Parental sensitivity towards infants’ needs influences both the way caregiver-infant interactions unfold and individuals’ own development throughout lifetime. The pivotal role of this early interaction with caregivers is especially highlighted by the fact that when the interaction is non-adaptive, infants’ development may be severely hindered in various domains, such as cognitive, social, and emotional. Moreover, the quality of the early interaction with caregivers has long-lasting effects since it constitutes a lens through which individuals interpret the social world throughout lifetime. Caregivers’ influence on individuals’ subsequent behavior is also moderated by their own genetic predispositions. However the way behavioral, physiological and genetic mechanisms dynamically interact over time in shaping the development of caregiver-infant bonding and the long term effects on individuals remains largely unknown. The present project aimed to investigate behavioral and physiological mechanisms underling caregiver-infant interactions and their long-term effects applying a multilevel approach including behavioral, physiological and genetic measurements as well as a comparative approach between human and non-human primates. Specifically, in a first study focused on human adults we investigated the effect of the interaction between early parental care and individuals' own genetic predispositions in moderating adults' subsequent peripheral physiological responses to distressing social stimuli. Next, a second study on a primate model, the marmosets (\textit{Callithrix Jacchus}), focused directly on caregiver-infant dyads applying micro-behavioral analysis during infants' first month of life. Overall findings highlighted a differential importance of environmental and genetic factors in moderating caregiver-infant dyads vs individuals' long-term development. The leading role of environmental factors, namely parental behaviors, in determining infants' responses to specific caregivers within caregiver-infant interactions seems to be, on the contrary, smoothed out by individuals' own genetic predispositions when focusing on the long-term effects. Indeed, genetic characteristics determine individuals' sensitivity to environment, either weakening or strengthening the effect of environmental contribution in shaping individuals' physiological mechanisms. Also, interesting similarities between marmosets’ and humans’ caregiver-infant interactions’ structure have been found, making way for future studies investigating the brain mechanisms underlying the development of parent-infant bonding.

Object manipulation is central to our daily interactions with the environment. Failing to select, prepare or perform correct prehension movements results in dramatic limitations for the affected individual. Whereas we begin to have a better understanding of the neural mechanisms underlying the execution of object-directed movements, less is known about how exactly our brain makes the plan for action. Previous studies examining movement planning suggested that neuronal populations in parieto-frontal areas contain information about upcoming movements moments before they actually take place. However, such studies typically used experiments in which the participant was instructed about the movement to plan with visual or auditory cues, making it difficult to disentangle movement planning from the processing of cues and stimulus- response (S-R) mapping. In our first functional magnetic resonance imaging (fMRI) study (Study I), we compared an instructed condition with a free-choice condition that allowed participants to select which prehension movement to perform: a condition in which the task was not tied to specific external cues (i.e., no direct S-R mapping). Using multi-variate pattern analysis (MVPA), we found contralateral parietal and frontal regions containing abstract representations of planned movements that generalize across the way these movements were generated (internally vs externally). The majority of previous studies were based on delayed-movement tasks, which introduce brain responses unrelated to movement preparation. Consequently, whether these findings would generalize to immediate movements remained unclear. In our second fMRI study (Study II), we directly compared delayed and immediate reaching and grasping movements. Using time-resolved MVPA allowed us to reveal shared representations for delayed and non-delayed movement planning in human primary motor cortex and examine how movement representations unfolded throughout the different stages of planning and execution. Overall, our findings expand previous understanding of the regions implicated in movement planning and offer new insights into the dynamics of the human prehension system.

