PSYC2100 Mind, Brain & Behaviour Week 2 Lecture 1 PDF

1 PSYC2100 Mind, Brain &  Behaviour Dr. Hui YU ([email protected]) Week 2 Lecture 1 Learning & Memory PART 1  2 Learning &...

1 PSYC2100 Mind, Brain &  Behaviour Dr. Hui YU ([email protected]) Week 2 Lecture 1 Learning & Memory PART 1  2 Learning & Memory Brain Plasticit y Case studies Searchin & g the Animal engram studies  Brain Plasticity Thinking “brain plasticity” as the thread to link these topics together  3 Brain plasticity overview  A concept that had been overlooked for a long time.  Does brain work like a machine with parts?  Learning focus of this module: Brain and behaviour  Different levels of brain plasticity  Macro: changes in behaviour  Micro: changes in DNA activation, in protein synthesis, in neural connection.  4 For all humans and animals, everything they can do tomorrow that they cannot do today, is accounted for by the changes in the brain.  Learning and Memory  5 Learning & Memory  Two interrelated topics  Learning requires “storing information” into memory  Definition  Kolb & Wishaw (your textbook)  Learning: relatively permanent change in behavior that results from experience.  Memory: the ability to recall or recognize previous experience.  Okano, Hirano, & Balaban (2000)  Memory: behavioral change caused by an experience  Learning: a process for acquiring memory  6 Two types of learning  Two types of learning  Non-associative learning  Habituation  Sensitization  Associative learning  Classic conditioning  Operant conditioning  7 Non-associative Learning  Simplest type of “learning”  Changes in behavior produced by simple exposure to a stimulus  change in the strength of response to a stimulus due to repeated exposure to that stimulus  8 Types of Non-associative Learning  Habituation Learning behavior in which a response to a stimulus weakens with repeated stimulus presentations.  Sensitization Learning behavior in which the response to a stimulus strengthens with repeated presentations of that stimulus  An example of habituation & sensitization  9 Recap: Chemical Synapse  How Is Non-associative Learning Studied  Eric Kandel was awarded a Nobel Prize in 2000 for his descriptions of the synaptic basis of learning using Aplysia  Used enduring changes in simple defensive behaviors to study underlying changes in the snail’s nervous system  11 Habituation Learning behvior in which a response to a stimulus weakens with repeated stimulus presentations Depends upon a change in the synapse between the sensory neuron and the motor neuron; Sensory neurons fail to excite motor neurons as they did previously (it is not that the motor neurons become less able to respond).  12 Habituation Calcium Channels “Habituate”: As habituation takes place, Ca2+ influx decreases in response to voltage changes associated with an action potential Reduced sensitivity of Ca2+ channels and decreased release of neurotransmitter The excitatory postsynaptic potentials in the motor neuron become smaller Motor neuron is receiving less neurotransmitter from the sensory neuron across the synapse  13 Habituation  Specificity  Specific to the stimulus presented; a different stimulus will NOT produce a habituated response  Spontaneous recovery  When stimulation ends, behaviour recovers  14 Sensitization Learning behavior in which the response to a stimulus strengthens because the stimulus is novel or stronger than normal Occurs due to strong/painful stimulation (occurs within a context) Can occur with a single painful stimulation  15 Sensitization Potassium Channels “Sensitize”: As sensitization takes place, serotonin released from a facilitating neuron blocks potassium channels in the presynaptic neuron K+ ions cannot repolarize the membrane quickly, so action potential lasts longer than normal Prolongs the inflow of Ca2+ and more transmitter is released  Sensitisation in Aplysia DAN activation Protein synthesis Neural connection  17 Sensitization  Repetition  More noxious (painful) stimulation, more sensitization  Stimulus intensity  Stronger stimulus, more sensitization  18 Associative Learning  Encyclopedia Britannica  Associative learning in animal behaviour, any learning process in which a new response becomes associated with a particular stimulus.  In its broadest sense, the term has been used to describe virtually all learning except simple habituation. In a more restricted sense, it has been limited to learning that occurs through classical and instrumental conditioning  19 Classical Conditioning  20 You Have Learnt It  US  UR  Pairing CS with US  CS  CR  Dog, food, salivation, a ring of bell  21 Name All Components US, _______________ CS, _______________ UR, _______________ CR, _______________  22 Classical conditioning & biology  The speed of conditioning depends on a number of factors, such as the nature and strength of both the CS and the US, previous experience and the animal's motivational state  Example: Selective conditioning (saccharin aversion)  If rats made ill following consumption of saccharin solution they will drink water in preference to saccharin  Saccharin aversion not found if a shock rather than illness is used as a reinforcer  Conditioning sensitive to the causal relevance of the CS and the reinforcer  23 New Knowledge to Learn  Stimulus Substitution Theory According to Pavlov, conditioning does not involve the acquisition of any new behavior, but rather the tendency to respond in old ways to new stimuli. Thus, he theorized  24 Karl Lashley’s Search of the Engram  25 Karl Lashley’s Search of the Engram  IF learning depends on new or strengthened connections between two brain areas, then ______________________.  