Editing Aphasia (section)

=== Neuroimaging methods ===
[[Magnetic resonance imaging]] (MRI) and [[functional magnetic resonance imaging]] (fMRI) are the most common neuroimaging tools used in identifying aphasia and studying the extent of damage in the loss of language abilities. This is done by doing MRI scans and locating the extent of lesions or damage within brain tissue, particularly within areas of the left frontal and temporal regions- where a lot of language related areas lie. In fMRI studies a language related task is often completed and then the BOLD image is analyzed. If there are lower than normal BOLD responses that indicate a lessening of blood flow to the affected area and can show quantitatively that the cognitive task is not being completed.

There are limitations to the use of fMRI in aphasic patients particularly. Because a high percentage of aphasic patients develop it because of stroke there can be [[Infarction|infarct]] present which is the total loss of blood flow. This can be due to the thinning of blood vessels or the complete blockage of it. This is important in fMRI as it relies on the BOLD response (the oxygen levels of the blood vessels), and this can create a false hyporesponse upon fMRI study.<ref>{{Cite journal |last1=Crinion |first1=Jenny |last2=Holland |first2=Audrey L. |last3=Copland |first3=David A. |last4=Thompson |first4=Cynthia K. |last5=Hillis |first5=Argye E. |date=2013-06-01 |title=Neuroimaging in aphasia treatment research: Quantifying brain lesions after stroke |journal=NeuroImage |language=en |volume=73 |pages=208–214 |doi=10.1016/j.neuroimage.2012.07.044 |issn=1053-8119 |pmc=3534842 |pmid=22846659}}</ref> Due to the limitations of fMRI such as a lower spatial resolution, it can show that some areas of the brain are not active during a task when they in reality are. Additionally, with [[stroke]] being the cause of many cases of aphasia the extent of damage to brain tissue can be difficult to quantify therefore the effects of stroke brain damage on the functionality of the patient can vary.

;Neural substrates of aphasia subtypes
MRI is often used to predict or confirm the subtype of aphasia present. Researchers compared three subtypes of aphasia&nbsp;— nonfluent-variant primary progressive aphasia (nfPPA), logopenic-variant primary progressive aphasia (lvPPA), and semantic-variant primary progressive aphasia (svPPA), with [[primary progressive aphasia]] (PPA) and Alzheimer's disease. This was done by analyzing the MRIs of patients with each of the subsets of PPA.<ref>{{Cite journal |last1=Sajjadi |first1=S. A. |last2=Sheikh-Bahaei |first2=N. |last3=Cross |first3=J. |last4=Gillard |first4=J. H. |last5=Scoffings |first5=D. |last6=Nestor |first6=P. J. |date=2017-05-01 |title=Can MRI Visual Assessment Differentiate the Variants of Primary-Progressive Aphasia? |url=http://www.ajnr.org/content/38/5/954 |journal=American Journal of Neuroradiology |language=en |volume=38 |issue=5 |pages=954–960 |doi=10.3174/ajnr.A5126 |issn=0195-6108 |pmc=7960364 |pmid=28341715}}</ref> Images which compare subtypes of aphasia as well as for finding the extent of lesions are generated by overlapping images of different participant's brains (if applicable) and isolating areas of lesions or damage using third-party software such as MRIcron. MRI has also been used to study the relationship between the type of aphasia developed and the age of the person with aphasia. It was found that patients with fluent aphasia are on average older than people with non-fluent aphasia. It was also found that among patients with lesions confined to the anterior portion of the brain an unexpected portion of them presented with fluent aphasia and were remarkably older than those with non-fluent aphasia. This effect was not found when the posterior portion of the brain was studied.<ref>{{Cite journal |last1=Basso |first1=Anna |last2=Bracchi |first2=Maurizio |last3=Capitani |first3=Erminio |last4=Laiaconal |first4=Marcella |last5=Zanobio |first5=M. Ester |date=1987-09-01 |title=Age and Evolution of Language Area Functions. A Study on Adult Stroke Patients |journal=Cortex |language=en |volume=23 |issue=3 |pages=475–483 |doi=10.1016/S0010-9452(87)80008-4 |issn=0010-9452 |pmid=3677734 |s2cid=4478097 |doi-access=free}}</ref>