Perceptual decision making is the process that makes a rich environment manageable by compartmentalizing stimuli into various categories. Parietal cortex is involved in many tasks that require perceptual decisions. While much work in both the human and monkey domains has investigated processes related to visual decision making in the frontal and parietal lobes in a predominantly unimodal fashion, relatively little research has explored auditory and tactile perceptual decisions. As such, we wanted to know whether these regions also play a role in auditory and tactile decision making and to what extent information therein may be represented supramodally. Using functional magnetic resonance imaging and a paradigm requiring human participants to categorize auditory and tactile frequency-modulated sweeps, we sought to disentangle motor confounds and minimize linguistic processing from the perceptual decisions that participants made. We ran a series of experiments that utilized whole-brain multivariate pattern analysis implemented via linear discriminant analysis classification in order to detect cortical representations of such potentially supramodal information. Ultimately, we showed that learned categories were best decoded within the right parietal lobe and the medial frontal gyrus, supramodal representations of “up- vs. down-sweeps” were localized to the left parietal-temporal-occipital junction, and, most consequentially, cross-modality decoding of category membership was strongest in the left posterior insula and precuneus. Given our choice of paradigm, such results appear to demonstrate that the information representations in the posterior insula and precuneus are independent of motor and language processing and instead reflect supramodal or modality-free mechanisms that underlie the categorization process.

The honeybee, Apis mellifera, is an established model for the study of olfactory processing, olfactory learning and memory, and the related plasticity. The primary centre for olfactory processing in the bee brain, the antennal lobe, has a very important function in odour coding and odour discrimination. Nevertheless, both its structure and its function are plastic. In this thesis, I analysed the structural antennal lobe plasticity related to associative learning, and that related to a non-associative experience, i.e. prolonged odour exposure, in the adult honeybee. Subsequently, I analysed the functional modification taking place in the latter case within the output units of the antennal lobe, showing that parallel structural and functional changes occur. In the last part of the thesis, I focused on the effects of a common neonicotinoid pesticide, imidacloprid, on antennal lobe function and the discrimination abilities of honeybees. I demonstrated that both are strongly impaired in the acute treatment of the brain with such substance.

In everyday life, the emotional perception often occurred in different modalities at once but knowledge about multisensory perception on emotion was minimal. To understand emotional integration, odors and touch were used in two experiments. The first experiment was conducted to distinguish the emotional effects of different odors and to examine the effect of gender difference with respect to emotional perception. The aim of the second experiment was to determine the emotional integration of bimodal stimuli. The self-report and psychophysiological responses from forty-five participants were computed. Data were analyzed by two-way mixed ANOVA and two-way repeated measures ANOVA, statistical significance at the .05 level. The findings highlight that there was no crossed interaction between olfactory and tactile modalities in the aspect of emotion. The bimodal stimuli did not enhance the emotional perception of unimodal stimuli. Civet oil markedly elicited an unpleasantness. Michelia oil elicited objective arousal, meanwhile, Lavender oil elicited a pleasant feeling. In addition, 3 cm/s stroking touch elicited subjective pleasantness with moderate arousal, and 30 cm/s stroking touch elicited high arousal without the feeling of pleasantness. Moreover, men are more sensitive to some type of odor than women especially unpleasant odors and arousing odors. This was the first work that studied the bimodal emotional perception between olfactory and tactile modalities and was a first study that revealed the peripheral psychophysiological effect of CT afferents. A further study should investigate an impact of gender and culture to emotional integration and a consistency of finding.

A near continuous stream of information reaches our eyes and the task of the visual system is to make sense of it. Visual stimuli arrive in quick succession: sometimes it is necessary to integrate stimuli over time, but other times it is necessary to segregate them. These opposing processes of integration and segregation are two forms of temporal processing, a topic which is underrepresented in the literature as compared to spatial processing. In particular, there is limited understanding about how temporal processing is influenced by selective attention. Selective attention refers to a family of mechanisms by which the limited resources of our mental architecture are diverted to preferentially process stimuli more likely to be relevant. Here, a number of empirical investigations into the effect of endogenous, covert spatial attention on temporal processing are presented. This includes use of a task in which visual stimulation is held constant and only the temporal processing goal (integration versus segregation) and the spatial location of attention are manipulated. There were strong spatial cueing effects: a benefit to performance when validly cued and a cost when invalidly cued. These attentional effects are reliable for both opposing processes of temporal integration and segregation. Furthermore, these spatial cueing effects are robust even when the cues provide no implicit temporal expectations. We used magnetoencephalography and the same task to measure changes in the brain signal associated with these effects, namely shifts in peak alpha frequency for integration as compared to segregation, as well as spatially specific modulations in this metric relative to the locus of attention. These findings of robust spatial cueing effects on temporal processing and of strategic shifts in oscillatory frequency associated with temporal processing goals and allocation of attention are discussed within a temporal windows framework and in the context of other candidate mechanisms. The empirical evidence reported here can be accounted for by the idea of a flexible adaptation of the size of temporal windows, essentially changing the sampling rate of perception in line with task demands.

