Behavioural evidence for enhanced olfactory and trigeminal perception in congenital hearing loss.

Sensory deprivation, especially hearing loss (HL), offers a valuable model for studying neuroplasticity in the human brain and adaptive behaviours that support the daily lives of those with limited or absent sensory input. The study of olfactory function is particularly important as it is an understudied aspect of sensory deprivation. This study aimed to compare the effects of congenital HL on olfactory capacity by using psychophysical tasks. Methodological concerns from previous studies regarding the onset of HL and cognitive assessments were addressed. We recruited 11 individuals with severe-to-profound sensorineural HL (SNHL) since birth and 11 age- and sex-matched typical hearing non-signers. We used standardized neuropsychological tests to assess typical cognition among participants with SNHL. We evaluated olfactory functions by assessing olfactory detection threshold, odour discrimination and odour identification. Hearing-impaired participants outperformed their typical hearing counterparts in olfactory tasks. We further evaluated the accuracy and response time in identifying and localizing odours to disentangle olfactory sensitivity from trigeminal system sensitivity. Participants with SNHL demonstrated higher sensitivity to both the identification and localization tasks. These findings suggest that congenital SNHL is associated with enhanced higher-level olfactory processing and increased trigeminal sensitivity.

Revealing robust neural correlates of conscious and unconscious visual processing: Activation likelihood estimation meta-analyses.

Our ability to consciously perceive information from the visual scene relies on a myriad of intrinsic neural mechanisms. Functional neuroimaging studies have sought to identify the neural correlates of conscious visual processing and to further dissociate from those pertaining to preconscious and unconscious visual processing. However, delineating what core brain regions are involved in eliciting a conscious percept remains a challenge, particularly regarding the role of prefrontal-parietal regions. We performed a systematic search of the literature that yielded a total of 54 functional neuroimaging studies. We conducted two quantitative meta-analyses using activation likelihood estimation to identify reliable patterns of activation engaged by i. conscious (n = 45 studies, comprising 704 participants) and ii. unconscious (n = 16 studies, comprising 262 participants) visual processing during various task performances. Results of the meta-analysis specific to conscious percepts quantitatively revealed reliable activations across a constellation of regions comprising the bilateral inferior frontal junction, intraparietal sulcus, dorsal anterior cingulate, angular gyrus, temporo-occipital cortex and anterior insula. Neurosynth reverse inference revealed conscious visual processing to be intertwined with cognitive terms related to attention, cognitive control and working memory. Results of the meta-analysis on unconscious percepts revealed consistent activations in the lateral occipital complex, intraparietal sulcus and precuneus. These findings highlight the notion that conscious visual processing readily engages higher-level regions including the inferior frontal junction and unconscious processing reliably recruits posterior regions, mainly the lateral occipital complex.

What's that on Your Phone? Effects of Mobile Device Task Type on Pedestrian Performance.

BACKGROUND: The number of accidents due to distracted pedestrian is on the rise and many governments and institutions are enacting public policies which restrict texting while walking. However, pedestrians do more than just texting when they use their mobile devices on the go. OBJECTIVE: Exploring pedestrian multitasking, this paper aims to examine the effects of mobile device task type on pedestrian performance outcomes. METHOD: We performed two studies in lab simulations where 78 participants were asked to perform different tasks on a mobile device (playing a game, reading, writing an email, texting one person, group texting) while performing a pedestrian visual discrimination task while either standing or walking on a treadmill. Behavioral performance as well as neurophysiological data are collected. RESULTS: Results show that compared to a no-phone control, multitasking with any of the tasks on a mobile device leads to poor performance on a pedestrian visual discrimination task. Playing a game is the most cognitively demanding task and leads to the greatest performance degradation. CONCLUSION: Our studies show that multitasking with a mobile device has the potential to negatively impact pedestrian safety, regardless of task type. However, the impacts of different mobile device tasks are not all equivalent. More research is needed to tease out the different effects of these various tasks and to design mobile applications which effectively and safely capture pedestrians' attention. APPLICATION: Public policy, infrastructure, and smart technologies can be used to mitigate the negative effects of mobile multitasking. A more thorough understanding of mobile device task-specific factors at play can help tailor these counter-measures to better aid distracted pedestrians.

