Transcript Emotion and Motivation

Emotion and Motivation
A: Emotional states
Chapter 32
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 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.
Visceral
afferents
Hypothalamic
nuclei
Hormonal
output
Nucleus
Of the
Solitary
tract
Target
organs
Autonomic
output
Brain stem
nuclei
Autonomic
Preganglionic
nuclei
The hypothalamus controls
the 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
B: Motivation
Chapter 33
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
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 hypothalamus
alter feeding behavior
Each type of nutrient is regulated with different
neurotransmitters
- norepinephrine
- peptide galanin
- opiates
carbohydrates
fat
protein
Temperature regulation involves
integration of autonomic, endocrine
and skelomotor responses
Hypothalamus regulates body temperature
Anterior hypothalamus
Posterior hypothalamus
heat dissipation
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 neurons
cold -sensitive neurons
Feeding behavior is regulated by
short-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 longterm signal reflecting body weight (related to total fat stores)
Feeding behavior is regulated by a
great 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 various
from animal to animal ,
the daily expenditure of
energy is constant
across and within species
Dual controlling elements are involved
in the control of food intake
Lateral hypothalamus
Medial hypothalamus
feeding center
satiety center
Hypothalamic lesions
alter the feeding behavior
1- Alteration of sensory information
2- Alteration of set point
3- Alteration of hormonal balance
4- 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 by
factors 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