Posts Tagged cerebral activity.
Obsessive-compulsive disorder (OCD) is a condition marked by inescapable, intrusive thoughts that cause anxiety (hence “obsessive”), and repetitive, ritualistic behaviors aimed at reducing that feeling (hence “compulsive”).
OCD can be a debilitating condition and can severely impair daily functioning. The National Institutes of Mental Health estimate that, in the United States, the yearly prevalence of OCD amounts to 1 percent of the total adult population. Around half of these cases are deemed “severe.”
Researchers from the University of California, Los Angeles – who were led by Dr. Jamie Feusner – have conducted a study aiming to find out whether and how CBT might change levels of activity and network connectivity in the brains of people diagnosed with OCD.
They explain that although the efficacy of CBT in treating OCD has been previously explored, this is likely the first study to use functional MRI (fMRI) to monitor what actually happens in the brains of people with OCD after exposure to this kind of therapy.
The researchers’ findings were recently published in the journal Translational Psychiatry.
Changes in key brain regions following CBT
The team specifically targeted the effects of exposure and response prevention (ERP)-based CBT, which entails exposure to triggering stimuli and encouraging the individual to wilfully resist responding to those stimuli in the way that they normally would.
For the study, 43 people with OCD and 24 people without it were recruited. The results for the two groups were later compared, at which point the 24 individuals without OCD were taken as the control group.
All the participants diagnosed with OCD received intensive ERP-based CBT on an individual basis in 90-minute sessions on 5 days per week, for a total of 4 weeks.
Participants from both groups underwent fMRI. Those diagnosed with OCD, who had received CBT, were scanned both before the treatment period and after the 4 weeks of treatment. Participants from the control group, who did not undergo CBT, also had fMRI scans after 4 weeks.
When the scans of participants with OCD were compared, the results from before exposure to CBT and after it were found to be largely contrasting.
The researchers noticed that the brains of people with OCD exhibited a significant increase in connectivity between eight different brain networks, including the cerebellum, the caudate nucleus and putamen, and the dorsolateral and ventrolateral prefrontal cortices.
The dorsolateral and ventrolateral prefrontal cortices are involved with planning action and movement, as well as regulating certain cognitive processes.
Dr. Feusner and team point out that an increased level of connectivity between these cerebral regions suggests that the brains of the people who underwent CBT were “learning” new non-compulsive behaviors and activating different thought patterns.
He suggests that these changes may be novel ways of coping with the cognitive and behavioral idiosyncrasies of OCD.
“The changes appeared to compensate for, rather than correct, underlying brain dysfunction. The findings open the door for future research, new treatment targets, and new approaches.”
Dr. Jamie Feusner
First study author Dr. Teena Moody adds that being able to show that there are quantifiable positive changes in the brain following CBT may give people diagnosed with OCD more confidence in following suitable treatments.
“The results could give hope and encouragement to OCD patients,” says Dr. Moody, “showing them that CBT results in measurable changes in the brain that correlate with reduced symptoms.”
Neuro-rehabilitation (physical therapy, occupational therapy, etc.) helps hemaparetic stroke patients confronted with loss of motor skills on one side of their body, to recover some of their motor functions after a cerebrovascular accident. One of the most promising tracks in neuro-rehabilitation consists of amplifying the motor learning ability after a stroke, in other words how to learn (again) how to make movements with the parts of the human body impacted after a stroke.
Pilot studies have shown that tDCS (transcranial direct current stimulation) – a non-invasive and painless cerebral stimulation method – modulated the cerebral activity and increased the motor performances of patients who have had a stroke. This method consists of applying low voltage electric currents to the patient’s head by means of electrodes during short periods of time. In 2012, a first study conducted by the teams of Professors Yves Vandermeeren and Patrice Laloux demonstrated that tDCS amplified the motor learning and the long-term motor memory of the patient after a stroke. This study was awarded the Fernand Depelchin Prize of the Université catholique de Louvain (UCL) and allowed the CHU Neurology Team to continue its research, in particular via the use of functional Magnetic Resonance Imaging (fMRI) of the brain.
Nineteen hemiparetic stroke patients (with a motor deficit in the upper limb) participated in this new clinical trial. In order to avoid study bias, the stimulations were performed in a double-blind, randomised fashion. Each patient received a real stimulation as well as a placebo-stimulation during two separate sessions. It was impossible for patients to determine whether they received a true or a placebo-stimulation.
During the first stimulation session (real or placebo), the patients learned how to perform a task with a paralysed hand, combining speed and accuracy. One week later, they performed the learned task while the functional MRI scanner recorded their cerebral activity. After one week, this experience was repeated with the other stimulation (placebo or real).
As in the previous study, the non-invasive cerebral stimulation amplified the motor learning capacity with the paralyzed hand and the long-term memory retention in a spectacular way for patients following chronic stroke.
Thanks to functional MRI, this second study demonstrated that the combination of motor learning and non-invasive cerebral stimulation improves the efficiency of the cerebral activity. Indeed, one week after the placebo stimulation, the cerebral activations measured via the functional MRI was very diffuse. Large cerebral zones were somehow ‘recruited’ although motor performance was low (poor retention). On the other hand, one week after real stimulation, the cerebral activation was focused on the essential motor zones, almost identical to a person without stroke-impact although the motor performance was significantly better (enhanced task retention). In other words, the combination of motor learning and tDCS reinforced the essential motor zones and this specific network was reactivated one week after the real intervention.
For thousands of stroke victims, this study opens considerable perspectives in the domain of neuro-rehabilitation. A better understanding of the cerebral functioning after a stroke and how non-invasive cerebral stimulation works will help researchers to develop the neuro-rehabilitation of the future. The results of this study will be implemented within the consortium Louvain Bionics, inaugurated recently at UCL.