[Show abstract][Hide abstract] ABSTRACT: Deep brain stimulation (DBS) is a remarkably effective clinical tool, used primarily for movement disorders. DBS relies on precise targeting of specific brain regions to rebalance the oscillatory behaviour of whole-brain neural networks. Traditionally, DBS targeting has been based upon animal models (such as MPTP for Parkinson’s disease) but has also been the result of serendipity during human lesional neurosurgery. There are, however, no good animal models of psychiatric disorders such as depression and schizophrenia, and progress in this area has been slow. In this paper, we use advanced tractography combined with whole-brain anatomical parcellation to provide a rational foundation for identifying the connectivity ‘fingerprint’ of existing, successful DBS targets. This knowledge can then be used pre-surgically and even potentially for the discovery of novel targets. First, using data from our recent case series of cingulate DBS for patients with treatment-resistant chronic pain, we demonstrate how to identify the structural ‘fingerprints’ of existing successful and unsuccessful DBS targets in terms of their connectivity to other brain regions, as defined by the whole-brain anatomical parcellation. Second, we use a number of different strategies to identify the successful fingerprints of structural connectivity across four patients with successful outcomes compared with two patients with unsuccessful outcomes. This fingerprinting method can potentially be used pre-surgically to account for a patient’s individual connectivity and identify the best DBS target. Ultimately, our novel fingerprinting method could be combined with advanced whole-brain computational modelling of the spontaneous dynamics arising from the structural changes in disease, to provide new insights and potentially new targets for hitherto impenetrable neuropsychiatric disorders.
New Journal of Physics 01/2015; 17(1):015001. · 3.67 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Oxytocin has been implicated in parent-infant attachment and social recognition. With respect to emotion recognition memory, both memory-enhancing and impairing effects have been observed, suggesting an influence of individual factors. We assessed the effects of oxytocin on memory for infant cues, and whether these effects are moderated by self-reported childhood emotional maltreatment. Nulliparous females (N = 102) participated in a randomized, double-blind, between-subjects study with intranasal oxytocin or placebo administration. Participants' memory was tested using the Baby Social Reward Task, where participants were asked to select the happier infant from a pair of two infants based on the information that they received about the infants' mood in the previous phase. Participants reporting more childhood emotional maltreatment were less accurate in this task after inhaling oxytocin. Our findings add to a growing body of literature showing that the effects of intranasal oxytocin on memory and social behavior are moderated by adverse early life experiences.
[Show abstract][Hide abstract] ABSTRACT: Sound moves us. Nowhere is this more apparent than in our responses to genuine emotional vocalizations, be they heartfelt distress cries or raucous laughter. Here, we present perceptual ratings and a description of a freely available, large database of natural affective vocal sounds from human infants, adults and domestic animals, the Oxford Vocal (OxVoc) Sounds database. This database consists of 173 non-verbal sounds expressing a range of happy, sad, and neutral emotional states. Ratings are presented for the sounds on a range of dimensions from a number of independent participant samples. Perceptions related to valence, including distress, vocalizer mood, and listener mood are presented in Study 1. Perceptions of the arousal of the sound, listener motivation to respond and valence (positive, negative) are presented in Study 2. Perceptions of the emotional content of the stimuli in both Study 1 and 2 were consistent with the predefined categories (e.g., laugh stimuli perceived as positive). While the adult vocalizations received more extreme valence ratings, rated motivation to respond to the sounds was highest for the infant sounds. The major advantages of this database are the inclusion of vocalizations from naturalistic situations, which represent genuine expressions of emotion, and the inclusion of vocalizations from animals and infants, providing comparison stimuli for use in cross-species and developmental studies. The associated website provides a detailed description of the physical properties of each sound stimulus along with cross-category descriptions.
Frontiers in Psychology 06/2014; 5:562. · 2.80 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Childhood emotional maltreatment has been associated with a higher risk for maltreating one’s own offspring. In the current study, we explored a possible role of oxytocin in mediating the association between childhood emotional maltreatment and participants’ interpretation of infant facial expressions. Oxytocin levels were measured in 102 female participants using saliva samples. They rated the mood of thirteen infants with happy, sad and neutral facial expressions. Emotional maltreatment indirectly influenced responses to happy infant faces by modulating oxytocin levels: Higher self-reported emotional maltreatment was related to higher levels of salivary oxytocin which were in turn related to a more positive evaluation of happy infant expressions, but not to the evaluation of sad infant expressions. Oxytocin receptor polymorphism rs53576 did not moderate the relation between maltreatment experiences and salivary oxytocin levels. Early emotional maltreatment might indirectly affect emotional information processing by altering the oxytonergic system.
