Dr-MUSIC: An Effective Device for Investigating Multisensory Mechanisms during Development with EEG recordings.

From birth, we are continuously exposed to multisensory stimuli that we learn to select and integrate during development to perceive a coherent world. To date, there are no optimal solutions to investigate how auditory, visual and tactile signals are integrated during EEG recording in infants and children. The present work aims to introduce Dr-MUSIC, a novel multisensory device with EEG-compatible timing and an attractive design for children. It is composed of audio, visual, and tactile stimulators arranged in the form of a couple of chubby dragons that can simultaneously provide selectable uni-, bi-, or tri-modal information. We first validated the system's EEG compatibility in 8 adults by implementing an audio-tactile oddball task during a high-density EEG recording. Then, we replicated the same task in a couple of toddlers to validate the device's usability for young children. The results suggest that the system can be effectively used for setting new experimental protocols to understand the neural basis of multisensory integration in the first years of life.Clinical Relevance- The amusing design and the possibility of changing the stimulation's characteristics (i.e., light, sound, and vibrotactile features) make it attractive in children with and without sensory impairments. Therefore, Dr-MUSIC could be used to investigate multisensory development and related neural correlates in typical and atypical children to design new early rehabilitation protocols.

MultiTab: A Novel Portable Device to Evaluate Multisensory Skills.

To infer spatial-temporal features of an external event we are guided by multisensory cues, with intensive research showing an enhancement in the perception when information coming from different sensory modalities are integrated. In this scenario, the motor system seems to also have an important role in boosting perception. With the present work, we introduce and validate a novel portable technology, named MultiTab, which is able to provide auditory and visual stimulation, as well as to measure the user's manual responses. Our preliminary results indicate that MultiTab reliably induces multisensory integration in a spatial localization task, shown by significantly reduced manual response times in the localization of audiovisual stimuli compared to unisensory stimuliClinical relevance- The current work presents a novel portable device that could contribute to the clinical evaluation of multisensory processing as well as spatial perception. In addition, by promoting and recording manual actions, MultiTab could be especially suitable for the design of rehabilitative protocols using multisensory motor training.

Audio-Corsi: a novel system to evaluate audio-spatial memory skills.

Spatial memory (SM) is a multimodal representation of the external world, which different sensory inputs can mediate. It is essential in accomplishing everyday activities and strongly correlates with sleep processes. However, despite valuable knowledge of the spatial mechanisms in the visual modality, the multi-sensory aspects of SM have yet to be thoroughly investigated due to a lack of proper technologies.This work presents a novel acoustic system built around 3D audio spatial technology. Our goal was to examine if an afternoon nap can improve memory performance, measured through the acoustic version of the Corsi Block Tapping Task (CBTT), named Audio-Corsi. We tested five adults over two days. During one of the two days (Wake), participants performed the Audio-Corsi before (Pre) and after (Post) a wake resting period; while the other day (Sleep), participants performed the Audio-Corsi before (Pre) and after (Post) a nap. Day orders were randomized. We calculated the memory span for the Pre and Post session in both the Wake and Sleep days. Preliminary results show a significant difference in the memory span between the Wake and Sleep days. Specifically, memory span decreased between the pre-and post-test during the wake day. The opposite trend was found for the sleep day. Results indicate that SM can be improved by sleeping also in the acoustic modality other than the visual one.Clinical Relevance- The technology and procedure we designed and developed could be suitable in clinical and experimental settings to study high-level cognitive skills in the auditory sensory modality and their relationship with sleep, especially when vision is absent or distorted (i.e. blindness).

Task-dependent spatial processing in the visual cortex.

To solve spatial tasks, the human brain asks for support from the visual cortices. Nonetheless, representing spatial information is not fixed but depends on the reference frames in which the spatial inputs are involved. The present study investigates how the kind of spatial representations influences the recruitment of visual areas during multisensory spatial tasks. Our study tested participants in an electroencephalography experiment involving two audio-visual (AV) spatial tasks: a spatial bisection, in which participants estimated the relative position in space of an AV stimulus in relation to the position of two other stimuli, and a spatial localization, in which participants localized one AV stimulus in relation to themselves. Results revealed that spatial tasks specifically modulated the occipital event-related potentials (ERPs) after the onset of the stimuli. We observed a greater contralateral early occipital component (50-90 ms) when participants solved the spatial bisection, and a more robust later occipital response (110-160 ms) when they processed the spatial localization. This observation suggests that different spatial representations elicited by multisensory stimuli are sustained by separate neurophysiological mechanisms.

Distinct brain signatures of content and structure violation during action observation.

Sentences, musical phrases and goal-directed actions are composed of elements that are linked by specific rules to form meaningful outcomes. In goal-directed actions including a non-canonical element or scrambling the order of the elements alters the action's content and structure, respectively. In the present study we investigated event-related potentials of the electroencephalographic (EEG) activity recorded during observation of both alterations of the action content (obtained by violating the semantic components of an action, e.g. making coffee with cola) and alterations of the action structure (obtained by inverting the order of two temporally adjacent pictures of sequences depicting daily life actions) interfering with the normal flow of the motor acts that compose an action. Action content alterations elicited a bilateral posterior distributed EEG negativity, peaking at around 400 ms after stimulus onset similar to the ERPs evoked by semantic violations in language studies. Alteration of the action structure elicited an early left anterior negativity followed by a late left anterior positivity, which closely resembles the ERP pattern found in language syntax violation studies. Our results suggest a functional dissociation between the processing of action content and structure, reminiscent of a similar dissociation found in the language or music domains. Importantly, this study provides further support to the hypothesis that some basic mechanisms, such as the rule-based structuring of sequential events, are shared between different cognitive domains.

