Cortex; a journal devoted to the study of the nervous system and behavior
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The last couple of decades have seen the development of a number of non-invasive brain stimulation (NIBS) techniques that are capable of inducing short-lasting plasticity in the human cortex. Importantly, the induction of lasting plastic changes can, under some conditions, reversibly modify behaviour and interact with learning. ⋯ We then outline the areas in which these techniques might be useful, namely, investigating the mechanisms of human cortical plasticity, the characterisation of influences on plasticity, and the investigation of the role of cortical regions in behaviour. Finally, we conclude by highlighting some current limitations of the techniques and suggest that further development of the current NIBS paradigms and more focussed targeting should further enhance the utility of these powerful non-invasive techniques for the investigation of the cortical plasticity and pathophysiology.
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Cognitive changes in the prodromal phase of Huntington disease (prHD) are found in multiple domains, yet their neural bases are not well understood. One component process that supports cognition is inhibitory control. In the present fMRI study, we examined brain circuits involved in response inhibition in 65 prHD participants and 36 gene-negative (NEG) controls using the stop signal task (SST). ⋯ The results were not related to changes in cortical volume and thickness, which did not differ among the groups. However, greater hypoactivation of classic right-hemisphere inhibition centers [inferior frontal gyrus (IFG)/insula, SMA/anterior cingulate cortex (ACC)] during inhibition failures correlated with greater globus pallidus atrophy. These results are the first to demonstrate that response inhibition in prHD is associated with altered functioning in brain networks that govern inhibition, attention, and motor control.
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The brain transforms sensory input to motor coordinates to accommodate for changes of posture and gaze direction. Neurophysiological and neuropsychological evidence supports the existence of multiple representations of space. A debated issue regards whether objects that we see are encoded in egocentric frames only or also maintain an object-centered frame of reference. ⋯ We then displayed these stimuli at different egocentric positions allowing us to independently measure the effects of allocentric position, egocentric position as well as their interaction. In a group of stroke patients with neglect we demonstrate that allocentric biases are modulated as a function of egocentric position. These findings help adjudicate between the different models of space representation, demonstrating that specific allocentric deficits not only exist but also often co-exist with egocentric biases.