Altered morphological traits along central olfactory centres in congenitally blind subjects.

It is well documented that early sensory loss typically alters brain morphology in the areas associated with the lost sense. However, much less is known about the impact of early sensory loss on the remainder of the sensory regions. Therefore, we investigated whether congenitally blind (CB) individuals show brain alterations in the olfactory system by comparing cortical morphology and olfactory bulb (OB) volume between 16 congenitally blind individuals and 16 sighted matched controls. Our results showed that not only CB blind individuals exhibited smaller OB but also alterations of cortical density in some higher olfactory processing centres, but unchanged cortical thickness. Our current findings suggest that a lifelong absence of visual input leads to morphological alterations in olfactory processing areas.

Prefrontal cortex and amygdala anatomy in youth with persistent levels of harsh parenting practices and subclinical anxiety symptoms over time during childhood.

Childhood adversity and anxiety have been associated with increased risk for internalizing disorders later in life and with a range of brain structural abnormalities. However, few studies have examined the link between harsh parenting practices and brain anatomy, outside of severe maltreatment or psychopathology. Moreover, to our knowledge, there has been no research on parenting and subclinical anxiety symptoms which remain persistent over time during childhood (i.e., between 2.5 and 9 years old). Here, we examined data in 94 youth, divided into four cells based on their levels of coercive parenting (high / low) and of anxiety (high / low) between 2.5 and 9 years old. Anatomical images were analyzed using voxel-based morphometry (VBM) and FreeSurfer. Smaller gray matter volumes in the prefrontal cortex regions and in the amygdala were observed in youth with high versus low levels of harsh parenting over time. In addition, we observed significant interaction effects between parenting practices and subclinical anxiety symptoms in rostral anterior cingulate cortical thickness and in amygdala volume. These youth should be followed further in time to identify which youth will or will not go on to develop an anxiety disorder, and to understand factors associated with the development of sustained anxiety psychopathology.

The functional characterization of callosal connections.

The brain operates through the synaptic interaction of distant neurons within flexible, often heterogeneous, distributed systems. Histological studies have detailed the connections between distant neurons, but their functional characterization deserves further exploration. Studies performed on the corpus callosum in animals and humans are unique in that they capitalize on results obtained from several neuroscience disciplines. Such data inspire a new interpretation of the function of callosal connections and delineate a novel road map, thus paving the way toward a general theory of cortico-cortical connectivity. Here we suggest that callosal axons can drive their post-synaptic targets preferentially when coupled to other inputs endowing the cortical network with a high degree of conditionality. This might depend on several factors, such as their pattern of convergence-divergence, the excitatory and inhibitory operation mode, the range of conduction velocities, the variety of homotopic and heterotopic projections and, finally, the state-dependency of their firing. We propose that, in addition to direct stimulation of post-synaptic targets, callosal axons often play a conditional driving or modulatory role, which depends on task contingencies, as documented by several recent studies.

Altered functional activations of prefrontal brain areas during emotional processing of fear in Inuit adolescents exposed to environmental contaminants.

Exposure to mercury, lead and polychlorinated biphenyls (PCBs) have been associated with emotional dysregulation, but their neuronal correlates have yet to be examined. Inuit from Nunavik (Northern Quebec, Canada) face internalizing problems and are among the most exposed individuals to these environmental contaminants in the world. The aim of this study was to examine the link between pre- and postnatal exposure to these contaminants and brain fear-circuitry in Inuit adolescents. Facial expression stimuli were presented to participants (mean age = 18.3 years) in a magnetic resonance imaging (MRI) scanner. Fear conditioning and extinction tasks included neutral faces as the conditioned threat and safety cues and a fearful face paired with a shrieking scream as the unconditioned stimulus. Functional MRI data were gathered at the conditioning phase (n = 71) and at the extinction phase (n = 62). Mercury, lead and PCB 153 concentrations were measured in blood samples at birth (cord blood) and at the time of the adolescent testing to estimate pre- and postnatal exposure, respectively. For each time point, exposures were categorized in tertiles (low, moderate and high exposed groups). Mixed analyses of variance were conducted for each contaminant of interest controlling for sex, age, socioeconomic status, drug/alcohol use, food insecurity and contaminant co-exposure. Results revealed greater differential activation during the conditioning phase in the right orbitofrontal cortex in participants with moderate and high concentrations of cord blood PCB 153 compared to those in the low exposure group. During the extinction phase, the high prenatal mercury exposed group showed a lower differential activation in the right and left anterior cingulate cortex compared to those in the low-exposed group; whereas there was a higher differential activation in right dorsolateral prefrontal cortex in the high postnatal lead exposed group compared to the moderate- and low-exposed groups. Our study is the first to show alterations in the prefrontal brain areas in fear conditioning and extinction tasks in relation to environmental contaminant exposures. The observed brain correlates may advance our understanding of the emotional problems associated with environmental chemical toxicity.

