Week 9 Flashcards
(29 cards)
The content of experience matters to the brain
multiple memory systems
memory researchers believe that
- complete understanding of memory can only be achieved by recognizing that the content of experience is important
- memories are segregated into different brain regions according to their content
what is the multiple memory system perspective?
the idea that memory researchers believe that (1) + (2) - these ideas are the central premise of this perspective
A multiple memory systems: Brenda Miller and the Hippocampus
The multiple memory systems view and the significance of the hippocampus begins with Brenda
Milner’s analysis of patient H.M.
Why did Giulio Cesare Aranzi name this brain region the Hippocampus?
A hippocampus dissected from a human brain (left) and the tropical fish hippocampus or seahorse
(right). The striking similarity in shape is undoubtedly why the Bolognese anatomist Giulio Cesare
Aranzi named this brain region the hippocampus.
Who is Brenda Miller?
- 106 year old Canadian neuroscientist
- pioneer of cognitive neuroscience
- PhD with Dr. Donald Hebb at McGill
- studied dr. Wilder Penfield’s patients (including HM)
- giving talks in her 90s
Henry Molaison: Snapshots of HM’s contributions to the science of memory
Who is Suzanne Corkin?
The Hippocampus and Episodic Memory: HM’s contributions to memory research
- Henry Gustav Molaison (H.M.) is the most famous patient in
the history of memory research. - He suffered profound epilepsy.
- In an attempt to alleviate this problem, a region of the brain
called the medial temporal lobe was bilaterally removed. - This region included the hippocampus, amygdala, and
surrounding cortex. - As a consequence, H.M. became severely amnestic.
HM’s contribution to memory research: not all memory functions were lost
- H.M.’s short-term memory
remained intact, but he could
not convert a short-term
memory into a long-term
episodic memory. - He could acquire new skills,
such as mirror tracing. - Even though his performance
improved, H.M. could not
remember participating in the
tasks.
Milner also reported of HM
- He had a conscience—for example, noting that he could not
fulfill a wish to be a neurosurgeon out of concern that his need
for glasses might lead him to injure patients. - He had insight into and awareness of his own memory
problems—for example, observing that he was unable to
recall even the techniques he used to help him remember
information. - He had a sense of humor, joking often about his situation.
what else was known from the case of HM
- H.M. was not the first patient to display amnesia for certain
types of information. What was unique was that the
location of his brain damage was known. - This meant that specific regions of the brain may be critical
to memory and, for the first time, researchers had a
testable hypothesis about just what regions were critical. - That his intellectual capacities were intact also meant that
memory functions could be separated from other cognitive
abilities. - That H.M.’s anterograde and retrograde amnesia was
restricted to certain kinds of content also is part of the
foundation for the multiple memory systems view.
The tissue removed from HM’s Brain
(A) This sagittal view of the brain shows that
most of the amygdala and hippocampus
were removed.
(B) This view shows the extent to which
underlying cortical tissue was removed.
(C) This coronal section illustrates the
combined loss of the cortical regions and
hippocampus.
(D) Another coronal view shows the cortical
regions (entorhinal cortex, perirhinal
cortex, parahippocampal cortex) and hippocampus in more detail
HM live stream brain sectioning
- Henry died in 2008 and in 2009,
his brain was frozen and sliced
(2401 slices), uninterrupted 53-
hour procedure - The dissection of the brain was
video-recorded and streamed
live on the web to permit
scientific scrutiny and to foster
public engagement in the study
what was the leading theory coming from HM research?
medial temporal lobe memory system (Squire and Zola-Morgan)
medial temporal lobe memory system (Squire and Zola-Morgan)
- placed the hippocampus in a central position, working together with adjacent
regions such as the entorhinal cortex, perirhinal cortex, and parahippocampal
cortices - responsible for governing long-term memories
- fundamental principle was that acquiring new memories was distinct and
separable from other cognitive abilities, such as perception - Most theories focus on the different types of memory and neglect underlying
components that may transcend the categories, such as how similarity of inputs
can interfere with mnemonic processes
How to study declarative/episodic memory in animal models?
the delayed nonmatching-to-sample task
delayed nonmatching-to-sample task
The animal’s task is to remember the object it sampled and
to choose the novel object on the choice trial.
Mishkin’s Experiments (DNMS) - findings of the animal (DNMS)
Miskin found that neither hippocampus (H) damage or amygdala (A) damage
impaired performance but damage to both regions (AH) seriously impaired
performance on the DNMS task
Damage to the Rhinal Cortices but Not the Amygdala and Hippocampus
Impaired Performance on the DNMS Task…
- Larry Squire suggested that it is the cortices surrounding
the hippocampus that support DNMS performance. - Primates in this experiment had selective damage to the
hippocampus and amygdala or to the underlying perirhinal
cortex. - Note that only damage to the rhinal cortex impaired
performance.
The DMNS paradox
- Since DNMS was trying to model
episodic memory…
Based on the results of the DNMS
task, one would have to conclude
that either (a) the hippocampus is
not part of the episodic memory
system or (b) the DMNS task has a
solution that does not depend on
episodic memory.
-The later explanation is likely correct.
The DMNS Paradox Resolved
- Dual Process Theories of
Recognition Memory: The DNMS
task does not depend only on the
episodic memory system. It has two
solutions—one that depends on the
hippocampus and one that does not. - According to this analysis, monkeys
without a hippocampus can still
perform correctly on the DNMS task
because they still have the neural
system (perirhinal cortex/ “rhinal
cortex”) needed to make familiarity-
based judgments.
What is another explanation for the DNMS taks
the level of representation needed is “object level” which depends on the perirhinal cortex, not hippocampus
Representational Hierarchal Theory
brain regions are specialized for housing representations at a specific level of complexity, not for performing specific functions; thus, each brain region can contribute to any cognitive function, including
memory or perception
