Table 1.

Summary of localization of important aphasic syndromes

Aphasia type	Localization		Characteristics
	Functional	Anatomical
Wernicke’s aphasia	Phonemic retrieval Plus Semantic system*	pSTG, SMG (G) SLF, AF (WM) MTG, ITG, AG (G) MLF, IFOF (WM)	Phonemic paraphasias Impaired repetition and naming Semantic paraphasias Impaired word and sentence comprehension Intact fluency due to preserved dorsal stream
Transcortical sensory aphasia	Semantic system**	MTG, ITG, AG (G) MLF, IFOF (WM)	Impaired comprehension Semantic paraphasias Intact repetition due to preserved phonemic retrieval syste Intact fluency due to preserved dorsal stream
Conduction aphasia	Phonemic retrieval	pSTG, SMG (G) SLF, AF (WM)	Phonemic paraphasias Impaired repetition and naming Intact comprehension and fluency
Transcortical motor aphasia	Dorsal stream	SMA (G) FAT (WM)	Impaired fluency Intact comprehension and repetition due to preserved ventral stream and phonemic retrieval respectively
Broca’s aphasia	Dorsal stream Fronto-temporal subnetwork	IFG, Middle and inferior precentral gyrus (G) SLF, AF (WM) UF/IFOF mediated	Impaired fluency Impaired repetition and naming Impaired syntax (grammar) Intact comprehension due to preserved ventral stream, except for comprehension of sentences with complex syntax
Non fluent PPA	Dorsal stream	Broca’s area STG, anterior insula	Effortful speech Agrammatism Impaired comprehension of sentences with complex syntax Intact single word comprehension and object knowledge
Semantic PPA	Semantic system	Anterior MTG, ITG (temporal pole)	Impaired single word comprehension, object knowledge and confrontation naming Intact repetition, grammar and motor speech
Logopenic variant PPA	Phonemic retrieval	Posterior STG, adjacent SMG	Impaired repetition, single word retrieval in spontaneous speech and naming, phonemic paraphasias Intact single word comprehension, object knowledge and motor speech

*Left inferior frontal cortex plays a role in initiating and controlling activation of semantics,[11,12,13] while the temporal and inferior parietal components are the actual repositories of concepts ** left prefrontal lesions have also been reported to produce transcortical sensory aphasia.[52,53,54] pSTG = posterior superior temporal gyrus, SMG = supramarginal gyrus, SLF = superior longitudinal fasciculus, AF = arcuate fasciculus, MTG = middle temporal gyrus, ITG = inferior temporal gyrus, AG = angular gyrus, IFOF = inferior frontal occipital fasciculus, SMA = supplementary motor area, FAT = frontal aslant tract, UF = uncinate fasciculus, PPA = primary progressive aphasia, G = grey, WM = white matter