Paper Summaries #2
1.) Jang, Sung Ho, and Kwon, Hyeok Gyu, Neural Connectivity of the Amygdala in the Human Brain: A Diffusion Tensor Imaging Study, 2014, Neural Network World, 6:14, 591-599
Sung Ho Jang and other researchers wanted to investigate the neural connectivity of the amygdala in normal subjects using DTI tractography. 48 heathy individuals consisting of 26 males and 22 females participated in the study. The researchers got images of the participants brains from the anterior commissure and posterior commissure view. A seed region of interest was placed on the known anatomical locations of the amygdala on the axial image to trace its connectivity. The researchers found that the images showed 100% amygdala connectivity to the hippocampus, thalamus, hypothalamus, and medial temporal cortex.
2.) Huang H., Zhang J., Jiang H., Wakana S., Poetscher L., Miller M.I., Van Zijl P.CM., Hillis A.E., Wytik R., Mori S., DTI Tractography Based Parcellation of White Matter: Application to the Mid-Sagittal Morphology of the Corpus Callosum, 2005, 26:1, 195-205
Hao Huang and other researcher investigated whether DTI can enable the study of anatomical divisions of the corpus callosum. 8 healthy subjects and one stroke patient participated in the study. DTI was used to get scans of each participant’s brain and then the fiber tracking was based on a linear line propagation model with a FA threshold. The researchers were able to find significant atrophy in the motor and sensory tracts of the corpus callosum of the stroke patient compared to the healthy subjects.
3.) Hinkley L.B.N., Marco E.J., Findlay A.M., Honma S., Jeremy R.J., Strominger Z., Bukshpun P., Wakahiro M., Brown W.S., Paul L.K., Barkovich J.A., Mukherjee P., and Nagarajan S.S., Sherr E.H., The Role of Corpus Callosum Development in Functional Connectivity and Cognitive Processing, 2012, PLOS ONE 7:8
Leighton Hinkley and other researchers wanted to demonstrate that the lack of normal callosal development can lead to deficits in functional connectivity and cognitive impairments. In order to demonstrate this, they examined the resting state functional connectivity of individuals with agenesis of the corpus callosum and compared them to the connectivity of healthy individuals. They hypothesized that agenesis of the corpus callosum will alter connectivity. 18 individuals with partial and complete agenesis of the corpus callosum and 18 individuals with no agenesis of the corpus callosum. An MRI was used to scan each participant’s brain using magnetoencephalographic imaging. The researchers found that the absence of a fully developed corpus callosum impacts the connectivity between the brain’s hemispheres. This is related to behavioral and social impairments within the individuals who have agenesis of the corpus callosum.
4.) Badaruddin D.H., Andrews G.L., Bolte S., Schilmoeller K.J., Schilmoeller G., Paul L.K., Brown W.S., Social and Behavioral Problems of Children with Agenesis of the Corpus Callosum, 2007, 38, 287-302
Denise Badaruddin and other researchers wanted to determine the social and behavioral problems in children with agenesis of the corpus callosum. They analyzed a survey given to parents with high function children with agenesis of the corpus callosum. They hypothesized that behavioral problems of children with agenesis of the corpus callosum would be consistently evident among the parent’s answers. 61 high functioning children with agenesis of the corpus callosum were surveyed through their parents. The most common behavioral disorder among the children noted by their parents was difficulties in attention, social interactions, and sleeping problems.
5.) Galinowski A., Miranda R., Lemaitre H., Martinot Paillère M.-L., Artiges E., Vulser H., Goodman R., Penttilä J., Struve M., and Barbot A., Resilience and corpus callosum microstructure in adolescence, 2015 Psychological Medicine, 45:11, 2285-2294
Galinowski and other researchers hypothesized that resilience in adolescents would be associated with higher FA in the corpus callosum. To test their hypothesis, 2224 healthy adolescents and 55 resilient adolescents were scanned to get diffusion tensor images. The diffusion tensor images showed that FA values were higher within the anterior body and the genu of the corpus callosum in the resilient adolescents compared to the healthy individuals.
