Martine Lamy

Functional magnetic resonance imaging brain activation in bipolar mania: evidence for disruption of the ventrolateral prefrontal-amygdala emotional pathway.

BACKGROUND Bipolar I disorder is defined by the occurrence of mania. The presence of mania, coupled with a course of illness characterized by waxing and waning of affective symptoms, suggests that bipolar disorder arises from dysfunction of neural systems that maintain emotional arousal and homeostasis. We used functional magnetic resonance imaging (fMRI) to study manic bipolar subjects as they performed a cognitive task designed to examine the ventrolateral prefrontal emotional arousal network. METHODS We used fMRI to study regional brain activation in 40 DSM-IV manic bipolar I patients and 36 healthy subjects while they performed a continuous performance task with emotional and neutral distracters. Event-related region-of-interest analyses were performed to test the primary hypothesis. Voxelwise analyses were also completed. RESULTS Compared with healthy subjects, the manic subjects exhibited blunted activation to emotional and neutral images, but not targets, across most of the predefined regions of interest. Several additional brain regions identified in the voxelwise analysis also exhibited similar differences between groups, including right parahippocampus, right lingual gyrus, and medial thalamus. In addition to these primary findings, the manic subjects also exhibited increased activation in response to targets in a number of brain regions that were primarily associated with managing affective stimuli. Group differences did not appear to be secondary to medication exposure or other confounds. CONCLUSIONS Bipolar manic subjects exhibit blunted brain fMRI response to emotional cues throughout the ventrolateral prefrontal emotional arousal network. Disruption of this emotional network may contribute to the mood dysregulation of bipolar disorder.

Brain-Mapping Techniques for Evaluating Poststroke Recovery and Rehabilitation: A Review

Abstract Brain-mapping techniques have proven to be vital in understanding the molecular, cellular, and functional mechanisms of recovery after stroke. This article briefly summarizes the current molecular and functional concepts of stroke recovery and addresses how various neuroimaging techniques can be used to observe these changes. The authors provide an overview of various techniques including diffusion-tensor imaging (DTI), magnetic resonance spectroscopy (MRS), ligand-based positron emission tomography (PET), single-photon emission computed tomography (SPECT), regional cerebral blood flow (rCBF) and regional metabolic rate of glucose (rCMRglc) PET and SPECT, functional magnetic resonance imaging (fMRI), near infrared spectroscopy (NIRS), electroencephalography (EEG), magnetoencephalography (MEG), and transcranial magnetic stimulation (TMS). Discussion in the context of poststroke recovery research informs about the applications and limitations of the techniques in the area of rehabilitation research. The authors also provide suggestions on using these techniques in tandem to more thoroughly address the outstanding questions in the field.

Magnetic resonance imaging brain activation in first-episode bipolar mania during a response inhibition task.

Aims: Impulsivity is common in bipolar disorder, especially during mania. Understanding the functional neuroanatomy of response inhibition, one component of impulsivity, might clarify the neural substrate of bipolar disorder.

Functional MRI of sustained attention in bipolar mania

We examined sustained attention deficits in bipolar disorder and associated changes in brain activation assessed by functional magnetic resonance imaging (fMRI). We hypothesized that relative to healthy participants, those with mania or mixed mania would (1) exhibit incremental decrements in sustained attention over time, (2) overactivate brain regions required for emotional processing and (3) progressively underactivate attentional regions of prefrontal cortex. Fifty participants with manic/mixed bipolar disorder (BP group) and 34 healthy comparison subjects (HC group) received an fMRI scan while performing a 15-min continuous performance task (CPT). The data were divided into three consecutive 5-min vigilance periods to analyze sustained attention. Composite brain activation maps indicated that both groups activated dorsal and ventral regions of an anterior-limbic network, but the BP group exhibited less activation over time relative to baseline. Consistent with hypotheses 1 and 2, the BP group showed a marginally greater behavioral CPT sustained attention decrement and more bilateral amygdala activation than the HC group, respectively. Instead of differential activation in prefrontal cortex over time, as predicted in hypothesis 3, the BP group progressively decreased activation in subcortical regions of striatum and thalamus relative to the HC group. These results suggest that regional activation decrements in dorsolateral prefrontal cortex accompany sustained attention decrements in both bipolar and healthy individuals. Stable amygdala overactivation across prolonged vigils may interfere with sustained attention and exacerbate attentional deficits in bipolar disorder. Differential striatal and thalamic deactivation in bipolar disorder is interpreted as a loss of amygdala (emotional brain) modulation by the ventrolateral prefrontal-subcortical circuit, which interferes with attentional maintenance.

