Editing Aphasiology (section)

===Expressive aphasia===
{{Main article|Expressive aphasia}}
First described by the [[France|French]] neurologist [[Paul Broca]] in the nineteenth century, expressive aphasia causes the speech of those affected to display a considerable vocabulary but to show grammatical deficits.<ref name="Burns 2010">{{cite journal |vauthors=Burns MS, Fahy J |title=Broca's area: rethinking classical concepts from a neuroscience perspective |journal=Top Stroke Rehabil |volume=17 |issue=6 |pages=401–10 |year=2010 |pmid=21239364 |doi=10.1310/tsr1706-401 |s2cid=45975702 }}</ref> It is characterized by a halting speech consisting mainly of content words, i.e. nouns and verbs, and, at least in [[English language|English]], distinctly lacking small grammatical function words such as articles and prepositions.  This observation gave rise to the terms telegraphic speech and, more recently, [[agrammatism]].  The extent to which expressive aphasics retain knowledge of grammar is a matter of considerable controversy.  Nonetheless, because their comprehension of spoken language is mostly preserved, and because their speech is usually good enough to get their point across, the agrammatic nature of their speech suggests that the disorder chiefly involves the expressive mechanisms of language that turn thoughts into well-formed sentences.<ref name="Hillis 2007">{{cite journal |author=Hillis AE |title=Aphasia: progress in the last quarter of a century |journal=Neurology |volume=69 |issue=2 |pages=200–13 |date=July 2007 |pmid=17620554 |doi=10.1212/01.wnl.0000265600.69385.6f |s2cid=219199296 |url=http://cel.huji.ac.il/courses/structureandprocesses/Bibliography/Hillis_2007.pdf}}</ref>

The view of expressive aphasia as an expressive disorder is supported by its frequent co-occurrence with facial motor difficulties, and its anatomical localization.  Although expressive aphasia may be caused by brain damage to many regions, it is most commonly associated with the [[inferior frontal gyrus]], a region that overlaps with [[motor cortex]] controlling the [[Human mouth|mouth]] and [[tongue]], extending into the periventricular white matter.<ref name="Helm-Estabrooks 2004">{{cite book |author1=Albert, Martin L. |author2=Helm-Estabrooks, Nancy |title=Manual of aphasia and aphasia therapy |publisher=Pro-Ed |location=Austin, Tex |year=2004 |isbn=0-89079-963-6 |oclc=51009586 }}</ref> Not surprisingly, this region has come to be known as "[[Broca's area]]".  However, an intriguing line of research has demonstrated specific comprehension deficits in expressive aphasics as well.  These deficits generally involve sentences that are grammatical, but atypical in their word order.  The simplest example is sentences in the [[passive voice]], such as "The boy was chased by the girl."  Expressive aphasics may have quite a hard time realizing that the girl is doing the chasing, but they do much better with "The mouse was chased by the cat," where world knowledge constraints contribute to the correct interpretation.  However, "The cat was chased by the mouse" would likewise be incomprehensible.  This evidence suggests that grammatical competence may be a specific function of Broca's area.{{citation needed|date=August 2021}}

Lesions exclusive to Broca's area (the foot of the [[inferior frontal gyrus]]) do not produce Broca's aphasia but instead mild [[dysprosody]] and [[agraphia]], sometimes accompanied by word-finding pauses and mild [[dysarthria]]. Not much is known about what other areas must be damaged in order to produce Broca's aphasia, but some maintain damage to the inferior pre-Rolandic motor strip (the motor cortex region responsible [[glossopharyngeal]] muscle control) is also necessary.{{cn|date=January 2024}}