Clwork1a - 1 Course Notes Psych 363 Set#1 Is Behaviour...

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Unformatted text preview: 1 Course Notes Psych 363 Set #1 Is Behaviour Lawful? -in chemistry there are laws that govern how substances interact -in physics there are laws that determine how matter behaves- in Psychology our goal is to determine laws that regulate behaviour- that is if we believe that behaviour is governed by laws. - Determinism: peoples behaviour is entirely governed by their genes and their environment - vs. Free Will: Humans are fundamentally free, we have the power to govern our own actions. - Middle ground? How to discover laws of behaviour? - Introspection?- senses are not infallible, problem of confirming reports - Conscious vs unconscious thought- only a small portion of the brain’s activity is at the level we call “consciousness” - Experimental approach- objective, controlled approach to problem Psychology is a data-based discipline - a science with the objective of understanding the laws of behaviour 2 What is a science? - not defined by subject matter - interesting that throughout history strong forces have tried to place human beings outside the realm of scientific investigation - Science is not defined by a particular apparatus - Science is not defined by a specifics method - Science is a way of thinking about & observing the universe that leads to a deep understanding of its workings - Science is governed by general principles 1) systematic empiricism 2) production of public knowledge 3) examination of solvable problems - - - - Systematic Empiricism - empiricism = the practice of relying on observation - “let’s take a look!” - seems obvious, but early philosophers felt logic could replace observation however, just observing everything from dawn ‘til dusk is insufficient – you get a number of facts, but not much greater understanding. Scientific observation is ‘systematic’ because it is structured so that the results of the observation reveal something about the underlying nature of the world Scientific observations are usually theory-driven 3 - they test different explanations of the nature of the world they are structured so that, depending on the outcome of the observation, some theories are supported, others are rejected Publicly Verifiable knowledge - - scientific knowledge does not exist until it has been publicly submitted for criticism and empirical testing. scientific knowledge is open to scrutiny and verification a finding must be presented in a way that enables other scientists to attempt the same experiment and obtain the same results this ensures that a particular finding is not due simply to errors or biases of a researcher thus all research is based on replication & is interconnected – researchers constantly build on previous knowledge to go beyond what is known Thus they way information is recorded and communicated is critical When presented with ‘scientific claims’ of uncertain validity, ask “Have the findings been published in a recognized scientific journal that employs some type of peer review procedure?” not all information in journals is correct, but it has met a minimum standard of peer criticism and scrutiny 4 Solvable Problems - Science deals with solvable or specifiable problems. - types of questions asked are answerable with currently available empirical techniques - for example “Will 3 yr old given structured language stimulation during day care be ready to read early than children not given extra stimulation?” is a testable question – while “Are human beings inherently good or evil?” is not testable Learning - study of learning from an objective, scientific approach - learning is a very large area - increase a behavior - decrease a behavior - physical tasks - cognitive tasks - simple behavior - complex behavior - many attempts to define learning - learning is an enduring change in the mechanisms of behavior that results from experience with environmental events rule out - fatigue - change in stimulus conditions 5 - alterations in physiological or motivational state - maturation - problem of performance Use of Animals: - control of environment - shorter developmental time course - simpler systems to understand basic foundations of function (flashlight vs computer) - question of similarity – neurons and nervous systems are similar – simplest conclusion is that fundamentals of behaviour will be similar - Darwin “Emotions of Animals and Man” - Ethics? Value of animal vs human? Non-Associative Learning - alternations in elicited behavior occur as a result of repeated presentations of a stimulus both increases and decreases in responding can occur with repeated or continuous presentation of a stimulus Decreases in responsiveness are called Habituation. Increases in responsiveness are called Sensitization. organisms are constantly bombarded with stimulation – habituation and sensitization help organize and focus attention Habituation occurs in all organisms from humans to mammals to invertebrates to single celled protozoa 6 - properties of habituation & sensitization appear to be the same across most organisms Listed in Thompson & Spencer (1966) HABITUATION 1. The course of habituation – whenever a stimulus is repeatedly presented – large response decrements at first, progressively slower as habituation proceeds. 2. Response recovers over time if no stimulus presented. – Spontaneous recovery 3. Relearning effects – habituation should be more rapid when stimulus is presented again. 