[Show abstract][Hide abstract] ABSTRACT: Moving to music is an essential human pleasure particularly related to musical groove. Structurally, music associated with groove is often characterised by rhythmic complexity in the form of syncopation, frequently observed in musical styles such as funk, hip-hop and electronic dance music. Structural complexity has been related to positive affect in music more broadly, but the function of syncopation in eliciting pleasure and body-movement in groove is unknown. Here we report results from a web-based survey which investigated the relationship between syncopation and ratings of wanting to move and experienced pleasure. Participants heard funk drum-breaks with varying degrees of syncopation and audio entropy, and rated the extent to which the drum-breaks made them want to move and how much pleasure they experienced. While entropy was found to be a poor predictor of wanting to move and pleasure, the results showed that medium degrees of syncopation elicited the most desire to move and the most pleasure, particularly for participants who enjoy dancing to music. Hence, there is an inverted U-shaped relationship between syncopation, body-movement and pleasure, and syncopation seems to be an important structural factor in embodied and affective responses to groove.
PLoS ONE 04/2014; 9(4):e94446. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Positive clinical outcomes are now well established for deep brain stimulation, but little is known about the effects of long-term deep brain stimulation on brain structural and functional connectivity. Here, we used the rare opportunity to acquire pre- and postoperative diffusion tensor imaging in a patient undergoing deep brain stimulation in bilateral subthalamic nuclei for Parkinson's Disease. This allowed us to analyse the differences in structural connectivity before and after deep brain stimulation. Further, a computational model of spontaneous brain activity was used to estimate the changes in functional connectivity arising from the specific changes in structural connectivity.
We found significant localised structural changes as a result of long-term deep brain stimulation. These changes were found in sensory-motor, prefrontal/limbic, and olfactory brain regions which are known to be affected in Parkinson's Disease. The nature of these changes was an increase of nodal efficiency in most areas and a decrease of nodal efficiency in the precentral sensory-motor area. Importantly, the computational model clearly shows the impact of deep brain stimulation-induced structural alterations on functional brain changes, which is to shift the neural dynamics back towards a healthy regime. The results demonstrate that deep brain stimulation in Parkinson's Disease leads to a topological reorganisation towards healthy bifurcation of the functional networks measured in controls, which suggests a potential neural mechanism for the alleviation of symptoms.
The findings suggest that long-term deep brain stimulation has not only restorative effects on the structural connectivity, but also affects the functional connectivity at a global level. Overall, our results support causal changes in human neural plasticity after long-term deep brain stimulation and may help to identify the underlying mechanisms of deep brain stimulation.
PLoS ONE 01/2014; 9(1):e86496. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Deep brain stimulation (DBS) has shown promise for relieving nociceptive and neuropathic symptoms of refractory chronic pain. We assessed the efficacy of a new target for the affective component of pain, the anterior cingulate cortex (ACC). A 49-year-old man with neuropathic pain underwent bilateral ACC DBS. Patient-reported outcome measures were collected before and 2 years after surgery using a Visual Analogue Scale, Short-Form 36 quality of life survey, McGill pain questionnaire, EuroQol-5D questionnaires (EQ-5D; Health State) and neuropsychological assessments. The patient improved with DBS. Two years after surgery, the Visual Analogue Scale decreased from 6.7 to 3.0, McGill pain questionnaire improved by 42% and EQ-5D Health State increased by 150%. Stimulating the ACC at 130 Hz, 330 µs and 3 V facilitated neuropathic pain relief. The DBS remained efficacious during the 2-year follow-up period. Affective ACC DBS can relieve chronic neuropathic pain refractory to pharmacotherapy and restore quality of life.
[Show abstract][Hide abstract] ABSTRACT: Crying is the most powerful auditory signal of infant need. Adults' ability to perceive and respond to crying is important for infant survival and in the provision of care. This study investigated a number of listener variables that might impact on adults' perception of infant cry distress, namely parental status, musical training, and empathy. Sensitivity to infant distress was tested using a previously validated task, which experimentally manipulated distress by varying the pitch of infant cries. This task required that participants discriminate between pitch differences and interpret these as differences in infant distress. Parents with musical training showed a significant advantage on this task when compared with parents without. The extent of the advantage was correlated with the amount of self-reported musical training. For non-parents, individual differences in empathy were associated with task performance, with higher empathy scores corresponding to greater sensitivity to infant distress. We suggest that sensitivity to infant distress can be impacted by a number of listener variables, and may be amenable to training.
