Vivid visual mental imagery in the absence of the primary visual cortex

The role of the primary visual cortex in visual mental imagery has provided significant debate in the imagery literature. Functional neuroimaging studies show considerable variation depending on task and technique. Patient studies can be difficult to interpret due to the diverse nature of cortical damage. The type of cortical damage in patient SBR is exceedingly rare as it is restricted to the gray matter of the calcarine sulcus. In this study, we show that in spite of his near-complete cortical blindness, SBR exhibits vivid visual mental imagery both behaviorally and when measured with functional magnetic resonance imaging. The pattern of cortical activation to visual mental imagery in SBR is indistinguishable from individual sighted subjects, in contrast to the visual perceptual responses, which are greatly attenuated

P301S Mutant Human Tau Transgenic Mice Manifest Early Symptoms of Human Tauopathies with Dementia and Altered Sensorimotor Gating

Tauopathies are neurodegenerative disorders characterized by the accumulation of abnormal tau protein leading to cognitive and/or motor dysfunction. To understand the relationship between tau pathology and behavioral impairments, we comprehensively assessed behavioral abnormalities in a mouse tauopathy model expressing the human P301S mutant tau protein in the early stage of disease to detect its initial neurological manifestations. Behavioral abnormalities, shown by open field test, elevated plus-maze test, hot plate test, Y-maze test, Barnes maze test, Morris water maze test, and/or contextual fear conditioning test, recapitulated the neurological deficits of human tauopathies with dementia. Furthermore, we discovered that prepulse inhibition (PPI), a marker of sensorimotor gating, was enhanced in these animals concomitantly with initial neuropathological changes in associated brain regions. This finding provides evidence that our tauopathy mouse model displays neurofunctional abnormalities in prodromal stages of disease, since enhancement of PPI is characteristic of amnestic mild cognitive impairment, a transitional stage between normal aging and dementia such as Alzheimer's disease (AD), in contrast with attenuated PPI in AD patients. Therefore, assessment of sensorimotor gating could be used to detect the earliest manifestations of tauopathies exemplified by prodromal AD, in which abnormal tau protein may play critical roles in the onset of neuronal dysfunctions

Memory training programs in memory complainers: Efficacy on objective and subjective memory functioning

The present study aims to assess the efficacy of memory training programs (MTP) on objective and subjective memory measures in non-demented, non-depressed community-dwelling elderly individuals with spontaneous memory complaints. Fifty-nine subjects were subdivided into two subgroups, one (n = 39) with only subjectively experienced memory decline (subjective memory complainers SMC), the other (n = 20) fulfilling aging-associated cognitive decline criteria (AACD). At start, AACD elderly individuals were significantly older in age, cognitively less efficient (revealed by MMSE) and more impaired on both objective and subjective memory measures compared to SMC. After MTP, both groups significantly improved objective memory functioning, but this improvement was greater in AACD, in particular in short-term memory processing and attentive abilities, in terms both of gains (delta score percentages) and of frequency of clinically relevant responsiveness [i.e., a delta score equal or greater than one standard deviation of the mean value on the overall memory index of the Randt memory test, derived form an age-matched memory unimpaired sample). In addition, the two subgroups also obtained better scores on metamemory questions tapping age-related memory decline, but in the AACD group alone enhancement in objective memory functioning was accompanied by improved subjective appraisals (metamemory) of current memory ability in everyday situations. We may conclude that MTPs are beneficial in elderly memory complainers, although they act differently according to whether or not complaints are associated with actual memory deficits

The validity of informant reports in assessing the severity of dementia: Evidence from the CAMDEX interview

The evaluation of a patient's mental state, overall clinical profile and behavioural disturbance in the process of diagnosing dementia requires at least two sources of information: the patient and the informant. Since the severity of the dementia may interfere with the subjective perception of these disorders, it is important to evaluate the consistency between these two sources of information and the clinical and psychometric evaluation made by the physician. Accordingly, in this study five behavioural areas, derived from the semi-structured interview schedule provided by the Cambridge Examination for Mental Disorders of the Elderly (CAMDEX, i.e., Sleep, Depressed Mood, Everyday Activity, Memory and Global Mental Functioning) have been tested on the patient and his/her informant. Eighty dementia patients (mean age = 74 years) and their informants participated in the study. The dementia group was subdivided into two levels of severity according to DSM-IIIR criteria: 41 with mild dementia and 39 with moderate dementia, respectively, matched for age and schooling. The rating of impairment was found to increase along with the severity of dementia in all the above-mentioned areas, except for sleep. However, the source of information pel se significantly influenced the evaluation of memory functioning. Moreover, the significant interaction between the two factors considered indicates that memory functioning is evaluated quite differently by the patients and the informants, as only in the assessment made by the latter group did the impairment increase in parallel with severity of dementia. Finally, whereas none of the subjective measures recorded in the patients were significantly correlated with their test scores, the correlations between the informant memory appraisals and patient test results proved to be significant. The present findings confirm the validity of informant reports in assessing cognitive and memory disorders in early-stage dementia, as well as in distinguishing patients with mild from those with moderate dementia