In the absence of visual input from the external world, humans are able to internally generate vivid mental images of external stimuli. This cognitive process is known as visual mental imagery, and it is involved in many forms of complex reasoning and problem-solving. Using functional neuroimaging, several studies revealed that visual mental imagery recruits a network of prefrontal, parietal and inferotemporal regions. Moreover, under certain conditions, imagining external entities have been shown to induce recruitment of retinotopically-organized visual areas, traditionally thought to be dedicated to the perception of external stimuli. The recruitment of low-level visual areas following visual mental imagery of different stimuli could have important implications for the implementation of new rehabilitative techniques directed to patients suffering from visual field defects. In fact, following lesions affecting retrochiasmatic visual pathways, one of the most common deficits is homonymous hemianopia. This visual impairment is characterized by the loss of sight in one half of the visual field and has a profound impact on patients’ emotional and social wellbeing. Several studies indicated preserved visual imagery abilities in hemianopic patients, both in the sighted and damaged hemifield. This led us to hypothesize the possibility to recruit functionally preserved portions of early visual cortices in the affected hemisphere of hemianopic patients by means of visual mental imagery. If this revealed to be true, the recruitment of early visual areas would potentially induce plastic mechanisms of change that could reinstate perceptual awareness, increasing the size of the perceived visual field. In the present thesis, we explored neural substrates of visual mental imagery both in the healthy and in the damaged brain using fMRI. In Study 1, by means of a delayed spatial judgment task, we investigated in healthy participants the degree of complexity of the information encoded in primary visual cortex, its similarities and differences with representations of perceived stimuli, and how this information is encoded in areas outside early visual cortex. We found significant encoding of complex stimulus categories in early visual areas, as well as in inferotemporal and parietal cortices. Additionally, in agreement with previous studies, we found that a subset of these regions showed a certain degree of shared representations with perception. Moreover, in Study 2, we explored whether it is possible to selectively recruit individual quadrants within the visual field using visual mental imagery. To this aim, we tested a group of normal-sighted individuals and patients suffering from homonymous hemianopia in a visual imagery paradigm. Results indicated that normal-sighted individuals are able to recruit early visual cortex by means of top-down mechanisms. In the group of patients, we observed a large amount of interindividual variability that allowed reliable recruitment limited to the healthy hemisphere. Together, the results of this thesis provide evidence for distinct roles of parietal and premotor areas, involved in processing the spatial layout of imagined stimuli, and temporal regions, representing the content of internally generated representations. Moreover, the results are in line with the view that, in the absence of bottom-up visual stimulation, early visual cortex is able to access information about both content and spatial layout of imagined stimuli via feedback connections. In addition, we demonstrated that the top-down modulation of low-level visual areas occurring during visual mental imagery is feasible to recruit retinotopically-organized early visual cortex, both in normal-sighted participants and in the healthy hemisphere of hemianopic patients. Albeit preliminary, these results open new perspectives on the potential use of visual mental imagery as a rehabilitation tool in the clinical treatment of visual field defects.

