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Analyzing a Brain Imaging Paper

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Analyzing a Brain Imaging Paper Hanna Damasio, Thomas J. Grabowski, Daniel Tranel, Laura L. B. Ponto, Richard D. Hichwa, and Antonio R. Damasio – PowerPoint PPT presentation

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Title: Analyzing a Brain Imaging Paper


1
Analyzing a Brain Imaging Paper
  • Hanna Damasio, Thomas J. Grabowski, Daniel
    Tranel, Laura L. B. Ponto, Richard D. Hichwa, and
    Antonio R. Damasio
  • (2001)
  • Neural Correlates of Naming Actions and of Naming
    Spatial Relations
  • NeuroImage, 131053-1064
  • Questions
  • What are the mechanisms of naming
  • How do they differ for nouns and verbs, and
    their subcategories?

2
Bibliography
  • Our concern today is to carefully analyze this
    paper both
  • for content, and
  • to classify its material for entry into a
    database
  • thus setting the stage for your own contribution
    to our initial database of brain imaging studies
    related to action, action recognition, imitation,
    and language.
  • An important step is to enter all references you
    find of interest into the database. Where
    possible, insert abstracts and links to full
    text.
  • However Do not restrict your follow-up reading
    only to Web-accessible papers.

3
Page 1053
  • ... evidence from lesion studies that retrieval
    of words for actions can be related to structures
    in the left premotor/prefrontal region and in the
    left posterior temporal regions (Caramazza and
    Hillis, 1991 Damasio and Tranel, 1993 Daniele
    et al., 1994 Hillis and Caramazza, 1995 Miceli
    et al., 1988 Miozzo et al., 1994
    Thompson-Schill et al., 1998 Zingneser and
    Berndt, 1990).
  • Suggests a possible annotation to add to these 8
    papers. Later reading of such papers could then
    expand the information for individual papers.
  • Some convergent evidence can also be found in
    several functional imaging and electrophysiologica
    l studies (Fiez et al., 1996 Grabowski et al.,
    1996 Hinke et al., 1993 Koenig et al., 1999
    Martin et al., 1995 Martin et al., 2000 Perani
    et al., 1999 Petersen et al., 1988 Pulvermuller
    et al., 1999 Raichle-et al., 1994 Warburton et
    al., 1996 Wise et al., 1991).
  • Note that to annotate these 12 papers we have to
    rephrase the comment preceding them
  • ... evidence from functional imaging or
    electrophysiological studies that retrieval of
    words for actions can be related to structures in
    the left premotor/prefrontal region and in the
    left posterior temporal regions

4
Pages 1053-54
  • In agrammatic aphasics there is often an impaired
    use of prepositions, the closed class words, some
    of which denote spatial relations (e.g.,
    Friederici, 1982, 1985 Friederici et al., 1982
    Schwartz et al., 1980 Tesak and Hummer, 1994
    Zurif and Caramazza, 1976).
  • As above. Issue Simply entering the annotation
    for each paper versus crediting the source of the
    annotation.
  • The next clump is to be entered for this paper
    as Guiding Hypothesis
  • The salient aspects of the neural activations
    caused by naming actions and naming spatial
    relations occur in left frontal operculum and
    left parietal cortices but not in left
    infero-temporal cortices (IT) or right parietal
    cortices. The actions focused on are those
    denoted by action verbs, while the spatial
    relations are those denoted by locative
    prepositions (e.g., in, on, above, below).
  • But note that this has to be linked to the
    outcome of the study Was the hypothesis
    confirmed or not? As the richness of the database
    increases, we will search for data in other
    papers pro and con each hypothesis and we will
    want to post summaries of the best hypotheses.
    What is best?

