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Lecture

Kinesiology 3480A/B Lecture Notes - Brenda Milner, Temporal Lobe, Neurosurgery


Department
Kinesiology
Course Code
Kinesiology 3480A/B
Professor
Matthew Heath

Page:
of 4
Topic #5: Memory Systems
talking about memory in 2 different contexts:
o memories that are EXPLICIT in nature
cognitive detail; semantic (general factual knowledge) or episodic
(memories that are personally relevant to you) info
tend to involve high level cortical structures
in order to access these memories you have to be consciously aware
of them, or else they will not exist (have to be consciously interpreted)
formation through linkages between the temporal lobe and the
hippocampus; work in conjunction with one another to form explicit
memories
o IMPLICIT memories
don’t have to have conscious access to them; we can access them
without top-down conscious awareness
tend to be motor related, more often than not
e.g., tying shoelace requires minimal top-down conscious awareness
thought to be retained subcortically, particularly in the cerebellum
(responsible for storing these memories)
there is a continuum of memories
o not necessarily that any given memory is purely implicit or purely explicit
motor learning/how you learn a new task can prove this
thought that when you learn a new motor task, you progress through 3
distinct stages of learning - cognitive stage, associative stage, and
autonomous stage
cognitive stage is more explicit; autonomous is more implicit - use for
continuum
cognitive: completely conscious of what you are doing; make a lot of
mistakes but do not know how to correct them
associative: nexus between cognitive and autonomous; require less
top-down cognitive involvement; become highly aware of the fact that
you are making mistakes, but not necessarily sure how to correct
those mistakes; still under conscious system
autonomous: no top-down conscious involvement in the task,
essentially; make very few if any errors; if you make an error you are
able to correct that error; able to make these error corrections without
being aware that you made an error in the first place; happen very fast
because they are mediated without this top-down control
o imaging studies that have shown the validity of this 3-stage model; paul fitz
model of learning
studies have shown a shift from high-level cortical structures as
someone learns a motor task, to more basic structures residing in
cerebellum
memory can be divided into various subsystems: STSS, STM (aka working
memory), and LTM
implicit and explicit memories mentioned above are long-term memories (LTM)
Clive:
- Bilateral hippocampi lesions as a result of viral encephalitis
- Large temporal and frontal structures lesions on left side (spared on the right side)
- Mostly intact on right side
- demonstrates the inability to produce new episodic or semantic memories (explicit)
- HE was a musician still able to learn some musical...
o Sparing of frontal and temp structures in right brain
o Musical things lateralized to right side
- Cerebellum intact can formulate new implicit memories
- Most profound amnesia, most intense form
- HM (classic amnesic patient):
o Intractable epilepsy as child and young adult, profound (multiple seizures a
day)
o Mid 20s neurosurgeon wanted to do surgery on him to relieve his epilepsy
§ Wanted to remove fragments what we know now as bilateral
hippocampus
§ Successful not nearly as many seizures
§ BUT could not formulate new explicit memories as a result of this
surgery (could not remember names, faces)
§ Has a dense form of amnesia
o Around same time when epileptic brain was being mapped
o Brenda Milner
§ Canadian
§ Wanted to see if we can dissociate diff memory types
§ Used a 5-point star mirror tracing task difficult task
§ HM could perform the task perfectly after 3 days he had learned the
task; could still do it months later; lead to dissociation of explicit and
implicit memories, and where in the CNS these memories are stored
§ High degree of involvement of cerebellum and frontal motor areas,
which are involved in maintaining long-term implicit memories huge
discovery
- ultimate goal is to get info into long-term memory store
1. STSS a. Most basic of all memory systems (low level sensory processing, in V1,
auditory cortex, etc.)
b. How can we determine the existence of a STSS? Sperling 1960
c. Info gains access into system and hopefully maps onto something
meaningful so that it can be used
d. Brief presentation of matrix of letter/numbers, very fast (20-50ms)
i. Found they cannot recall anything, no level of recall accuracy
ii. Using whole report technique recalling any or all info in the
matrix
e. 1959 Sperling
i. STSS is so short term that by the time someone is retrieving info
from it, it is lost
ii. Partial repost technique same matrix of numbers flashed, but
they are provided with a cue for which row to recall (pyramid) used
diff tones
iii. Found there was 100% recall accuracy when the cue was
presented concurrently with the matrix of letters evidence of a short
term memory store
iv. Temp offset of matrix and cue??
Graph (~15 min.)
- Red vertical line when tone and matrix came on at same time
- Flash of matrix then delay and tone for which row to recall at diff delay intervals to see
how long info can reliably persist in STSS
o 300 ms around 50%
o Can reliably persist in STSS for up to 300 ms
Veridical nature associated with STSS
- True representation of visual world, very accurate = veridical
- Exists on a moment to moment basis
- Any new info that comes into system will erase previously contained info in STSS
- Thought to have an unlimited capacity
- Simple partial report technique found 0% recall accuracy
o Ellipse occupying same space as previous stimulus, so it erases the info of the
previous stimuli
- STSS is a pre-categorical memory system
o Demonstrated in matrix experiment as well
o Sperling’s original technique can be modified
§ Low tone to recall letters, high tone to recall numbers presented
afterwards
§ Found 0% recall accuracy
o STSS does not know if dealing with letters or numbers therefore pre-
categorical
o In order to attach a representation to stimulus it has to be identified as imp to
the STSS
§ Becomes short term/working memory
4 defining characteristics of STSS:
- Veridical, pre-categorical, large and reliably retains info for 300 ms
2. Short term Memory (STM)
- Aka working memory system
- Categorical
o Have to be aware of info, conscious memory system
- Very limited capacity
o 7 +/- 2 bits of info (discovered by George Miller, telephone numbers)
- Relatively brief duration
- Not veridical
o Not precise, how you make things up
- Info can persist for an infinite amount of time in STM
o Have to attend to it for it to persist (e.g., someone’s name)
o Active attentional process to maintain