Chapter 13 http://web.bvu.edu/faculty/ferguson/Course_Material/2011_Courses/Bio...

Syllabus pdf file Course Schedule

Some Basics From Psyc 100

Memory = the ability to retain information over a period of time (central to our individual sense of self)

Some examples:

Without looking back, what was the first word in this sentence? Who was the last person you talked with before coming into this classroom? What did you have for dinner last night? Where did you eat? With whom? In high school, who taught your freshman English course? What was the name of the school where you attended first grade?

Important terms:

Encoding Retrieval Short term/working memory Long term Capacity Consolidation Autobiographical memory

Why memory is important: Check out this video before coming to class.

Some more terms:

Classical Conditioning = Learning to associate two stimuli with each other (or, learning that one stimulus predicts another)

Some examples:

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bell – food – salivation light – puff of air in eye – blink see a dog – attack by dog – fear the name ‘Aaron’ – Aaron bullies you – fear/anger

Important terms:

Unconditioned stimulus Unconditioned response Conditioned stimulus Conditioned response Generalization Discrimination Extinction

Operant Conditioning = learning to alter behavior as a result of its consequences

Some examples:

rat presses lever – gets food you raise your hand in class – instructor stops and helps you you say hello to the person next door – they ignore you and walk on by child throws a tantrum – parents ignore child till tantrum is over you ask a person to go out to dinner w/ you – they laugh and say ‘never in a million years’ child brings home a good math grade – parents remove grounding

Important terms:

Positive reinforcement Negative reinforcement Punishment Extinction Generalization Discrimination

Brain Processes: Lashley & Thompson

Questions about how/where memories are stored in the brain are not new. How did Karl Lashley investigate this issue and what did he find? What were his twin concepts of equipotentiality and mass action? How do they stand up today? R.F. Thompson conducted a series of elegant experiments to identify the location of learning in a simple eyeblink conditioning task. What did he do and what did he find?

Declarative (Explicit) Memory & The Medial

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Some early data from human patients

Profound anterograde amnesia for of people, places, events and objects. Severe problems w/ Digit Span +1 tasks, both verbal and motor Much better performance, though no recall of prior trials: Mirror drawing Incomplete pictures Pursuit rotor Eyeblink conditioning

Later studies of other MTL patients (Clive Wearing, etc)

Relatively unimparied repetition priming performance (w/o awareness) Large deficits of declarative memory, with episodic worse than semantic (Schachter's amnesic golfer)

An important question:

What do all these findings suggest about the role of the MTL in the various types of memory diagrammed at the top of this page?

Some more recent data:

Early attempts to develop an animal model of hippocampal amnesia failed for two reasons: most research initially used operant or classical conditioning. (Why was that a problem???) failure to distinguish between Rhinal Cortex and ...both were typically destroyed in the early animal studies. Later hippocampal lesion research using delayed response tasks and other declarative/episodic memory tests showed significant deficits. Hippocampal lesions also produce deficits in radial arm and water mazes, which require declarative/spatial memory. Rhinal cortex lesions produce significant deficits in memory tasks involving object recognition

Summary:

Hippocampus is essential to normal functioning of declarative memory, especially episodic. spatial memory may also be implicated in memory consolidation (see graded retrograde amnesia) Rhinal cortex is important for remembering familiar objects

Before finishing this section, let's look at the possibility of a 'super memory'. (Thanks Alex)

Also, what's going on during the creation of false memories? (Thanks Bridgett)

It's well known that memory impairment is one of the early indicators of dementia. From Ayana, here's a

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look at some current research (note...see if you can spot the error of logic in this video)

Finally, how about the relationship between stress and memory? (Thanks Gladiola)

Working Memory, Executive Functions and The Prefrontal Cortex

In the introduction to a 2006 article in the Journal of the International Neuropsychological Society, Mark D’Esposito and coleagues noted that:

Working memory refers to the temporary representation of information that was just experienced or just retrieved from long-term memory but is no longer accessible in the external environment (Baddeley, 1986). These internal representations

are short-lived, but they can be maintained for longer periods of time through active rehearsal or maintenance strategies, and can be subjected to various operations that manipulate the information such that it becomes useful for goal-directed behavior. Working memory is a system that is critically important in cognition and seems necessary in the course of performing many other cognitive functions such as reasoning, language comprehension, planning, and spatial processing.

Clearly, working memory is more than just a passive storehouse for recent information...it also involves a complex set of executive functions needed to monitor, manipulate and evaluate that information. The prefrontal cortex (PFC) receives highly processed information from all sensory areas as well as emotional and memory areas. In other words, the PFC has an overview of everything that's currently happening in the individual's environment, plus memories and emotions related to those events. It is therefore in a perfect position to serve as the brain's executive processor and to perform the functions of working memory. As a result, the relationship between working memory and the PFC has been closely studied, primarily via the delayed response task. For example:

Funahashi et al (1989) recorded from individual cells in the PFC and found that activity in individual cells continued throughout the delay interval on trials when the correct response was made, while disruptions to the activity during the delay occurred on trials where the animals made an error. Pascual-Leone and Hallett (1994) found that using magnetic stimulation to disrupt PFC activity during the delay increased response errors. D'Esposito et al (2006) used fMRI imaging and the delayed response task to study human stroke victims who had unilateral damage to the PFC. Their data suggested that working memory processes (e.g., rehearsal) occur in both hemispheres of the PFC and that damage in one hemisphere could be overcome by activity in the other.

Where Are Memories Stored?

The short answer is that we don't know. However, this question is the focus of much recent research and a few general principles seem to be emerging:

1. Memories are stored difusely in the brain, not in a single location. 2. The memory of a particular experience appears to be stored in the brain structures that participated in processing the original experience. For example, your memory of a simple conversation with a friend would presumably include storage in: the inferotemporal cortex (who were you talking to and what objects were present) the parietal cortex (where the friend and all the objects were located) the primary auditory cortex of the temporal lobe (sound of your friend's voice and other noises that were present) the basal ganglia and/or primary motor cortex (movements you made during the conversation) etc. 3. Brain regions that are needed for a particular memory function to occur (e.g., the hippocampus is essential for normal episodic memory) don't necessarily store the memories themselves.

The Multiple Trace theory of memory storage:

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The main features of the multiple trace theory:

1. Memories are encoded in hippocampal–cortical networksTraces in the cortex are context-free (or semantic) in nature 2. Traces in the hippocampus provide spatial and temporal context 3. Retrieval of contextually rich episodic memories always depends on hippocampal–cortical networks 4. Retrieval of remote semantic memories is possible in the absence of a functional hippocampus

An interesting question: if the memory traces for an event in my past are stored in many different locations, how are they all knit together to form a single memory? This is called the binding problem.

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