6.) Mueller S.C., Maheu F.S., Dozier M., Peloso E., Mandell D., Leibenluft E., Pine D.S, and Ernst M., Early-life stress is associated with impairment in cognitive control in adolescence: An fMRI study, 2010, Neuropsychologia, 48:10, 3037-3044
Mueller and other researchers hypothesized that adolescents with a history of early stress would display an anxious performance on a cognitive control task. In addition, they hypothesized that adolescents who experienced early stress would show deficits in cognitive control on the change task compared to adolescents who haven’t experienced early stress. 12 adolescents who have experienced early stress and 21 adolescents who haven’t experienced early stress participated in a cognitive control task test using a variant of the stop-signal task. The researchers scanned their brains using fMRI. The researchers found that the adolescents who have experienced early life stress showed slower reaction times compared to the adolescents who have not experienced early stress.
7.) Cyprien F., Courtet P., Malafosse A., Maller J., Meslin C., Bonafe A., Le Bars E., de Champfleur N.M., Ritchie C., and Artero S., Suicidal Behavior is Associated with Reduced Corpus Callosum Area., 2011, 70:4, 320-326
Cyprien and other researchers examined the association between the size of the corpus callosum and suicidal behavioral. 21 elders who have suicidal behavior, 234 elders with a history of depression but no suicidal behavior, and 180 healthy controls participated in the study. Each participant underwent an MRI to get their brain scanned and their brain volumes were computed. The researchers concluded that the elders with a history of suicidal behavior showed a reduced size of the posterior third of the corpus callosum suggesting a diminished interhemispheric connectivity.
8.) Villarreal G., Hamilton D.A., Graham D.P., Driscoll I., Qualls C., Petropoulos H., Brooks W.M., Reduced area of the corpus callosum in posttraumatic stress disorder, 2004, Psychiatry Research: Neuroimaging, 131, 227-235
Villarreal and other researchers hypothesized that reductions in the corpus callosum area is seen in adults with PTSD. To test their hypothesizes, the researchers measured the mid-sagittal area of the corpus callosum of twelve women who have PTSD and ten women who do not have PTSD. Each participant had their brains scanned through an MRI and their total gray matter, white matter, and cerebrospinal fluid volume was measured through an automated k-means-based segmentation of the cerebrum. The researchers found a decrease in several regions of the mid-sagittal corpus callosum in the adults with PTSD compared to the adults without PTSD. In addition, the researchers found that the adults with smaller corpus callosum have higher anxiety scores.
9.) Hanson J.L., Nacewicz B.M., Sutterer M.J., Cayo A.A., Schaefer S.M., Rudolph K.D., Shirtcliff E.A., Pollak S.D., Davidson R.J., Behavioral Problems After Early Life Stress: Contributions of the Hippocampus and Amygdala, 77:4, 314-323
Hanson and other researchers hypothesized early life stress would lead to smaller volumes in the amygdala. In addition, they predicted that greater stress exposure would be associated with a smaller amygdala and behavioral changes. To test their hypothesis, the researchers traced the amygdala and hippocampus of children who either experienced physical abuse, early neglect, or low socioeconomic status. 61 children who experienced early neglects, 11 children who experienced physical abuse, and 20 children who are from low socioeconomic status households participated in the study. The researcher found that a smaller amygdala was seen in children exposed to physical abuse, early neglect and low socioeconomic households. Smaller hippocampal volumes was seen in children who were exposed to physical abuse and low socioeconomic households.
10.) Cohen M.M., Jing D., Yang R.R., and Casey B.J., Early-life stress has persistent effects on amygdala function and development in mice and humans, 2013, PNAS, 10:45, 18274-18278
Cohen and other researchers examined the long-term effects of early life experience and whether they reverse after the stressor is removed using a rodent model of early life stress. To analysis the effects of early life stress on the rodents, they underwent a go/no-go task. Male mice who were raised under stressful or standard conditions underwent the go/no-go task. Neural activity in the basolateral amygdala and the infralimbic cortex. In addition, the researchers collected from 26 orphan children that underwent a go/no go task to compare the results from the rodents to humans. Researchers found that in both rodents and humans, persistent alterations of the amygdala were found in human and rodents who experienced early life stress. The effects are no reversed when the stressor was removed.
