Contrasting frontal cortical responses to food versus money rewards across BMI groups.

Previous research has linked obesity with an altered perception of rewards. This study aimed to contrast frontal cortical activities across body mass index (BMI) groups, in responding to differential rewards (monetary versus food). A total of 60 male participants (27.43 ± 6.07 years of age; 21 normal weight [BMI: 18.5-24.9 kg·m-2]; 20 overweight [BMI: 25.0-29.9 kg·m-2]; and 19 individuals with obesity [BMI ≥ 30 kg·m-2]) were tested for their response bias towards food and money rewards using the Probabilistic Reward Task (PRT), while their frontal cortical responses were recorded using electroencephalography (EEG). The feedback-related negativity (FRN), a reliable measure of reward valuation and learning, was calculated for food (FRN(Food)) and money (FRN(Money)). Results indicate a left-lateralised frontal cortical activity associated with the food reward condition, in the group of overweight and obesity. In contrast, a right-lateralisation was observed in the money reward condition only in the group with obesity. More specifically, FRN(Food) was shown to significantly differ between left and right frontal cortical areas among individuals with obesity (p = 0.035) and overweight (p = 0.012), but not in normal-weight individuals (p = 0.153). Additionally, results revealed that FRN(Food) and FRN(Money) were significantly different for individuals with obesity (p = 0.019), but such a significant difference was not evident in the overweight and normal-weight individuals (p ≥ 0.05). These findings offer intriguing new insights into neuropsychological differentiation across BMI groups, adding to the understanding of obesity-related behaviour.

The utilisation of resting-state fMRI as a pre-operative mapping tool in patients with brain tumours in comparison to task-based fMRI and intraoperative mapping: A systematic review.

PURPOSE: Resting-state functional Magnetic Resonance Imaging (rs-fMRI) is suggested to be a viable option for pre-operative mapping for patients with brain tumours. However, it remains an open issue whether the tool is useful in the clinical setting compared to task-based fMRI (T-fMRI) and intraoperative mapping. Thus, a systematic review was conducted to investigate the usefulness of this technique. METHODS: A systematic literature search of rs-fMRI methods applied as a pre-operative mapping tool was conducted using the PubMed/MEDLINE and Cochrane Library electronic databases following PRISMA guidelines. RESULTS: Results demonstrated that 50% (six out of twelve) of the studies comparing rs-fMRI and T-fMRI showed good concordance for both language and sensorimotor networks. In comparison to intraoperative mapping, 86% (six out of seven) studies found a good agreement to rs-fMRI. Finally, 87% (twenty out of twenty-three) studies agreed that rs-fMRI is a suitable and useful pre-operative mapping tool. CONCLUSIONS: rs-fMRI is a promising technique for pre-operative mapping in assessing the functional brain areas. However, the agreement between rs-fMRI with other techniques, including T-fMRI and intraoperative maps, is not yet optimal. Studies to ascertain and improve the sophistication in pre-processing of rs-fMRI imaging data are needed.

The role of an individual's olfactory discriminability in influencing snacking and habitual energy intake.

Recent studies have revealed close links between human olfaction, appetite, and food choice. However, it remains unclear whether olfactory sensitivity plays a direct role in determining food and energy intake. The present study addresses this question by assessing relationships between individual olfactory discriminability (at a suprathreshold level), snacking, and habitual energy intake. A total of 92 healthy Caucasian males (mean age = 26.1, SD = 5.8) were tested for their olfactory discriminability (measured by d') to three food-related odorants (O1 - Vanillin, O2 - Methional, and O3 - Maltol/Furaneol mixture) with a 2-AFC method of constant stimuli. These sensory data were then analysed with two separate measures of food consumption - (1) snack energy intake within an ad libitum buffet setting; (2) habitual energy intake using four-day weighed food records. Univariate analyses of variance revealed significant results with regards to O1. Specifically, individuals with higher discriminability consumed significantly less energy from snacking as opposed to their less sensitive counterparts (p = 0.05). However, no significant relationship was found between individual olfactory discriminability and habitual energy intake. While recent years have seen increasing research focus on how external olfactory cues affect food consumption, our study offers particularly novel insights regarding the role of individual olfactory sensitivity in shaping eating behaviour.