5
Support for the Hypothesis
  • The following must be linked to the hypothesis it
    supports. The judgement call is whether Support
    for hypothesis is a label for the entry or a
    label for the link between it and the hypothesis.
    My point The database you will work with is an
    initial design. Thus your assignment will both to
    enter data and to suggest better ways to
    structure the database for searches, report
    generation, etc., etc.
  • The parietal and frontal regions are
    hypothesized to pertain to both actions and
    spatial relations because of their known
    involvement in the processing of space and of
    motion in space. This involvement was first
    suggested in classical human neuropsychological
    studies (Newcombe, 1969), and in nonhuman primate
    studies (Ungerleider and Mishkin, 1982).
  • The selection of the left as opposed to right
    aspect of those structures derives from the
    assumption that the linguistic denotation of
    actions and spatial relations will be
    preferentially handled by the language-dominant
    hemisphere. NSR No supporting reference.
  • The prediction that left IT would not be
    activated came both from the fact that left IT is
    active when words denoting concrete entities are
    retrieved and the fact that there is no
    compelling reason to expect this region to be
    involved when spatial manipulations are being
    performed on concrete entities that are not being
    specifically identified or named. NSR
  • There is some evidence suggesting that left IT is
    not necessary for the retrieval of words for
    actions (Damasio and Tranel, 1993)

6
Clumps Need Not Have Contiguous Atoms
  • The next paragraph on p.1054 breaks into 2 parts
  • Additions to the Hypothesis
  • We predicted that word retrieval for actions
    would activate the lateral temporo-occipital
    cortices related to motion processing,
    specifically those known as area MT, but we did
    not predict activation in lateral
    temporo-occipital cortices during word retrieval
    for spatial relations.
  • Support for these portions of the hypothesis
  • Area MT has been identified by neurophysiological
    and neuroimaging studies to be involved in the
    perception of real motion, or motion suggested by
    consecutive presentation of static images (Goebel
    et al., 1998 Kaneoke et al., 1997 Stevens et
    al., 2000 Tootell et al., 1995 Watson et al.,
    1993 Zeki et al., 1991, 1993). However, there
    is no compelling evidence to suggest that area MT
    might be involved in the processing of spatial
    relations.
  • Note then the issue of (a) aggregating the
    hypothesis from separate parts of the paper but
    (b) then decomposing it into the separate pieces
    for which different supporting data may be
    marshaled. Again, as the database progresses,
    some parts of a hypothesis may be further
    supported others may be modified while yet
    others will come to be rejected outright. What
    database tools will support this kind of dynamic
    knowledge management?

7
The Structure of the Lexicon
  • What is the structure of the lexicon?
  • Conceptual issue How does a conceptual structure
    propagate to, e.g., different lexical forms?
    Relate to general issues of metaphor and analogy?
    What is stored for later retrieval, what is
    computed on the fly?
  • Later lectures will explore the idea of
    Verb-Argument structure, as in
  • Hit(Harry, hammer, nail)
  • Bite(Yingshu, kaki)
  • and suggest that the representation of a verb may
    obligatorily involve representation of the
    general characteristics of nouns which fill its
    slots.
  • We may thus wish to post hypotheses as we enter
    material into the database, and then gradually
    link the hypothesis to supporting or contrary
    data as we build the database and search it for
    the contributions of others.
  • But then we need an inference engine to (a)
    assess reliability of each possibly relevant
    datum and then (b) compute a confidence value for
    the hypothesis.

8
Semi-Models and Experiment Design
  • Need to better tease apart
  • the recognition processes engaged in naming an
    object or an action
  • going from a representation of the recognized
    entity to a representation of its name
  • going from the representation of a name to a
    representation of the recognized entity
  • the use of words in sentence production and
    perception
  • p.1054 . In addition to regions involved in
    implementing the actual vocalization of the
    response, other regions must be involved in
    processing the conceptual knowledge behind a
    given action or spatial relation, and in
    retrieving the specific morphemes used in the
    correct response.
  • The experiments conducted in this study aimed at
    identifying regions involved in conceptual
    processing and intermediary word retrieval and at
    excluding activation of regions involved in
    implementing responses, which were shared by the
    target and control tasks, and were to be canceled
    out in the subtraction of the former from the
    latter.
  • The experiments do not address the issue of the
    degree to which conceptual processing and word
    retrieval can be functionally separated.
  • To what extent should this analysis of key
    subprocesses be entered as part of the
    hypothesis. Is the appeal to subtraction
    theory-free?

9
Theoretical framework
  • p.1054 Damasio, 1989 Damasio et al., 1990,
    1996 Damasio and Damasio, 1994 Tranel et al.,
    1997a, 1997b
  • Word-form production is dependent on three kinds
    of neural structures
  • (1) those which support conceptual knowledge and
    are located in early and high-order sensory
    cortices of both hemispheres
  • (2) those which support the vocal implementation
    of word forms and are located in classical left
    perisylvian language areas and
  • (3) language-related mediational or intermediary
    structures, located in inferotemporal and
    parieto-frontal regions, which are engaged by the
    structures described in (1) to guide the
    implementation described in (2).

