Transcript a memory - Human Kinetics

Lecture 18:
Memory
"Dualism"
MIND
BODY
"Reductionism"
BODY SUBSTRATE
MIND
"Complex Systems"
BODY SUBSTRATE
MIND
"Neodualism"
BODY
SUBSTRATE MIND
Memories
 Memory 1: a lasting consequence of an
event (a broken glass)
 Memory 2: a trace of an event that needs
recovery with a key (a recollection about a
broken glass)
Hysteresis
Stim
F, L
F
Curve 1
Curve 2
L
An isolated muscle is being
stimulated at a constant rate
and strength. Muscle force
will depend on muscle length.
During slow stretching and
slow shortening, the muscle
will display different
dependences F(L). This
behavior is called hysteresis.
Memories
Declarative (explicit)
Facts and events
Hippocampus,
medial temporal lobe,
diencephalon
Nondeclarative (implicit)
Nonassociative
Associative
Reflexes
Amygdala,
cerebellum,
BG,
cortex
Skills, habits
Memory
 Habituation: learning not to respond to a
stimulus following its multiple presentations
(usually, when it is not very meaningful)
 Sensitization: learning to respond to smaller
magnitudes of a stimulus (usually, if it is very
meaningful)
Skill
 A motor program? Can it be applied
to different effectors?
 Are there control functions stored in
the brain? In what variables?
 A reflex?
 Perception-action coupling? How
different is it from a reflex?
Learning Mirror Writing
Three Stages
 Encoding: putting an event into an internal code
 Storage: maintaining the code over time
 Retrieval: using a key (intrinsic or extrinsic) to
recover the code/event
Short-Term Memory
 Encoding: typically an acoustic, visual, or
somatosensory code
 Storage: limited capacity (7 ± 2 “pieces”); decay;
followed by consolidation or loss of memory
A Reverberating Circuit
In
Out
The activity in this simple reverberating circuit will
persist until some crucial substances are depleted.
Open circles show excitatory synapses.
Consolidation of Memory
Input
Receptor
Long-term
memory
Central
processing
Consolidation
Short-term
memory
Effector
Output
Processing a sensory
stimulus may lead to
creating a short-term
memory trace in parallel
with producing an
effector (motor) output.
Short-term memory can
be consolidated into
long-term memory.
Conditioning
 Classical conditioning: associating a response
with a stimulus based on repetitive presentations
(e.g., ringing a bell is associated with getting
food); the animal has no initiative
 Operant conditioning: searching for an action
that leads to a desired consequence; active
exploration. Even monosynaptic reflexes can
show it (as demonstrated by Jon Wolpaw)!
Conditioning
 Classical conditioning: Pavlov’s experiments
 The theory of conditioned reflexes starting from
inborn reflexes
 Towers of silence
Holography
Key beam
A
Photo
plate
Object
Key beam
B
Image
Object
beam
Holography creates an image
(a memory) of an object on a
photographic plate with the
help of two light beams: the
object beam and the key beam
(A). One plate can store a
number of images using
different key beams. If the
plate is illuminated by a key
beam, an image of the
corresponding object will
emerge (B).
Synapses as the Site for Memory
Pro:
 There are phenomena of LTP and LTD (cerebellum,
hippocampus)
 Where else?
Contra:
 Repetition without repetition
 “Disposable synapses”
 Lashley: Each neuron takes part in many memories; each
memory is represented all over
 LTP: too short, mostly animal studies
 Importance of whole-brain (emotion) mechanisms
 Eccles: use and disuse of synapses, spinal memory
 Spinal memory experiments
Spinal Memory Experiments
 Stage 1: extirpation of half of the cerebellum. This
leads to asymmetrical monosynaptic reflexes.
 Stage 2: spinalization. If enough time elapses
between the two surgeries, the asymmetry persists.
If not, it disappears.
 Cooling experiments: MSRs appear, followed by
their asymmetry.
Questions Without Answers
 Which of the external events are being remembered?
 Which of the brain processes that accompany the events
are being fixed in memory?
 Can all or only some of the neural elements fix memories?
 What are the neural substrates of STM and LTM, and
what are the mechanisms of exchange between them?
 What happens in memory disorders? What is affected—
whole-brain mechanisms, storage, attention, classification,
retrieval, etc.?
Memory Disorders: Amnesia
Amnesia is a partial loss of memory.
 Causes: brain injury, stroke, encephalitis,
electric shock, etc.
 Anterograde: affects the ability to recollect
events that occurred after an injury
 Retrograde: affects the ability to recollect
events that occurred prior to an injury
Memory Disorders
Korsakoff’s syndrome:
 Chronic alcohol abuse
 Defective retrieval
 Partial cues or prompts help
Alzheimer’s:
 Motor skills are not affected
 Priming experiments show major defects