Innate Behaviours

1. Innate Behaviours

2. Behavioural Systems • Complexity • Observe behavioural “endpoint” • Reductionism • Constituent elements • Simple systems interact producing complex outcomes • Gestält

3. 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

4. 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.

5. Homeostasis • Internal balance of the body • Drives • Regulatory drives

6. 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!

7. Control System • Comparator • Reference input • Actual input • Action system • Output • Feedback system (closed-loop system) • Response lag

8. Comparator Reference input Output Actual input Action System Blood Salinity Eat more peanuts! Drink water! Eat peanuts!

9. Reflexes • Stereotypic movement patterns • Reliably elicited by appropriate stimulus • Survival benefit

10. Principles • C.S. Sherrington • Spinal animals (dogs) • Threshold for activation • Latency until response • Irradiation of response

11. 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

12. 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

13. 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

14. 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

15. Simple Agent Excitatory or inhibitory Propulsion system + Sensor - Body

16. Movement: Environment Perfectly homogenous Non-homogenous

17. + + Kinesis Homogenous Locally cool so stops slower fast Non-homogenous Locally cool so stops

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

19. + + + + Taxis

20. - - - - Taxis

21. + + + + What Would This Do?

22. 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

23. 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

24. Supernormal Stimuli • Extreme version of sign stimulus • Size • Colouration • Preference for supernormal stimuli • Sometimes detrimental

25. 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

26. 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

27. Reaction Chains • Initiated by a particular stimulus • Progression condition dependent • Starts with most appropriate behaviour in chain • Can end before chain complete

28. Reaction Chain Stimulus Action (behaviour) Outcome (new stimulus)

29. Reaction Chain S1 A1 A2 A3 A4 S2 S3 S4

30. Sequential Organization • Functionally effective behaviour sequences • Non-random • Appetitive behaviour • Early components of sequence • Consummatory (i.e., completion) behaviour • End components of sequence

31. Variability to Fixed • Appetitive behaviours • Can take a variety of forms dependent upon situation • Consumatory behaviours • Highly stereotypic

32. E.g., Foraging • General search mode • Focal search mode • Food handling • Injestion General to specific

33. Habituation and Sensitization Simplest form of Learning

34. 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

35. 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

36. 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)

37. Spontaneous Recovery • Post habituation or sensitization • Return of original level of responding • Due to passage of time

38. Dishabituation • Quickly restores response after habituation • Exposure to extraneous stimulus • Essentially, sensitization • Habituation and sensitization working in opposition

39. 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

40. Response Fatigue • Due to use neurons or muscle fibers no longer functioning optimally or at all • Habituation is stimulus specific, response fatigue is not

41. Physiological Mechanisms of Habituation • Neurologically simple • Seen across species • Example: Aplysia

42. Aplysia Gill-Withdrawal Reflex gill withdrawal muscle sensory receptor sensory neuron motor neuron interneuron

43. Synaptic Effects of Habituation • Decrease in excitatory conductance • No change in postsynaptic sensitivity • Reduced neurotransmitter release • Decrease in active zones

44. Neurochemical Level: Calcium

45. Learning Through Habituation • Learning without new axons/synapses • Chemical change at synapse • Plasticity

46. Opponent-Process Theories • Assumes two opposing components • Observable behaviour • Net sum of two underlying processes

47. 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

48. SENSITIZATION HABITUATION S + + Net S Net H H - -

49. Habituation Process • S-R system • Shortest neural path connecting sense organs to muscles • Reflex arc • Activated with each presentation of eliciting stimulus

50. Sensitization Process • State system • Nervous system components determining organisms general level of responsiveness • Only activated by arousing events • Altered by drugs, emotional experiences