Cerebral perfusion and neuropsychological follow up in mild traumatic brain injury: Acute versus chronic disturbances?

In a subgroup of patients with mild traumatic brain injury (TBI) residual symptoms, interfering with outcome and return to work, are found. With neuropsychological assessment cognitive deficits can be demonstrated although the pathological underpinnings of these cognitive deficits are not fully understood. As the admission computed tomography (CT) often is normal, perfusion CT imaging may be a useful indicator of brain dysfunction in the acute phase after injury in these patients.In the present study, directly after admission perfusion CT imaging was performed in mild TBI patients with follow-up neuropsychological assessment in those with complaints and a normal non-contrast CT. Neuropsychological tests comprised the 15 Words test Immediate Recall, Trailmaking test part B, Zoo Map test and the FEEST, which were dichotomized into normal and abnormal. Perfusion CT results of patients with normal neuropsychological test scores were compared to those with abnormal test scores.In total eighteen patients were included. Those with an abnormal score on the Zoo Map test had a significant lower CBV in the right frontal and the bilateral parieto-temporal white matter. Patients with an abnormal score on the FEEST had a significant higher MTT in the bilateral frontal white matter and a significant decreased CBF in the left parieto-temporal grey matter. No significant relation between the perfusion CT parameters and the 15 Words test and the Trailmaking test part B was present.In conclusion, impairments in executive functioning and emotion perception assessed with neuropsychological tests during follow up were related to differences in cerebral perfusion at admission in mild TBI. The pathophysiological concept of these findings is discussed.     

Sensory substitution: an approach to the experimental study of perception / Sustitución sensorial: un abordaje para el estudio experimental de la percepción

Abstract

Sensory substitution refers to the phenomenon where object and environment information normally acquired through one sense can be obtained by another sense. For example, visual input being provided by hearing or touching. Sensory substitution devices are technological designs that transform the characteristics of one sensory modality into stimuli of another sensory modality. These devices were developed with two purposes: (1) to assist people with sensory disabilities in daily tasks; and (2) to study the involved mechanisms of brain plasticity. This article reviews studies in which sensory substitution phenomenon is employed as a methodological strategy to study visual perception. Furthermore, its use is discussed as an experimental platform to contrast new perceptual theories and underlying neurophysiological mechanisms that are currently under review.