TY - JOUR
T1 - What is semantic in semantic dementia? The
decay of knowledge of physical entities but not of
verbs, numbers and body parts
AU - Silveri, Maria Caterina
AU - Brita, Anna Clelia
AU - Liperoti, Rosa
AU - Piludu, Francesca
AU - Colosimo, Cesare
PY - 2018
Y1 - 2018
N2 - Background: Conceptual knowledge does not decay randomly in
patients with cerebral damage, suggesting that dedicated neural
substrates may support different categories of knowledge.
Semantic dementia is an optimal natural model for studying the
organization of semantic memory. Nevertheless, in a pathology
primarily characterized by a semantic memory disorder categorical-
and modality- specific effects are not obvious findings. In fact,
there is no clear evidence of categorical effects, at least concerning
two broad categories of knowledge, that is, natural items and
artifacts. Furthermore, transmodal deficits do not seem to be the
rule in SD. Also quite robust is the observation that some conceptual
domains are relatively spared in this pathology, that is,
numerical knowledge, abstract words, and action verbs.
Aims: To explore category specific and modality specific deficit in
SD and to support the evidence that semantic degradation in SD
primarily involves knowledge of the objects in the real world,
whereas categories of knowledge whose items can be less easily
identified by surface attributes, such as verbs, numbers and body
parts, are more preserved.
Methods and Procedures: We investigated the semantic impairment
in 8 patients with Semantic Dementia (SD). Voxel-based morphometry
(VBM) in each patient was also obtained
Outcomes and Results: In some patients manmade objects were
significantly more preserved than natural items, verbs more preserved
than nouns and the number system entirely preserved; the
body parts category was the least impaired in all subjects; finally,
in three patients visual semantic knowledge was significantly more
preserved than verbal semantic knowledge. VBM showed that
atrophy of the anterior inferior temporal regions was insufficient
to impair knowledge about verbs, numbers and body parts, whose
impairment was associated with more widespread atrophy. In
subjects whose verbal semantic knowledge was significantly
more impaired than visual semantic knowledge, atrophy was principally
distributed in the left hemisphere. In patients with significant impairment for natural items compared to manmade
objects, atrophy was not confine in the temporal lobes.
Conclusion: We conclude that in SD semantic decay primarily
involves the real-world items whose knowledge is processed by
surface sensorifunctional features and that this is the type of
knowledge stored in the temporal lobes. Our data support a
model that associates a semantic hub with modality/category
specific neural substrates.
AB - Background: Conceptual knowledge does not decay randomly in
patients with cerebral damage, suggesting that dedicated neural
substrates may support different categories of knowledge.
Semantic dementia is an optimal natural model for studying the
organization of semantic memory. Nevertheless, in a pathology
primarily characterized by a semantic memory disorder categorical-
and modality- specific effects are not obvious findings. In fact,
there is no clear evidence of categorical effects, at least concerning
two broad categories of knowledge, that is, natural items and
artifacts. Furthermore, transmodal deficits do not seem to be the
rule in SD. Also quite robust is the observation that some conceptual
domains are relatively spared in this pathology, that is,
numerical knowledge, abstract words, and action verbs.
Aims: To explore category specific and modality specific deficit in
SD and to support the evidence that semantic degradation in SD
primarily involves knowledge of the objects in the real world,
whereas categories of knowledge whose items can be less easily
identified by surface attributes, such as verbs, numbers and body
parts, are more preserved.
Methods and Procedures: We investigated the semantic impairment
in 8 patients with Semantic Dementia (SD). Voxel-based morphometry
(VBM) in each patient was also obtained
Outcomes and Results: In some patients manmade objects were
significantly more preserved than natural items, verbs more preserved
than nouns and the number system entirely preserved; the
body parts category was the least impaired in all subjects; finally,
in three patients visual semantic knowledge was significantly more
preserved than verbal semantic knowledge. VBM showed that
atrophy of the anterior inferior temporal regions was insufficient
to impair knowledge about verbs, numbers and body parts, whose
impairment was associated with more widespread atrophy. In
subjects whose verbal semantic knowledge was significantly
more impaired than visual semantic knowledge, atrophy was principally
distributed in the left hemisphere. In patients with significant impairment for natural items compared to manmade
objects, atrophy was not confine in the temporal lobes.
Conclusion: We conclude that in SD semantic decay primarily
involves the real-world items whose knowledge is processed by
surface sensorifunctional features and that this is the type of
knowledge stored in the temporal lobes. Our data support a
model that associates a semantic hub with modality/category
specific neural substrates.
KW - Semantic dementia
KW - categories of knowledge
KW - objects
KW - semantic hub
KW - temporal pole
KW - Semantic dementia
KW - categories of knowledge
KW - objects
KW - semantic hub
KW - temporal pole
UR - http://hdl.handle.net/10807/106631
U2 - 10.1080/02687038.2017.1387227
DO - 10.1080/02687038.2017.1387227
M3 - Article
SN - 1464-5041
VL - 32
SP - 989
EP - 1009
JO - Aphasiology
JF - Aphasiology
ER -