Brain : a journal of neurology
-
Randomized Controlled Trial
Why do patients with neurodegenerative frontal syndrome fail to answer: 'In what way are an orange and a banana alike?'.
Concept formation is the ability to create an abstract link between dissimilar objects or thoughts and is crucial for abstract and creative thinking. This process is related to the integrity of the prefrontal cortex, given the altered performances reported in patients with frontal damage, particularly those suffering from the behavioural variant of frontotemporal dementia. However, the cognitive mechanisms and neural bases of verbal concept formation are not clearly understood. ⋯ Linking and abstraction deficits were related to partially different areas: the linking deficit to the dorsal anterior cingulate cortex, right middle frontal gyrus and both inferior parietal lobules and the abstraction deficit to the head of the caudate nuclei and the left superior frontal gyrus. These data suggest that verbal concept formation requires the integrity of the prefrontal-basal-ganglion functional network. In addition, it can be divided into two distinct cognitive processes, which are underlain by two partially different neural networks.
-
Randomized Controlled Trial
Neural substrates underlying stimulation-enhanced motor skill learning after stroke.
Motor skill learning is one of the key components of motor function recovery after stroke, especially recovery driven by neurorehabilitation. Transcranial direct current stimulation can enhance neurorehabilitation and motor skill learning in stroke patients. However, the neural mechanisms underlying the retention of stimulation-enhanced motor skill learning involving a paretic upper limb have not been resolved. ⋯ Finally, dual transcranial direct current stimulation applied during the first session enhanced continued learning with the paretic limb 1 week later, relative to the sham series. This lasting behavioural enhancement was associated with more efficient recruitment of the motor skill learning network, that is, focused activation on the motor-premotor areas in the damaged hemisphere, especially on the dorsal premotor cortex. Dual transcranial direct current stimulation applied during motor skill learning with a paretic upper limb resulted in prolonged shaping of brain activation, which supported behavioural enhancements in stroke patients.
-
Randomized Controlled Trial
Oxytocin improves behavioural and neural deficits in inferring others' social emotions in autism.
Recent studies have suggested oxytocin's therapeutic effects on deficits in social communication and interaction in autism spectrum disorder through improvement of emotion recognition with direct emotional cues, such as facial expression and voice prosody. Although difficulty in understanding of others' social emotions and beliefs under conditions without direct emotional cues also plays an important role in autism spectrum disorder, no study has examined the potential effect of oxytocin on this difficulty. Here, we sequentially conducted both a case-control study and a clinical trial to investigate the potential effects of oxytocin on this difficulty at behavioural and neural levels measured using functional magnetic resonance imaging during a psychological task. ⋯ Behaviourally, oxytocin significantly increased the correct rate in inferring others' social emotions (P = 0.043, one-tail). At the neural level, the peptide significantly enhanced the originally-diminished brain activity in the right anterior insula during inferring others' social emotions (P = 0.004), but not in the dorsomedial prefrontal cortex during inferring others' beliefs (P = 0.858). The present findings suggest that oxytocin enhances the ability to understand others' social emotions that have also required second-order false belief rather than first-order false beliefs under conditions without direct emotional cues in autism spectrum disorder at both the behaviour and neural levels.
-
Randomized Controlled Trial
Stimulation of the pedunculopontine nucleus area in Parkinson's disease: effects on speech and intelligibility.
Improvement of gait disorders following pedunculopontine nucleus area stimulation in patients with Parkinson's disease has previously been reported and led us to propose this surgical treatment to patients who progressively developed severe gait disorders and freezing despite optimal dopaminergic drug treatment and subthalamic nucleus stimulation. The outcome of our prospective study on the first six patients was somewhat mitigated, as freezing of gait and falls related to freezing were improved by low frequency electrical stimulation of the pedunculopontine nucleus area in some, but not all, patients. Here, we report the speech data prospectively collected in these patients with Parkinson's disease. ⋯ Although limited in our group of patients, speech impairment following pedunculopontine nucleus area stimulation is a possible outcome that should be considered before undertaking such surgery. Deleterious effects could be dependent on electrode insertion in this brainstem structure, more than on current spread to nearby structures involved in speech control. The effect of deep brain stimulation on speech in patients with Parkinson's disease remains a challenging and exploratory research area.
-
Randomized Controlled Trial
Directional deep brain stimulation: an intraoperative double-blind pilot study.
Deep brain stimulation of different targets has been shown to drastically improve symptoms of a variety of neurological conditions. However, the occurrence of disabling side effects may limit the ability to deliver adequate amounts of current necessary to reach the maximal benefit. Computed models have suggested that reduction in electrode size and the ability to provide directional stimulation could increase the efficacy of such therapies. ⋯ The observed side effects related to direction of stimulation were consistent with the anatomical location of surrounding structures. This new approach opens the door to an improved deep brain stimulation therapy. Chronic implantation is further needed to confirm these findings.