;Associated conditions
In a study on the features associated with different disease trajectories in [[Alzheimer's disease]] (AD)-related primary progressive aphasia (PPA), it was found that metabolic patterns via PET SPM analysis can help predict progression of total loss of speech and functional autonomy in AD and PPA patients. This was done by comparing an MRI or CT image of the brain and presence of a radioactive biomarker with normal levels in patients without Alzheimer's Disease.<ref>{{Cite journal |last1=Mazzeo |first1=Salvatore |last2=Polito |first2=Cristina |last3=Lassi |first3=Michael |last4=Bagnoli |first4=Silvia |last5=Mattei |first5=Marta |last6=Padiglioni |first6=Sonia |last7=Berti |first7=Valentina |last8=Lombardi |first8=Gemma |last9=Giacomucci |first9=Giulia |last10=De Cristofaro |first10=Maria Teresa |last11=Passeri |first11=Alessandro |last12=Ferrari |first12=Camilla |last13=Nacmias |first13=Benedetta |last14=Mazzoni |first14=Alberto |last15=Sorbi |first15=Sandro |date=2022-09-01 |title=Loss of speech and functional impairment in Alzheimer's disease-related primary progressive aphasia: predictive factors of decline |url=https://www.sciencedirect.com/science/article/pii/S0197458022001087 |journal=Neurobiology of Aging |language=en |volume=117 |pages=59–70 |doi=10.1016/j.neurobiolaging.2022.05.002 |issn=0197-4580 |pmid=35665686 |s2cid=248726399}}</ref> Apraxia is another disorder often correlated with aphasia. This is due to a subset of apraxia which affects speech. Specifically, this subset affects the movement of muscles associated with speech production, [[apraxia]] and aphasia are often correlated due to the proximity of neural substrates associated with each of the disorders.<ref>{{Cite journal |last1=Ogar |first1=Jennifer |last2=Slama |first2=Hilary |last3=Dronkers |first3=Nina |last4=Amici |first4=Serena |last5=Luisa Gorno-Tempini |first5=Maria |date=2005-12-01 |title=Apraxia of Speech: An overview |url=https://doi.org/10.1080/13554790500263529 |journal=Neurocase |volume=11 |issue=6 |pages=427–432 |doi=10.1080/13554790500263529 |issn=1355-4794 |pmid=16393756 |s2cid=8650885}}</ref> Researchers concluded that there were 2 areas of lesion overlap between patients with apraxia and aphasia, the anterior temporal lobe and the left inferior parietal lobe.<ref>{{Cite journal |last1=Goldenberg |first1=Georg |last2=Randerath |first2=Jennifer |date=2015-08-01 |title=Shared neural substrates of apraxia and aphasia |url=https://www.sciencedirect.com/science/article/pii/S002839321530035X |journal=Neuropsychologia |language=en |volume=75 |pages=40–49 |doi=10.1016/j.neuropsychologia.2015.05.017 |issn=0028-3932 |pmid=26004063 |s2cid=46093007}}</ref>

;Treatment and neuroimaging
Evidence for positive treatment outcomes can also be quantified using neuroimaging tools. The use of fMRI and an automatic classifier can help predict language recovery outcomes in stroke patients with 86% accuracy when coupled with age and language test scores. The stimuli tested were sentences both correct and incorrect and the subject had to press a button whenever the sentence was incorrect. The fMRI data collected focused on responses in regions of interest identified by healthy subjects.<ref>{{Cite journal |last1=Saur |first1=Dorothee |last2=Ronneberger |first2=Olaf |last3=Kümmerer |first3=Dorothee |last4=Mader |first4=Irina |last5=Weiller |first5=Cornelius |last6=Klöppel |first6=Stefan |year=2010 |title=Early functional magnetic resonance imaging activations predict language outcome after stroke |journal=Brain |volume=133 |issue=4 |pages=1252–1264 |doi=10.1093/brain/awq021 |pmid=20299389 |doi-access=free}}</ref>  Recovery from aphasia can also be quantified using diffusion tensor imaging. The accurate fasciculus (AF) connects the right and left superior temporal lobe, premotor regions/posterior inferior frontal gyrus. and the primary motor cortex. In a study which enrolled patients in a speech therapy program, an increase in AF fibers and volume was found in patients after 6-weeks in the program which correlated with long-term improvement in those patients.<ref>{{Cite journal |last1=Schlaug |first1=Gottfried |last2=Marchina |first2=Sarah |last3=Norton |first3=Andrea |date=July 2009 |title=Evidence for Plasticity in White-Matter Tracts of Patients with Chronic Broca's Aphasia Undergoing Intense Intonation-based Speech Therapy |journal=Annals of the New York Academy of Sciences |language=en |volume=1169 |issue=1 |pages=385–394 |bibcode=2009NYASA1169..385S |doi=10.1111/j.1749-6632.2009.04587.x |pmc=2777670 |pmid=19673813}}</ref> The results of the experiment are pictured in Figure 2. This implies that [[Diffusion MRI|DTI]] can be used to quantify the improvement in patients after speech and language treatment programs are applied.