Innate Behaviours
Behavioural Systems
•
•
•
•
•
Complexity
Observe behavioural “endpoint”
Reductionism
Constituent elements
Simple systems interact producing
complex outcomes
• Gestält
Why Study Innate
Behaviours?
• Evolved
– Learned behaviours have roots in innate
behaviours
– Parallels between learned and innate
behaviours
• Some innate behaviours modifiable
• Types of innate behaviours
– Homeostasis, reflexes, tropisms, modal action
patterns, reaction chains
Elicited Behaviours
• Behaviour occurs in reaction to an
environmental stimulus
• For example:
– Face moving stimulus in peripheral vision
– Sneeze if inhaling dust, a bug, etc.
Homeostasis
• Internal balance of the body
• Drives
• Regulatory drives
Osmotic Homeostasis
• Regulating body H2O level
• Example: at a party
– Eat peanuts/popcorn/chips
• Increase salt concentration
– Thirsty...drink beer
• Increases H20; dilutes salt concentration
– But, alcohol = diuretic
• Pee...decreases H20; increases salt concentration even more
– Thirsty ... drink more beer
• Pee even more; salt concentration increased again
– Etc.
• Solution? Drink water!
Control System
•
•
•
•
•
•
•
Comparator
Reference input
Actual input
Action system
Output
Feedback system (closed-loop system)
Response lag
Blood Salinity
Comparator
Reference input
Output
Actual input
Action System
EatEat
more
peanuts!
Drink
water!
peanuts!
Reflexes
• Stereotypic movement patterns
• Reliably elicited by appropriate stimulus
• Survival benefit
Principles
•
•
•
•
•
C.S. Sherrington
Spinal animals (dogs)
Threshold for activation
Latency until response
Irradiation of response
Reflex Arc
• Monosynaptic
– One sensory and one motor
neuron
• Polysynaptic
– One or more interneurons
connect sensory and motor
neurons
– Interneurons allow
processing and/or inhibition
within spinal cord
– All but simplest reflexes
Patellar Reflex
• Monosynaptic
– Patellar tendon struck
– Stimulates stretch sensory
receptors (muscle spindles)
– Triggers afferent impulse in
sensory nerve fiber of femoral
nerve leading to L4 of spinal cord
– Sensory neuron synapses directly
with motor neuron, conveying
efferent impulse to quadriceps
• Necessary for walking without
conscious thought
en.eikipedia.org/wiki/File:Patellar-knee-reflex.png
Animation
Pupillary Light Reflex
• Controls diameter of pupil
– Greater light --> pupil contracting
– Lower light --> pupil expands
• Cranial nerves; two sensory, two motor
en.wikipedia.org/wiki/File:Ciliary
_ganglion_pathways.png
Tropisms
• Orientation or movement of whole
organism
• Kinesis
– Movement random with respect to stimulus
• Taxis
– Non-random (directed) movement with
respect to stimulus
• Control systems
Simple Agent
Excitatory or
inhibitory
+
-
Sensor
Body
Propulsion
system
Movement: Environment
Perfectly homogenous
Non-homogenous
Kinesis
Homogenous
Locally
cool so
stops
+
slower
fast
Non-homogenous
+
Locally
cool so
stops
Only Slightly More Complex
Agent
Excitatory or
inhibitory
+
+
-
Sensors
Body
Propulsion
system
Taxis
+
+
Taxis
-
What Would This Do?
