Preparation Lecture 8
King (2004). The hippocampal role in spatial memory and the familiarity-recollection
distinction: a case study
The hippocampus plays a crucial role in memory, and damage to it and related systems is central to
amnesic syndrome. The most reliable impairments associated with hippocampal damage concern
delayed recall of test stimuli. Deficits have also been notes in spatial navigation, paralleling the effects
of hippocampal lesions in other mammals.
Episodic memory
This is the ability to recollect personally experienced events. It has often been defined as context-
dependent memory. An event may be defined as a discontinuous change in some aspect of the
world and the context as the remaining unchanged aspects of it. Episodic recollection can be contrasted
with (at least) three other forms of memory:
- Semantic memory or non-contextual knowledge for facts.
- Procedural memory or the knowledge of how to do things.
- The ability to recognize the familiarity of a stimulus.
Assumption -> the authors assume that on the one hand, episodic recollection, in which detailed
contextual information can be reconstructed from a cue, includes processes tested by context-
dependent or associative recognition. On the other hand, they assume that familiarity-based
recognition simply required the detection of the strength of the match between a test stimulus and some
stored representation of it. Thus, familiarity-based recognition would be sufficient to enable a person
to say which of two items was familiar but would not be sufficient for that person to say which of two
equally familiar items had been received in a particular context. By contrast, episodic recollection
would be sufficient for either task.
Role of the hippocampus -> one hypothesis posits that a system including the medial thalamus and
perirhinal cortex, but not the hippocampus, supports familiarity-based recognition, whereas a
complimentary system including the mammillary bodies, anterior thalamus, and hippocampus
supports episodic recollection.
Hippocampal damage -> there is a clear role in anterograde episodic memory deficits. It is also
associated with retrograde deficits but less clear.
Spatial memory
Hippocampus is required for spatial navigation in animals such as rats, specifically in situations in
which following or approaching a simple sensory stimulus or a well-learned route is not sufficient to
solve the task.
- Allocentric system -> provide a record of an object’s location relative to other objects, features,
or landmarks in the environment.
- Egocentric system -> providing a record of an object’s location relative to some part of the body.
1
, The authors found a specific deficit in shifted-view object-location memory compared with same-view
object-location memory in a developmental case of focal hippocampal damage. There is a direct link
between the egocentric and familiarity processes; if the same visual scene is used at test as at
presentation, then a process familiarity-based recognition acting on any egocentric visual or motoric
representations of location could be used to solve the task.
A case of developmental amnesia
J. suffered perinatal anoxia and shows a reduction of hippocampal volume of about 50% bilaterally
with apparently preserved surrounding cortical tissue. He presented with three types of memory
impairment:
1. Episodic -> forgetting what he had done that day.
2. Temporal -> forgetting regularly scheduled appointments and events.
3. Spatial -> being unable to find his way around, forgetting where he put things.
He had a deficit in delayed recall in all episodic tasks compared with a relative preservation of semantic
knowledge and good performance in recognition memory. His performance IQ was above average.
However, his navigation and map drawing were very inaccurate. He was impaired at recognizing
scenes from the town compared with foils involving rearrangements of the visual textures from the
town.
Forced-choice recognition test of memory in a VR environment
The authors designed a series of tests to manipulate the use of familiarity-based recognition versus
context-dependent retrieval processes (or associative recognition) within the same forced-choice
recognition paradigm. They first developed an episodic memory test within the VR town, in which
participants follow a path, meeting virtual characters in different places and receiving a different object
each time, for a total of 16 objects. Next, they investigated Jon’s spatial memory within a forced choice
VR paradigm. They also tested Jon using two foil objects at random locations. He performed
significantly worse than controls in the shifted-view conditions and performed better in the same-view
condition.
Current investigations
One question regarding the interpretation of these findings concerns differences in difficulty within the
episodic memory and the spatial memory tasks, as judged by the average scores of the healthy control
participants. A second question concerns the specific nature of the representation that Jon uses to solve
the same-view task and the specific nature of his problem with the shifted-view task.
- Hypothesis -> Jon might perform the same-view task in one of two ways:
1. He might store object locations as egocentric vectors -> ventral stream.
2. He might store sensory-bound representations of the scene (or parts of it) suitable for
subsequent pattern matching -> dorsal stream.
Method
There are three experiments. The first consists of performance-matched context-dependent and object-
recognition tests. The second experiment consists of performance-matched shifted-view and same-view
object-location tests. The third experiment consists of changing the background scene in the object-
location test.