Utilization of functional MRI language paradigms for pre-operative mapping: a systematic review.

PURPOSE: Functional MRI (fMRI) can be employed to non-invasively localize brain regions involved in functional areas of language in patients with brain tumour, for applications including pre-operative mapping. The present systematic review was conducted to explore prevalence of different language paradigms utilised in conjunction with fMRI approaches for pre-operative mapping, with the aim of assessing their effectiveness and suitability. METHODS: A systematic literature search of brain tumours in the context of fMRI methods applied to pre-operative mapping for language functional areas was conducted using PubMed/MEDLINE and Scopus electronic database following PRISMA guidelines. The article search was conducted between the earliest record and March 1, 2019. References and citations were checked in Google Scholar database. RESULTS: Twenty-nine independent studies were identified, comprising 1031 adult participants with 976 patients characterised with different types and sizes of brain tumours, and the remaining 55 being healthy controls. These studies evaluated functional language areas in patients with brain tumours prior to surgical interventions using language-based fMRI. Results demonstrated that 86% of the studies used a Word Generation Task (WGT) to evoke functional language areas during pre-operative mapping. Fifty-seven percent of the studies that used language-based paradigms in conjunction with fMRI as a pre-operative mapping tool were in agreement with intra-operative results of language localization. CONCLUSIONS: WGT was most commonly utilised and is proposed as a suitable and useful technique for a language-based paradigm fMRI for pre-operative mapping. However, based on available evidence, WGT alone is not sufficient. We propose a combination and convergence paradigms for a more sensitive and specific map of language function for pre-operative mapping. A standard guideline for clinical applications should be established.

Mu rhythm suppression is associated with the classification of emotion in faces.

The mirror neuron system (MNS) has been mooted as a crucial component underlying human social cognition. Initial evidence based on functional magnetic resonance imaging (fMRI) suggests that the MNS plays a role in emotion classification, but further confirmation and convergent evidence is needed. This study employed electroencephalography (EEG) to examine modulations in the mu rhythm associated with the inference of emotions from facial expressions. It was hypothesised that mu suppression would be associated with classifying the emotion portrayed by facial expressions. Nineteen participants viewed pictures of facial expressions or emotion words and were asked to either match the stimulus to an emotion word or to passively observe. Mu activity following stimulus presentation was localised using a 3-D distributed inverse solution, and compared between conditions. Subtractive logic was used to isolate the specific processes of interest. Comparisons of source localisation images between conditions revealed that there was mu suppression associated with recognising emotion from faces, thereby supporting our hypothesis. Further analyses confirmed that those effects were not due to activity associated with the motor response or the observation of facial expressions, offering further support for the hypotheses. This study provides important convergent evidence for the involvement of the MNS in the inference of emotion from facial expressions.

How does consciousness for action relate to attention for action?

The interesting target article by Morsella et al. addresses critical issues that impact our understanding of consciousness. It is surprising, however, to see no treatment of the relationship between attention and consciousness, particularly given available models. Whether olfaction is most suitable as a model system to study consciousness for action also seems questionable. These issues are elaborated in the present commentary.

The effects of aging on the brain activation pattern during a speech perception task: an fMRI study.

