As previously described, the CC is organized topographically in its connections with the corresponding brain regions surrounding it. The left hemisphere which receives the right visual field stimulus must relay the stimulus to the right hemisphere which controls the left hand.
Clark and Zaidel found that RTs in the uncrossed condition tended to be shorter than RTs in the crossed condition, presumably because of the additional time required for the signal to cross via the CC.
In normal development, this myelination process, particularly of the middle and posterior subregions of the Tbi essays, spans the first 18 years of life or more and results in increased area of the isthmus and splenium throughout childhood and adolescence Rajapakse, Giedd, Rumsey, Vaituzis, Hamburger et al.
In contrast, DAI represents widespread versus focal damage to white matter via axonal shearing or stretching as a result of inertial forces that cause the brain to rapidly accelerate, decelerate, or rotate within the skull Caeyenberghs, Leemans, Geurts, Linden, Smits-Engelsman et al.
Over forty percent of these injuries are sustained by children and adolescents, resulting in approximatelyemergency department visits, 60, hospitalizations, and 6, deaths per year within the years age Tbi essays Faul et al. Because the role of the splenium is to interhemispherically transfer visual information, damage to the splenium contributes to asymmetries in tachistoscopic performance, yet few of the children had extensive splenial damage.
As viewed from the midsagittal plane from anterior to posterior, the subregions of the CC include the genu, the rostrum ventral to the genu and bending underneath the CCthe rostral body, anterior and posterior midbodies, the isthmus, and the splenium.
Even after controlling for age, CC area was correlated with performance in intelligence, visuospatial processing, and two frontal measures Trail Making Test A and B. EPs have none of these limitations and more directly measure neural potentials. Thus, the sample was divided into three groups accordingly: In the absence of pathological processes, the CC begins to develop in utero and continues to develop into young adulthood.
For example, Brown, Jeeves, Dietrich, and Burnison used the EP method to examine the interhemispheric integration of visual information in a sample that included adult subjects with complete agenesis of the corpus callosum ACCpartial agenesis, total commissurotomy, and normals. As noted above, the relationship between brain metabolites and IHTT was found to be significant only in the posterior CC Babikian et al.
Two other frontal measures Wisconsin Card Sorting Task categories and perseverative errorsverbal memory, and visual reaction time differences were only statistically significant before controlling for age.
Their findings indicated that callosal functioning e. The most commonly utilized topology to study the CC has been that of Witelson who divided it into five vertical regions with seven subregions on the midsaggital plane.
This speed is operationalized as the difference in latency of the contralateral direct pathway versus ipsilateral callosal pathway P1 or N1 components. The anterior portions of the CC have commonly been found to be atrophied following CHI as these portions connect to the frontal and temporal lobes which are often damaged Wilde, Hunter, Newsome, Scheibel, Bigler et al.
Endrass, Mohr, and Rockstroh and Barnett, Corballis, and Kirk found that controls demonstrated a faster right-to-left hemispheric transfer that was absent in schizophrenics, though Whitford, Kubicki, Ghorashi, Schneiderman, Hawley et al.
The post-acute group demonstrated significantly longer IHTT compared to the chronic one year post-injury group, and post-acute IHTT was significantly negatively correlated with post-acute FA.
However, Barr, Hamm, Kirk, and Corballis conducted a RT study using a high-density channel system and found evidence of ipsilateral activation in all three of their Tbi essays with callosal agenesis. The CC is the crossroads of widespread interhemispheric connections and its primary function is to mediate the communication of complementary and supplementary information between hemispheres, thus affecting a wide range of cognitive domains.
While the overall morbidity rate for children following TBI is lower than that of adults, the morbidity rate of younger children less than age 4 years and mid-to-late adolescents is higher than that of school-aged children. On a verbal dichotic listening task, investigators found that the severe injury group demonstrated a significant association between increased right ear advantage more efficient left hemisphere processing of verbal information and CC lesions and atrophy.
Longitudinally, decreased splenium size was related to decreased accuracy on the cBCT trials that required asymmetric movement and lacked visual control. Myelination is especially rapid in the first ten years of life Denckla, ; Levin et al. However, the posterior portions of the CC, particularly the posterior body and splenium, are typically the most affected in DAI.
However, CT and various MR techniques often underestimate the frequency of axonal injuries to the CC because these are typically microstructural Rutgers et al. Furthermore, functional recovery is less likely in DAI because neuroplasticity appears to apply more to focal damage and is thus more of a gray matter phenomenon, though damaged white matter axons can potentially mend if they did not disconnect entirely Smith et al.
Changes in the midbody regions were also noted. Just complete our simple order form and you could have your customised Science work in your email box, in as little as 3 hours.
The crossed condition was so named because it involved a contralateral response to the stimulus, such as a left hand response to a right visual field stimulus, therefore requiring interhemispheric transmission.
After controlling for age, only WCST categories scores were significantly different between groups. The high variability of callosal size in the healthy brain presents another challenging aspect to CC measurement.
The investigators concluded that future studies involving more cases of splenium damage would find stronger associations with nonverbal tachistoscopic performance. Typical Brain Development The study of the pediatric brain is complicated by developmental processes.
CC Morphology and Measurement Research has firmly established that the central role of the CC is to mediate interhemispheric communication. EP-IHTT as a Functional Indicator of Callosal Damage IHTT, which is the speed at which information crosses between hemispheres, was originally measured via a manual reaction time RT paradigm by Poffenberger who had subjects quickly press a button in response to a unilateral visual stimulus.What is TBI?
Traumatic Brain Injury (TBI) may happen from a blow or jolt to the head or an object penetrating the brain. When the brain is injured, the person can experience a change in consciousness that can range from becoming disoriented and confused to slipping into a coma.
Traumatic Brain Injury Traumatic brain injury, also called acquired brain injury or simply head injury, is a result of a sudden blow to the head when an external force is applied causing a disruption of the physiological stability of the brain locally.
Brain Injury Essays. This page will take you to a collection of brain injury essays. Traumatic brain injury lawyers have written several brain injury essays and articles over the years that explain different aspects of the legal issues that relate to a TBI.
Traumatic Brain Injury (TBI) Almost two million Americans sustain a traumatic brain injury (TBI) every year, making TBI a significant public health concern (Faul, Xu, Wald, & Coronado, ). Traumatic Brain Injury - Traumatic brain injury (TBI) is the result of an external force against the head that causes displacement of the cranial structures, either through impact with an object or through acceleration and deceleration.
Understanding TBI Traumatic brain injury, also known as TBI, is the leading cause of dearth and disability in adolescents.
and young adults. TBI is defined as damage to the brain resulting from external mechanical force, such as rapid acceleration or deceleration, impact, blast waves, or .Download