I undertook a search on Medline for Brodmann Area 20 (BA20) using the search term “Brodmann Area 20” which returned 108 results at the time of writing. By examining the abstracts for these results in more detail this was reduced to 20 results I thought most relevant to the search question. The results can be broadly divided into research investigating the physiology of BA20 and studies investigating BA20 in relation to illness. In terms of psychophysiological studies, researchers have identified a relationship between creativity and activity in BA20. There is also an investigation of this area in relation to interoception the awareness of internal bodily sensations possibly due to a close relationship to the Insular Cortex. Three illnesses have been investigated in relation to BA20 – Schizophrenia, Alzheimer’s Disease and Semantic Dementia and these are of particular interest in relation to BA20’s posited role in semantic processing.
In this data mining study, BA20 and 7 other studied areas were found to manifest repeated cycles of thickening and thinning of all layers of the cortex in this neurodevelopmental study over the initial 72 months of development. In one electrotomography study (n=22) looking at the effects of exercise on the brain researchers found that 15 minutes after exercise there was a decrease in alpha-2, beta-1 and gamma activity in BA20 and 3 other areas. The researchers in this study note from their literature review a high concentration of D2 receptors in BA20. Bladder cold stimulation was associated with increased activity in BA20 in this fMRI study (n=14) investigating the neural correlates of bladder sensation. Spinal cord stimulation was associated with bilateral decreases in regional Cerebral Blood Flow in BA20 in this H(2)(15)O PET study although the researchers state that BA20 is part of the Insular Cortex (although in other studies it is reported as part of the Temporal Lobe). BA20 activation was restricted to the left hemisphere during semantic processing in this fMRI study. High creative performance measured using the Torrance Tests of Creative Thinking was correlated with increased cerebral blood flow in BA20 as well as other areas in this study. Cocaine dependence was associated with reduced grey matter volume in BA20 and a number of other areas in this structural MRI study.
In terms of studies investigating the relation of BA20 to illness significant increases in neuropeptide Y-like immunoreactivity in BA20 were found in people who had been diagnosed with Huntington’s Disease in this immunoreactivity study. Cortical atrophy occurred in BA20 (left side) in semantic dementia in one case-controlled voxel morphometry study. Activity in BA20 (right-sided) was reduced in people with Alzheimer’s Disease compared to a control group in this O-15-water PET activation study investigating sustained and divided attention. A prominent reduction in SMI32 positive neurons was found in layers III and V of BA20 in Alzheimer’s Disease compared to a control group in this immunoreactivity study (paper freely available here). [3H]SCH23390 receptor binding was increased in BA20 and several other areas in people who had been diagnosed with Schizophrenia compared to a control group in this autopsy study (n=23). Levels of SNAP-25 did not differ between people with schizophrenia and a control group in BA20 in this autopsy study (n=56).
In an autopsy study (n=73) investigating the relation of the glutamate neurotransmitter system to Vascular Dementia and Stroke, researchers found that VGLUT1 (vesicular glutamate transporter 1) was significantly correlated with total CAMCOG scores and also with CAMCOG memory scores. The researchers note that this evidence supports the hypothesis that glutamatinergic synapses are protective against dementia. Compared to a control group, people with Cerebral Amyloid Angiopathy exhibit lower perfusion in BA20 as well as a number of other areas in this 99mc Tc-ECD brain perfusion SPECT study (n=24)(paper freely available here). In a fMRI study (paper freely available here) researchers found a negative correlation between BOLD signals in BA20 and dissociative psychopathology in people with a diagnosis of Borderline Personality Disorder. α-[11C]methyl-L-tryptophan trapping was increased in BA20 in 21 medication free people with OCD compared to a control group. People with ambylopia were found to have a reduction in glucose metabolism in BA20 and 4 other areas in this F18 Fluorodeoxyglucose Positron-emission Tomography study (n=23). In idiopathic REM behaviour disorder there was found to be reduced perfusion to BA20 and other areas compared to a control group in this (99m)Tc-Ethylene Cysteinate Dimer (ECD) SPECT study (n=17).
