The brain is a complex structure and but can be organised according to several principles. One approach is to characterise the brain regions according to the microscopic properties of these regions. More specifically the neurons are organised differently between regions. Some regions may contain unique types of neurons. This approach to understanding the organisation of the brain was proposed by the German Neuropathologist Korbinian Brodmann and resulted in the eponymously named Brodmann Area. There are 52 areas in all and I have covered other Brodmann Areas elsewhere in this Blog. This is the fifth in a series on one of these areas – Brodmann Area 22. A simple search strategy was adopted. The term ‘Brodmann Area 22′ was used to search in Medline using the PubMed interface. Relevant results were identified and included.
In this paper, the authors note that BA22 is one of the areas shown lateralisation in early infancy. In this study, researchers looked at brain activity during musical activities using 15 O Positron Emission Tomography. The researchers found tha BA22 was active when musicians sang novel melodies, harmonised melodies and also sang monotonically. This was contrasted with activity in BA38 which they correlated with higher order musical activities. In a functional Magnetic Resonance Imaging study, subjects were asked to play notes on the piano either sequentially or in double octaves. The researchers found that BA22 was activated most frequently on the right side. Negative correlates for stuttering rate in right-handed female stutterers (compared to a control group) were found bilaterally in BA22 in this PET study investigating cerebral blood flow correlates of stuttering rate (additional data were used from a previous study investigating male stutterers). BA22 formed part of a brain region referred to as the Temporo-peri-Sylvian Vestibular Cortex (TPSVC) where vestibular symptoms were elicited and particularly rotatory sensations in this cortical electrical stimulation study. When a series of sounds are presented to a person any sound that deviates from this pattern causes the brain to produce a specific response known as an automatic mismatch negativity event related potential (ERP). The researchers in this functional Magnetic Resonance Imaging study investigated the fMRI correlates of the ERP signals. The technique was complicated by the sound that the MRI scanner makes which can result in brain activity. They solved this problem by analysing segments of the data and found that activity in the right BA22 was correlated with the MMN ERP.
In a functional Magnetic Resonance Imaging study investigating children with an average of 6.8 years of age, the researchers were interested in the brain activity correlates of auditory comprehension assessed during story reading. The researchers found that the group analysis showed significantly increased activity in the left Superior Temporal gyrus (BA22). In another paper by the same group, the researchers report on a finding of increased activity in the left BA22 during a reading task in children with an average age of 7.2 years. In an fMRI study investigating language comprehension in older adults, researchers found that subjects who had more difficulty in comprehending spoken language were also less likely to exhibit activity in brain regions including BA22. In a Magnetoencephalography study, the researchers found that in the majority of cases the sensory speech area was located in the posterior aspect of the left BA22. In one fMRI study the researchers found activity in BA22 correlated with performance in a face-gender discrimination task and motion detection task suggesting an association with aspects of visual processing (paper freely available here). In an fMRI study the correlates of vestibular stimulation were investigated by separating the cutaneous and ocular motor stimuli that may have confounded the results (paper freely available here). The researchers correlated vestibular stimulation with activity in BA22.
The researchers in this study found histological evidence to support the hypothesis of lateralisation in BA22. BA22 was not activated during presentation of auditory clicks to 5 people who were in a persistent vegetative state in this H2O15 PET study (paper freely available here). Synaptophysin mRNA was reduced in BA22 in females who had received a diagnosis of Schizophrenia compared to a control group in this post-mortem study (paper freely available here). Subjects appeared to focus on the sound of their breathing when asked to voluntarily control respiratory rate in this fMRI study which found increased activity in BA22 amongst several other areas during the task (paper freely available here). Complex as compared to simple auditory stimuli were more likely to be correlated with activity in BA22 in this O15 water PET study. The left BA22 was active during three reasoning tasks in this [(15)O] H(2)O PET study. The researchers in this post-mortem study comparing people who had received a diagnosis of Schizophrenia with a control group found evidence of a change in the density of D2 receptors in the Superior Temporal Cortex which is significant in light of their previous findings of an increase in D2 receptors in a control sample in this region.
A reduction in human Corticotrophin-releasing factor was found in BA22 in people who had been diagnosed with Alzheimer’s Disease compared to a control group in this small post-mortem study. The authors of this paper provide evidence of an increased protease activity in BA22 in people who had been diagnosed with Alzheimer’s Disease. The researchers in a study using (CTI 953B) and 15O-labelled water PET found evidence of increased activity in the left BA22 during a divided attention task in which subjects assessed melody and pitch (paper freely available here). In this post-mortem study researchers found significant correlations with cognition in BA22. In BA22 they found a reduction in Choline Acetyltransferase levels as well as an increase in senile plaques and neurofibrillary tangles which were correlated with prior cognitive performance. In this positron emission tomography (PET) and [18F]2-fluoro-2-deoxy-D-glucose (FDG) coregistration study, researchers found left BA22 activity during a word repetition task. Phospholipid levels in BA22 discriminated people who had received a diagnosis of early onset versus late onset Alzheimer’s Disease in this post-mortem study. Another post-mortem study showed elevation in peptidases in BA22 in people who had been diagnosed with Alzheimer’s Disease compared to a control group. ACE inhibitor recognition site density was higher by 70% compared to controls in people who had been diagnosed with Alzheimer’s Disease in this post-mortem study. The authors of this paper argue that there is altered gene expression in BA22 in Alzheimer’s Disease as there is an altered mRNA pool size relative to controls. Neurofibrillary tangles were observed in BA22 in this postmortem study.
Neuropeptide Y-like immunoreactivity was increased in BA22 in people who had received a diagnosis of Huntingtons Disease in this post-mortem study. Creatinine Kinase levels in BA22 did not discriminate people who had been diagnosed with Alzheimer’s Disease from controls in this post-mortem study. Different levels of Choline Acetyltransferase were found between the left and right BA22 in this post-mortem study.
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