Enhanced Odorant Localization Abilities in Congenitally Blind but not in Late-Blind Individuals.

Although often considered a nondominant sense for spatial perception, chemosensory perception can be used to localize the source of an event and potentially help us navigate through our environment. Would blind people who lack the dominant spatial sense-vision-develop enhanced spatial chemosensation or suffer from the lack of visual calibration on spatial chemosensory perception? To investigate this question, we tested odorant localization abilities across nostrils in blind people compared to sighted controls and if the time of vision loss onset modulates those abilities. We observed that congenitally blind individuals (10 subjects) outperformed sighted (20 subjects) and late-blind subjects (10 subjects) in a birhinal localization task using mixed olfactory-trigeminal stimuli. This advantage in congenitally blind people was selective to olfactory localization but not observed for odorant detection or identification. We, therefore, showed that congenital blindness but not blindness acquired late in life is linked to enhanced localization of chemosensory stimuli across nostrils, most probably of the trigeminal component. In addition to previous studies highlighting enhanced localization abilities in auditory and tactile modalities, our current results extend such enhanced abilities to chemosensory localization.

Cross-modal plasticity and central deficiencies: the case of deafness and the use of cochlear implants.

The primary objective of this chapter is to describe the consequences of central deficiencies on the neurodevelopment of children. We approach this topic from the standpoint of congenital deafness. Thus we first present the current state of knowledge on cortical reorganization following congenital deafness. The allocation of auditory cortices to other sensory systems can enhance sensory processing and therefore the cognitive functions related to them. Second, we explore the linguistic development of deaf children. Given that the English written system is speech-based, its acquisition is complex and atypical for deaf children, usually leading to poorer achievements. Next, we explore the impact of a neural prosthesis named the cochlear implant on the neurocognitive and linguistic development of deaf children. In some cases, it allows the individuals to, at least partially, regain access to the lost sense. We also comment on the specific needs of the deaf population when it comes to neuropsychological assessment. Finally, we touch on the specific context of deaf children born of deaf parents, and therefore naturally exposed to sign language as the only means of communication.

Enhancement of visual biological motion recognition in early-deaf adults: Functional and behavioral correlates.

Deafness leads to brain modifications that are generally associated with a cross-modal activity of the auditory cortex, particularly for visual stimulations. In the present study, we explore the cortical processing of biological motion that conveyed either non-communicative (pantomimes) or communicative (emblems) information, in early-deaf and hearing individuals, using fMRI analyses. Behaviorally, deaf individuals showed an advantage in detecting communicative gestures relative to hearing individuals. Deaf individuals also showed significantly greater activation in the superior temporal cortex (including the planum temporale and primary auditory cortex) than hearing individuals. The activation levels in this region were correlated with deaf individuals' response times. This study provides neural and behavioral evidence that cross-modal plasticity leads to functional advantages in the processing of biological motion following lifelong auditory deprivation.

Expected value and sensitivity to punishment modulate insular cortex activity during risky decision making.

The exact contribution of the insula to risky decision making remains unclear, as are the specific outcome parameters and inter-individual characteristics that modulate insular activity prior to a risky choice. This fMRI study examines the contributions of outcome valence, magnitude, probability, and expected value (EV) to insular activity during risky decision making, and explores the influence of sensitivity to reward and to punishment, and anxiety, to insular activity. Participants (N = 31) performed a gambling task requiring choice between two roulettes with different outcome magnitude, probability and EV, under gain and loss conditions separately, and filled questionnaires assessing sensitivity to punishment/reward, and state/trait anxiety. Parametric analyses were conducted to examine the modulation of brain activity during decision making in relation to each task parameter. Correlations were examined between insular activity and psychometric questionnaires. EV of the selected roulette was associated with right posterior insula activation during decision making. Higher sensitivity to punishment was associated with lower bilateral insular activation. These findings suggest that the right posterior insula is involved in tracking the EV of a risky option during decision making. The involvement of the insula when making risky decisions also appears to be influenced by inter-individual differences in sensitivity to punishment.

