Dawn Bowers

Pseudoneglect: effects of hemispace on a tactile line bisection task.

Abstract The purpose of this study was to determine whether tactile laterality effects can be attributed to an anatomical pathway-transmission model or to some hemispheric mechanism involved in the perception and/or mediation of activities in the contralateral hemispatial field. Hemispace is not the same as the visual half field, but refers to the external space to the left or right of body midline. To differentiate between these two hypotheses, 24 normal dextrals performed a tactile line bisection task using the left or right hand in each of three spatial conditions: at midline, in left hemispace and right hemispace. The findings indicated that both hemisphere-hemispace mechanisms and hemisphere-hand connections contributed to laterality effects. Furthermore, a pseudoneglect phenomenon was observed.

Cognition and Mood in Parkinson's Disease in Subthalamic Nucleus versus Globus Pallidus Interna Deep Brain Stimulation: The COMPARE Trial

Our aim was to compare in a prospective blinded study the cognitive and mood effects of subthalamic nucleus (STN) vs. globus pallidus interna (GPi) deep brain stimulation (DBS) in Parkinson disease.

Comprehension of affective and nonaffective prosody

We studied patients with damage of either the right (RHD) or left hemisphere (LHD) and control subjects to determine whether the RHD patients had a global or limited prosodic defect. Compared with LHD patients and controls, RHD subjects had decreased comprehension of emotional prosody. Both LHD and RHD groups had more impaired comprehension of propositional prosody than controls, but the RHD and LHD groups did not differ. The right hemisphere, therefore, seems to be dominant for comprehending emotional prosody but not propositional prosody.

Recognition and discrimination of emotional faces and pictures

Abstract In order to learn whether patients with right-hemisphere disease (RHD) had a deficit in their ability to discriminate and comprehend emotional faces and pictures, we studied nine patients with RHD, nine patients with left-hemisphere disease (LHD), and nine controls. The subjects were presented with six picture tests that comprised either emotional faces or emotional scenes. Their task was either to denote (name or choose) an emotion or to discriminate (same, different) between two faces or emotions. Patients with RHD performed significantly worse than subjects with LHD when asked to discriminate between faces, to discriminate between emotional faces, and to name emotional scenes. There was also a trend for the RHD group to be more impaired than the LHD group when asked to name the emotional face or choose the emotional face. Except for the facial and emotional discrimination tests, the LHD patients also performed worse than controls.

Dissociating apathy and depression in Parkinson disease

Objective: To examine the hypothesis that apathy is a core feature of Parkinson disease (PD) and that apathy can be dissociated from depression. Methods: Eighty patients with PD and 20 patients with dystonia completed depression and apathy measures including the Marin Apathy Evaluation Scale (AES), Beck Depression Inventory (BDI), and Centers for Epidemiologic Studies–Depression Scale (CES-D). Results: There was a significantly higher severity and frequency of apathy in PD (frequency = 51%, 41/80) than in dystonia (frequency = 20%, 4/20). Apathy in the absence of depression was frequent in PD and did not occur in dystonia (PD = 28.8%, dystonia = 0%). Conclusions: Patients with Parkinson disease (PD) experienced significantly higher frequency and severity of apathy when compared with patients with dystonia. Apathy may be a “core” feature of PD and occurs in the absence of depression.

Processing of faces by patients with unilateral hemisphere lesions: I. Dissociation between judgments of facial affect and facial identity

In this study, right-hemisphere-damaged (RHD) subjects performed significantly worse than LHD and NHD controls across a series of seven facial identity and facial affect tasks. Even when the patient groups were statistically equated on a measure of visuoperceptual ability, the RHD group remained impaired on three emotional tasks--naming, picking, and discriminating emotional faces. These findings suggest that the defects shown by RHD patients on facial affect tasks cannot be solely attributed to defects in visuoperceptual processing and that the right-hemisphere superiority for processing facial affect exists above and beyond its superiority for processing facial identity.

Hemispace and Hemispatial Neglect

A patient with hemispatial neglect may fail to report, respond, or orient toward novel or meaningful stimuli presented in the hemispace contralateral to a brain lesion. Hemispatial neglect may be induced by a sensory-attentional, motor-intentional, memory, or an exploratory disorder. This chapter defines hemispatial neglect and describes how it may be tested in patients. There is a review of hemispace studies in normal subjects. The pathophysiology of the attentional, intentional memory, and exploratory defects is discussed. Finally, recovery of function and treatments are also discussed.

