PSYC 356 Chapter Notes - Chapter 2: Neuroscience, Drug Tolerance, Addiction
Chapter Two: Elicited Behavior, Habituation and Sensitization
The Nature of Elicited Behavior:
● Simplest form: reflexive behavior
The Concept of the Reflex:
● Reflex: two closely related events: an eliciting stimulus and a corresponding response
○ The stimulus and
response are linked
● Simple reflexes are
typically mediated by three
neurons
● An environmental stimulus for a reflex activates a sensory neuron (afferent neuron)
→ transmits sensory message to the spinal cord
→ neural impulses are relayed to the motor neuron (efferent neuron)
→activates the muscles involved in the reflex response
○ The impulses from sensory to motor neurons are usually relayed through at least
one interneuron
● One reflex response is elicited only by a specific set of stimuli
● Together, the afferent neuron, interneuron and efferent neuron constitute the reflex arc
● Reflex arc: represents the fewest neural connections necessary for reflex action
○ Additional neural structures may be involved
○ Simple reflexes can be influenced by higher nervous system activity
● Important Reflexes:
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○ Newborn reflexes for feeding: finger on cheek/ in mouth
○ Milk- letdown reflex: initially triggered by infants suckling behavior; can later be
stimulated by cues that predict infant’s suckling
○ Respiratory occlusion reflex: stimulated by reduction of air flow to the baby
■ Baby will first move away, then move hands, then cry
Modal Action Patterns:
● Various forms of elicited behavior occur in just one species or a small group of related
species
○ ie. feeding behavior
■ Ring Gull
chicks peck at
the tip of the
parent’s bill
causing
regurgitation
● Modal action patterns (MAPs): response sequences that are typical of a particular
species
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○ ie. Ring Doves: sexual behavior begins with a courtship interaction that
culminates in the selection of a nest site and cooperative construction of the nest
by the male and female
Vs
ie. Stickleback: male first establishes a territory and constructs a nest and then
court females who enter the territory who lay eggs
- After the eggs are laid, the female is chased away and the male cares for
offspring
● Threshold for eliciting activities varies in MAPs
○ Same stimulus can have widely different effects depending on the physiological
state of the animal and its recent actions
■ ie. Male stickleback will not court a female in its territory if the nest has
not been built yet / Male will chase female away from territory after she
has laid eggs
● The sexual/ territorial responses only occur when environmental
cues induce physiological changes that are characteristic of the
breeding season for both males and females
Eliciting Stimulus for Modal Action Patterns:
● What exactly stimulates the response?
● Tinbergen/ Perdeck with herring gull chicks: what elicits the chick’s pecking response?
○ May be by the color, shape or length of the parent’s bill, the noise the parents
make, the head movements of the parent, or a combination
○ Results: the eliciting stimulus has to be a long, thin moving object that was
pointed downward and had a contrasting red patch near the tip
■ Color, shape/ coloration of parent’s head, and noises the parents made
were not required for eliciting pecking
● Essential features= sign stimulus (releasing stimulus) that elicit response (ie. chicks
pecking)
● Supernormal stimulus: exaggerating the sign stimulus to elicit a vigorous response
● In humans:
○ PTSD: traumatic events have come to elicit strong defensive MAPs
○ Early components of defensive action pattern: eye blink reflex and the startle
response
The Sequential Organization of Behavior:
● Responses do not occur in isolation of one another
○ Individual actions are organized into functionally effective behavior sequences
● All motivated behavior involves systematically organized sequences of actions
● Appetitive behavior: early components of a behavior sequence
○ Serve to bring organism into contact with the stimuli that will release
consummatory behavior
○ More variable than consummatory; can take a variety of forms depending on the
situation
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Document Summary
Reflex: two closely related events: an eliciting stimulus and a corresponding response. Simple reflexes are typically mediated by three neurons. An environmental stimulus for a reflex activates a sensory neuron (afferent neuron) Transmits sensory message to the spinal cord. Neural impulses are relayed to the motor neuron (efferent neuron) Activates the muscles involved in the reflex response. The impulses from sensory to motor neurons are usually relayed through at least one interneuron. One reflex response is elicited only by a specific set of stimuli. Together, the afferent neuron, interneuron and efferent neuron constitute the reflex arc. Reflex arc: represents the fewest neural connections necessary for reflex action. Simple reflexes can be influenced by higher nervous system activity. Newborn reflexes for feeding: finger on cheek/ in mouth. Milk- letdown reflex: initially triggered by infants suckling behavior; can later be stimulated by cues that predict infant"s suckling. Respiratory occlusion reflex: stimulated by reduction of air flow to the baby.
