Apr. 8, 2013 — Fascinating new studies into brain activity and behavioural responses have highlighted the overlap between pathological gambling and drug addiction. The research, which is presented at the British Neuroscience Association Festival of Neuroscience (BNA2013) has implications for both the treatment and prevention of problem gambling.
Dr Luke Clark, a senior lecturer at the University of Cambridge (UK), told the meeting that neurocognitive tests of impulsivity and compulsivity, and also positron emission tomography (PET) imaging of the brain have started to show how gambling becomes addictive in pathological gamblers -- people whose gambling habit has spiralled out of control and become a problem.
"Around 70% of the British population will gamble occasionally, but for some of these people, it will become a problem," he said. "Our work has been seeking to understand the changes in decision-making that happen in people with gambling problems. It represents the first large scale study of individuals seeking treatment for gambling problems in the UK, at a time when this disorder is being re-classified alongside drug addiction as the first 'behavioural addiction'. Given the unique legislation around gambling from country to country, it is vital that we understand gambling at a national level. For example, 40% of the problem gamblers at the National Problem Gambling Clinic report that the game they have a problem with is roulette on Fixed Odds Betting Terminals; this kind of gambling machine is peculiar to the British gambling landscape."
In collaboration between the University of Cambridge and Dr Henrietta Bowden-Jones, director of the UK's only specialist gambling clinic in the Central and North West London NHS Trust, Dr Clark and his colleagues compared the brains and behaviours of 86 male, pathological gamblers with those of 45 healthy men without a gambling problem.
"We approach gambling within the framework of addiction, where we think that problematic gambling arises from a combination of individual risk factors, such as genetics, and features of the games themselves. To study individual factors, we have been testing gamblers at the National Problem Gambling Clinic on neurocognitive tests of impulsivity and compulsivity, and we have also measured their dopamine levels using PET imaging," said Dr Clark.
The tests showed that problem gamblers had increased impulsivity, similar to people with alcohol and drug addictions, but there was less evidence of compulsivity. Levels of dopamine -- a neurotransmitter involved in signalling between nerve cells and which is implicated in drug addiction -- showed differences in the more impulsive gamblers.
"Previous PET research has shown that people with drug addiction have reduced dopamine receptors. We predicted the same effect in pathological gamblers, but we did not see any group differences between the pathological gamblers and healthy men. Nevertheless, the problem gamblers do show some individual differences in their dopamine function, related to their levels of impulsivity: more impulsive gamblers showed fewer dopamine receptors," said Dr Clark. "These studies highlight the overlap between pathological gambling and drug addiction.
"To study the properties of the games themselves and how they relate to problem gambling, we have focussed on two psychological distortions that occur across many forms of gambling: 'near-miss' outcomes (where a loss looks similar or 'close' to a jackpot win) and the 'gambler's fallacy' (for example, believing that a run of heads means that a tail is 'due', in a game of chance). In one important discovery, we were the first lab to show that gambling 'near-misses' recruit brain regions that overlap with those recruited in gambling 'wins'. These responses may cause 'near-misses' to maintain gambling play despite their objective status as losses."
Dr Clark said that these findings had implications for both prevention and treatment. "Gambling distortions like the 'near-miss' effect may be amenable to both psychological therapies for problem gambling, and also by drug treatments that may act on the underlying brain systems. By understanding the styles of thinking that characterise the problem gambler, we may also be able to improve education about gambling in teenagers and young adults, to reduce the number of people developing a gambling problem."
The researchers also found a striking demonstration of the underlying brain regions that are involved in gambling when they studied the gambling behaviour of patients who had experienced brain injury due to a tumour or stroke.
"We have seen that two gambling distortions -- the 'gambler's fallacy' and the 'near-miss' effect -- that are evident in the general population, and which appear to be increased in problem gamblers, are actually abolished in patients with damage to the insula region of the brain," he said. "This suggests that in the healthy brain, the insula may be a critical area in generating these distorted expectancies during gambling play, and that interventions to reduce insula activity may have treatment potential.
"The insula is quite a mysterious part of the brain, tucked deep inside the lateral fissure. It is important in processing pain and, more broadly, in representing the state of the body in the brain, and it is striking that gambling is a very visceral, exciting activity. Our ongoing neuroimaging work will look at the relationship between responses in the insula and the body during our gambling tests."
Future work will investigate the styles of thinking that are in evidence when the problem gamblers at the National Problem Gambling Clinic play the simplified games the researchers have developed. "This is the first study to directly look at whether these biases are more pronounced in problem gamblers. We are also starting to recruit the siblings of problem gamblers (those who do not have a gambling problem themselves) in order to look at underlying vulnerability factors," concluded Dr Clark.
This research is funded by grants from the UK's Medical Research Council, and involves further collaboration with researchers at Imperial College London and the University of Oxford.
Tuesday, April 9, 2013
Non-Invasive Mapping Helps to Localize Language Centers Before Brain Surgery
Apr. 8, 2013 — A new functional magnetic resonance imaging (fMRI) technique may provide neurosurgeons with a non-invasive tool to help in mapping critical areas of the brain before surgery, reports a study in the April issue of Neurosurgery, official journal of the Congress of Neurological Surgeons.
Evaluating brain fMRI responses to a "single, short auditory language task" can reliably localize critical language areas of the brain -- in healthy people as well as patients requiring brain surgery for epilepsy or tumors, according to the new research by Melanie Genetti, PhD, and colleagues of Geneva University Hospitals, Switzerland.