In the present study, brain activation associated with speech perception processing was examined across four groups of adult participants with age ranges between 20 and 65 years, using functional MRI (fMRI). Cognitive performance demonstrates that performance accuracy declines with age. fMRI results reveal that all four groups of participants activated the same brain areas. The same brain activation pattern was found in all activated areas (except for the right superior temporal gyrus and right middle temporal gyrus); brain activity was increased from group 1 (20-29 years) to group 2 (30-39 years). However, it decreased in group 3 (40-49 years) with further decreases in group 4 participants (50-65 years). Result also reveals that three brain areas (superior temporal gyrus, Heschl's gyrus and cerebellum) showed changes in brain laterality in the older participants, akin to a shift from left-lateralized to right-lateralized activity. The onset of this change was different across brain areas. Based on these findings we suggest that, whereas all four groups of participants used the same areas in processing, the engagement and recruitment of those areas differ with age as the brain grows older. Findings are discussed in the context of corroborating evidence of neural changes with age.

Agency attribution: event-related potentials and outcome monitoring.

Knowledge about the effects of our actions is an underlying feature of voluntary behavior. Given the importance of identifying the outcomes of our actions, it has been proposed that the sensory outcomes of self-made actions are inherently different from those of externally caused outcomes. Thus, the outcomes of self-made actions are likely to be more motivationally significant for an agent. We used event-related potentials to investigate the relationship between the perceived motivational significance of an outcome and the attribution of agency in the presence of others. In our experiment, we assessed agency attribution in the presence of another agent by varying the degree of contiguity between participants' self-made actions and the sensory outcome. Specifically, we assessed the feedback correct-related positivity (fCRP) and the novelty P3 measures of an outcome's motivational significance and unexpectedness, respectively. Results revealed that both the fCRP and participants' agency attributions were significantly influenced by action-outcome contiguity. However, when action-outcome contiguity was ambiguous, novelty P3 amplitude was a reliable indicator of agency attribution. Prior agency attributions were also found to influence attribution in trials with ambiguous and low action-outcome contiguity. Participants' use of multiple cues to determine agency is consistent with the cue integration theory of agency. In addition to these novel findings, this study supports growing evidence suggesting that reinforcement processes play a significant role in the sense of agency.

Viewer perspective in the mirroring of actions.

A remarkable capability of the brain's action representation system is that neurons with 'mirroring' properties respond both when an agent (human or monkey) executes an action and also when the agent observes a similar action performed by someone else. Curiously, however, observed actions involve numerous viewer perspectives, whereas execution of actions occur with respect to 'self' coordinate space, and the mapping between viewer perspectives is not a known property of the so-called mirror neuron system (MNS). Toward a resolution of this paradox, we demonstrate in humans striking new evidence that key areas defined as part of the MNS of the frontal lobe, directly encode viewer perspective during action observation (Exps 1, 2). What is more, this property applies only to observation of embodied actions and not when disembodied movements of objects are observed (Exp 3). These findings raise the intriguing possibility that the MNS plays a critical role in the formation of action memories.

John Hughlings Jackson's evolutionary neurology: a unifying framework for cognitive neuroscience.

John Hughlings Jackson was a pioneer in neurology who thought deeply about the structure of the brain and how that manifested itself in the various syndromes that he saw in the clinic. He enunciated a theory of the evolution and dissolution of neural function based on the idea that basic sensorimotor processes become embedded in networks of connections that relate them in successively more complex ways to allow for performance of more and more nuanced and adaptive functions. Hughlings Jackson noted the curious link between human thought, action and speech. He further recognized that disinhibition or release from control and direction marked neurological damage. His integrative framework remains deeply relevant to the plethora of results being produced by the careful and diverse experimentation currently undertaken with the aid of brain imaging techniques of which he could only dream. In celebration of the memory of John Hughlings Jackson, we revisit his concept of neural evolution and development, which led to what eventually became a leading model of brain organization, whereby a new order of behavioural control--the conscious mind--is created out of simpler elements, in a manner similar to Herbert Spencer's evolutionary theory. By this Hughlings Jackson did not mean anything dualistic but merely that the highest layer of evolution of nervous arrangements was 'highly complicated' and that dissolution of that higher level leaves 'a lower consciousness and a shallower nervous system'.

Cortical oscillatory dysfunction in Parkinson disease during movement activation and inhibition.