Cognitive impairment in degenerative parkinsonisms: role of radionuclide brain imaging.

Cognitive impairment in Parkinson's disease (PD) and atypical parkinsonian syndromes is gaining increased clinical significance. The neurochemical and neuropathological basis in the various parkinsonian forms and even in an individual patient are not fully elucidated yet and could be heterogeneous. Loss of dopaminergic, cholinergic and noradrenergic innervation has been suggested to be the underlying neurochemical deficits for cognitive impairment and dementia in PD, but the onset of cognitive impairment and the progression to dementia may not share the same underlying neurochemical basis. Similarly, pathological evidence is also heterogeneous, ranging from subcortical pathology, limbic or cortical Lewy body type degeneration, and Alzheimer's type pathology that can be found even in the same patient with PD dementia (PDD). Typically, the prototype of early cognitive deficit in PD is a dysexecutive syndrome, but other cognitive domains are more involved when dementia develops, mainly including visuospatial, language and memory dysfunction. Functional radionuclide neuroimaging, by means of single-photon emission computed tomography and positron emission tomography, are contributing to characterize the topographic cortical pattern of cognitive impairment, as well as to define the underlying neurochemical deficit. Lastly, the advent of amyloid PET may help clarifying the meaning of amyloid load in diffuse Lewy body disease and PDD. Knowing the neurochemical and pathophysiological substrate of cognitive deficit in patients with PD or other degenerative Parkinsonisms may help the clinician in understanding the clinical condition of an individual patient in order to plan pharmacological and non-pharmacological intervention. The introduction of acetylcholinesterase inhibitors for therapy of PDD is an example of information integration between clinical-neuropsychological and pathophysiological-neurochemical aspects obtained also with the key contribution of functional neuroimaging.

Tactile exploration of virtual objects for blind and sighted people: the role of beta 1 EEG band in sensory substitution and supramodal mental mapping.

The neural correlates of exploration and cognitive mapping in blindness remain elusive. The role of visuo-spatial pathways in blind vs. sighted subjects is still under debate. In this preliminary study, we investigate, as a possible estimation of the activity in the visuo-spatial pathways, the EEG patterns of blind and blindfolded-sighted subjects during the active tactile construction of cognitive maps from virtual objects compared with rest and passive tactile stimulation. Ten blind and ten matched, blindfolded-sighted subjects participated in the study. Events were defined as moments when the finger was only stimulated (passive stimulation) or the contour of a virtual object was touched (during active exploration). Event-related spectral power and coherence perturbations were evaluated within the beta 1 band (14-18 Hz). They were then related to a subjective cognitive-load estimation required by the explorations [namely, perceived levels of difficulty (PLD)]. We found complementary cues for sensory substitution and spatial processing in both groups: both blind and sighted subjects showed, while exploring, late power decreases and early power increases, potentially associated with motor programming and touch, respectively. The latter involved occipital areas only for blind subjects (long-term plasticity) and only during active exploration, thus supporting tactile-to-visual sensory substitution. In both groups, coherences emerged among the fronto-central, centro-parietal, and occipito-temporal derivations associated with visuo-spatial processing. This seems in accordance with mental map construction involving spatial processing, sensory-motor processing, and working memory. The observed involvement of the occipital regions suggests that a substitution process also occurs in sighted subjects. Only during explorations did coherence correlate positively with PLD for both groups and in derivations, which can be related to visuo-spatial processing, supporting the existence of supramodal spatial processing independently of vision capabilities.

Periodic limb movements both in non-REM and REM sleep: relationships between cerebral and autonomic activities.

OBJECTIVE: To investigate the temporal relationship between cerebral and autonomic activities before and during periodic limb movements in NREM and REM sleep (PLMS). METHODS: Patterns of EEG, cardiac and muscle activities associated with PLMS were drawn from polysomnographic recordings of 14 outpatients selected for the presence of PLMS both in NREM and REM sleep. PLMS were scored during all sleep stages from tibial EMG. Data from a bipolar EEG channel were analyzed by wavelet transform. Heart rate (HR) was evaluated from the electrocardiogram. EEG, HR and EMG activations were detected as transient increase of signal parameters and examined by analysis of variance and correlation analysis independently in NREM and REM sleep. Homologous parameters in REM and NREM sleep were compared by paired t-test. RESULTS: The autonomic component, expressed by HR increase, took place before the motor phenomenon both in REM and NREM sleep, but it was significantly earlier during NREM. In NREM sleep, PLM onset was heralded by a significant activation of delta-EEG, followed by a progressive increase of all the other bands. No significant activations of delta EEG were found in REM sleep. HR and EEG activations positively correlated with high frequency EEG activations and negatively (in NREM) with slow frequency ones. CONCLUSIONS: Our findings suggested a heralding role for delta band only in NREM sleep and for HR during both NREM and REM sleep. Differences in EEG and HR activation between REM and NREM sleep and correlative data suggested a different modulation of the global arousal response. SIGNIFICANCE: In this study, time-frequency analysis and advanced statistical methods enabled an accurate comparison between brain and autonomic changes associated to PLM in NREM and REM sleep providing indications about interaction between autonomic and slow and fast EEG components of arousal response.