Brain Structure Shows Who is Most Sensitive to Pain

Everybody feels pain differently, and brain structure may hold the clue to these differences.

In a study published in the current online issue of the journal Pain, scientists at Wake Forest Baptist Medical Center have shown that the brain’s structure is related to how intensely people perceive pain.

“We found that individual differences in the amount of grey matter in certain regions of the brain are related to how sensitive different people are to pain,” said Robert Coghill, Ph.D., professor of neurobiology and anatomy at Wake Forest Baptist and senior author of the study.

The brain is made up of both grey and white matter. Grey matter processes information much like a computer, while white matter coordinates communications between the different regions of the brain.

The research team investigated the relationship between the amount of grey matter and individual differences in pain sensitivity in 116 healthy volunteers. Pain sensitivity was tested by having participants rate the intensity of their pain when a small spot of skin on their arm or leg was heated to 120 degrees Fahrenheit. After pain sensitivity testing, participants underwent MRI scans that recorded images of their brain structure.

“Subjects with higher pain intensity ratings had less grey matter in brain regions that contribute to internal thoughts and control of attention,” said Nichole Emerson, B.S., a graduate student in the Coghill lab and first author of the study. These regions include the posterior cingulate cortex, precuneus and areas of the posterior parietal cortex, she said.

The posterior cingulate cortex and precuneus are part of the default mode network, a set of connected brain regions that are associated with the free-flowing thoughts that people have while they are daydreaming.

“Default mode activity may compete with brain activity that generates an experience of pain, such that individuals with high default mode activity would have reduced sensitivity to pain,” Coghill said.

Areas of the posterior parietal cortex play an important role in attention. Individuals who can best keep their attention focused may also be best at keeping pain under control, Coghill said.

“These kinds of structural differences can provide a foundation for the development of better tools for the diagnosis, classification, treatment and even prevention of pain,” he said.

University experts spot early signs of Alzheimer’s

Early signs of Alzheimer’s disease can be detected years before diagnosis, according to researchers at Birmingham City University.

The study found that sufferers of a specific type of cognitive impairment have an increased loss of cells in certain parts of the brain, which can be vital in detecting which patients will progress to a diagnosis of Alzheimer’s.

A team of researchers from Birmingham City University (UK), in association with colleagues from Lanzhou University (China) and the Alzheimer’s Disease Neuroimaging Initiative, conducted a brain scan analysis over two years, of patients suffering from amnestic mild cognitive impairment (aMCI) – a condition involving the diminishing of cognitive abilities, from which 80% of patients progress to a diagnosis of Alzheimer’s.

Scans showed that the loss of grey matter in the left hemisphere of the brain was particularly widespread and degenerative for those patients at high risk of developing Alzheimer’s, compared with those with no active neurological disorders.

This region of the brain has been associated with language, decision making, expressing personality, executing movement, planning complex cognitive behaviour and moderating social behaviour. 

One of the researchers involved in the study, Professor Mike Jackson, from Birmingham City University, said: “Continuous loss of cells within the regions of the brain highlighted in this study should act as alarm bells for doctors, as they may indicate that the patient is on course to developing Alzheimer’s.”

The brains parahippocampal gyrus, a region which is known to be related to memory encoding and retrieval, was highlighted as an area that should be looked at carefully when examining brain scans to detect early signs of the disease.

Treating Alzheimer’s early is thought to be vital to prevent damage to memory and thinking. Although treatments are available to temporarily ease symptoms, there has been little in the way of success in slowing down the cognitive decline in patients with mild to moderate Alzheimer’s, which has been partly put down to the late timing of the diagnosis.

Experts at Birmingham City University hope that this study will aid other researchers to find an effective clinical treatment to delay the conversion to Alzheimer’s.

CI Therapy Produces Increase in Grey Matter in Brains of Children with Cerebral Palsy

Researchers at the University of Alabama at Birmingham (UAB) report that children with cerebral palsy who underwent Constraint Induced Movement therapy (CI therapy) saw a significant increase in grey matter volume in areas of the brain associated with movement. The findings, published online April 22, 2013 in Pediatrics, are the first to show that structural remodeling of the brain occurs during rehabilitation in a pediatric population.

“It is well understood that CI therapy produces a re-wiring of the brain, leading to functional improvement in motor skills in children and adults who have experienced a brain injury,” said Edward Taub, Ph.D., the developer of CI therapy and a study co-author. “This study reinforces the idea that CI therapy also remodels the brain, producing a real, physical change in the brain.”

Grey matter is a component of the central nervous system, consisting primarily of neuronal cell bodies, glial cells and dendrites. The study examined ten children with cerebral palsy, between the ages of 2 and 7, who underwent a three week course of CI therapy. Changes in grey matter were assessed with a technique called voxel-based morphometry (VBM), performed on images acquired through magnetic resonance imaging.

“We saw increases in grey matter volume in the sensorimotor cortices on both sides of the brain and in the hippocampus,” said Chelsey Sterling, M.A., a graduate student in medical psychology and first author of the study. “These increases were accompanied by large improvements in spontaneous arm use in the home environment. Notably, increases in grey matter correlated with improvement in motor activity.”

Sterling says the significant correlation between increases in grey matter volume and magnitude of motor improvement raises the possibility of a causal relationship.

The researchers suggest the observed increase in grey matter could be due to one or more different processes, including an increase in synaptic density, the creation of new neurons or glial cells or the establishment of new blood vessels within the brain.

“An increase in grey matter is indicative that the brain is capable of supporting increased motor activity and function,” said Gitendra Uswatte, Ph.D., a study co-author. “Along with the improvements observed in the dexterity and everyday use of the arm that was the target of rehabilitation, this is a strong indication that a child with cerebral palsy can have substantial gains in motor function when provided with the correct stimulation.”

VBM analysis was performed three weeks prior to therapy, at the beginning of therapy and at the end of the three week therapy period. The authors say that no significant grey matter change was seen during the three weeks before treatment.

The children underwent intensive motor training for three hours each weekday for a three week period in which the child’s less-affected arm was continuously restrained in a long arm cast. Each child’s caregiver received a transfer package, which included steps to induce continuation of use of the more-affected arm at home. The MRI scans were performed at Children’s of Alabama.

Taub, a university professor in the Department of Psychology, developed the family of techniques called CI therapy. The therapy has been shown to be effective in improving the rehabilitation of movement after stroke and other neurological injuries in both children and adults.

“The motor improvement and changes in grey matter following CI therapy observed in this study are similar to those observed previously in adults,” said Taub. “It is further evidence that the brain has a remarkable capacity to heal itself when presented with an efficacious rehabilitation intervention such as CI therapy.”