Appendix – Articles Reviewed in relation to Brodmann Areas or other Structures
Brodmann Area 1 – Somatosensory Cortex: An Investigation of D3 Receptors and Brodmann Area 1 in Schizophrenia, YouTubing the Somatosensory Cortex Brodmann Area 4 – The Primary Motor Cortex: Brodmann Areas– Part 2: Area 4. The Primary Motor Cortex – A Brief Literature Review, YouTubing the Motor Cortex Brodmann Area 6 (Agranular Frontal Area 6): FDG-PET, Frontal Dysfunction and Mild Cognitive Impairment, Brodmann Area 6 – Premotor Cortex and the Supplementary Motor Area , YouTubing Brodmann Area 6 Brodmann Areas 5 and 7 (Somatosensory Association Cortex): Brodmann Areas 5 and 7 (Somatosensory Association Cortex) Brodmann Area 8: Brodmann Area 8 Youtubing Brodmann Area 8 Brodmann Area 9: Brodmann Area 9 YouTubing Brodmann Area 9 Brodmann Area 10: Brodmann Area 10 YouTubing Brodmann Area 10 Brodmann Area 11: Brodmann Area 11. A Brief Review of the Literature. Brodmann Area 12 YouTubing Brodmann Area 12 Brodmann Area 12: A Brief Overview of the Literature Brodmann Areas 13, 14 and 52 (Insular Cortex) YouTubing the Insular Cortex What does the Insular Cortex Do Again? Insular Cortex Infarction in Acute Middle Cerebral Artery Territory Stroke The Insular Cortex and Neuropsychiatric Disorders Developing a Model of the Insular Cortex and Emotional Regulation Part 1 Developing a Model of the Insular Cortex: A Recap The Relationship of Blood Pressure to Subcortical Lesions Pathobiology of Visceral Pain Interoception and the Insular Cortex A Case of Neurogenic T-Wave Inversion Video Presentations on a Model of the Insular Cortex MR Visualisations of the Insula The Subjective Experience of Pain* How Do You Feel? Interoception: The Sense of the Physiological Condition of the Body How Do You Feel – Now? The Anterior Insula and Human Awareness Role of the Insular Cortex in the Modulation of Pain The Insular Cortex and Frontotemporal Dementia A Case of Infarct Connecting the Insular Cortex and the Heart The Insular Cortex: Part of the Brain that Connects Smell and Taste? Stuttered Swallowing and the Insular Cortex Brodmann Area 15 (Anterior Temporal Lobe – Controversial Area in Humans): Review: The Anterior Temporal Lobes and Semantic Memory Brodmann Area 17 Turning a Person’s Visual Experiences into a Movie Brodmann Area 25 – Anterior Cingulate Cortex: Brodman Areas Part 3. Brodmann Area 25 – The Anterior Cingulate Cortex Brodmann Area 27 (Piriform Cortex): Anosmia in Lewy Body Dementia Brodmann Area 28 (Entorhinal Cortex): MRI Measures of Temporoparietal Atrophy During Prodromal Alzheimer Disease* Brodmann Areas 45, 46, 47 (Inferior Frontal Gyrus): Which Bit of the Brain Detects the Emotions in Speech? Medial Temporal Lobe: The Medial Temporal Lobe and Recognition Memory Hippocampus: Review: Differences in Hippocampal Metabolism Between Amnestic and Non-Amnestic MCI Subjects Anatomy of the Hippocampus Review: Involvement of BDNF in Age-Dependent Alterations in the Hippocampus Miscellaneous Subcortical Structures: Book Review: Subcortical Vascular Dementia Review: Subcortical Vascular Ischaemic Dementia Review: Psychiatric Disturbances in CADASIL Review: Cognitive Decline in CADASIL Review: Relationship Between 24-hour Blood Pressure, Subcortical Ischemic Lesions and Cognitive Impairment Hypocretin and Neurological Disorders A Case of Pontine and Extrapontine Myelinolysis with Catatonia Generic Articles Relating to Localisation: A History of Human Brain Mapping Book Review: Brain Architecture Brain Folding and the Size of the Human Cerebral Cortex
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