BA22 is the Superior Temporal Cortex also referred to as part of the Auditory Association Cortex. In this review, the PubMed interface for Medline was searched using the term ‘Brodmann Area 21’ (without parentheses). Articles of relevance to the search were retrieved and included in the brief literature review below. This is broadly divided into physiological and pathological studies.
In an fMRI study, the researchers found that stimulation of the right ear resulted in bilateral activation in BA22 in 15 subjects with intact hearing. The researchers propose that BA22 is amongst the areas that responds to changes in the middle ear and that BA22 may also be involved in a hypothetical reflex which facilitates speech. Linguistic inference recruited BA22 in this fMRI study which was not the case for logical inference. Stimulation of BA22 with repetitive Transcranial Magnetic Stimulation was associated with a reduction in the loudness of Tinnitus in this study.
In a post-mortem study of people diagnosed with Schizophrenia compared to a control group, researchers looked at the expression of genes in Brodmann Areas 22 and 10 n the two groups. Approximately twice as many of the disease associated transcription factors were age associated in BA10 compared to BA22. The researchers characterised further differences between the two areas. In a post-mortem study of people diagnosed with Alzheimer’s Disease or Schizophrenia, researchers found that there was a similarly high dysregulation of expression of genes in BA22 compared to a control group leading the researchers to suggest a common pathology to the two illnesses in BA22.Reduction in grey matter volume was identified in BA22 in people with Bipolar Disease or Schizophrenia in this structural MRI study. Grey matter reduction in BA22 differentiated people with schizophrenia with predominantly negative symptoms from those with schizophrenia without in this structural MRI study. Grey matter volume was greater in older adults with Schizophrenia than in a group of people with Alzheimer’s Disease but less than an older adult control group in this structural MRI study. However the researchers found that BA22 was one of the areas in which the grey matter volume in the older adults with Schizophrenia and people with Alzheimer’s Disease was similar. The right BA22 was one of the areas with reduced perfusion in people with Cerebral Amyloid Angiopathy (CAA) (which predisposes to intracerebral haemmorhage) in this SPECT study comparing people with CAA with a control group. In a study comparing people with traumatic brain injury with a control group the researchers found that the latter group were more likely to activate BA22 during a cognitive test – the Paced Auditory Serial Addition Tests (PASAT) which is effective in picking up subtle cognitive difficulties.
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