Lashley trained rats on maze running and a variety of other tasks such as a brightness discrimination task.  26 Karl Lashley’s Search of the Engram  27 Lashley Failed…  Lashley proposed two key principles about the nervous system (based on his search result):  Equipotentiality – all parts of the cortex contribute equally to complex functioning behaviours (e.g. learning)  Mass action – the cortex works as a whole, not as solitary isolated units.  Alternative interpretation of Lashley’s result? Is the cerebral cortex the best or only place to search for an engram?  28 If one brain structure to be linked to MEMORY WHAT’S YOUR ANSWER?  29 Function of The Hippocampus (Theories)  How to study memories in relationship with a particular brain area?  Case study  Animal model  However, how could we test the following hypothesis, for example, with nonhumans or humans with brain damage, who cannot “declare” any memory?  Hypothesis:  Hippocampus is critical for declarative memory.  30 Recap: Long-Term Memory  31 Function of The Hippocampus (Theories)  Research in the role of the hippocampus in episodic memory shows damage impairs abilities on two types of tasks:  Delayed matching-to-sample tasks – a subject sees an object and must later choose the object that matches.  Delayed non-matching-to-sample tasks – subject sees an object and must later choose the object that is different than the sample.  32 Clever Design  33 Function of The Hippocampus (Theories)  Research of the function of the hippocampus suggests the following:  The hippocampus is critical for declarative memory functioning (especially episodic).  The hippocampus is especially important for spatial memory.  The hippocampus is especially important for contextual memory. 34  35 The Morris Water Maze  36 Hippocampus and Nevigation  Hippocampal lesions produce specific deficit in the ability of rats to nevigate mazes using place cues  Morris et al (1982) – rats with lesions of hippocampus took longer to find hidden platform  Deficit not due to disruption of motor coordination or visual perception 37  38 The London Taxi Driver  MRI scans revealed that the taxi drivers have a larger than average posterior hippocampus and that the longer they had been taxi drivers, the larger their posterior hippocampus (Maguire et al., 2000).  39 Contextual Learning  The hippocampus is important for remembering details and context.  A recent memory, which generally depends on the hippocampus, includes much detail.  As time passes, memory becomes less detailed, less dependent on the hippocampus, and more dependent on the cerebral cortex (Takehara-Nishiuchi & McNaughton, 2008).  We understand this “shift” very poorly.  40 The Basal Ganglia  The basal ganglia is more important for procedural memory.  The basal ganglia damage: Parkinson’s Disease  Will learn under “movement”  They don’t learn “implicit memories” very well.  41 Other Brain Areas  Amygdala associated with fear learning  Parietal lobe associated with piecing information together  Anterior and inferior region of the temporal lobe and semantic memory  semantic dementia (loss of semantic memory)  Prefrontal cortex and learning about rewards and punishments  Basal ganglia, anterior cingulate cortex also involved  42 RECAP: Biological basis of habituation and sensitisation  What is a good example of habituation? How about sensitization?  Habituation Learning behavior in which a response to a stimulus weakens with repeated stimulus presentations.  Sensitization Learning behavior in which the response to a stimulus strengthens with repeated presentations of that stimulus  43 Please note:  There is no need to distinguish simpler VS more complicated forms of “learning”, not from a biological perspective.  The key element: a relatively permanent change in behaviour that is supported by brain plasticity  Actually, there is very little need to distinguish classical VS operant conditioning, or learning VS memory here.  44 RECAP: memory studies  Case studies and animal models bring the most information we know about brain and memory.  BUT, your subjects are unable to tell you about their memories?  Case studies: the subjects normally have lost their memory.  Animal models: the animals won’t be able to tell you they remember or not.  Study design is of crucial importance here.