Frontiers in Psychology 01/2014; 5:1440. · 2.80 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Attractive individuals are perceived as having various positive personality qualities. Positive personality qualities can in turn increase perceived attractiveness. However, the developmental origins of the link between attractiveness and personality are not understood. This is important because infant attractiveness ('cuteness') elicits caregiving from adults, and infant personality ('temperament') shapes caregiving behaviour. While research suggests that adults have more positive attitudes towards cuter infants, it is not known whether positive infant temperament can increase the perception of infant cuteness. We investigated the impact of experimentally established infant temperament on adults' perception of cuteness and desire to view individual faces. Ataseline, adults rated the cuteness of, and keypressed to view, images of unfamiliar infants with neutral facial expressions. Training required adults to learn about an infant's 'temperament', through repeated pairing of the neutral infant face with positive or negative facial expressions and vocalizations. Adults then re-rated the original neutral infant faces. Post-training, there were significant changes from baseline: infants who were mostly happy were perceived as cuter and adults expended greater effort to view them. Infants who were mostly sad were not perceived as cuter and adults expended less effort to view them. Our results suggest that temperament has clear consequences for how adults perceive 'bonnie' babies. Perception of infant cuteness is not based on physical facial features alone, and is modifiable through experience.
[Show abstract][Hide abstract] ABSTRACT: Spontaneous (or resting-state) brain activity has attracted a growing body of neuroimaging research over the last decades. Whole-brain network models have proved helpful to investigate the source of slow (<0.1Hz) correlated hemodynamic fluctuations revealed in fMRI during rest. However, the mechanisms mediating resting-state long-distance correlations and the relationship with the faster neural activity remain unclear. Novel insights coming from MEG studies have shown that the amplitude envelopes of alpha- and beta-frequency oscillations (~8-30Hz) display similar correlation patterns as the fMRI signals. In this work, we combine experimental and theoretical work to investigate the mechanisms of spontaneous MEG functional connectivity. Using a simple model of coupled oscillators adapted to incorporate realistic whole-brain connectivity and conduction delays, we explore how slow and structured amplitude envelopes of band-pass filtered signals - fairly reproducing MEG data collected from 10 healthy subjects at rest - are generated spontaneously in the space-time structure of the brain network. Our simulation results show that the large-scale neuroanatomical connectivity provides an optimal network structure to support a regime with metastable synchronization. In this regime, different subsystems may temporarily synchronize at reduced collective frequencies (falling in the 8-30Hz range due to the delays) while the global system never fully synchronizes. This mechanism modulates the frequency of the oscillators on a slow time-scale (<0.1Hz) leading to structured amplitude fluctuations of band-pass filtered signals. Taken overall, our results reveal that the structured amplitude envelope fluctuations observed in resting-state MEG data may originate from spontaneous synchronization mechanisms naturally occurring in the space-time structure of the brain.
[Show abstract][Hide abstract] ABSTRACT: The neuropathology of schizophrenia remains unclear. Some insight has come from modern neuroimaging techniques, which offer an unparalleled opportunity to explore in vivo the structure and function of the brain. Using functional magnetic resonance imaging, it has been found that the large-scale resting-state functional connectivity (rsFC) in schizophrenia - measured as the temporal correlations of the blood-oxygen-level-dependent (BOLD) signal - exhibit altered network topology, with lower small-world index. The origin of these rsFC alterations and link with the underlying structural connectivity remain unclear. In this work, we used a computational model of spontaneous large-scale brain activity to explore the role of the structural connectivity in the large-scale dynamics of the brain in health and schizophrenia. The structural connectomes from 15 adolescent patients with early-onset schizophrenia and 15 age- and gender-matched controls were built from diffusion tensor imaging data to detect the white matter tracts between 90 brain areas. Brain areas, simulated using a reduced dynamic mean-field model, receive excitatory input from other areas in proportion to the number of fibre tracts between them. The simulated mean field activity was transformed into BOLD signal, and the properties of the simulated functional networks were analyzed. Our results suggest that the functional alterations observed in schizophrenia are not directly linked to alterations in the structural topology. Instead, subtly randomized and less small-world functional networks appear when the brain operates with lower global coupling, which shifts the dynamics from the optimal healthy regime.