10
Theoretical framework
  • pp.1054-55 The same system of ensembles and
    pathways is not recruited equally, in the same
    subject, on all occasions. Moreover, there is
    more than one system of ensembles and pathways to
    support a particular function, i.e., in all
    likelihood there are several systems assisting
    with the retrieval of the action verbs and
    locative prepositions required by our tasks, and
    those different systems can be engaged depending
    on the task demands the subject has to do, among
    other factors. We presume that certain systems
    probably support the most effective and complete
    version of a certain performance, and are thus a
    "preferred" system, but there are other systems
    that can support the same performance, albeit not
    necessarily as efficiently.
  • The sensorimotor patterns that embody the
    explicit representations of word-forms, e.g., the
    word forms for actions or spatial relations, do
    not occur at the intermediary sites. But those
    patterns are triggered by language-related
    intermediary ensembles and circuits, which have
    in turn been triggered by the concept-related
    intermediary ensembles and circuits.
  • Such intermediary roles are presumed to be played
    by the frontal and parietal sites hypothesized to
    be activated by the tasks.

11
Methods Protocol
  • We can pretty much tease apart three components
    inn this kind of experiment
  • Subjects
  • Imaging Procedure
  • includes scanning method, warping method, and
    statistical analysis
  • Tasks
  • The main data gathered will be of the kind
  • When subjects execute task A as compared to task
    B, then regions R1, R2, .. are more significantly
    activated
  • Activation may depend on an indirect estimate of
    rCBF (regional cerebral blood flow, in PET
    Positron Emission Tomography) or the BOLD signal
    (based on the measurement of local changes in the
    electromagnetic field, due to changes in the
    concentration of oxygenated blood diamagnetic
    and deoxygenated blood paramagnetic, in fMRI
    functional Magnetic Resonance Imaging)
  • The regions R1, R2, clearly depend on the
    confidence level set for the test of
    significance.

12
Caveats
  • A region that is more significantly active in
    task A than in task B may nonetheless play a
    critical role in task B.
  • What is the neural activity which rCBF or BOLD
    in a region correlates with?
  • My favorite Integrated synaptic activity
  • Needed The vampire model of the neuron (and
    glia).

13
Methods
  • Typically, theorists eyes tend to glaze over
    when getting to the Methods section, which is
    often skipped.
  • However, once one accumulates data from multiple
    experiments, one may find apparent discrepancies,
    and it may only be by examining details of the
    Methods that we can resolve these discrepancies
    or form judgements of the weight to give to
    various data in forming a summary one will use as
    a basis for later work, whether designing new
    experiments, creating models, or
  • Thus it is crucial that methods be included in
    the database.
  • Having said this, I will leave you to read the
    paper for Subject and PET Imaging methodology,
    and proceed to the tasks.

14
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15
Two Cohorts
  • The subjects were divided into two cohorts of 10
    subjects with 5 men and 5 women each. One of the
    cohorts was studied for the retrieval of words
    denoting actions and the other for the retrieval
    of words denoting spatial relations. Each
    subject received 8 injections of 50 mCi of 15O
    water. For each cohort there were four tasks.
    Each of the tasks was performed twice. The
    session was divided, and in each half-session the
    sequence of tasks was randomized.
  • For the cohort involved in the retrieval of
    words denoting actions the tasks were as follows
    (1) retrieval of words denoting actions performed
    with an implement, mostly manipulable tools and
    utensils (ISI 1.8 s) (2) retrieval of words
    denoting an action performed without an
    implement, movements of the body or body parts of
    the agent (ISI 1.8 s) (3) retrieval of words
    denoting tools and utensils (ISI 1.8 s) and (4)
    an orientation judgment performed on the faces of
    unknown persons requiring the response up if the
    face was in the canonical position (up) and down
    if the face was inverted (ISI 1.0 s).
  • For the cohort involved in the retrieval of
    words denoting spatial relations the tasks were
    as follows (1) retrieval of words denoting the
    spatial relation between two (or among three)
    concrete entities (mostly tools and utensils)
    depicted as realistic line drawings, in which the
    target object was shaded in red (ISI 1.5 s) (2)
    the same task as (1) but using abstract rather
    than realistic drawings (ISI 1.5 s) (3)
    retrieval of the words denoting the names of the
    red shaded tools/utensils in the stimuli used in
    (1), (ISI 1.5 s) and (4) an orientation judgment
    performed on the faces of unknown persons
    requiring the response yes if the face was in the
    canonic position (up) and no if the face was
    inverted (ISI 1.0 s).

