Paul Broca identified an approximate region of the brain in 1861 which, when damaged in two of his patients, caused severe deficits in speech production, where his patients were unable to speak beyond a few monosyllabic words. This deficit, known as Broca's or expressive aphasia , is characterized by difficulty in speech production where speech is slow and labored, function words are absent, and syntax is severely impaired, as in telegraphic speech . In expressive aphasia, speech comprehension is generally less affected except in the comprehension of grammatically complex sentences.  Wernicke's area is named after Carl Wernicke , who in 1874 proposed a connection between damage to the posterior area of the left superior temporal gyrus and aphasia, as he noted that not all aphasic patients had suffered damage to the prefrontal cortex.  Damage to Wernicke's area produces Wernicke's or receptive aphasia , which is characterized by relatively normal syntax and prosody but severe impairment in lexical access, resulting in poor comprehension and nonsensical or jargon speech .