4. Effects of stimulus intensity – habituation is more rapid with weak stimuli. Freq: ↑ = more hab 5. Ø = less Effects of overlearning - “below-zero” habituation this increases long-term retention of habituation 7 6. Stimulus specificity – amount of generalization depends on similarity of stimuli 7. Restoration of habituated response by changing the nature of the eliciting stimulus – “dishabituation SENSITIZATION 1. Amount and duration of sensitization are directly related to stimulus intensity. 2. Sensitization decays spontaneously 3. Repeated presentations of a sensitization stimulus results in progressively less sensitization 4. Response sensitization will exhibit generalization. 5. Sensitization occurs in state systems, not S-R pathways. 6 Dishabituation is a special instance of sensitization. Dual Process Theory - neural processes are hypothesized to underlie habituation & sensitization. response decrement = habituation process response increment = sensitization process 8 - a stimulus activates both processes at once – the behavior we see is the sum of the two processes. these processes occur in different parts of the nervous system habituation in the S-R system which is the shortest neural path connecting stimulus and response sensitization in the state system which governs responsiveness, arousal In many cases a stimulus first elicits sensitization then habituation 9 Rat startle response (Davis ’74) - with 60db little state arousal, so predominantly habituation - with loud background noise opposite occurs. The assumption is that this increased arousal via the state system and so increased responsiveness. Sucking reflex (Lipsitt & Kaye 1965) - _” tubing produces a decrement in responding - tube influences only S-R system, = habituation - nipple is a more powerful stimulus – elicits more vigorous sucking even at the beginning – assume nipple also activates state system = sensitization 10 Simple systems approach is to use invertebrate with smaller, more tractable nervous system. Late ‘60’s early 70’s Eric Kandel (Nobel Prize 2000) chose Aplysia californica to study how neurons change when learning occurs. Habituation is a decrease in response magnitude as a result of repeated stimulation. Dishabituation is the facilitation of a decremented response. Sensitization is the facilitation of a non-decremented response. Originally thought to be the same process, later controversial. 11 Aplysia has about 20,000 neurons, many are quite large. Identified neurons means that the same cell is in the same location and has the same function in all members of the species. This allows researchers to carry out many different types of experiments. 12 The gill withdrawal response shows habituation following repeated stimulation as well as spontaneous recovery following a rest. If a shock is delivered to the neck or tail of the animal we see dishabituation (here incorrectly called sensitization). 13 The neural circuit for the siphon withdrawal reflex. 14 After showing habituation and dishabituation of the behaviour Kandel and colleagues investigated the neural basis of these behaviours. The connections between the siphon sensory neurons and the gill motor neurons also showed plasticity. 15 Kandel’s research showed that the mechanism of shortterm sensitization involved changing the action potential in the sensory neuron so that more neurotransmitter was released onto the motor neuron. 16 This was the first mechanism of learning to be described. This showed that learning could be studied and understood at a cellular level. 17 In addition to short-term changes in behaviour that lasted minutes to hours, Aplysia could also show long–term changes or memory that lasted hours to weeks. Like humans this memory was best produced by spaced training. 18 Long-term memory was represented by changes in the anatomy of the connections between sensory neurons and motor neurons. When behaviour decreased, synaptic strength decreased- when behaviour increased so did synaptic strength. This was the first demonstration of a morphological basis of memory. 19 Dishabituation does not equal sensitization! 1) development (dishab first), 2) best stimulus (dishab weak, sens strong), 3) time of onset after shock (dishab –seconds; sens- 20-30 min) and 4) spike broadening (sens not dishab). 20 C. elegans was chosen by Sidney Brenner (Nobel Prize 2002) in the late 60’s as an organism in which to study how genes produce an organisms (development) and how they regulate behaviour. With only 302 neurons every neuron in the worm is an identified neuron. With the genome sequenced and the many genetic tools available C. elegans is an ideal organisms to investigate how genes regulate behavioural plasticity. 21 22 23 24 Studies with C. elegans mutants have shown that the amount of neurotransmitter available presynaptically in the sensory neurons together with the rate of stimulation produce the rate of decrement of the tap response (eat-4 worms with lower levels of neurotransmitter habituate more rapidly at both short and long ISIs). In C. elegans long-term habituation is the result of a down-regulation of glutamate receptors on the interneurons of the tap withdrawal circuit. Interestingly, there was no change in the number of vesicles in the presynaptic sensory neurons. This appears to not be consistent with the data from Aplysia- however in the experiment with Aplysia they over-trained their animalswhen we over-trained C. elegans we did see decreases in presynaptic vesicles. This suggests that post-synaptic receptors change more rapidly and with a lower amount of experience than presynaptic vesicles. ...
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