It has been postulated that bilingualism may act as a cognitive reserve and recent behavioral evidence shows that bilinguals are diagnosed with dementia about 4-5 years later compared to monolinguals. In the present study, we investigated the neural basis of these putative protective effects in a group of aging bilinguals as compared a matched monolingual control group. For this purpose, participants completed the Erikson Flanker task and their performance was correlated to grey matter (GM) volume in order to investigate if cognitive performance predicts GM volume specifically in areas affected by aging. We performed an ex-Gaussian analysis on the resulting RTs and report that aging bilinguals performed better than aging monolinguals on the Flanker task.Bilingualism was overall associated with increased GM in the ACC Task performance correlated with decreased GM in the DLPFC only in monolinguals. Taken together, these neural regions might underlie the benefits of bilingualism and act as a neural reserve that protects against the cognitive decline that occurs during aging..

No abstract

Warm and cold stimuli have affective components such as feeling pleasant or unpleasant, and these components may have survival value, for approach to warmth and avoidance of cold may be reinforcers or goals for action built into us during evolution to direct our behaviour to stimuli that are appropriate for survival. Understanding the brain processing that underlies these prototypical reinforcers provides a direct approach to understanding the brain mechanisms of emotion. In an fMRI investigation in humans, we showed that the mid-orbitofrontal and pregenual cingulate cortex and the ventral striatum have activations that are correlated with the subjective pleasantness ratings made to warm (41°C) and cold (12°C) stimuli, and combinations of warm and cold stimuli, applied to the hand. Activations in the lateral and some more anterior parts of the orbitofrontal cortex were correlated with the unpleasantness of the stimuli. In contrast, activations in the somatosensory cortex and ventral posterior insula were correlated with the intensity but not the pleasantness of the thermal stimuli. A principle thus appears to be that processing related to the affective value and associated subjective emotional experience of thermal stimuli that are important for survival is performed in different brain areas to those where activations are related to sensory properties of the stimuli such as their intensity. This conclusion appears to be the case for processing in a number of sensory modalities, and the finding with such prototypical stimuli as warm and cold provides strong support for this principle.

Developmental prosopagnosia (DP) is a cognitive condition characterised by a severe deficit in face recognition. Few investigations have examined whether impairments at the early stages of processing may underpin the condition, and it is also unknown whether DP is simply the "bottom end" of the typical face-processing spectrum. To address these issues, we monitored the eye-movements of DPs, typical perceivers and "super recognizers" (SRs) while they viewed a set of static images displaying people engaged in naturalistic social scenarios.Three key findings emerged: (1) individuals with more severe prosopagnosia spent less time examining the internal facial region, (2) as observed in acquired prosopagnosia, some DPs spent less time examining the eyes and more time examining the mouth than controls, and (3) SRs spent more time examining the nose -a measure that also correlated with face recognition ability in controls. These findings support previous suggestions that DP is a heterogeneous condition, but suggest that at least the most severe cases represent a group of individuals that qualitatively differ from the typical population. While SRs seem to merely be those at the "top end" of normal, this work identifies the nose as a critical region for successful face recognition.Keywords: prosopagnosia, super recognizers, face recognition, eye movements, individual differences. Eye Movements and Face Recognition 3Eye-Movement Strategies in Developmental Prosopagnosia and "Super" Face Recognition Prosopagnosia is a neuropsychological disorder characterized by a failure to recognize familiar faces. While some individuals acquire the condition following neurological trauma (e.g. Damasio, Damasio, & Von Hoesen, 1982), it is thought that approximately two per cent of the population have developmental prosopagnosia (DP: Bennetts, Murray, Boyce, & Bate, under review for this review; Bowles et al., 2009). This form of the disorder has been attributed to a failure to develop the visual recognition mechanisms necessary for successful face recognition, despite intact low-level visual and intellectual functions (Susilo & Duchaine, 2013). Interestingly, there also appears to be a genetic component to the condition in at least some individuals (Duchaine, Germine, & Nakayama, 2007; Grueter et al., 2007).Due to considerable difficulties hindering early diagnosis of face recognition difficulties, it is essentially impossible to distinguish the former, developmental, from the latter, congenital, form of prosopagnosia. For the purpose of this paper we are thus referring to all types of prosopagnosia unrelated to known neurological trauma and without concomitant disorders known to affect face processing as "developmental".A multitude of work with both healthy and impaired participants has contributed to cognitive neuropsychological theories of face recognition, such that it is generally accepted that the process consists of a series of sequential stages that can selectively be damaged by neurological trauma (e.g. Bruce & Young, ...

