Long-term Memory and the Amnesias

divisions of LTM

declarative and non-declarative

Declarative Memory

explicit - knowledge that can be consciously remembered -the what, why, where and when. e.g., facts, events, personal experiences. Hippocampal-dependent

Non-declarative Memory

implicit - knowledge implicitly expressed as a change in behavior rather than as conscious remembering. - knowing how e.g. motor skills, habits (driving to work without thinking) and cognitive skills. non-hippocampal dependent

Episodic Memory

Memory of events in our own personal past - retrieval of info regarding the spatial and temporal context events occurred = mental time travel to recover contextualised details about event

Semantic Memory

general knowledge about things in the world and their meaning includes facts, concepts and their interrelations = not bound by context

Procedural memory

Learning and performance of motor and cognitive skills

Priming

Demonstrated by a change in the ability to identify a stimulus as the result of prior exposure to that stimulus, or a related stimulus.

e.g. in lexical decision task where tasked to respond to and distinguish words from non-words showing doctor causes faster response to related words like nurse

Classical conditioning

associative learning - learns association between initially NS and a UCS and its UCR so NS becomes CS and produces CR on its own

Operant conditioning

associative learning - Learning to produce/avoid a behaviour because it has become associated with rewarding/punishing consequences

non-associative learning

• habituation - Learning to ignore a stimulus because it is trivial

• sensitisation - learning to attend to a potentially threatening stimulus

Amnesia

Deficits in memory caused by brain damage, disease, drug abuse, or psychological trauma.

Retrograde amnesia:

An inability to remember episodes acquired before the brain injury, usually temporally graded. Most cases only memories most recently acquired before amnesia are affected with more distant memories unaffected

Anterograde amnesia:

An inability to recall any declarative knowledge experienced after the time of the brain injury - includes semantic and episodic info = no new LTMs

what does amnesia tell us about declarative and non-declarative

Indicates that procedural learning can proceed independently of the brain systems required for declarative memories.

divisions of declarative memory

episodic and semantic (medial temporal lobes)

divisions of non-declarative

• priming = cortex

• procedural = striatum

• associative learning (conditioning) = cerebellum (skeletal musculature) and amygdala (emotional)

• non-associative learning = reflex pathways

H.M case study

• accident at 9 = seizures

• 1953 = 29 yrs = surgery that removed medial portion of both temporal lobes including both hippocampi

• dense anterograde amnesia = no new LTM or retain new semantic info

• temporally graded retrograde = the closer the memory to before the surgery more likely to forget

• normal sensory and STM

• still able to form new procedural memories

• = medial temporal lobes critical for consolidation of LTM to cortex

role of hippocampus

crucial for consolidation of new declarative information aiding in formation and retrieval of LTM.

mirror tracing task

procedural memory task - double-outlined star and have to draw 3rd outline while looking in a mirror

• H.M’s performance improved each day = declarative and non-declarative (spec. procedural) LTM can be distinguished in amnesia