The present thesis addresses the cross-modal plasticity occurring in the visual modality due to profound deafness. In Chapter 1, we review the current perspective on the general mechanisms of cross-modal plasticity and, in particular, the changes occurring in visual modality in the case of profound deafness. Enhanced visual abilities in the deaf have typically been reported when in tasks that involve visual attention resources and processing of peripheral portions of the visual field. In this thesis, we present a series of four experimental studies aimed at specifying which visual attentional components display modulations in case of deafness. In Chapter 2 and 3, we contrasted the role of endogenous and exogenous capture of visual attention. The results showed that endogenous attention, when tested in a transient-free context, does not reveal compensations effects due to deafness (i.e., enhancement). By contrast, enhanced performance for peripheral portion of the visual field emerged when exogenous capture of selective attention was involved. We suggest that enhanced visual performance in the deaf is transients selective. In Chapter 4, we contrasted the ability to simply react to a visual event (simple detection task) and the ability to orient visual attention (shape discrimination task). The results showed that deaf posses marked enhanced reactivity compared to hearing controls, when detecting targets presented at both central and peripheral locations. Reactivity is thus an enhanced visual skill in the deaf that is not spatially selective, in the sense that it does not emerge solely at peripheral locations. In addition, RTs results support the hypothesis that deaf may display a different neural representation of the peripheral portion of the visual field. These effects were not paired by enhanced ability to discriminate between different shapes regardless of their relative position, suggesting that enhanced reactivity was not due to a better mechanism of 6 attention orienting. Finally, in Chapter 5, we present the electrophysiological data recorded during a simple visual detection task. The ERPs analysis revealed that deafness determines quantitative and qualitative modulations of visual processing already at the early stages (C1, P1). Finally, Chapter 6 resumes and discusses the implications of the overall set of results.

The general aim of the present dissertation was to participate in the progress of our understanding of how sensory input and sensory experience impact on how the human brain implements categorical knowledge. The goal was twofold: (1) understand whether there are brain regions that encode information about different categories regardless of input modality and sensory experience (study 1); (2) deepen the investigation of the mechanisms that drive cross-modal and intra-modal plasticity following early blindness and the way they express during the processing of different categories presented as real-world sounds (study 2). To address these fundamental questions, we used fMRI to characterize the brain responses to different conceptual categories presented acoustically in sighted and early blind individuals, and visually in a separate sighted group. In study 1, we observed that the right posterior middle temporal gyrus (rpMTG) is the region that most reliably decoded categories and selectively correlated with conceptual models of our stimuli space independently of input modality and visual experience. However, this region maintains separate the representational format from the different modalities, revealing a multimodal rather than an amodal nature. In addition, we observed that VOTC showed distinct functional profiles according to the hemispheric side. The left VOTC showed an involvement in the acoustical categorization processing at the same degree in sighted and in blind individuals. We propose that this involvement might reflect an engagement of the left VOTC in more semantic/linguistic processing of the stimuli potentially supported by its enhanced connection with the language system. However, paralleling our observation in rpMTG, the representations from different modalities are maintained segregated in VOTC, showing little evidence for sensory-abstraction. On the other side, the right VOTC emerged as a sensory-related visual region in sighted with the ability to rewires itself toward acoustical stimulation in case of early visual deprivation. In study 2, we observed opposite effects of early visual deprivation on auditory decoding in occipital and temporal regions. While occipital regions contained more information about sound categories in the blind, the temporal cortex showed higher decoding in the sighted. This unbalance effect was stronger in the right hemisphere where we, also, observed a negative correlation between occipital and temporal decoding of sound categories in EB. These last results suggest that the intramodal and crossmodal reorganizations might be inter-connected. We therefore propose that the extension of non-visual functions in the occipital cortex of EB may trigger a network-level reorganization that reduce the computational load of the regions typically coding for the remaining senses due to the extension of such computation in occipital regions.

