Original scientific paper
https://doi.org/10.22210/suvlin.2017.084.01
Semantic categorization in aphasic patients with impaired language comprehension: An event–related potentials study
Karolina Lice
orcid.org/0000-0003-0131-3693
; Faculty of Education and Rehabilitation Sciences, University of Zagreb
Marijan Palmović
orcid.org/0000-0002-4587-4348
; Faculty of Education and Rehabilitation Sciences, University of Zagreb
Abstract
Many studies have tackled the question of the organization of our conceptual knowledge
in the brain, mainly conducting behaviour studies in healthy and impaired individuals.
Animacy and inanimacy are among the most frequently studied categories and there are
three main theories or models that explain semantic processing of animate and inanimate
objects: the sensory/functional theory, the domain–specific semantic knowledge representation model and the connectionist model of the conceptual structure. Although the event–
related potentials (ERP) technique has been used in aphasia research and many studies
have used some variation of the semantic categorization task in healthy individuals, to
our knowledge there are no studies that were intended to answer the question about
semantic categorization in the aphasic population using the ERP technique. The aim of
this study is to determine the differences in processing animate and inanimate objects
between patients with aphasia with language comprehension difficulties and age, gender
and education matched controls using the ERP technique. Results in this study show
that the group of aphasic patients with impaired language comprehension have a lower
amplitude and a longer latency of the N400 and the LPC amplitude, fewer correct behavioural responses and a slower reaction time on the behavioural categorization task than
their controls. It can be concluded that aphasic patients have difficulties in both phases of
lexico–semantic processing, the lexical retrieval or recognition phase and the categorization
phase. The absence of differences in the processing of animate and inanimate objects in
the N400 window and similar topographic distribution for animate and inanimate objects
in both groups are consistent with the connectionist model of a single semantic system
which claims that the same semantic system is active no matter which category is being
processed. However, the observed differences between animate and inanimate objects in
the LPC time window in the control group lead to the conclusion that inanimate objects
are harder to categorize due to a smaller number of common features needed for the
categorization processes.
Keywords
semantic categorization; categories animate–inanimate; aphasia; connectionist model; ERP; N400; LPC
Hrčak ID:
190746
URI
Publication date:
15.12.2017.
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