16
Reasons for Experimental Design
  • For word retrieval for actions they considered
    that the processing of actions performed without
    an implement, mostly whole body actions, might be
    partially segregated from that of words denoting
    actions performed with an implement
  • For the retrieval of words denoting spatial
    relations they predicted that using abstract
    stimuli might activate regions specifically
    related to recognition of a given spatial
    relation and its subsequent verbal labeling,
    uncontaminated" by associations with the
    concrete objects used in the stimulus (e.g., ring
    on the finger versus ring around the finger the
    latter is correct relative to the spatial
    relation, the former is the one that reflects
    typical usage).
  • They have used the control task of judging the
    orientation of unknown faces before, but did not
    want subjects in the second cohort to say up or
    down in the control task because they reflect a
    word denoting a spatial relation between the
    position of the face and the surround. Thus they
    preferred to use yes for the canonic presentation
    of the face and no when it was inverted. But
    then why not do this for both cohorts?
  • They used a second control task for the
    target tasks involving concrete objects so as to
    compare directly the retrieval of words denoting
    actions produced with an implement or denoting
    relations between concrete entities, to the
    retrieval of words denoting those entities.

17
Displaying Regions
  • Plotting confidence levels on a 3D structure
    based on an MRI (i.e., non-functional) of the
    subjects brain
  • Plotting confidence levels on a 3D structure
    based on a standard structure obtained by warping
    the subjects brain MRI to a standard brain,
    e.g., that of a French woman given in Talairach,
    J., Tournoux, P. (1988) Co-Planar Stereotaxic
    Atlas of the Human Brain. Georg Thieme Verlag,
    Stuttgart, Germany.
  • 2D displays showing contour maps of confidence
    level for active blobs on various views of the
    brain.
  • Giving the names of the neuroanatomical
    structures in which (much of) the mass of each
    blob is located.
  • Giving the T88 Talairach coordinates of the
    (perhaps loosely determined) center of each
    blob.
  • But not every lab uses the Talairach atlas, human
    brains differ greatly, and so do warping methods.

18
For now, consider the display, not the data
19
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20
I do not plan to look at this or the other 3
tables in detail in class Get the idea now,
review the paper later.
  • But
  • What do you notice about Table 1A as compared to
    1B?
  • And what about 2A compared to 2B?
  • See last paragraph of p.1058 and last page of
    penultimate paragraph of p.1060 for the answer.
  • What does this suggest for database construction?
  • A wish list for the database
  • Explicit links between
  • Talairach coordinates in a table and
  • a view of the brain showing the blob containing
    those coordinates.

21
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22
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23
The results in the search volume
  • (1) Naming actions performed with or without an
    implement) minus the standard control task
    orientation of unknown faces showed
    significant maxima in left frontal operculum,
    left posterior middle frontal gyrus, left IT,
    left and right inferior parietal lobule (angular
    and supramarginal gyri). The left and right
    supramarginal gyri also showed significant minima
    as did the right angular gyrus (see Table 1A).
  • For entry in the data base, the term control
    task is inadequate.
  • (2) Naming spatial relations (using
    tools/utensils or abstract shapes), minus the
    standard control task showed significant maxima
    in left frontal operculum, left posterior middle
    frontal gyrus, and left IT when using
    tools/utensils, but no maxima in the inferior
    parietal lobule, either on the left or on the
    right (see Table 2A).
  • (3) Naming actions performed with an implement
    minus naming actions performed with an implement
    showed a cluster of significantly active voxels
    in the depth of the posterior sector of the
    middle temporal gyrus (-45, -52, -1, t 4.76),
    and two additional smaller clusters in the left
    supramarginal gyrus (-55, -27, 29 and -42, -42,
    46 with t 4.37 and 4.12, respectively)
    i.e., there was more activation in this region
    during the task in which tools/utensils were used
    (Fig. 2A).
  • Are there any implications of such differences
    for syntax or only for the underlying perception
    of actions?

