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L3 Neural basis of behavior

Development of Behavior

  • Behavior development depends on both genetics and the environment.

  • Variation of behaviors determined by:

    • G: Genetics

    • E: Environment

    • G x E: Interaction between genetics and environment.

Traditional Behavior Categories

  1. Innate Behavior:

    • Genetically hardwired and stereotypical.

    • Can perform without prior learning.

    • Resistant to environmental variation.

  2. Learned Behavior:

    • Influenced by environmental factors.

    • Requires learning from previous experiences.

Innate Behavior (Instinct)

  • Definition: Behavioral pattern in response to a simple stimulus without prior experience.

  • Components:

    • Sign Stimulus (Releaser): The cue that triggers innate behavior (e.g., the red dot on gull beaks).

    • Fixed Action Pattern (FAP): Stereotypical response to stimuli (e.g., gull chick begging).

    • Innate Releasing Mechanism: Neural network activating the instinct.

Innate Behaviors in Humans

  • Early behaviors include:

    • Grasping objects (primate ancestry)

    • Smiling, grabbing, suckling.

Exploitation of Innate Behaviors

  • Male bees attempt to mate with blister beetle larvae (a type of parasite).

  • The deception of bee orchids which mimic shape and pheromones.

  • African Vidua finches as nest parasites that mimic characteristics of their host.

Neuroethology

  • Ethology: Study of animal behavior.

  • Neuroethology: Examines neural basis of natural behaviors, focusing on:

    • Sensory systems capturing stimuli.

    • Central nervous system processing information.

    • Motor system producing behavior.

Neurology Basics

Types of Neurons

  • Sensory Neurons: Relay sensory input to interneurons.

  • Interneurons: Process information.

  • Motor Neurons: Transmit signals to muscles.

Action Potential

  • Definition: All-or-nothing change in membrane electrical charge.

  • Proliferation occurs if signal reaches threshold; no gradient in firing.

  • Strength of signal is indicated by:

    1. Number of times a neuron fires.

    2. Number of neurons firing.

How Neurons Work Neurons communicate through electrical impulses and neurotransmitter release, with each neuron's firing rate and pattern influencing the strength and type of signal transmitted to other neurons.

  • Electrical pulses (action potentials) travel within neurons.

  • Upon reaching axon terminals, convert to chemical signals (neurotransmitters) for inter-neuronal communication.

  • Neurotransmitter binding triggers postsynaptic responses.

From Stimulus to Behavior

  • The sequence involves:

    1. Sensory Cells

    2. Sensory Neurons

    3. Interneurons

    4. Central Nervous System

    5. Interneurons

    6. Motor Neurons

    7. Muscle Cells

Example: Sea Slug Escape Behavior

  • Escape movements involve alternating contraction of dorsal and ventral muscles in response to predator touch.

Sensory Systems in Animals

  • Sensory Modality: Different channels through which animals perceive information (visual, acoustic, tactile, chemical).

  • Each species has different sensory systems, dictating how they perceive the environment.

Example: Moth Evasion of Bat Ultrasound

  • A1 receptor activity varies with bat proximity, influencing moth response to predation.

Example: Cricket Flight Orientation

  • Response to auditory stimuli for mate attraction or predator evasion.

  • Requires interneuron AN2 for appropriate behavioral response.

Stimulus Filtering

  • Importance of focusing on relevant stimuli due to limited processing capacity.

  • Ensures crucial survival behaviors are prioritized over irrelevant stimuli.

Key Takeaway: From Stimulus to Behavior

  • Understanding neuronal roles in processing stimuli is critical for behavior interpretation; includes cellular and anatomical aspects.