Measuring the Switch Cost of Smartphone Use While Walking.

This paper presents a study protocol to measure the task-switching cost of using a smartphone while walking. This method involves having participants walk on a treadmill under two experimental conditions: a control condition (i.e., simply walking) and a multitasking condition (i.e., texting while walking). During these conditions, the participants must switch between the tasks related to the experimental condition and a direction determining task. This direction task is done with a point-light walker figure, seemingly walking towards the left or the right of the participant. Performance on the direction task represents the participant's task-switching costs. There were two performance measures: 1) correct identification of the direction and 2) response time. EEG data are recorded in order to measure the alpha oscillations and cognitive engagement occurring during the task switch. This method is limited in its ecological validity: pedestrian environments have many stimuli occurring simultaneously and competing for attention. Nonetheless, this method is appropriate for pinpointing task-switching costs. The EEG data allow the study of the underlying mechanisms in the brain that are related to differing task-switching costs. This design allows the comparison between task switching when doing one task at a time, as compared to task switching when multitasking, prior to the stimulus presentation. This allows understanding and pinpointing both the behavioral and neurophysiological impact of these two different task-switching conditions. Furthermore, by correlating the task-switching costs with the brain activity, we can learn more about what causes these behavioral effects. This protocol is an appropriate base for studying the switching cost of different smartphone uses. Different tasks, questionnaires, and other measures can be added to it in order to understand the different factors involved in the task-switching cost of smartphone use while walking.

Spatiotemporal dynamics of auditory information processing in the insular cortex: an intracranial EEG study using an oddball paradigm.

Functional neuroimaging studies using auditory stimuli consistently show activation of the insular cortex. However, due to the limited temporal resolution of non-invasive neuroimaging techniques, the role(s) of the insula in auditory processing remains unclear. As the anterior insula (aI) and the posterior insula (pI) have different connections and are thought to be functionally distinct, it is likely that these two areas contribute differently to auditory processing. Our study examines the spatiotemporal dynamics of auditory processing in the insula using intracranial electroencephalography (EEG). Eight epileptic patients completed two passive listening tasks and one three-stimulus auditory oddball detection task during the intracranial EEG monitoring of their drug-resistant seizures. Recordings were obtained from depth electrodes implanted in 11 insulae. Event-related potentials (ERPs) were analyzed using permutation analyses during the N100 and the P300 intervals, and modulations of alpha, theta, and gamma band responses were compared using Wilcoxon/Mann-Whitney analyses. N100 responses to auditory stimuli were mostly observed in the pI and were little affected by task conditions. Auditory target detection was associated with P300 ERPs, and alpha, theta, high- and low-gamma responses, preferentially at aI contacts. Results suggest that the aI is involved in voluntary attentional processing of task-relevant information, whereas the pI is involved in automatic auditory processing.

The Impact of Early Deafness on Brain Plasticity: A Systematic Review of the White and Gray Matter Changes.

Background: Auditory deprivation alters cortical and subcortical brain regions, primarily linked to auditory and language processing, resulting in behavioral consequences. Neuroimaging studies have reported various degrees of structural changes, yet multiple variables in deafness profiles need to be considered for proper interpretation of results. To date, many inconsistencies are reported in the gray and white matter alterations following early profound deafness. The purpose of this study was to provide the first systematic review synthesizing gray and white matter changes in deaf individuals. Methods: We conducted a systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement in 27 studies comprising 626 deaf individuals. Results: Evidence shows that auditory deprivation significantly alters the white matter across the primary and secondary auditory cortices. The most consistent alteration across studies was in the bilateral superior temporal gyri. Furthermore, reductions in the fractional anisotropy of white matter fibers comprising in inferior fronto-occipital fasciculus, the superior longitudinal fasciculus, and the subcortical auditory pathway are reported. The reviewed studies also suggest that gray and white matter integrity is sensitive to early sign language acquisition, attenuating the effect of auditory deprivation on neurocognitive development. Conclusions: These findings suggest that understanding cortical reorganization through gray and white matter changes in auditory and non-auditory areas is an important factor in the development of auditory rehabilitation strategies in the deaf population.