24
The results in the search volume
  • (4) Naming spatial relations using tools/utensils
    minus naming spatial relations using abstract
    shapes showed significant activation in left IT
    (-37, -47, -10, t 5.05) i.e., there was more
    activation in this region during the retrieval of
    words for spatial relations using tools/utensils
    than when using abstract drawings. This
    subtraction also revealed a significant
    negativity in the right supramarginal gyrus (46,
    -44, 41, t -4.39), suggesting that there was
    more activity during the retrieval of words for
    spatial relations using abstract shapes rather
    than when using tools/utensils (Fig. 2B).
  • (5) Naming of actions performed with an implement
    minus naming of implements showed two maxima in
    the posterior temporo-occipital region, at the
    level of the middle temporal gyrus, one within
    the search volume, in the left hemisphere (-43,
    -72, 9, t of 6.33), and the other outside the
    search volume, in the right hemisphere (49, -69,
    3, t of 5.45). See Fig. 3A.
  • (6) Naming spatial relations minus naming of
    implements shows significant activation in the
    left supramarginal gyrus (-62, -41, 27, t of
    4.29). See Fig. 3B.
  • (7) A matter of taste as to whether to include or
    omit?
  • Note the different judgements of an author
    versus a collator transferring a paper into a
    database.

25
Discussion
  • The subtraction of naming actions performed with
    a tool or utensil minus naming tools or utensils,
    reveals activation in both MT areas, as
    predicted. The subtraction of naming spatial
    relations using stimuli with real objects) minus
    naming tools or utensils reveals activation in
    left supramarginal gyrus, but not in the MT
    region also as predicted.
  • The bilateral activation of MT, a region which
    both neurophysiological studies (Zeki, 1993, for
    review) and functional imaging studies (Corbetta
    et al., 1990 Watson et al., 1993 Zeki et al.,
    1991) have implicated in the perception of
    movement is intriguing, considering that the
    stimuli used in this study are static.
  • We presume that in order to perform the naming of
    an action from a static stimulus the subject will
    generate a mental simulation of the movement.
  • Courts and Kanwisher (2000) observed activation
    of MT? with viewing of static pictures
    representing motion, a finding entirely consonant
    with ours.
  • The activation site seen here is posterior to the
    sites noted in several previous studies engaged
    in the generation of a verb from the viewing of a
    concrete entity as opposed to the depiction of an
    action (Fiez et al., 1996 Martin et al., 1995
    Warburton et al., 1996 Wise et al., 1991
    summarized in Martin et al., 2000).
  • Note the need to tease apart summary of data from
    elsewhere, summary of data from this study, and
    hypotheses (presumptions) and interpretations
    supported by the data.

26
Discussion
  • The finding of left frontal opercular activation
    during the naming of actions is concordant with
    previous findings of activation at this site when
    "verb generation" tasks were used, as in Peterson
    et al.'s original study (1988) and in the several
    subsequent studies using the same or similar
    paradigms (e.g., Fiez et at., 1996 Grabowski et
    al., 1996 Hinke et al., 1993 Koenig et al.,
    1999 Martin et al., 1995 Perani et al., 1999
    Raichle et al., 1994 Warburton et al., 1996
    Wise et al., 1991.
  • The fact that naming spatial relations did not
    show activation sites in the parietal lobe when
    the subtraction involved the standard control
    task is probably explained by the nature of this
    task. Although we asked subjects to say yes and
    no, instead of up or down, in order to avoid the
    retrieval of a word denoting a spatial relation,
    the task still relies on the perception and
    recognition of a spatial relation, namely the
    spatial orientation of a face. It is possible
    that this process engages parietal structures
    that are also engaged in the production of the
    word that denotes the spatial relation between
    the two target objects. The fact that we did
    detect activation in left parietal cortices when
    the retrieval of words denoting concrete entities
    is used as control task (subtraction 6), favors
    this explanation.

