Ch. 17: Learning & Memory

Learning

the process of acquiring new and relatively enduring information, behavior patterns, or abilities, characterized by modifications of behavior as a result of practice, study, or experience

• the process of acquiring new information

Memory

1. the ability to retain information, based on the metal process of learning or encoding, retention across some interval of time, and retrieval or reactivation of the information

• aka. the ability to store and retrieve information

2. the specific information that’s stored in the brain

Long-term Memory

• “archive” of information about past events and knowledge learned

• works closely with working memory

• storage stretches from a few moments ago to as far back as one can remember

• more recent memories are more detailed

• Neuropsychology:

  • the hippocampus is responsible for one’s ability to encode new long-term memories

  • H.M.: surgery for epilepsy

Patient H.M.

a person who, because of damage to medial temporal lobe structure, was unable to encode new declarative memories

• Henry Molaison

  • in 1953, a 29y.o. man suffered from uncontrollable epilepsy

  • underwent experimental surgery: bilaterally removed hippocampus and other parts of medial temporal lobe

  • epilepsy was cured and he recovered

  • side effects:

    • unable to form new explicit long term memories

    • has normal STM, working memory

    • excellent recall for his youth

      • retrograde amnesia - 11 years

  • deficit: information transfer from STM to LTM

  • as he got older:

    • thought he was a young man (17-11)

    • thought that it was the 50’s or 60’s

    • couldn’t recall that his parents had died

    • recognized faces from the 40’s and 50’s, and not more recent

  • could hold items in working memory until distracted and then it was gone

Amnesia

severe impairment of memory

Retrograde Amnesia

difficulty in retrieving memories formed before the onset of amnesia

Hippocampus

a medial temporal lobe structure important for learning, memory, and spatial navigation

Declarative Memory

a memory that can be stated or described

Non-declarative/Procedural Memory

a memory that’s shown by performance rather than by conscious recollection

Korsakoff’s Syndrome

a memory disorder, related to a thiamine deficiency, that’s generally associated w/chronic alcoholism

Episodic Memory

memory of a particular incident or a particular time and place

Semantic Memory

generalized memory; for instance, knowing the meaning of a word without knowing where or when you learned that word

Amnesia & Tetris

• study of sleep of Tetris ability included amnesics Stickgold et al.

  • woken up in the middle of the night

  • were asked to report their dreams

• most participants reported Tetris dreams

  • 9 out of 12 healthy controls

  • 3 out of 5 amnesic patients

  • “images that are turned on their side. I don’t know whay they’re from. I wish I could remember, but they are like blocks.”

Delayed Non-Matching-to-Sample Task

a test in which, on each trial, the participant must se;lect the stimulus that wasn’t seen previously

• aminal model of declarative memory

• hippocampal damage severely impairs this task

Patient K.C.

a person who sustained damage to the cortex that rendered him unable to retrieve autobiographical memories

• Kent Cochran

  • had episodic memory deficits

    • both anterograde (like HM) and retrograde

    • anterograde, like HM, likely due to damage to hippocampus + retrograde likely due to damage cerebral cortex

    • semantic memory was intact

Subtypes of Non-Declarative Memory

• skill learning

• priming

• associative learning

Skill Learning

learning to perform a task that requires motor coordination

Priming (Repetition Priming)

the phenomenon by which exposure to a stimulus faciliates subsequent responses to the same or a similar stimulus

• exposure to a stimulus facilitates subsequent responses to the same or similar stimulus

Associative Learning

a type of learning in which an association is formed between two stimuli or between a stimulus and a response

• it includes both classical and operant conditioning

• the association of 2 stimuli or of a stimulus and a response

Operant/Instrumental Conditioning

a form of associative learning in which the likelihood that an act (instrumental response) will be performed depends on the consequences (reinforcing stimuli) that follow it

• lab animals easily learn to press a lever to gain the reward of a food pellet in a Skinner box