Using a smartphone while walking: The cost of smartphone-addiction proneness.

Distracted walking is an ever-increasing problem. Studies have already shown that using a smartphone while walking impairs attention and increases the risk of accidents. This study seeks to determine if smartphone-addiction proneness magnifies the risks of using a smartphone while walking. In an experimental design, participants, while walking on a treadmill and engaged in a smartphone task, were required to switch tasks by responding to an external stimulus, i.e., determining the direction of movement of a point-light walker. Participants were chosen to cover a range of smartphone-addiction proneness. Four smartphone-use conditions were simulated: a control condition with no smartphone-use, an individual conversation condition, a gaming condition, and a group conversation condition. Our results show that using a smartphone while walking decreases accuracy and increases the number of missed stimuli. Moreover, participants with higher smartphone-addiction proneness scores were also prone to missing more stimuli, and this effect was found regardless of experimental condition. The effect of the smartphone task on accuracy and the number of missed stimuli was mediated by the emotional arousal caused by the smartphone task. Smartphone-addiction proneness was positively correlated with a declared frequency of smartphone use while walking. Furthermore, of all the smartphone tasks, the gaming condition was found to be the most distracting.

Impact of visual and auditory deprivation on speech perception and production in adults.

Speech perception relies on auditory and visual cues and there are strong links between speech perception and production. We aimed to evaluate the role of auditory and visual modalities on speech perception and production in adults with impaired hearing or sight versus those with normal hearing and sight. We examined speech perception and production of three isolated vowels (/i/, /y/, /u/), which were selected based on their different auditory and visual perceptual saliencies, in 12 deaf adults who used one or two cochlear implants (CIs), 14 congenitally blind adults, and 16 adults with normal sight and hearing. The results showed that the deaf adults who used a CI had worse vowel identification and discrimination perception and they also produced vowels that were less typical or precise than other participants. They had different tongue positions in speech production, which possibly partly explains the poorer quality of their spoken vowels. Blind individuals had larger lip openings and smaller lip protrusions for the rounded vowel and unrounded vowels, compared to the other participants, but they still produced vowels that were similar to those produced by the adults with normal sight and hearing. In summary, the deaf adults, even though they used CIs, had greater difficulty in producing accurate vowel targets than the blind adults, whereas the blind adults were still able to produce accurate vowel targets, even though they used different articulatory strategies.

Within- and Cross-Modal Integration and Attention in the Autism Spectrum.

Although impairment in sensory integration is suggested in the autism spectrum (AS), empirical evidences remain equivocal. We assessed the integration of low-level visual and tactile information within and across modalities in AS and typically developing (TD) individuals. TD individuals demonstrated increased redundancy gain for cross-modal relative to double tactile or visual stimulation, while AS individuals showed similar redundancy gain between cross-modal and double tactile conditions. We further observed that violation of the race model inequality for cross-modal conditions was observed over a wider proportion of the reaction times distribution in TD than AS individuals. Importantly, the reduced cross-modal integration in AS individuals was not related to atypical attentional shift between modalities. We conclude that AS individuals displays selective decrease of cross-modal integration of low-level information.

Role of the insula in top-down processing: an intracranial EEG study using a visual oddball detection paradigm.

