Connectivity of the Human Number Form Area Reveals Development of a Cortical Network for Mathematics

The adult brain contains cortical areas thought to be specialized for the analysis of numbers (the putative number form area, NFA) and letters (the visual word form area, VWFA). Although functional development of the VWFA has been investigated, it is largely unknown when and how the NFA becomes specialized and connected to the rest of the brain. One hypothesis is that NFA and VWFA derive their special functions through differential connectivity, but the development of this differential connectivity has not been shown. Here, we mapped the resting state connectivity of NFA and VWFA to the rest of the brain in a large sample (n = 437) of individuals (age 3.2–21 years). We show that within NFA-math network and within VWFA-reading network the strength of connectivity increases with age. The right NFA is significantly connected to the right intraparietal cortex already at the earliest age tested (age 3), before formal mathematical education has begun. This connection might support or enable an early understanding of magnitude or numerosity In contrast, the functional connectivity from NFA to the left anterior intraparietal cortex and to the right dorsolateral prefrontal cortex is not different from the functional connectivity of VWFA to these regions until around 12–14 years of age. The increase in connectivity to these regions was associated with a gradual increase in mathematical ability in an independent sample. In contrast, VWFA connects significantly to Broca’s region around age 6, and this connectivity is correlated with reading ability. These results show how the differential connectivity of the networks for mathematics and reading slowly emerges through years of training and education

Action and non-action oriented body representations. insight from behavioural and grey matter modifications in individuals with lower limb amputation

Following current model of body representations, we aimed to systematically investigate the association between brain modifications, in terms of grey matter loss, and body representation deficits, in terms of alterations of the body schema (BS) and of non-action oriented body representations (NA), in individuals with lower limb amputation (LLA)

Does aging affect the formation of new topographical memories? Evidence from an extensive spatial training

A decline in navigational abilities is a consistent feature of aging. Although many studies focused on recall of navigational informa- tion, the impact of time and type of learning on recall has received little attention. We submitted older adults and young participants to an extensive training of an ecological environment, from both route and survey perspectives. Then, we tested participants’ learn- ing using from both route and survey perspectives. Although older adults benefit from the extensive training, they did not reach the same performance of the young participants. Despite this main effect of age, the effect of the type of learning was the same in the two groups. Congruence between type of learning and recall led to better performance in both groups. We discuss these findings in the light of cognitive models of human navigation and aging. Useful suggestions about how these findings may inform a specific cognitive intervention in older adults are also provided

Transcranial Electric Stimulation Can Impair Gains during Working Memory Training and Affects the Resting State Connectivity

Transcranial electric stimulation (tES) is a promising technique that has been shown to improve working memory (WM) performance and enhance the effect of cognitive training. However, experimental set up and electrode placement are not always determined based on neurofunctional knowledge about WM, leading to inconsistent results. Additional research on the effects of tES grounded on neurofunctional evidence is therefore necessary. Sixty young, healthy, volunteers, assigned to six different groups, participated in 5 days of stimulation or sham treatment. Twenty-five of these subjects also participated in MRI acquisition. We performed three experiments: In the first one, we evaluated tES using either direct current stimulation (tDCS) with bilateral stimulation of the frontal or parietal lobe; in the second one, we used the same tDCS protocol with a different electrode placement (i.e., supraorbital cathode); in the third one, we used alternating currents (tACS) of 35 Hz, applied bilaterally to either the frontal or parietal lobes. The behavioral outcome measure was the WM capacity (i.e., number of remembered spatial position) during the 5 days of training. In a subsample of subjects we evaluated the neural effects of tDCS by measuring resting state connectivity with functional MRI, before and after the 5 days of tDCS and visuo-spatial WM training. We found a significant impairment of WM training-related gains associated with parietal tACS and frontal tDCS. Five days of tDCS stimulation was also associated with significant change in resting state connectivity revealed by multivariate pattern analysis. None of the stimulation paradigms resulted in improved WM performance or enhanced WM training gains. These results show that tES can have negative effects on cognitive plasticity and affect resting-state functional connectivity

Cognitive maps in imagery neglect

Patients with imagery neglect (RI+) show peculiar difficulties in orienting themselves in the environment. Navigational impairments could be due to a deficit in creating or using a mental representation of the environment (Guariglia, Piccardi, Iaria, Nico, & Pizzamiglio, 2005) or, according to the BBB model (Burgess, Becker, King, & O'Keefe, 2001), to a specific deficit in a mechanism that transforms an allocentric representation into an egocentric one and vice versa. Previous studies, however, do not allow discerning between a deficit in forming or in using a cognitive map, taking no notice of the fact that these are two different abilities underlain by different neuroanatomical areas, which could be independently impaired. Furthermore, the BBB model has never been verified in a population of brain-damaged patients. Therefore, we administered two tasks that separately assess the ability to create and use a cognitive map of the environment to 28 right brain-damaged patients (4 patients with imagery neglect and 4 patients with perceptual neglect) and 11 healthy participants. RI+ patients showed no specific deficit in creating or using a cognitive map, but failed to transform an egocentric representation of the environment into an allocentric one and vice versa, as predicted by the BBB model. (C) 2012 Elsevier Ltd. All rights reserved

Navigating toward a novel environment from a route or survey perspective. neural correlates and context dependent connectivity

When we move toward a novel environment we may learn it in different ways, i.e., by walking around or studying a map. Both types of learning seem to be very effective in daily life navigation and correspond to two different types of mental representation of space: route and survey representation. In the present study, we investigated the neural basis of route and survey perspectives during learning and retrieval of novel environments. The study was carried out over 5 days, during which participants learned two paths from a different perspective (i.e., route learning and survey learning). Then participants had to retrieve these paths using a survey or route perspective during fMRI scans, on the first and fifth day. We found that the left inferior temporal lobe and right angular gyrus (AG) were activated more during recall of paths learned in a survey perspective than in a route perspective. We also found a session by perspective interaction effect on neural activity in brain areas classically involved in navigation such as the parahippocampal place area (PPA) and the retrosplenial cortex (RSC). A set of frontal, parietal and temporal areas showed different patterns of activity according to the type of retrieval perspective. We tested the context-dependent connectivity of right PPA, RSC and AG, finding that these areas showed different patterns of connectivity in relation to the learning and recalling perspective. Our results shed more light on the segregation of neural circuits involved in the acquisition of a novel environment and navigational strategies

Direct and indirect parieto-medial temporal pathways for spatial navigation in humans. evidence from resting-state functional connectivity

Anatomical and functional findings in primates suggest the existence of a dedicated parieto-medial temporal pathway for spatial navigation, consisting of both direct and indirect projections from the caudal inferior parietal lobe (cIPL) to the hippocampus and the parahippocampal cortex, with indirect projections relaying through the posterior cingulate and retrosplenial cortex. This neural network is largely unexplored in humans. This study aimed at testing the existence of a parieto-medial temporal pathway for spatial navigation in humans. We explored the cortical connectivity patterns of the parahippocampal place area (PPA), the retrosplenial cortex (RSC), and the hippocampus (HC) using resting-state functional connectivity MRI. Our results demonstrate the existence of connections between the medial temporal lobe structures, i.e., PPA and HC, and the angular gyrus (AG), the human homologue of cIPL, as well as between RSC and AG. These connectivity patterns seem to reflect the direct and the indirect projections found in primates from cIPL to the medial temporal lobe. Such a result deserves feasible considerations to better understand the brain networks underpinning human spatial navigation