Classical/Pavlovian Conditioning

a type of associative learning in which an originally neutral (conditioned) stimulus acquires he power to elicit the response normally elicited by another (unconditioned) stimulus after the 2 stimuli are paired

• Unconditioned Reponse (UR): a reponse elicited by the unconditioned stimulus (US)

• Conditioned Response (CR): a reponse elicited by the conditioned stimulus (CS)

• an initally neutral stimulus comes to predict an event

3 Stages to Create & Store Memories

1. Encoding: sensory information is passed into short-term memory

2. Consolidation: short-term memory transferred to long-term storage

3. Retrieval: stored information is used

Consolidation

• permanent storage of information tends to occur in regions where it was first processed

• retrieval from LTM (long-term memory)

  • retrieving information can strengthen memory trace

  • retrieving information can alter memory trace

Neurons that fire together, wire together - Donald Hebb (1948)

• high frequency stimulation (tetanus) led to increased EPSP slope

• in other words the same stimulation is more likely to create an action potential

• for the first time showed that learning and memory occurs the synapse

Cognitive Map

a mental representation of a spatial relationship

Short-Term Memory (STM)

a form of memory that usually lasts only for seconds, or as long as rehearsal continues, especially while being used during performance of a task

Working Memory

a tupe of short-term memory that holds a limited amount of information available for ready access during performance of a task

Prefrontal Cortex

the most anterior portion of the frontal lobe

Intermediate-Term Memory

a form of memory that lasts longer than short-term memory but not as long as long-term memory

Long-term Memory (LTM)

an enduring form of memory that lasts days, weeks, months, or years and has a very large capacity

Encoding

a stage of memory formation in which the information entering sensory channels is passed into short-term memory

• sensory information is passed into short-term memory

Consolidation

a stage of memory formation in which information in short-term or intermediate-term memory is transferred to long-term memory

• short-term memory transferred to long-term storage

Retrieval

a process in memory during which a stored memory is used by an organism

• stored information is used

• retrieval from LTM (long-term memory)

  • retrieving information can strengthen memory trace

  • retrieving information can alter memory trace

Reconsolidation

the process by which a retrieved memory may be strengthened or altered before being returned to LTM

Posttraumatic Stress Disorder (PTSD)

a disorder in whcih memories of an unpleasent episode repeatedly plague the victim

Neuroplasticity

the ability of the nervous system to change in response to experience of the environment

• ability of neurons and neural circuits to be remodeled by events

  • synaptic activity can also be modulated by inputs from other neurons

  • can occur due to increased neurotransmitter release

  • greater effect due to changes in neurotransmitter-receptor interactions

Glutamate

NMDA receptors act as “coincidence detectors”, for instance, spatial summation

GABA

• important for pruning connections during development

• connections that aren’t often active are removed

Structural Changes Due to Learning

• lab animals living in a complex environment show biochemical and anatomical changes in the brain

• experiments used 3 housing conditions:

  • Standard Condition

  • Impoverished Condition

  • Enriched Condition

• a variety of plastic changes in the brain are linked to environmental enrichment

• animals housed in EC, compared to those in IC, have:

  • heavier, thicker cortexes; enhanced cholinergic activity; cortical neurons with more dendritic branches, especially basal dendrites

Standard Condition (SC)

the usual enviornment for laboratory rodents, with a few animals in a cage and adequate food and water. ut no complex stimulation

Impoverished Condition (IC)

a condition in which laboratory rodents are housed singly in a small cage without complex stimuli

Enriched Condition (EC)

a condition in which laboratory rodents are group-housed with a wide variety of stimulus objects

Nonassociate Learning

a type of learning in which presentation of particular stimulus alters the strength or probability of a response according to the strength and temporal spacing of that stimulus

• includes habituation and sensitization

Habituation

a form of non-associative learning in which an organism becomes less responsive following repeated presentations of a stimulus

Sensitization

a form of nonassociative learning in which an organism becomes more responsive to most stimuli after being exposed to unusually strong or painful stimulation