Alertness and visuospatial attention in clinical depression

<p>Abstract</p> <p>Background</p> <p>Cognitive deficits are a substantial burden in clinical depression. The present study considered dysfunction in the right-hemispheric attention network in depression, examining alertness and visuospatial attention.</p> <p>Methods</p> <p>Three computerized visuospatial attention tests and an alertness test were administered to 16 depressive patients and 16 matched healthy controls.</p> <p>Results</p> <p>Although no significant group effect was observed, alertness predicted reduced visuospatial performance in the left hemifield. Furthermore, sad mood showed a trend towards predicting left visual field omissions.</p> <p>Conclusions</p> <p>Decreased alertness may lead to lower left hemifield visuospatial attention; this mechanism may be responsible for a spatial bias to the right side in depression, even though treatment of depression and anxiety may reduce this cognitive deficit.</p

The spatial representation of numbers: Evidence from neglect and pseudoneglect.

The aim of the present paper is to provide an overview of the evidence that links spatial representation with representation of number magnitude. This aim is achieved by reviewing the literature concerning the number interval bisection task in patients with left hemispatial neglect and in healthy participants (pseudoneglect). Phenomena like the Spatial Numerical Association of Response Codes (SNARC) eVect and the shifts of covert spatial attention caused by number processing are thought to support the notion that number magnitude is represented along a spatially organized mental number line. However, the evidence provided by chronometric studies is not univocal and is open to alternative, non-spatial interpretations. In contrast, neuropsychological studies have offered convincing evidence that humans indeed represent numbers on a mental number line oriented from left to right. Neglect patients systematically misplace the midpoint of a numerical interval they are asked to bisect (e.g., they say that 5 is halfway between 2 and 6) and their mistakes closely resemble the typical pattern found in bisection of true visual lines. The presence of dissociations between impaired explicit knowledge and spared implicit knowledge supports the notion that neglect produces a defcit in accessing an intact mental number line, rather than a distortion in the representation of that line. Other results show that the existence of a strong spatial connotation constitutes a specific property of number representations rather than a general characteristic of all ordered sequences