Functional neuroimaging studies suggest that the insular cortex-and more especially the anterior insula (aI)-is involved in attentional processes and plays a crucial role in the "salience network". However, its specific role in attentional processing remains unclear, which is partly attributable to the low temporal resolution of non-invasive neuroimaging techniques. This study aims to examine the spatio-temporal dynamics of visual target processing using intracranial EEG recorded directly from the insula. Eight epileptic patients (four women, age 18-44 years) completed a three-stimulus visual oddball task during the extraoperative invasive intracranial EEG (iEEG) monitoring of their drug-resistant seizures. Depth electrodes were implanted in ten insular lobes (5 left and 5 right) and provided a total of 59 recording contacts in the insula. Event-related potentials (ERPs) and high-gamma-band responses (GBRs) were processed offline. Permutation analyses were performed to compare ERP signals across conditions during the P300 (225-400) interval, and modulations of GBRs (70-150 Hz) were computed for separate 100 ms time windows (from 0 to 1000 ms post-stimulus) and compared across conditions using non-parametric Wilcoxon test. Target stimuli were associated with a P300 (250-338 ms) component for 39% of contacts implanted in the aI, most probably reflecting voluntary attentional processing. Amplitude was significantly greater for target than for standard stimuli for all of these contacts, and was greater than for novel stimuli for 72%. In the posterior insula (pI), 16% of contacts showed preferential responses to target stimulus in the P300 interval. Increased GBRs in response to targets were observed in 53% of aI contacts (from ≈ 200 to 300 ms) and in 43% of pI contacts (from ≈ 400 to 500 ms). This study is the first to characterize the spatio-temporal dynamics of visual target processing in the insula using iEEG. Results suggest that visual targets elicit a P300 in the aI which corresponds in latency to the P3b component, suggesting that this region is involved in top-down processing of task-relevant information. GBRs to visual targets occur earlier in the aI than in the pI, further characterizing their respective roles in voluntary attentional processing.

Chronic harsh parenting and anxiety associations with fear circuitry function in healthy adolescents: A preliminary study.

Previous studies have reported altered fear circuitry function during fear conditioning in highly anxious individuals and in adults with a history of severe childhood adversity; less is known regarding younger populations and more common forms of adversity. We investigated fear circuitry functioning in healthy youths with histories of high (HH) or low (LH) chronic harsh parenting and high (HA) or low (LA) anxiety levels. 84 youths aged 13-16 performed an fMRI fear conditioning task. HH displayed decreased selective medial temporal lobe deactivations to CS+> CS- relative to LH. In addition, we found less amygdala-insula connectivity in HH vs LH. Interestingly, we observed distinct patterns of anxiety differences in amygdala-rostral ACC connectivity and subjective fear ratings depending on harsh parenting levels, suggesting a history of harsh parenting is linked with unique neural and behavioral anxious manifestations, which are different from anxiety manifestations in a context of low adversity.

Neuronal mechanisms of motion detection underlying blindsight assessed by functional magnetic resonance imaging (fMRI).

Brain imaging offers a valuable tool to observe functional brain plasticity by showing how sensory inputs reshape cortical activations after a visual impairment. Following a unilateral post-chiasmatic lesion affecting the visual cortex, patients may suffer a contralateral visual loss referred to homonymous hemianopia. Nevertheless, these patients preserve the ability to unconsciously detect, localize and discriminate visual stimuli presented in their impaired visual field. To investigate this paradox, known as blindsight, we conducted a study using functional magnetic resonance imaging (fMRI) to evaluate the structural and functional impact of such lesion in a 33-year old patient (ML), who suffers a complete right hemianopia without macular sparing and showing strong evidences of blindsight. We thus performed whole brain and sliced thalamic fMRI scan sequences during an event-related motion detection task. We provided evidence of the neuronal fingerprint of blindsight by acquiring and associating neural correlates, specific structures and functional networks of the midbrain during blindsight performances which may help to better understand this condition. Accurate performance demonstrated the presence of residual vision and the ability to unconsciously perceive motion presented in the blind hemifield, although her reaction time was significantly higher in her blind-field. When the normal hemifield was stimulated, we observed significant contralateral activations in primary and secondary visual areas as well as motion specific areas, such as the supramarginal gyrus and middle temporal area. We also demonstrated sub-thalamic activations within the superior colliculi (SC) and the pulvinar. These results suggest a role of secondary subcortical structures in normal spontaneous motion detection. In a similar way, when the lesioned hemifield was stimulated, we observed contralateral activity in extrastriate areas with no activation of the primary lesioned visual cortex. Moreover, we observed activations within the SC when the blind hemifield was stimulated. However, we observed unexpected ipsilateral activations within the same motion specific areas, as well as bilateral frontal activations. These results highlight the importance of abnormal secondary pathways bypassing the primary visual area (V1) in residual vision. This reorganization in the structure and function of the visual pathways correlates with behavioral changes, thus offering a plausible explanation for the blindsight phenomenon. Our results may potentially impact the development of rehabilitation strategies to target subcortical pathways.