27
Discussion
  • Our prediction that inferotemporal cortices would
    not be involved in naming actions or spatial
    relations was not supported.
  • Note link needed from hypothesis to data which
    disconfirm it.
  • Both naming actions as well as naming spatial
    relations (minus the standard control task) show
    that the posterior sector of IT also becomes
    active. However, this activation is
    significantly stronger when concrete entities are
    part of the stimuli, as seen in the results of
    subtraction 3 and 4, and depicted in Fig. 2.
  • We do not believe that IT is involved in
    retrieving words for actions or spatial
    relations, but rather that the words denoting the
    objects represented in the stimuli are also
    retrieved, consciously or not along with the
    words that denote the actions and spatial
    relations.
  • MAA Note this for my later discussion of
    verb-argument structure.
  • The possibility that naming actions performed
    with an implement versus actions performed
    without an implement might produce different
    results was not confirmed. The contrast between
    the two conditions revealed only a small region
    of activation in posterior IT during naming
    actions performed with an implement. Again, this
    activation may point to the conscious or
    nonconscious concurrent retrieval of the names of
    objects (tools or utensils) used in the stimuli.

28
Discussion
  • The contrast between naming spatial relations
    from concrete objects and from abstract shapes
    seems to support our prediction that using
    abstract stimuli might activate regions
    specifically related to the recognition of a
    given spatial relation. The stronger activation
    of the right supramarginal gyrus during naming
    spatial relations from abstract shapes speaks to
    this point.
  • The last sentence seems to lack force.
  • The left supramarginal activation identified in
    association with the process of naming the
    spatial relation between two entities (using the
    subtraction of naming concrete entities from
    naming spatial relations) suggests a major
    involvement of systems involved in object
    manipulation in both personal and extrapersonal
    space.
  • The retrieval of concepts related to, say,
    "in-ness" or "on-ness" or "between-ness,"
    requires spatial analyses that engage components
    of the so called "where" system (Ungerleider and
    Mishkin, 1982 Kosslyn, 1994). MAA The how
    system. More specificity required.
  • The supramarginal activation lateralized to the
    left might also be related to the retrieval of
    the actual word (e.g., on, in, between). To
    clarify this issue further it will be necessity
    to gather additional evidence from lesion studies
    and functional imaging studies in which
    recognition and naming can be separated.

29
Discussion
  • To clarify this issue further it will be
    necessity to gather additional evidence from
    lesion studies and functional imaging studies in
    which recognition and naming can be separated.
    It is interesting to note that the direct
    contrast between the two conditions involving
    spatial relationships showed a strong activation
    in left posterior IT when the stimuli were
    concrete entities, the same site that becomes
    active when the words denoting those concrete
    entities were being retrieved.
  • This finding also seems to indicate that,
    regardless of the task, the presence of concrete
    entities as stimuli engages the system used to
    process words denoting those entities. This is
    in keeping with the fact that the spatial task
    using "abstract-shapes" significantly engaged the
    right supramarginal gyrus, a region not
    significantly activated when the stimuli are
    concrete objects.
  • The use of abstract shapes probably promotes a
    nonverbal strategy in which the subject is forced
    to analyze "coordinate spatial relations" in
    order (in the sense of Kosslyn, 1994) to produce
    the verbal response, without relying on an
    automatically selected verbal response usually
    associated with a particular object in a
    particular language. We interpret the right
    hemisphere engagement as signaling part of the
    conceptual process relative to spatial relations.
  • Do you find this argument convincing?
  • I feel the need for more explicit computational
    models which can be tuned and updated in the face
    of accumulating evidence.

30
Discussion
  • Because both the words for spatial relationship
    and the words for actions used in this study
    constitute a subtype of prepositions and verbs,
    respectively, the brain sites identified here
    should not be seen as representative of the
    networks necessary for retrieval of prepositions
    or verbs in general. We see our results simply
    as identifying part of the brain circuitry that
    we believe is necessary to retrieve words that
    designate spatial relationships or actions.
  • We are not suggesting that the frontal and
    parietal regions engaged in the retrieval of
    words for actions or for spatial relations are
    specific to the retrieval of this type of words.
    We know, even from the results of this study,
    that these regions are also engaged in the
    retrieval of words for concrete entities (the
    subtractions of naming concrete entities from
    naming actions, and from spatial relations, do
    not show any significant difference in activity
    in these regions). We are simply saying, in the
    perspective of the theoretical framework
    summarized in the background section, that word
    retrieval for actions and for spatial relations
    from visually presented stimuli, when performed
    in its most efficient way, does engage a system
    of which these areas are a component.
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