The palatability and pleasantness of the sensory properties of foods drive food selection and intake and may contribute to overeating and obesity. Oral fat texture can make food palatable and pleasant. To analyze its neural basis, we correlated humans' subjective reports of the pleasantness of the texture and flavor of a high- and low-fat food with a vanilla or strawberry flavor, with neural activations measured with functional magnetic resonance imaging. Activity in the midorbitofrontal and anterior cingulate cortex was correlated with the pleasantness of oral fat texture and in nearby locations with the pleasantness of flavor. The pregenual cingulate cortex showed a supralinear response to the combination of high fat and pleasant, sweet flavor, implicating it in the convergence of fat texture and flavor to produce a representation of highly pleasant stimuli. The subjective reports of oral fattiness were correlated with activations in the midorbitofrontal cortex and ventral striatum. The lateral hypothalamus and amygdala were more strongly activated by high- versus low-fat stimuli. This discovery of which brain regions track the subjective hedonic experience of fat texture will help to unravel possible differences in the neural responses in obese versus lean people to oral fat, a driver of food intake.

Understanding causal relationships and violations of those relationships is fundamental to learning about the world around us. Over time some of these relationships become so firmly established that they form part of an implicit belief system about what is possible and impossible in the world. Previous studies investigating the neural correlates of violations of learned relationships have focused on relationships that were task-specific and probabilistic. In contrast, the present study uses magic-trick perception as a means of investigating violations of relationships that are long-established, deterministic, and that form part of the aforementioned belief system. Compared to situations in which expected causal relationships are observed, magic trick perception recruited dorso-lateral prefrontal cortex (DLPFC) and anterior cingulate cortex (ACC), brain regions associated with the detection of conflict and the implementation of cognitive control. These activations were greater in the left hemisphere, supporting a role for this hemisphere in the interpretation of complex events. DLPFC is more greatly activated by magic tricks than by surprising events, but not more greatly activated by surprising than non surprising events, suggesting that this region plays a special role in causality processing. The results suggest a role for cognitive control regions in the left hemisphere in a neurobiology of disbelief.

Abstract■ Decision-making about affective value may occur after the reward value of a stimulus is represented and may involve different brain areas to those involved in decision-making about the physical properties of stimuli, such as intensity. In an fMRI study, we delivered two odors separated by a delay, with instructions on different trials to decide which odor was more pleasant or more intense or to rate the pleasantness and intensity of the second odor without making a decision. The fMRI signals in the medial prefrontal cortex area 10 (medial PFC) and in regions to which it projects, including the anterior cingulate cortex (ACC) and insula, were higher when decisions were being made compared with ratings, implicating these regions in decision-making. Decisionmaking about affective value was related to larger signals in the dorsal part of medial area 10 and the agranular insula, whereas decisions about intensity were related to larger activations in the dorsolateral prefrontal cortex (dorsolateral PFC), ventral premotor cortex, and anterior insula. For comparison, the mid orbitofrontal cortex (OFC) had activations related not to decision-making but to subjective pleasantness ratings, providing a continuous representation of affective value. In contrast, areas such as medial area 10 and the ACC are implicated in reaching a decision in which a binary outcome is produced. ■

It has been proposed that the inferior/ventrolateral frontal cortex plays a critical role in the inhibitory control of action during cognitive tasks. However, the contribution of this region to the control of eye movements has not been clearly established. Here, we describe the performance of a group of 23 frontal lobe damaged patients in an oculomotor rule switching task for which the association between a centrally presented visual cue and the direction of a saccade could change from trial to trial. A subset of 16 patients also completed the standard antisaccade task. Ventrolateral damage was found to be a significant predictor of errors in both tasks. Analysis of the rate at which patients corrected errors in the rule switching task also revealed an important dissociation between left and right hemisphere damaged patients. Whilst patients with left ventrolateral damage usually corrected response errors with secondary saccades, those with right hemisphere lesions often failed to do so. The results suggest that the inferior frontal cortex forms part of a wider frontal network mediating inhibitory control over stimulus elicited eye movements. The critical role played by the right ventrolateral region in cognitive tasks may arise due to an additional functional specialization for the monitoring and updating of task rules.