2
King (2004). The hippocampal role in spatial memory and the familiarity-recollection
distinction: a case study
The hippocampus plays a crucial role in memory, and damage to it and related systems is central to
amnesic syndrome. The most reliable impairments associated with hippocampal damage concern
delayed recall of test stimuli. Deficits have also been notes in spatial navigation, paralleling the effects
of hippocampal lesions in other mammals.
Episodic memory
This is the ability to recollect personally experienced events. It has often been defined as context-
dependent memory. An event may be defined as a discontinuous change in some aspect of the
world and the context as the remaining unchanged aspects of it. Episodic recollection can be contrasted
with (at least) three other forms of memory:
- Semantic memory or non-contextual knowledge for facts.
- Procedural memory or the knowledge of how to do things.
- The ability to recognize the familiarity of a stimulus.
Assumption -> the authors assume that on the one hand, episodic recollection, in which detailed
contextual information can be reconstructed from a cue, includes processes tested by context-
dependent or associative recognition. On the other hand, they assume that familiarity-based
recognition simply required the detection of the strength of the match between a test stimulus and some
stored representation of it. Thus, familiarity-based recognition would be sufficient to enable a person
to say which of two items was familiar but would not be sufficient for that person to say which of two
equally familiar items had been received in a particular context. By contrast, episodic recollection
would be sufficient for either task.
Role of the hippocampus -> one hypothesis posits that a system including the medial thalamus and
perirhinal cortex, but not the hippocampus, supports familiarity-based recognition, whereas a
complimentary system including the mammillary bodies, anterior thalamus, and hippocampus
supports episodic recollection.
Hippocampal damage -> there is a clear role in anterograde episodic memory deficits. It is also
associated with retrograde deficits but less clear.
Spatial memory
Hippocampus is required for spatial navigation in animals such as rats, specifically in situations in
which following or approaching a simple sensory stimulus or a well-learned route is not sufficient to
solve the task.
- Allocentric system -> provide a record of an object’s location relative to other objects, features,
or landmarks in the environment.
- Egocentric system -> providing a record of an object’s location relative to some part of the body.
1
, The authors found a specific deficit in shifted-view object-location memory compared with same-view
object-location memory in a developmental case of focal hippocampal damage. There is a direct link
between the egocentric and familiarity processes; if the same visual scene is used at test as at
presentation, then a process familiarity-based recognition acting on any egocentric visual or motoric
representations of location could be used to solve the task.
A case of developmental amnesia
J. suffered perinatal anoxia and shows a reduction of hippocampal volume of about 50% bilaterally
with apparently preserved surrounding cortical tissue. He presented with three types of memory
impairment:
1. Episodic -> forgetting what he had done that day.
2. Temporal -> forgetting regularly scheduled appointments and events.
3. Spatial -> being unable to find his way around, forgetting where he put things.
He had a deficit in delayed recall in all episodic tasks compared with a relative preservation of semantic
knowledge and good performance in recognition memory. His performance IQ was above average.
However, his navigation and map drawing were very inaccurate. He was impaired at recognizing
scenes from the town compared with foils involving rearrangements of the visual textures from the
town.
Forced-choice recognition test of memory in a VR environment
The authors designed a series of tests to manipulate the use of familiarity-based recognition versus
context-dependent retrieval processes (or associative recognition) within the same forced-choice
recognition paradigm. They first developed an episodic memory test within the VR town, in which
participants follow a path, meeting virtual characters in different places and receiving a different object
each time, for a total of 16 objects. Next, they investigated Jon’s spatial memory within a forced choice
VR paradigm. They also tested Jon using two foil objects at random locations. He performed
significantly worse than controls in the shifted-view conditions and performed better in the same-view
condition.
Current investigations
One question regarding the interpretation of these findings concerns differences in difficulty within the
episodic memory and the spatial memory tasks, as judged by the average scores of the healthy control
participants. A second question concerns the specific nature of the representation that Jon uses to solve
the same-view task and the specific nature of his problem with the shifted-view task.
- Hypothesis -> Jon might perform the same-view task in one of two ways:
1. He might store object locations as egocentric vectors -> ventral stream.
2. He might store sensory-bound representations of the scene (or parts of it) suitable for
subsequent pattern matching -> dorsal stream.
Method
There are three experiments. The first consists of performance-matched context-dependent and object-
recognition tests. The second experiment consists of performance-matched shifted-view and same-view
object-location tests. The third experiment consists of changing the background scene in the object-
location test.
2