Humans developed the ability to use their hands as tools to actively interact with the surrounding world. On a daily basis, without effort or a conscious will to act, we can manipulate dozens of objects placed in the environment to achieve different purposes. This, at first glance simple, ability relies on a network of cerebral areas computing a series of complex neural processes. The core cerebral regions involved in transforming visual inputs into hand actions have been identified within two distinct pareto-frontal networks, the dorsomedial and dorsolateral pathways. These pathways have been traditionally considered to process different types of information independently. The dual-route model of the hand motor system represents a milestone within the literature exploring the neural correlates of motor control. Nevertheless, following the recent improvement of the technical and analytical approaches adopted to investigate brainâ€TMs functioning, this initial description has been considered reductive. Nowadays, it is clear that the neural processes needed to produce a hand action require the integration of different information (e.g. spatial location of the object, spatial location of the arm, grip aperture, goal to pursue, etc.) that imply the exchange of information between anatomically distant, but functionally interconnected, cerebral areas. In light of the most recent neuroscientific advance in the field of motor control, we investigated the specific role of the cerebral areas of the motor system and their functional interactions during the planning and execution of hand actions. In the present thesis, we adopted several methodologies (TMS, fMRI) and analysis approaches (univariate, MVPA, DCM), to explore the involvement of defined areas in specific motor tasks, their representational content and their connectivity profiles. In the three neuroimaging studies here presented, we first considered the functional dynamics that occur within the hand network (Chapter 2). Secondly, we described a broader and integrated hand motor system including also the ventral stream, always considered as specialized in perceiving visual inputs (Chapter 3). Finally, we focused on the often neglected homologous regions within the right hemisphere (Chapter 4), providing a pan of the hand motor system in its entirety. The first study (Chapter 2) adopted a combined TMS-fMRI approach, and focused on understanding the interactions between the dorsomedial and dorsolateral pathways of the hand motor system. We adopted a delayed-reach-and-grasp task, performed under different perceptual conditions (eyes opened or closed), and we perturbed the activity of SPOC in the dorsomedial pathway of the left hemisphere by means of rTMS. We used univariate and multivariate analysis to investigate the modifications occurring during the planning phase of the action within areas functionally connected with the region stimulated with TMS. We found that when the normal activity of SPOC is altered, changes in encoding grasping action information occur within the dorsolateral pathway. This study showed a causal interaction between the dorsomedial and dorsolateral pathway of the hand motor network, which are traditionally considered to be specialized and independent. In the second study (Chapter 3), we adopted fMRI to explore the possible communication between dorsal and ventral stream, verifying the possible complementary and supportive role of the temporal cortex in motor control. To this aim, we adopted a delayed tool-pantomiming task known to recruit the ventral stream. Our delayed pantomiming task allowed us to consider the planning phase of the movement together with the execution of the pantomime. With multivariate analysis, we explored where in the dorsal and in the ventral streams different abstract goals of an action, i.e. independent from the tool identity, are represented in respect to more concrete aspects, related to the tool considered in the pantomime. In addition, we investigated the possible functional interactions between temporal and fronto-parietal regions, showing an exchange of information between the two pathways both with MVPA and connectivity analysis (DCM). Overall, these results point out a hand motor system that not only relies on the specialized-for-action dorsal network, but also on temporal lobe areas. In the third study of the thesis (Chapter 4), we combined data from Chapter 3 with a complementary fMRI session. In the second session we changed instruction modality and effector used to perform the pantomime, while experimental design and the task requirement were unchanged. This approach allowed focusing on understanding: (i) changes in the encoding of concrete and abstract representation based on task requirements (i.e. different instruction modality and effector) and (ii) the possible encoding of tool pantomimesâ€TM information also outside the classically-defined left-lateralized tool network, in homologous regions within the right hemisphere. Overall, we found task-dependent changes in the representational content of the considered areas both in the left and in the right hemisphere. These results provided novel insights into the neural correlates of tool pantomime, pointing towards the supportive role of the temporal cortices and of the right hemisphere when planning and pantomiming this type of action. Overall, our studies contributed delineating a novel view on the organization of the hand motor system describing (i) the functional specialization of its different cerebral areas and (ii) the interactions occurring between these regions. Our research highlighted how the hand motor system has a functionally interconnected organization in which, to different degrees, various areas located in three main cerebral routes (ventral stream, dorsolateral and dorsomedial pathways) communicate to build a meaningful motor output.