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 H 2 O level Example: at a party –Eat peanuts/popcorn/chips Increase salt concentration –Thirsty...drink beer Increases H 2 0; dilutes salt concentration –But, alcohol = diuretic Pee...decreases H 2 0; 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 Output Eat peanuts! Action System Actual input Eat more peanuts! Drink water! Reference input

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 Body Propulsion system Sensor + - Excitatory or inhibitory

Movement: Environment Perfectly homogenous Non-homogenous

Kinesis + Homogenous Locally cool so stops slowerfast + Locally cool so stops Non-homogenous

Only Slightly More Complex Agent Body Propulsion system Sensors + - Excitatory or inhibitory + -

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 videoMAP video

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 S1A1 S3 A2 S2 A3 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 sensory receptor sensory neuron interneuron motor neuron gill withdrawal muscle

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

+ - S Net H + - S H HABITUATION SENSITIZATION

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 0 Intensity of primary affect Intensity of affective after- reaction Hedonic Scale peak of primary affective reaction adaptation phase steady level peak of affective after-reaction decay of after-reaction stimulus Time

Habituation Intensity of primary affect Intensity of affective after- reaction Hedonic Scale 0 stimulus Time 0 Intensity of primary affect Intensity of affective after- reaction Hedonic Scale stimulus Time

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