Cognition, language, and clinical pathological features of non-Alzheimer's dementias: An overview

UNLABELLED There are many distinct forms of dementia whose pharmacological and behavioral management differ. Differential diagnosis among the dementia variants currently relies upon a weighted combination of genetic and protein biomarkers, neuroanatomical integrity, and behavior. Diagnostic specificity is complicated by a high degree of overlap in the initial presenting symptoms across dementia subtypes. For this reason, reliable markers are of considerable diagnostic value. Communication disorders have proven to be among the strongest predictors for discriminating among dementia subtypes. As such, speech-language pathologists may be poised to make an increasingly visible contribution to dementia diagnosis and its ongoing management. The value and durability of this potential contribution, however, demands an improved discipline-wide knowledge base about the unique features associated with different dementia variants. To this end we provide an overview of cognition, language, and clinical pathological features of four of the most common non-Alzheimers dementias: frontotemporal dementia, vascular dementia, Lewy body disease dementia, and Parkinsons disease dementia. LEARNING OUTCOMES Readers will learn characteristics and distinguishing features of several non-Alzheimers dementias, including Parkinsons disease dementia, frontotemporal dementia, vascular dementia, and Lewy body dementia. Readers will also learn to distinguish between several variants of frontotemporal dementia. Finally, readers will gain knowledge of the term primary progressive aphasia as it relates to the aforementioned dementia etiologies.

Affected Arm Use and Cortical Change in Stroke Patients Exhibiting Minimal Hand Movement

Background and Purpose . Conventional electrical stimulation modalities are limited by their lack of opportunities for motor learning and, consequently, their impact on function. Other rehabilitative regimens necessitate affected hand and wrist movement for patients to be included, making them implausible for most patients. In light of these challenges, the current study examined the efficacy of a repetitive task-specific training (RTP) regimen using an electrical stimulation neuroprosthesis in stroke patients exhibiting no affected wrist or hand movement. Method. Eight chronic stroke patients (mean = 46.5 months) with moderately affected arm motor deficits participated in 30-minute therapy sessions occurring every weekday for 8 weeks. During the sessions, they wore the neuroprosthesis to enable performance of valued activities identified largely by the patients. To ensure transfer to their real-world environments, most sessions were home based, with the patients coming to the clinic for “tune-up” sessions (eg, adjusting the stimulation parameters, exercises, and/or fit of the device) twice every other week (a total of 8 clinical visits). Outcomes were evaluated using the Action Research Arm Test (ARAT) and the upper extremity section of the Fugl-Meyer Assessment (FM), the amount of use scale of the Motor Activity Log (MAL), and high-field functional magnetic resonance imaging (fMRI). Results. Before the intervention, patients exhibited stable motor deficits. After the intervention, they exhibited ARAT and FM score increases (+2.85 and +2.2, respectively). Postintervention fMRI revealed significant increases in cortical activation, possibly brought about by markedly increased affected arm use patterns on the MAL (+0.97). Conclusions. An affected arm RTP program incorporating NEURSTIM appears to increase affected arm use and elicit neural changes in more impaired patients. These factors may conspire to produce motor changes, although motor changes are smaller in this population than with less impaired patients. The program may act as a “bridge” to other promising regimens.

Use of fMRI in the study of chronic aphasia recovery after therapy: a case study.

Abstract Purpose: The role of intensity of aphasia therapy was investigated using functional magnetic resonance imaging (fMRI) to document changes in neural activation patterns associated with massed versus distributed therapy in an individual with chronic conduction aphasia. Method: Language therapy targeted word-finding deficits and phonological processing. fMRI scans were acquired at baseline, after massed therapy, and after distributed therapy. Results: Treatment was effective, as demonstrated by increases in performance on standardized measures, narrative analysis, and task performance in the fMRI scanner. Task improvement across fMRI testing sessions corresponded with increases in fMRI blood oxygenation level dependent (BOLD) signal. Greatest behavioral gains and BOLD signal increases occurred after massed therapy, with slight gains accompanying distributed therapy. Increases in fMRI BOLD signal occurred after therapy in left basal ganglia and right hemisphere frontotemporal cortex. Conclusions: Intensity of aphasia therapy impacts the recovery process and warrants additional research. Basal ganglia and right hemisphere structures may be important neural substrates for aphasia recovery.

Bipolar I disorder and major depressive disorder show similar brain activation during depression

Despite different treatments and courses of illness, depressive symptoms appear similar in major depressive disorder (MDD) and bipolar I disorder (BP‐I). This similarity of depressive symptoms suggests significant overlap in brain pathways underlying neurovegetative, mood, and cognitive symptoms of depression. These shared brain regions might be expected to exhibit similar activation in individuals with MDD and BP‐I during functional magnetic resonance imaging (fMRI).

MRI brain activation in first-episode bipolar mania during a response inhibition task

Aims: Impulsivity is common in bipolar disorder, especially during mania. Understanding the functional neuroanatomy of response inhibition, one component of impulsivity, might clarify the neural substrate of bipolar disorder.

Differential brain activation during response inhibition in bipolar and attention‐deficit hyperactivity disorders

Aim: To identify differential patterns of brain activation between adolescents with bipolar disorder and adolescents with attention‐deficit hyperactivity disorder (ADHD) to better understand the neurophysiology of both disorders. We hypothesized that subjects with ADHD would show altered activation in brain regions involved in executive and sustained attention. In contrast, we hypothesized that bipolar subjects would show altered brain activation in regions responsible for emotionally homeostasis, including the striatum and amygdala.