+
+
+
+
Modal Action Patterns
• Originally “fixed”; variable to some
degree
• Species specific, often state dependent
• Sign stimulus activates a dedicated
neural network (innate releasing
mechanism)
• Go to completion in sequential
MAPs
• Graylag goose
– Rolls displaced egg
near its nest back
with beak
– Sign stimulus:
displaced egg
– Remove egg during
sequence
– Goose keeps pulling
head back as if egg
was there
– MAP video
www.cerebromente.org.br/n09/fastfacts/comportold_I.htm
Supernormal Stimuli
•
•
•
•
•
Extreme version of sign stimulus
Size
Colouration
Preference for supernormal stimuli
Sometimes detrimental
Beetles on the Bottle
• Gwynne & Rentz
(1983)
• Male Jewel beetles
(Julodimorpha
bakewelli)
• Colour and reflection
of bumps on bottle
as supernormal
stimuli for female
beetle
Mimicry
•
•
•
•
Code-breaking
Brood parasitism
Cowbird, cuckoo
Noisier, more
energetic behaviour
• Conveys urgent
need for food
Reed warbler feeding cuckoo
Wikipedia.org/wiki/Fixed_action_pattern
Reaction Chains
• Initiated by a particular stimulus
• Progression condition dependent
• Starts with most appropriate behaviour
in chain
• Can end before chain complete
Reaction Chain
Stimulus
Action
(behaviour)
Outcome
(new stimulus)
Reaction Chain
S1
A1
A2
A3
S2
S3
S4
A4
Sequential Organization
• Functionally effective behaviour
sequences
• Non-random
• Appetitive behaviour
– Early components of sequence
• Consummatory (i.e., completion)
behaviour
– End components of sequence
Variability to Fixed
• Appetitive behaviours
– Can take a variety of forms dependent
upon situation
• Consumatory behaviours
– Highly stereotypic
E.g., Foraging
•
•
•
•
General search mode
Focal search mode
Food handling
Injestion
General
to
specific
Habituation and Sensitization
Simplest form of Learning
Habituation
• Decrease in a response following
repeated stimulus presentation
• Note: not everything that results in a
decrease in response is habituation
Sensitization
• Increase in a response following
repeated stimulus presentation
Time Course
• Habituation
– Short-term
• Seconds to minutes
• When many stimuli presented frequently
– Long-term
• Hours to days
• When fewer stimuli presented less frequently
• Sensitization
– Short-lived
– Seconds to minutes
Stimulus Specificity
• Habituation
– Quite stimulus specific
– Stimulus generalization of habituation
• Sensitization
– Not very stimulus specific
– But not totally generalizable (e.g.,
sensitization to shock only generalizes to
other exteroceptive cues)
Spontaneous Recovery
• Post habituation or sensitization
• Return of original level of responding
• Due to passage of time
Dishabituation
• Quickly restores response after
habituation
• Exposure to extraneous stimulus
• Essentially, sensitization
• Habituation and sensitization working in
opposition
Sensory Adaptation
• Temporary change in neural response
to a stimulus as a result of the
preceding stimulus
• Habituation is response specific;
sensory adaptation is not
Response Fatigue
• Due to use neurons or muscle fibers no
longer functioning optimally or at all
• Habituation is stimulus specific,
response fatigue is not
Physiological Mechanisms of
Habituation
• Neurologically simple
• Seen across species
• Example: Aplysia
Aplysia Gill-Withdrawal Reflex
gill
withdrawal
muscle
sensory
receptor
sensory
neuron
interneuron
motor
neuron
Synaptic Effects of
Habituation
•
•
•
•
Decrease in excitatory conductance
No change in postsynaptic sensitivity
Reduced neurotransmitter release
Decrease in active zones
Neurochemical Level: Calcium
Learning Through Habituation
• Learning without new axons/synapses
• Chemical change at synapse
• Plasticity
Opponent-Process Theories
• Assumes two opposing components
• Observable behaviour
• Net sum of two underlying processes
Dual-Process Theory of
Habituation
• Groves & Thompson (1970)
• Competitive
• Habituation process and sensitization
process
• Behaviour of habituation or sensitization
is the net sum effect of the two
processes
SENSITIZATION
HABITUATION
+
-
+
S
S
Net
Net
H
H
-
Habituation Process
• S-R system
• Shortest neural path connecting sense
organs to muscles
• Reflex arc
• Activated with each presentation of
eliciting stimulus
Sensitization Process
• State system
• Nervous system components
determining organisms general level of
responsiveness
• Only activated by arousing events
• Altered by drugs, emotional experiences
Implications
• S-R system activated by each stimulus that
elicits a response
– Each activation is stimulus specific
– S-R activation and resultant habituation process
universal features of elicited behaviour
• State system only activated by particular
stimuli
– Not stimulus specific
• Both processes decay with time -->
spontaneous recovery
Emotions
• Solomon & Corbit (1974)
• Emotional reactions are biphasic
• Primary reaction becomes weaker with
repeated stimulations
• Weakening of primary reaction
accompanied by strengthening of after
reaction
• Change with experience
Examples
• Christmas
– Excitement and depression
– Young
– Older
– Incidence of suicides post-holidays
• Drug tolerance
• Thrill seekers
• Romance
OPT of Motivation
• Homeostatic theory
• Underlying neurophysiological
mechanisms
• Emotional stability
• Emotion-arousing stimuli pushes
emotional state out of stability
Processes
• Primary (a):
– Quality of emotion with stimulus
• Opponent (b):
– Elicited by primary process
– Opposite emotion
OPT of Emotional Response
peak of primary
affective reaction
Hedonic Scale
adaptation phase
Intensity of
primary
affect
steady level
0
Intensity of
affective
afterreaction
decay of
after-reaction
stimulus
Time
peak of affective
after-reaction
Intensity of
primary
affect
0
Intensity of
affective
afterreaction
stimulus
Time
Hedonic Scale
Hedonic Scale
Habituation
Intensity of
primary
affect
0
Intensity of
affective
afterreaction
stimulus
Time
+
-
same
bigger
sooner