Brief fMRI Task for Functional Brain Mapping
The researchers designed and evaluated a quick and simple fMRI task for use in functional brain mapping. Functional MRI can show brain activity in response to stimuli (in contrast to conventional brain MRI, which shows anatomy only). Before neurosurgery for severe epilepsy or brain tumors, functional brain mapping provides essential information on the location of critical brain areas governing speech and other functions.
The standard approach to brain mapping is direct electrocortical stimulation (ECS) -- recording brain activity from electrodes placed on the brain surface. However, this requires several hours of testing and may not be applicable in all patients. Previous studies have compared fMRI techniques with ECS, but mainly for determining the side of language function (lateralization) rather than the precise location (localization).
The new fMRI task was developed and evaluated in 28 healthy volunteers and in 35 patients undergoing surgery for brain tumors or epilepsy. The test used a brief (eight minutes) auditory language stimulus in which the patients heard a series of sense and nonsense sentences.
Functional MRI scans were obtained to localize the brain areas activated by the language task -- activated areas would "light up," reflecting increased oxygenation. A subgroup of patients also underwent ECS, the results of which were compared to fMRI.
Non-invasive Test Accurately Localizes Critical Brain Areas
Based on responses to the language stimulus, fMRI showed activation of the anterior and posterior (front and rear) language areas of the brain in about 90 percent of subjects -- neurosurgery patients as well as healthy volunteers. Functional MRI activation was weaker and the language centers more spread-out in the patient group. These differences may have reflected brain adaptations to slow-growing tumors or longstanding epilepsy.
Five of the epilepsy patients also underwent ECS using brain electrodes, the results of which agreed well with the fMRI findings. Two patients had temporary problems with language function after surgery. In both cases, the deficits were related to surgery or complications (bleeding) in the language area identified by fMRI.
Functional brain mapping is important for planning for complex neurosurgery procedures. It provides a guide for the neurosurgeon to navigate safely to the tumor or other diseased area, while avoiding damage to critical areas of the brain. An accurate, non-invasive approach to brain mapping would provide a valuable alternative to the time-consuming ECS procedure.
"The proposed fast fMRI language protocol reliably localized the most relevant language areas in individual subjects," Dr. Genetti and colleagues conclude. In its current state, the new test probably isn't suitable as the only approach to planning surgery -- too many areas "light up" with fMRI, which may limit the surgeon's ability to perform more extensive surgery with necessary confidence. The researchers add, "Rather than a substitute, our current fMRI protocol can be considered as a valuable complementary tool that can reliably guide ECS in the surgical planning of epileptogenic foci and of brain tumors."
Evaluating brain fMRI responses to a "single, short auditory language task" can reliably localize critical language areas of the brain -- in healthy people as well as patients requiring brain surgery for epilepsy or tumors, according to the new research by Melanie Genetti, PhD, and colleagues of Geneva University Hospitals, Switzerland.
Brief fMRI Task for Functional Brain Mapping
The researchers designed and evaluated a quick and simple fMRI task for use in functional brain mapping. Functional MRI can show brain activity in response to stimuli (in contrast to conventional brain MRI, which shows anatomy only). Before neurosurgery for severe epilepsy or brain tumors, functional brain mapping provides essential information on the location of critical brain areas governing speech and other functions.
The standard approach to brain mapping is direct electrocortical stimulation (ECS) -- recording brain activity from electrodes placed on the brain surface. However, this requires several hours of testing and may not be applicable in all patients. Previous studies have compared fMRI techniques with ECS, but mainly for determining the side of language function (lateralization) rather than the precise location (localization).
The new fMRI task was developed and evaluated in 28 healthy volunteers and in 35 patients undergoing surgery for brain tumors or epilepsy. The test used a brief (eight minutes) auditory language stimulus in which the patients heard a series of sense and nonsense sentences.
Functional MRI scans were obtained to localize the brain areas activated by the language task -- activated areas would "light up," reflecting increased oxygenation. A subgroup of patients also underwent ECS, the results of which were compared to fMRI.
Non-invasive Test Accurately Localizes Critical Brain Areas
Based on responses to the language stimulus, fMRI showed activation of the anterior and posterior (front and rear) language areas of the brain in about 90 percent of subjects -- neurosurgery patients as well as healthy volunteers. Functional MRI activation was weaker and the language centers more spread-out in the patient group. These differences may have reflected brain adaptations to slow-growing tumors or longstanding epilepsy.
Five of the epilepsy patients also underwent ECS using brain electrodes, the results of which agreed well with the fMRI findings. Two patients had temporary problems with language function after surgery. In both cases, the deficits were related to surgery or complications (bleeding) in the language area identified by fMRI.
Functional brain mapping is important for planning for complex neurosurgery procedures. It provides a guide for the neurosurgeon to navigate safely to the tumor or other diseased area, while avoiding damage to critical areas of the brain. An accurate, non-invasive approach to brain mapping would provide a valuable alternative to the time-consuming ECS procedure.
"The proposed fast fMRI language protocol reliably localized the most relevant language areas in individual subjects," Dr. Genetti and colleagues conclude. In its current state, the new test probably isn't suitable as the only approach to planning surgery -- too many areas "light up" with fMRI, which may limit the surgeon's ability to perform more extensive surgery with necessary confidence. The researchers add, "Rather than a substitute, our current fMRI protocol can be considered as a valuable complementary tool that can reliably guide ECS in the surgical planning of epileptogenic foci and of brain tumors."
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