypothalamus

Internal environment of the body is highly regulated so as to be maintained in a stable, narrow range.

This constancy is the result of homeostatic mechanisms that limit the variability of body state

Homeostatic processes such as temperature regulation, feeding and thirst correspond to motivational states

Homeostatic mechanisms can be understood by analogy with the control system or servo mechanisms

Chemical stimulation of the hypothalamusalter feeding behavior

Each type of nutrient is regulated with different neurotransmitters

- norepinephrine carbohydrates- peptide galanin fat- opiates protein

Temperature regulation involvesintegration of autonomic, endocrineand skelomotor responses

Hypothalamus regulates body temperature

Anterior hypothalamus heat dissipation Posterior hypothalamus heat conservation

Normal body temperature is the set point

In addition to driving appropriate autonomic, endocrine and nonvoluntary skeletal responses, the error signal of can also drive voluntary behaviors

warm-sensitive neuronscold -sensitive neurons

Feeding behavior is regulated byshort-term and long-term cues

Short-term cues regulate the size of individual meals and long term cues regulate the overall body weight

The effectiveness of short-term cues is modulated by some long-term signal reflecting body weight (related to total fat stores)

Feeding behavior is regulated by agreat variety of mechanisms

body weight is regulated around a set point

body must provide feedback signals that control nutrient intake and metabolism

Although body weight variousfrom animal to animal ,the daily expenditure of energy is constantacross and within species

Dual controlling elements are involvedin the control of food intake

Lateral hypothalamus feeding center Medial hypothalamus satiety center

Hypothalamic lesionsalter the feeding behavior

1- Alteration of sensory information2- Alteration of set point3- Alteration of hormonal balance4- Effect on fibers of passage

Thirst is regulated by tissue osmolality and vascular volume

The hypothalamus regulates water balance by direct physiological action

It also regulates the behavioral aspects of drinking

A set point of water intake appears to exist

Drinking is controlled by :

Tissue osmolality : osmoreceptors (or sodium-level receptors, probably neurons) can respond to the osmatic pressure of the extracellular fluid

Change in vascular volume : are detected in the low pressure side of the circulation

Dryness of the tongue and high body temperature : detected by thermosensitive neurons

Motivational states can be regulated byfactors other than tissue needs

Curiosity and sexual responses do not appear to be controlled by the lack of specific substances in the body

Homeostatic responses are modulated by innate and learned mechanisms

-Ecological constraints may shape motivated behaviors

- Behavior may anticipate physiological deficits

- Pleasure is an important but poorly understood factor in motivating behavior

- Intracranial stimulation cam simulate motivational states and reinforce behavior

Only once have I been made mute.It was when a man asked me, ‘Who are you’?

Gibran Kahlil Gibran