The Modification of Instinctive Behavior

1. The Modification of Instinctive Behavior

2. Elicited or Unconditioned Behavior 2 • Occurs without past experience • Modifiable with experience (examples: habituation and sensitization

3. 3

4. Some Types of Elicited Behaviour 4 • An eliciting or unconditioned stimulus elicits a response without any prior learning • Types of Elicited Behaviour • Simple Reflex • Orienting Reflex • Taxis (taxes) • Kinesis (kineses) • Fixed/Modal Action Patterns

5. FAPs/MAPs 5 • Sequence of behaviors directed at the eliciting (sign or releasing) stimulus • Sometimes requires underlying drive (hydraulic/energy model) • Vigor of response depends on how closely the sign stimulus corresponds to the ideal stimulus (e.g., cute baby) • Small (non-ideal), Normal (ideal), Supernormal (exaggerated ideal)

6. Releasing Stimuli 6

7. Supernormal stimulus An accurate 3-dimensional model of a herring gull's head (a), and a 'supernormal' bill (b). 7

8. Supernormalstimulus 8

9. Supernormal stimulus? 9 versus 1950s 1990s

10. Lorenz – Tinbergen Model 10

11. Energy Model • Action-specific energy: an internal force that motivates a specific action • Builds up “internal pressure” that motivates animal to behave in a certain way • IRM (innate releasing mechanism) releases stored energy • Appetitive behavior: instinctive or learned response motivated by action-specific energy and attracted to a sign stimulus

12. Environmental Release • Sign stimuli are environmental stimuli • Some are simple • Others are quite complex • Likelihood of eliciting a FAP depends on • Accumulated level of action-specific energy • Intensity of the sign stimulus • The relationship is inverse • The greater the level of accumulated energy, the weaker the sign stimulus that can release the FAP

13. Conflicting Motives • When two incompatible sign stimuli are encountered, the response may be different from the FAP from either acting alone • A third instinct system, different from either of the two conflicting systems, is activated • Displacement: in a conflict situation, the occurrence of a behavior unrelated to that conflict

14. Habituation 14 • a simple type of learning which is shown by a change in elicited behaviour over trials • defined as a reduction in responsiveness (frequency, magnitude) over successive trials • sometimes short-lasting and sometimes long lasting

15. Habituation-One Type of Modifiability 15 Eric Kandel and Aplysia

16. Kandel`s Experiments 16 Touch Siphon Gill Withdrawal

17. Habituation 17 gill withdrawal touch

18. Forms of Habituation 18 • Short-Term • lasts only a few minutes • best if stimulus applied at short intervals (2-s) • Long-Term • lasts weeks • best if stimulus applied at longer intervals (30-s)

19. Simplified Circuit 19

20. Mechanism of Short-term? 20 decreases in synaptic transmission loss of skin sensitivity decrease in motor synapse fatigue

21. Not Muscle Fatigue 21 Spontaneous Evoked Pinsker et al., (1970) Science 167:1740

22. Mechanism of Short-term? 22 decreases in synaptic transmission loss of skin sensitivity decrease in motor synapse fatigue

23. Not Motor Synapse 23 Before skin SN After electrical MN record gill Kupfermann et al., (1970) Science 167:1743

24. Mechanism of Short-term? 24 decreases in synaptic transmission loss of skin sensitivity decrease in motor synapse fatigue

25. Skin Sensitivity? touch skin SN MN record MN activity to assay habituation gill 25 Trials 1 to 8 Kupfermann et al., (1970) Science 167:1743

26. Not Skin Sensitivity touch skin SN block MN record MN activity to assay habituation gill 26 26 Trials 10 -20 Kupfermann et al., (1970) Science 167:1743

27. What’s the Mechanism of Short-term? 27 decreases in synaptic transmission loss of skin sensitivity decrease in motor synapse fatigue

28. Mechanism:Short-term Habituation 28 Decrease in neurotransmitter released at the synapse with both the motor neuron and the interneuron!

29. Mechanism of Long-Term Habituation 29 Change in the number of synapses!

30. Properties of Habituated Responses 30 • Spontaneous Recovery • Dishabituation • Generalization

31. Spontaneous Recovery Stimulus Hi Response Time Passes Lo Number of Presentations 31

32. Dishabituation Stimulus Novel Event (no time passes) 32 Hi Response Dishabituation Lo Number of Presentations

33. Generalization 33

34. Sensitization- Another Type of Modifiability 34 • enhanced response to a “benign” stimulus after exposure to a “noxious” one (most common) • for example, startle • enhanced response after repeated presentations of a “not so benign” stimulus (less common)

35. 35 Rat Startle

36. Human Startle 36

37. Thompson/Groves Dual Process Theory 37 Competition between two separate processes 1. S-R System: Habituation 2. State System: Sensitization

39. Conditions Favouring Habituation 39 • Calm organism • Shorter interstimulus intervals • Less variable interstimulus intervals • Low intensity • Less complexity • More trials • More Stimulus Specificity

40. Interstimulus Interval 40

41. Complexity 41 Looking Time Trials

42. One example of habituation is when animals gradually eat more of a novel food after initial ingestional neophobia • Ingestional neophobia: the avoidance of novel foods • Habituation of the neophobic response can lead to increased consumption of novel foods

43. Animals can also show an increased neophobic response • If an animal is ill when it ingests a novel food, it may avoid the food in the future • The greater neophobic response when animals are ill is due to sensitization process

44. Experience can also influence the properties of a reward • Homeostasis has traditionally been considered responsible for either increased or decreased effectiveness of a reward • Decreased effectiveness due to satiation • Increased effectiveness due to deprivation

45. However, it appears that habituation and sensitization can also influence • Habituation leads to decreased effectiveness • Sensitization leads to increased effectiveness • Habituation and sensitization can explain changes in reward effectiveness that cannot be explained by homeostasis

46. Habituation is the process that filters out external stimuli of little relevance by raising the sensory threshold to those stimuli • Sensitization decreases sensory thresholds to potentially relevant external events

47. Thus, habituation and sensitization are processes that optimize an animal’s likelihood of detecting significant external events

48. The Dishabituation Process • Dual process theory states that the arousing effect of the sensitizing stimulus causes the habituated response to return • In the absence of the sensitizing stimulus, habituation remains

49. The Nature of Dishabituation • Pavlov suggested that dishabituation is a reversal of habituation • Thus, the dishabituation of the withdrawal response in Aplysia would be a return to the pre-habituation level of neurotransmitter released from the sensory neuron

50. In contrast, Grether proposed that dishabituation results from a process similar to sensitization superimposed on habituation • In Aplysia, this would suggest two processes • Decreased neurotransmitter release as a result of habituation • Increased neurotransmitter release produced as a result of a sensitization experience