11.) Morey R.A., Gold A.L., LaBar K.S., Beall S.K., Brown V.M., Haswell C.C., Nasser J.D., Wagner R., and McCarthy G., Amygdala Volume Changes in Posttraumatic Stress Disorder in a Large Case-Controlled Veterans Group, 2012, Arch Gen Psychiatry, 69:11, 1169-1178
Morey and other researchers assessed the association of amygdala volume and find a smaller hippocampal volume in trauma exposed adults with PTSD. They hypothesized that adults with PTSD would show smaller amygdala volumes compared to a control group. 200 military service members and veterans with and without PTSD participated in the study. Each participate had an MRI to get images of their brains which were analyzed to check the volumes of their amygdala and hippocampus. The researchers found that the participants with PTSD showed smaller volumes in the left and right amygdala, and he left hippocampus, but they were not able to correlate lifetime trauma, illness chronicity, and depressive symptoms to the smaller volume of the left and right amygdala.
12.) Protopopescu X., Pan H., Tuescher O., Cloitre M., Goldstei M., Engelien W., Epstein J., Yang Y., Gorman J., LeDoux J., Silbersweig D.,and Stern E., Differential time courses and specificity of the amygdala activity in posttraumatic stress disorder subjects and normal control subjects and normal control subjects, 2005, 57:5, 464-473
Protopopescu and other researchers wanted to investigate the neurocircuitry underlying PTSD by examining the time course of the amygdala response time to trauma-relevant, panic relevant negative, and neutral words. They hypothesized that the PTSD subjects would show increased amygdala activity to the trauma-related words than the neutral words. 11 individuals who experienced sexual/physical assault and 21 individuals who did not experience any trauma participated in the study. The stimulus consisted of 18 negative/anxiety inducing words, 24 negative/PTSD inducing words, 24 negative/panic words, 48 neutral words, and 48 positive/safety words. Each participant underwent an MRI to see neuronal activity in the brain. The researchers found that the left amygdala showed increased activity in response to the trauma related words compared to the neutral words in the PTSD group.
13.) Buss C., Pruessner J.C., Mayberg H., Mletzko T., Nermeroff C., and Heim C., Larger amygdala volumes after childhood trauma associated with depression and cortisol response to psychosocial stress in adult hood, 2012, 3:1, 38-49
Buss and other researchers wanted to determine whether childhood trauma is linked to neurostructural changes in limbic brain regions after childhood trauma. 49 women with and without childhood trauma and depression participated in the study. Each participant went through an MRI and the volumes of the left and right amygdala were analyzed through an interactive software package, DISPLAY. The researchers found that women with both childhood
trauma and major depressive disorder had the largest right amygdala volumes.
14.) Khoury-Malhame M.E., Zendjidjian X., Pineda P.S., and Fakra E., Amygdala activity correlates with attentional bias in PTSD, 2011, Neuropsychologia, 49, 1969-1973
Khoury-Malhame and other researchers hypothesized that traumatized individuals with PTSD would exhibit increased amygdala activation compared to controls in response to angry and fearful faces. To test their hypothesis, 17 adults with PTSD and 17 adults without PTSD participated in the study. Participants were asked to focus on a cross on a screen with a dot and a cross on it. Then, the participants were asked to match faces that expressed the same emotion. Finally, each participant had an MRI done. The researchers found that there was an increase in amygdala activity in the PTSD group that correlated with their anxiety and attention abnormality.
15.) Fani N., Stenson A.F., Van Rooij S.J.H., La Barrie D.L., Jovanovic T., White Matter Microstructure in Trauma-exposed Children: Associations with pubertal stage, 2021, Developmental Science, 24:6
In this article, Negar Fani and other researchers examined the associations between white matter integrity in trauma exposed pubertal stage children. They hypothesized that trauma exposure would be inversely associated with white matter integrity and decreases in FA and increases in MD would be evident in the fronto-limbic tracts. 41 male and female African American children who have had trauma exposure along with a control group participated in the study. The researchers used DTI to mark the integrity of the white matter tracts using FA and MD. Violent trauma exposure was associated with in the in the corpus callosum, cingulum bundle and uncinate fasciculus. lower MD in the hippo-campal cingulum and uncinate fasciculus. Greater violent trauma was found to be associated