[Show abstract][Hide abstract] ABSTRACT: In recent years the study of the intrinsic brain dynamics in a relaxed awake state in the absence of any specific task has gained increasing attention, as spontaneous neural activity has been found to be highly structured at a large scale. This so called resting-state activity has been found to be comprised by nonrandom spatiotemporal patterns and fluctuations, and several Resting-State Networks (RSN) have been found in BOLD-fMRI as well as in MEG signal power envelope correlations. The underlying anatomical connectivity structure between areas of the brain has been identified as being a key to the observed functional network connectivity, but the mechanisms behind this are still underdetermined. Theoretical large-scale brain models for fMRI data have corroborated the importance of the connectome in shaping network dynamics, while the importance of delays and noise differ between studies and depend on the models' specific dynamics. In the current study, we present a spiking neuron network model that is able to produce noisy, distributed alpha-oscillations, matching the power peak in the spectrum of group resting-state MEG recordings. We studied how well the model captured the inter-node correlation structure of the alpha-band power envelopes for different delays between brain areas, and found that the model performs best for propagation delays inside the physiological range (5-10m/s). Delays also shift the transition from noisy to bursting oscillations to higher global coupling values in the model. Thus, in contrast to the asynchroneous fMRI state, delays are important to consider in the presence of oscillation.
[Show abstract][Hide abstract] ABSTRACT: The bond between a parent and an infant often appears to form effortlessly and intuitively, and this relationship is fundamental to infant survival and development. Parenting is considered to depend on specific brain networks that are largely conserved across species and in place even before parenthood. Efforts to understand the neural basis of parenting in humans have focused on the overlapping networks implicated in reward and social cognition, within which the orbitofrontal cortex (OFC) is considered to be a crucial hub. This review examines emerging evidence that the OFC may be engaged in several phases of parent-infant interactions, from early, privileged orienting to infant cues, to ongoing monitoring of interactions and subsequent learning. Specifically, we review evidence suggesting that the OFC rapidly responds to a range of infant communicative cues, such as faces and voices, supporting their efficient processing. Crucially, this early orienting response may be fundamental in supporting adults to respond rapidly and appropriately to infant needs. We suggest a number of avenues for future research, including investigating neural activity in disrupted parenting, exploring multimodal cues, and consideration of neuroendocrine involvement in responsivity to infant cues. An increased understanding of the brain basis of caregiving will provide insight into our greatest challenge: parenting our young.
Social neuroscience 11/2013; 8(6):525-43. · 3.17 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: There is strong evidence to suggest that data recorded from magnetoencephalography (MEG) follows a non-Gaussian distribution. However, existing standard methods for source localisation model the data using only second order statistics, and therefore usethe inherent assumption of a Gaussian distribution. In this paper, we present a new general method for non-Gaussian source estimation of stationary signals for localising brain activity from MEG data. By providing a Bayesian formulation for MEG source localisation, we show that the source probability density function (pdf), which is not necessarily Gaussian, can be estimated using multivariate kernel density estimators. In the case of Gaussian data, the solution of the method is equivalent to that ofwidely used linearly constrained minimum variance (LCMV) beamformer. The method is also extended to handle data with highly correlated sources using the marginal distribution of the estimated joint distribution, which, in the case of Gaussian measurements, corresponds to the null-beamformer. The proposed non-Gaussian source localisation approach is shown to give better spatial estimates than the LCMV beamformer, both in simulations incorporating non-Gaussian signals, and in real MEG measurements of auditory and visual evoked responses, where the highly correlated sources are known to be difficult to estimate.
[Show abstract][Hide abstract] ABSTRACT: Infant vocalisations are amongst the most biologically salient sounds in the environment and can draw the listener to the infant rapidly in both times of distress and joy. A region of the midbrain, the periaqueductal gray (PAG), has long been implicated in the control of urgent, survival-related behaviours. To test for PAG involvement in the processing of infant vocalisations, we recorded local field potentials (LFPs) from macroelectrodes implanted in this region in four adults who had undergone Deep Brain Stimulation. We found a significant difference occurring as early as 49ms from sound onset in activity recorded from the PAG in response to infant vocalisations compared to constructed control sounds and adult and animal affective vocalisations. This difference was not present in recordings from thalamic electrodes implanted in three of the patients. Time frequency analyses revealed distinct patterns of activity in the PAG for the three sound categories. These results suggest that human infant vocalisations can be discriminated from other emotional or acoustically similar sounds early in the auditory pathway. We propose that this specific, rapid activity in response to infant vocalisations may reflect the initiation of a state of heightened alertness necessary to instigate protective caregiving.
Social Cognitive and Affective Neuroscience 05/2013; · 5.04 Impact Factor