Clustering and switching in verbal fluency: a comparison between control and individuals with brain damage

ABSTRACT Purpose The aim of this study is to analyze and compare the performance and strategies used by control subjects and patients with unilateral brain damage on phonemic and semantic Verbal Fluency tasks. Methods The sample consisted of 104 participants divided into four groups (26 with left hemisphere damage and aphasia- LHDa, 28 with left hemisphere damage and no aphasia- LHDna, 25 with right hemisphere damage- RHD and 25 neurologically healthy control subjects). All participants were administered the phonemic (“M” letter-based) and semantic (animals) verbal fluency tasks from the Montreal-Toulouse Language Assessment Battery (MTL-BR). Results Patients in the LHDa group showed the worst performance (fewer words produced, fewer clusters and switches) in both types of fluency task. RHD group showed fewer switching productions when compared with controls and LHDna had fewer words productions than controls in the first 30 seconds block. Conclusion Our findings suggest that the LHDa group obtained lower scores in most measures of SVF and PVF when compared to the other groups.

Investigating Musical Emotions in People with Unilateral Brain Damage

The study under discussion sought to investigate the hemispheric laterality of musical emotions: Is one hemisphere of the brain preferentially involved in recognizing emotions in music? The authors took a neuropsychological approach to answer this question by studying emotional judgments of music in people with brain damage to either hemisphere. Their results indicated that individuals with left hemisphere damage were significantly impaired in recognizing musical emotions as compared to healthy comparison participants. In contrast, individuals with right hemisphere damage were not impaired at identifying emotions in music, but rated the perceived intensity of the emotions lower for sadness and fear (as compared to joy and serenity). Their work suggests that the identification of emotions in music and the perceived intensity of the emotions expressed may rely on different hemispheres of the brain.

Body Representation Alterations in Patients with Unilateral Brain Damage

Objective: Systematic studies about the impact of unilateral brain damage on the different body representations (body schema, body structural representation, and body semantics) are still rare. Aim of this study was to evaluate body representation deficits in a relatively large sample of patients with unilateral brain damage and to investigate the impact of right or left brain damage on body representations (BRs), independently from deficits in other cognitive processes. Method: Sixty-four patients with unilateral stroke (22 with left brain damage, LBD; 31 with right brain damage without neglect, RBD-N; 11 with right brain damage with neglect, RBD+N) and 41 healthy individuals underwent a specific battery including BR as well as control tasks. Results: In more than a third of the sample, selective (37.5%) and pure (31%) deficits of BR were presented and equally distributed among the different BRs (˜10% for each representation), with selective (27.2%) and pure (22.7%) body schema deficit mainly presented after left brain damage. As a group, patients with unilateral brain damage, independently of the side of lesion (LBD, RBD-N, RBD+N), had significantly worse performance on body structural representation with respect to healthy individuals, whereas LBD had numerically worse performance on body schema with respect to healthy individuals and RBD-N. No significant differences among groups were found on body semantics. Conclusion: BR deficits are not a rare consequence of unilateral brain damage and are independent of a more general cognitive dysfunction. Accordingly, the need for an accurate assessment and specific neuropsychological training in clinical settings is discussed.

Functional Lateralization of the Mirror Neuron System in Monkey and Humans

To date, both in monkeys and humans, very few studies have addressed the issue of the lateralization of the cortical parietal and premotor areas involved in the organization of voluntary movements and in-action understanding. In this review, we will first analyze studies in the monkey, describing the functional properties of neurons of the parieto-frontal circuits, involved in the organization of reaching-grasping actions, in terms of unilateral or bilateral control. We will concentrate, in particular, on the properties of the mirror neuron system (MNS). Then, we will consider the evidence about the mirror neuron mechanism in humans, describing studies in which action perception, as well as action execution, produces unilateral or bilateral brain activation. Finally, we will report some investigations demonstrating plastic changes of the MNS following specific unilateral brain damage, discussing how this plasticity can be related to the rehabilitation outcome

Quantitative assessment of motor neglect

Objectives. Patients with unilateral brain damage may avoid moving the limbs contralateral to their lesion, even in the absence of sensorimotor deficits. However, when asked to move their limbs these patients typically show normal strength and dexterity. In their seminal 1983 article on the Journal of Neurology, Neurosurgery and Psychiatry, Laplane and Degos dubbed this condition Motor Neglect (MN). MN can mimic hemiplegia, with severe clinical consequences. Its assessment has thus important clinical implications. However, MN diagnosis is at present highly subjective, because it is based on the clinical observation of patients' spontaneous motor behaviour. Here we introduce differential actigraphy as a novel, objective method to quantify MN. Methods. Patients wear wristwatch-like accelerometers, which record spontaneous motor activity of their upper limbs during 24 hours. Asymmetries of motor behaviour are then automatically computed offline. On the basis of normal participants' performance, we calculated cut-off scores of left/right motor asymmetry. Results. Differential actigraphy showed contralesional MN in nine of 35 patients with unilateral strokes, consistent with clinical assessment. An additional patient with clinical signs of MN obtained a borderline asymmetry score. Lesion location in a subgroup of 25 patients was highly variable, suggesting that MN is a heterogenous condition. Conclusions. Differential actigraphy provides an ecological measure of spontaneous motor behaviour, and can assess upper limb motricity in an objective and quantitative manner. It thus offers a convenient, cost-effective, and relatively automatized procedure for following-up motor behaviour in neurological patients, and to assess the effects of rehabilitation.

Are there sex differences in the brain basis of literacy related skills? Evidence from reading and spelling impairments after early unilateral brain damage

Reading and spelling performance was analysed for a sample of 45 children with unilateral brain damage. Boys showed impairments only when the lesion was on the left, while girls showed no significant impairments when either hemisphere was affected. The results support the hypothesis that specialised substrates, which underlie literacy acquisition, have limited plasticity and may be more strongly lateralised to the left hemisphere in males than in females.