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When we move our eyes, we easily keep track of where relevant things are in the world. Recent proposals link this stability to the shifting of receptive fields of neurons in eye movement and attention control areas. Reports of "spatiotopic" visual aftereffects have also been claimed to support this shifting connectivity even at an early level, but these results have not held up. Here we describe the process of updating visual location as predictive shifts of location "pointers" to attended targets, analogous to predictive activation seen cross-modally. We argue that these location pointers, the core operators of spatial attention, are linked to identity information and that such a link is necessary in order to establish a workable visual architecture and to explain frequently reported positive spatiotopic biases. The challenge of eye movementsBecause of our frequent eye and head movements, the image of the world moves constantly on our retina. Despite this instability, we know where things are around us, at least well enough to get by. Hurrying down the stairs we may slip but quickly grab hold of a handrail that we only glimpsed briefly a moment earlier. This knowledge might be represented in the brain as an explicit spatiotopic (see Glossary) map of the scene, where object locations are given in world-based coordinates that are independent of the orientations of our eyes, head, and body. This conjecture of an explicit spatiotopic map has been proposed several times [1][2][3][4][5], but has been vigorously challenged as unnecessary and unsupported [6][7][8][9][10][11][12]. This long debate has been completely transformed by two recent discoveries: remapping and spatiotopic visual aftereffects. In remapping, a neuron in attention and saccade control areas can be activated by a stimulus far outside its receptive field, even in the opposite visual field, if an impending saccade will bring that stimulus into the classical receptive field of the cell [13][14][15][16][17][18] (see Figure 1). This predictive transfer of activation has been attributed to shifting receptive fields and been proposed as a possible mechanism for visual stability. In the case of visual aftereffects, adaptation to a tilted grating, for example, causes a vertical test to appear tilted away from vertical in the direction opposite the adaptation grating. This negative aftereffect is typically © 2010 Elsevier Ltd. All rights reserved.Corresponding author: Cavanagh, P. (patrick.cavanagh@parisdescartes.fr). Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. seen at the same retinal location as the adap...

Tuberous Sclerosis Complex (TSC) is a multi-system genetic disorder associated with a wide range of physical features and very high rates of numerous neurocognitive manifestations. However, there is great variability of expression of these features and understanding of the mechanisms underlying this variability is still limited. Mental retardation (MR) and male gender are known to be associated with increased risks of psychopathologies in the general population, but no study has examined these subgroups in TSC as possible contributors to the variable expression observed. It has also remained unclear whether familial-sporadic differences may contribute to variable expression. In this postal survey, UK families reported the frequency and range of physical and behavioural abnormalities in 265 children and adolescents with TSC. Analysis revealed no gender or familial-sporadic differences. Children with MR were significantly more likely to have an autism spectrum disorder, attention deficit-related symptoms and speech and language difficulties. They were more likely to have a history of epilepsy, facial angiofibromata and shagreen patches and tended to have a greater number of physical features of the disorder. However, about one third of the children without MR had features suggestive of a developmental disorder. Anxiety symptoms, depressed mood and aggressive outbursts occurred at equally high rates in those with and without MR. These findings show that TSC can place any child or adolescent at significantly increased risk of a range of neurodevelopmental disabilities. These difficulties, often not recognised, require significant clinical and research attention.

Inhibition of return (IOR) describes a performance decrement for stimuli appearing at recently cued locations. Both attentional and motor processes have been implicated in the IOR effect. The present data reveal a double dissociation between the attentional and motor components of IOR whereby the motor-based component of IOR is present when the response is oculomotor, and the attention-based component of IOR is present when the response is manual. These 2 distinct components should be considered and studied separately, as well as in relation to each other, if a comprehensive theory of IOR is to be achieved. ((c) 2003 APA, all rights reserved)

Background The phenotype of Parkinson disease (PD) patients with and without LRRK2 G2019S mutations is reported to be similar; however large uniformly evaluated series are lacking. Objective To characterize the clinical phenotype of Ashkenazi Jewish (AJ) PD carriers of the LRRK2 G2019S mutation. Methods We studied 553 AJ PD patients, including 65 patients who were previously reported, from three sites (two in New York and one in Tel-Aviv). GBA mutation carriers were excluded. Evaluations included the Montreal Cognitive Assessment (MoCA), the Unified Parkinson's Disease Rating Scale (UPDRS), the geriatric depression scale (GDS) and the non-motor symptoms (NMS) questionnaire. Regression models were constructed to test the association between clinical and demographic features and LRRK2 status (outcome) in 488 newly recruited participants. Results LRRK2 G2019S carriers (n=97) and non-carriers (n=391) were similar in age and age-at-onset of PD. Carriers had longer disease duration (8.6years versus 6.1years, p<0.001), were more likely to be women (51.5% versus 37.9%, p=0.015) and more often reported first symptoms in lower extremities (40.0% versus 19.2%, p<0.001). In logistic models adjusted for age, disease duration, gender, education, and site, carriers were more likely to have lower extremity onset (p<0.001), postural instability gait difficulty (PIGD, p=0.043) and persistent levodopa response for>5 years (p=0.042). Performance on UPDRS, MoCA, GDS and NMS did not differ by mutation status. Conclusion PD in AJ-LRRK2 G2019S mutation carriers is similar to idiopathic PD, but characterized by more frequent lower extremity involvement at onset and PIGD without the associated cognitive impairment.

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The clinical relevance of white matter hyperintensities (WMH) seen on MRIs of elderly individuals is controversial. To resolve this issue, we performed MRI and neuropsychological testing on 46 healthy participants in the longitudinal Aging Process Study at the University of New Mexico. We graded the MRIs for severity of WMH using a scale tested on an elderly patient population. We found that 22% of normal subjects had moderate lesions and 9% had severe lesions. All subjects had normal neurologic examination findings and were within normal limits on a battery of neuropsychological tests. Neuropsychological performance decreased and the severity of WMH increased with age. However, when the data were corrected for age, there was no correlation between neuropsychological function and the presence of WMH. We conclude that white matter changes in the elderly by themselves are of doubtful clinical significance.

An estimate of the prevalence of autism in tuberous sclerosis (TSC) was made by interviewing the parents of 21 children between ages 3 and 11 ascertained during a previous population study of the condition in the West of Scotland. Five of the children (24%) were rated autistic and a further four (19%), all of whom were girls, had socially impaired behavior categorized as pervasive developmental disorder, without fulfilling all the DSM-III-R criteria for autism. One further boy had disruptive attention-seeking behavior that had excluded him from his normal school. The estimated prevalence from this study of autism in TSC is 1 in 4 children in general, and 1 in 2 of those with mental retardation. Tuberous sclerosis could be a significant cause of autism and pervasive developmental disorders, particularly in girls.