Chapter 13 Learning and Memory

Types of Memory Psychologists differentiate between learning and memory Hebb (1949) differentiated between two types of memory: Short-term memory: memory of events that have just occurred Long-term memory: memory of events from times further back

Types of Memory (cont’d.) Differences between STM and LTM Short-term memory has a limited capacity; long-term memory does not Short-term memory fades quickly without rehearsal; long-term memories persist Memories from long-term memory can be stimulated with a cue/ hint; retrieval of memories lost from STM do not benefit from the presence of a cue

Types of Memory (cont’d.) Researchers propose all information enters STM where the brain consolidates it into LTM Later research has weakened the distinction between STM and LTM Not all rehearsed short-term memories become long-term memories Time needed for consolidation varies Epinephrine and cortisol enhance consolidation of recent experiences by stimulating amygdala and hippocampus

Types of Memory (cont’d.) Reconsolidated: memory is strengthened again by a process that requires protein synthesis Working memory (WM) Proposed by Baddeley & Hitch as an alternative to short-term memory Emphasis on temporary storage of information to actively attend to it and work on it for a period of time TED talk on WM: https://www.youtube.com/watch?v=UWKvpFZJwcE

Types of Memory (cont’d.) Common test of working memory is the delayed response task Requires responding to something you heard or saw a short while ago Research points to the prefrontal cortex for the storage of this information Brain may use extra calcium to increase readiness to respond to new signals

Types of Memory (cont’d.) Older people often have impairments in working memory Changes in the prefrontal cortex are assumed to be the cause Declining activity of the prefrontal cortex in the elderly is associated with decreasing memory Increased activity in this area indicates compensation for other regions in the brain

The Hippocampus Amnesia is the loss of memory Studies on amnesia help to clarify the distinctions between and among different kinds of memories and their mechanisms Different areas of the hippocampus are active during memory formation and retrieval Damage results in amnesia

The Hippocampus (cont’d.) H.M. is a famous case study in psychology who had his hippocampus removed to prevent epileptic seizures Afterwards, H.M. had great difficulty forming new long-term memories STM or working memory remained intact Suggested that the hippocampus is vital for the formation of new long-term memories Memento: https://www.youtube.com/watch?v=mFV_ULPraJU

The Hippocampus (cont’d.) H.M. showed massive anterograde amnesia after the surgery Two major types of amnesia include: Anterograde amnesia: the loss of the ability to form new memory after the brain damage Retrograde amnesia: the loss of memory events prior to the occurrence of the brain damage

The Hippocampus (cont’d.) H.M. had difficulty with episodic memory and declarative memory Episodic memory: ability to recall single personal events Declarative memory: Memory of facts & events H.M.’s procedural memory remained intact Procedural memory: ability to develop motor skills (remembering or learning how to do things)

The Hippocampus (cont’d.) Patient H.M. also displayed greater “implicit” than “explicit” memory, as most patients with amnesia do Explicit memory (declarative memory): deliberate recall of information that one recognizes as a memory Implicit memory: the influence of recent experience on behavior without realizing one is using memory. Acquired and used unconsciously

The Hippocampus (cont’d.) People with amnesia generally show this pattern: Normal working memory Difficulty forming new declarative memories Some degree of retrograde amnesia Better implicit than explicit memory Nearly intact procedural memory

The Hippocampus (cont’d.) Research of the function of the hippocampus suggests that it is: Critical for declarative memory functioning (especially episodic) Especially important for spatial memory Especially important for contextual learning and binding

The Hippocampus (cont’d.) Damage to the hippocampus also impairs abilities on spatial tasks such as: Radial mazes: a subject must navigate a maze that has eight or more arms with a reinforcer at the end Morris water maze task: a rat must swim through murky water to find a rest platform just underneath the surface

Video: https://www.youtube.com/watch?v=LrCzSIbvSN4

The Hippocampus (cont’d.) Hippocampus may also be important for contextual learning Remembering the detail and context of an event Damage to the hippocampus impairs recent learning more than older learning The more consolidated a memory becomes, the less it depends on the hippocampus

The Basal Ganglia The hippocampus is not responsible for all memory, as gradual learning still takes place Implicit learning or habit learning depends on the basal ganglia The basal ganglia learns a strategy that leads to a correct response and develops a pattern People with Parkinson’s disease have impairments of the basal ganglia and can’t develop implicit memory

The Basal Ganglia (cont’d.) The “weather task” involves both declarative and implicit memory “Normal” people learn it slowly under conditions of extreme distraction, similar to the learning of those with hippocampal damage There is not a strict separation between basal ganglia tasks and hippocampal tasks All tasks activate both areas, and one type of memory can shift to another

Other Types of Amnesia Different kinds of brain damage result in different types of amnesia Two common types of brain damage include: Korsakoff’s syndrome Alzheimer’s disease

Other Types of Amnesia (cont’d.) Korsakoff’s syndrome: brain damage caused by prolonged thiamine (vitamin B1) deficiency Impedes the ability of the brain to metabolize glucose Leads to a loss of or shrinkage of neurons in the brain Often due to chronic alcoholism Symptoms include apathy, confusion, forgetting, and confabulation (taking guesses to fill in gaps in memory)

Other Types of Amnesia (cont’d.) Alzheimer’s disease is associated with a gradually progressive loss of memory (especially declarative memory) often occurring in old age Affects 50% of people over 85 and 5% of people 65-74 Early onset seems to be influenced by genes, but 99% of cases are late onset About half of all patients with late onset have no known relative with the disease

Other Types of Amnesia (cont’d.) The genes controlling early-onset Alzheimer’s disease cause the protein amyloid beta protein to accumulate both inside and outside neurons. The net effect is to damage dendritic spines, decrease synaptic input, and decrease plasticity An abnormal form of the tau protein

Other Types of Amnesia (cont’d.) Accumulation of the amyloid beta and tau proteins results in: Plaques: structures formed from degenerating neurons Tangles: structures formed from degenerating structures within a neuronal body

Other Types of Amnesia (cont’d.) At this point, no known drug is effective for treatment of Alzheimer’s disease, though research on some is underway A common treatment involves enhancing acetylcholine activity, thus increasing arousal Curcumin: an Indian spice that has been shown to inhibit amyloid-beta deposits and phosphate attachment to tau proteins Animal research has been done and human research is just beginning