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gyrus and the inferior parietal lobe. In their study, they needed as a result of the various meanings abstract
used auditory and visual targets and a pronunciation words could have, depending on the context. Their
and lexical decision task. Nakamura et al. [35] discovered results, indeed, suggested that the ventrolateral
a clear double dissociation. On the one hand, the prefrontal cortex worked as a kind of executive regulator
repetition priming during the pronunciation task was in abstract word processing. However, this was less the
eliminated when TMS was conducted on the left case when the abstract words were processed within
inferior parietal lobe, but not when it was conducted on a particular context because then the system was
the left superior temporal gyrus. On the other hand, the already guided in the direction of a specific meaning or
priming during the lexical decision task was eliminated interpretation. In contrast, regulation played a smaller
when TMS was conducted on the left superior temporal role in the processing of concrete words because in the
gyrus, but not when it was conducted on the left inferior processing of concrete words, the number of possible
parietal lobe [Table 1]. [35] meanings are already decreased as a result of their
physical referents; moreover, their meanings did not
Reading action verbs differ in various contexts. [37]
So far, we have discussed TMS studies on general visual
word recognition; however, from a neurolinguistic point Sentence‑level
of view, the study of what happens in the brain when a Having discussed the main results that were found on
specific type of verb is read, namely, an “action verb”, the word-level in normal readers using TMS, we will
is also interesting. These verbs all express some kind of now discuss the main findings that were found on the
action. Tomasino et al. [36] applied TMS to the hand area sentence-level. Note that these studies are closer to real
of the left primary motor cortex during experimental language situations, for instance, situations in which
trials of three different tasks (silent reading of action people are reading books or newspapers.
verbs, motor imagery of the action, and frequency
judgment) and to the vertex during the control trials of Sentence comprehension
these tasks. The authors found neuroscientific evidence Manenti et al. [39] conducted an rTMS study on
for the hypothesis that the primary motor cortex was sentence reading [Table 2]. They were particularly
critically involved in processing action verbs but that interested in if and how a specific area in the brain,
this was only the case when the participants were the dorsolateral prefrontal cortex, was involved in
simulating the corresponding movement. [36] the understanding of sentences. It had previously
been suggested that dorsolateral prefrontal cortex
Abstract versus concrete words engagement might reflect the working memory load in
Another important neurolinguistic word class sentence processing. [40,41] Manenti et al. [39] found that
distinction, besides the previously-discussed “action when rTMS was conducted on the left dorsolateral
verbs”, can be made between the so-called “concrete” prefrontal cortex, the participants needed more time to
words (an example is the word tree) and “abstract” complete a semantic task (i.e. was the meaning of the
words (an example is the word love). In a rTMS study, sentence correct or not), but not to complete a syntactic
Hoffman et al. [37] investigated the idea that abstract task (i.e. was the grammar of the sentence correct or
words depended on the ventrolateral prefrontal cortex not). Furthermore, when rTMS was conducted on the
for understanding, as was previously suggested based right dorsolateral prefrontal cortex, the opposite pattern
[38]
on neuroimaging findings. The authors hypothesized was visible, and the participants needed more time to
that an increase in the executive regulation would be finish the syntactic task, but did not need more time

Table 2: TMS findings on sentence‑reading in normal readers
Study Participants Brain area Main finding
Manenti et al. [39] Twelve right‑handed, Dorsolateral A double dissociation between the type of task (semantic vs.
native Italian speakers prefrontal syntactic) and the rTMS effects was found, supporting the idea
cortex that the underlying working memory resources in sentence
comprehension were processed differently by the two hemispheres
Cacciari et al. [42] Nine healthy Motor area The activity of the motor areas was affected by the motor
participants component of the verb. This phenomenon was visible when fictive
and metaphorical motion sentences were processed
Scorolli et al. [43] Sixteen healthy, Primary Early activation of the hand‑related motor system was found after
right‑handed, native motor‑cortex reading phrases with concrete verbs whereas a delay in the same
Italian speakers region was visible after reading phrases with abstract verbs
Acheson and Twenty participants in Inferior Their results supported the idea that the middle temporal gyrus
Hagoort [44] the TMS group and 20 frontal gyrus was involved in the retrieval of lexical‑syntactic information
in the control group and middle whereas the inferior frontal gyrus played a key role in the
temporal gyrus unification processes required in order to understand sentences
rTMS: rapid‑rate transcranial magnetic stimulation; TMS: transcranial magnetic stimulation

148 Neuroimmunol Neuroinflammation | Volume 2 | Issue 3 | July 15, 2015 Neuroimmunol Neuroinflammation | Volume 2 | Issue 3 | July 15, 2015 149