Motivation in Neuroscience

NEUR2020 Neuroscience for Psychologists - Lecture 9 (Semester 2, 2025)

Motivation

Table of Contents

  • Introduction

  • Behavioural Foundations

  • Motivation & Decision-Making

  • Dopamine & Reward

  • Habits & Control

  • Dysfunction: Addiction & Amotivation

  • Psychological Perspectives

  • Key Learnings

  • Resources

Introduction

Concept of Motivation

  • Motivation: Processes that initiate, direct, and sustain goal-directed behavior.

    • Determines the actions chosen and the intensity of effort.

    • More complex than merely “wanting” as it integrates needs, values, context, and effort.

    • Explains variability in performance and persistence.

    • Central to understanding learning, decision-making, emotion, and psychopathology.

Factors Influencing Motivation

  • External Factors: Environmental stimuli.

  • Internal Factors: Current state, past experiences, physiological needs, etc.

    • Sensory Input and Motor Output are influenced by evaluation processes.

Behavioural Foundations

Behavior Overview

  • Motivation, Reward, and Addiction: Essential for driving behaviors.

  • Purpose of the Brain: Controls purposeful action and leads to decision-making about which actions to execute.

Categories of Behavior

  1. Reflex

  2. Reaction

  3. Action

  4. Habit

Detailed Breakdown of Behavior Categories
Reflex

  • Nature: Unconscious and automatic response (hardwired / genetic).

  • Mechanism: Simple stimulus-evoked response using limited muscle groups.

  • Learning Component: Can learn associations via classical conditioning.

    • Example: Predictive nature of classical conditioning.

  • Types of Reflexes:

    • Somatic Reflexes: Voluntary muscle responses for protection (e.g., withdrawal reflex).

    • Autonomic Reflexes: Involve smooth muscle, cardiac muscle, glands (e.g., pupillary reflex).

Reaction

  • Complexity: Similar to reflex but engages the entire organism.

  • Characteristics: Unconscious, automatic, genetic, involves no preparation or experience.

    • Requires Central Nervous System (CNS) control beyond basic sensory processing.

    • E.g., species-typical behaviors like defensive freezing.

Action

  • Conscious and Deliberate: Involves complex behaviors tied to external stimuli and internal motivational factors.

  • Goal-Directed: Aims to maximize rewards and minimize costs while weighing substantial information.

    • Involves actions fulfilling basic needs and long-term goals.

    • E.g., Eating involves a reflexive action of salivation.

Habit

  • Definition: Actions that have become automatic through repetition.

  • Initially guided by outcomes but become insensitive to those outcomes over time (reward invariant).

  • Characteristics: Efficient, freeing cognitive resources, stable, and reliable responses in familiar contexts.

    • Example: Driving the same route home without conscious thought.

Classic Psychology

Key Theories of Motivation
Drive Reduction Theory (Hull, 1943)

  • Concept: Organisms act to reduce internal drives arising from physiological needs.

    • Example: Eating to alleviate hunger.

    • Limitation: Fails to explain behaviors performed without apparent drives, like curiosity.

Incentive Theory

  • Definition: External stimuli and rewards energize behavior.

    • Example: Eating popcorn triggered by the smell despite no hunger.

  • Shifts focus from “need-based” to “cue-based” motivation.

Homeostasis and Allostasis

  • Homeostasis: Maintaining internal variables within narrow limits (e.g., blood glucose levels).

  • Allostasis: Anticipatory regulation, where the brain predicts demands and prepares accordingly.

Integration of Internal States and External Cues

  • Motivated behavior results from weighing internal needs against external incentives.

    • Key brain regions involved: hypothalamus for internal states, reward circuits (dopamine) for external cues.

Motivation & Decision Making

Decision-Making Process

  • Brain as a Decision-Making Device: Integrates perceptual, memory, and motor capabilities to determine actions.

    • Ranges from simple decisions (to get up) to complex ones (who to vote for).

Rational and Irrational Decisions

  • Explains why people make decisions that seem irrational today, with historical context of evolution favoring calorie intake and energy conservation over present cues.

Ways to Reach Decisions

  • Action-Outcome: Evaluation based on expected outcomes leading to habitual responses; Stimulus-Response: Decisions based on direct stimuli without evaluation.

Representation of Value in Decision-Making

Economic Models

  • Value Representation: Computation of options' value and comparison.

    • Primary Reinforcers: Hardwired for survival (food, water, sex).

    • Secondary Reinforcers: Associated with primary rewards (money, status) but lack intrinsic value.

Factors in Value Representation

  1. Payoff (type and quantity)

  2. Probability

  3. Cost (including temporal discounting)

  4. Context (internal/external state, novelty)

  5. Preference

  • Subjective Value: Varies based on individual perspective and situational context.

Dopamine and Reward

Dopamine's Role in Decision Making

  • Study by Olds and Milner (1954) using electrodes implanted in rats demonstrated varying lever-pressing behavior linked to activations in dopaminergic pathways related to reward expectancy.

  • Modern research confirms dopamine's relationship with prediction error rather than merely reward size.

Prediction Error and Dopamine

  • Schultz et al.'s studies on classical conditioning show that classical conditioning occurs when dopamine neurons are activated through cue-recognition, predicting reward.

  • Initial unexpected rewards lead to dopamine firing; with time, expectations are established and dopamine responses modify based on reward predictability.

Habits and Control

Nature of Habits

  • Definition: Actions that become automatic through repetition and context.

    • Before forming a habit, actions involve purposeful goal-directed processes relying on outcomes.

    • The brain classifies chunked tasks into habits, making responses automatic to specific stimuli.

Advantages of Habits

  • Efficiency: Frees cognitive resources for other tasks.

  • Reliability: Provides stable and predictable responses in familiar contexts.

  • Evolutionary Advantage: Saves energy by enabling quick reactions.

Dysfunction: Addiction & Amotivation

Addiction Overview

  • Definition: Compulsive engagement in a behavior or substance use despite negative consequences.

  • Characteristics include chronicity, loss of control, and motivated behavior narrowing.

  • Examples include drug use, gambling, and gaming.

Types of Drug Addiction
Tolerance & Dependence

  • Tolerance: Shift in dose-response curves due to physiological changes reducing drug efficacy.

  • Dependence: Neuroplastic changes causing withdrawal symptoms.

Path to Addiction

  • Stages leading to addiction:

  1. Voluntary use: Goal-directed with hedonic value.

  2. Impulsive use: Driven by arousal and tension (positive reinforcement).

  3. Compulsive use: Anxiety and relief cycle leads to repeated action (negative reinforcement).

Psychological Perspectives on Motivation

Maslow’s Hierarchy

  • Describes levels of motivation but lacks empirical support and considerable simplification for such a complex construct.

Self-Determination Theory

  • Introduces three innate psychological needs:

  1. Autonomy: Control and choice.

  2. Competence: Mastery and skill development.

  3. Relatedness: Sense of social connection.

  • Higher motivation occurs when these needs are satisfied.

Intrinsic vs. Extrinsic Motivation

  • Intrinsic: Motivation derived from personal enjoyment and satisfaction from the task.

  • Extrinsic: Motivation driven mainly by external rewards or punishments (e.g., grades).

  • Both types can interact, emphasizing how external rewards can enhance or undermine intrinsic motivation.