Effects of left frontal transcranial magnetic stimulation on depressed mood, cognition, and corticomotor threshold

BACKGROUND The pathophysiology of depression may include synaptic hypoactivity of left prefrontal cortex. Several groups of investigators have described improved mood associated with rapid transcranial magnetic stimulation (rTMS) but have not looked for possible cognitive side effects associated with left prefrontal magnetic stimulation. METHODS We measured the effects of left prefrontal rTMS on mood, cognition, and motor evoked potential threshold in 10 patients with medication-resistant major depression. RESULTS In a 2-week open trial of left prefrontal rTMS off antidepressant medications, scores on the Hamilton Rating Scale for Depression and the Beck Depression Inventory decreased by 41% and 40%, respectively. After resuming pre-rTMS antidepressant medication, improvement in mood was still significant at 1 and 3 months later. rTMS had no adverse effects on neuropsychological performance. rTMS treatments were associated with significant decreases in motor evoked potential threshold in the 9 of 10 patients who remained off psychotropic medications during the 2-week treatment period. CONCLUSIONS These preliminary data suggest that left prefrontal rTMS is safe and improves mood in patients with medication-resistant major depression. Changes in motor evoked potential threshold suggest that prefrontal rTMS may alter brain activity at sites remote from the stimulation. Double-blind, sham-controlled studies are needed.

Emotional facial imagery, perception, and expression in Parkinson's disease.

Patients with Parkinsons disease (PD) may be impaired at expressing emotional faces and perceiving emotional facial affect.We tested the hypothesis that patients with PD may be impaired at imaging emotional faces. We first compared 12 patients with PD and 30 control subjects on perceptual and imagery tasks. Patients were significantly impaired on a task of emotional facial imagery but not on a control task of object imagery. Patients were also impaired on a task of perceiving emotional faces. Subsequently, we found that PD patients were impaired relative to controls on making emotional faces. Performance on both the perceptual and motor tasks of facial expression significantly correlated with performance on the emotional facial imagery task. We suggest that the basal ganglia, together with the right hemisphere, are part of a neural network subserving emotional facial tasks. NEUROLOGY 1995;45: 1696-1702

Deep brain stimulation in the internal capsule and nucleus accumbens region: responses observed during active and sham programming

Background: Recently, anterior limb of the internal capsule and nucleus accumbens deep brain stimulation (DBS) has been used in the treatment of medication-refractory obsessive–compulsive disorder (OCD). This region has been previously explored with lesion therapy, but with the advent of DBS there exists the possibility of monitoring the acute and chronic effects of electrical stimulation. The stimulation-induced benefits and side effects can be reversibly and blindly applied to a variety of locations in this region. Objective: To explore the acute effects of DBS in the anterior limb of the internal capsule and nucleus accumbens region. Methods: Ten total DBS leads in five patients with chronic and severe treatment-refractory OCD were tested. Patients were examined 30 days after DBS placement and received either “sham” testing or actual testing of the acute effects of DBS (the alternative condition tested 30 days later). Results: Pooled responses were reviewed for comparability of distribution using standard descriptive methods, and relationships between the variables of interest were sought using χ2 analysis. A total of 845 stimulation trials across the five patients were recorded and pooled. Of these 16% were elicited from sham stimulation and 17% from placebo (0 V stimulation). A comparison of active to sham trials showed that sham stimulation was not associated with significant side effects or responses from patients. Non-mood-related responses were found to be significantly associated with the ventral lead contacts (0 and 1) (p = 0.001). Responses such as taste, smell and smile were strongly associated with the most ventral lead positions. Similarly, physiological responses—for example, autonomic changes, increased breathing rate, sweating, nausea, cold sensation, heat sensation, fear, panic and panic episodes—were significantly associated with ventral stimulation (p = 0.001). Fear and panic responses appeared clustered around the most ventral electrode (0). Acute stimulation resulted in either improved or worsened mood responses in both the dorsal and ventral regions of the anterior limb of the internal capsule. Conclusion: The acute effects of DBS in the region of the anterior limb of the internal capsule and nucleus accumbens, particularly when obtained in a blinded fashion, provide a unique opportunity to localise brain regions and explore circuitry.