Response activation and inhibition are functions fundamental to executive control that are disrupted in Parkinson disease (PD). We used magnetoencephalography to examine event related changes in oscillatory power amplitude, peak latency and frequency in cortical networks subserving these functions and identified abnormalities associated with PD. Participants (N = 18 PD, 18 control) performed a cue/target task that required initiation of an un-cued movement (activation) or inhibition of a cued movement. Reaction times were variable but similar across groups. Task related responses in gamma, alpha, and beta power were found across cortical networks including motor cortex, supplementary and pre- supplementary motor cortex, posterior parietal cortex, prefrontal cortex and anterior cingulate. PD-related changes in power and latency were noted most frequently in the beta band, however, abnormal power and delayed peak latency in the alpha band in the pre-supplementary motor area was suggestive of a compensatory mechanism. PD peak power was delayed in pre-supplementary motor area, motor cortex, and medial frontal gyrus only for activation, which is consistent with deficits in un-cued (as opposed to cued) movement initiation characteristic of PD.

Physically coupling two objects in a bimanual task alters kinematics but not end-state comfort.

People often grasp objects with an awkward grip to ensure a comfortable hand posture at the end of the movement. This end-state comfort effect is a predominant constraint during unimanual movements. However, during bimanual movements the tendency for both hands to satisfy end-state comfort is affected by factors such as end-orientation congruency and task context. Although bimanual end-state comfort has been examined when the hands manipulate two independent objects, no research has examined end-state comfort when the hands are required to manipulate two physically-coupled objects. In the present experiment, kinematics and grasp behavior during a unimanual and bimanual reaching and placing tasks were examined, when the hands manipulate two physically-connected objects. Forty-five participants were assigned to one of three groups; unimanual, bimanual no-spring (the objects were not physically connected), and bimanual spring (the objects were connected by a spring), and instructed to grasp and place objects in various end-orientations, depending on condition. Physically connecting the objects did not affect end-state comfort prevalence. However, it resulted in decreased interlimb coupling. This finding supports the notion of a flexible constraint hierarchy, in which action goals guide the selection of lower level action features (i.e., hand grip used for grasping), and the particular movements used to accomplish that goal (i.e., interlimb coupling) are controlled throughout the movement.

Crosstalk disrupts the production of motor imagery brain signals in brain-computer interfaces.

Brain-computer interfaces (BCIs) target specific brain activity for neuropsychological rehabilitation, and also allow patients with motor disabilities to control mobility and communication devices. Motor imagery of single-handed actions is used in BCIs but many users cannot control the BCIs effectively, limiting applications in the health systems. Crosstalk is unintended brain activations that interfere with bimanual actions and could also occur during motor imagery. To test if crosstalk impaired BCI user performance, we recorded EEG in 46 participants while they imagined movements in four experimental conditions using motor imagery: left hand (L), right hand (R), tongue (T) and feet (F). Pairwise classification accuracies of the tasks were compared (LR, LF, LT, RF, RT, FT), using common spatio-spectral filters and linear discriminant analysis. We hypothesized that LR classification accuracy would be lower than every other combination that included a hand imagery due to crosstalk. As predicted, classification accuracy for LR (58%) was reliably the lowest. Interestingly, participants who showed poor LR classification also demonstrated at least one good TR, TL, FR or FL classification; and good LR classification was detected in 16% of the participants. For the first time, we showed that crosstalk occurred in motor imagery, and affected BCI performance negatively. Such effects are effector-sensitive regardless of the BCI methods used; and likely not apparent to the user or the BCI developer. This means that tasks choice is crucial when designing BCI. Critically, the effects of crosstalk appear mitigatable. We conclude that understanding crosstalk mitigation is important for improving BCI applicability. SUPPLEMENTARY INFORMATION: The online version of this article contains supplementary material available (10.1007/s13755-021-00142-y).

Conceptual unifying constraints override sensorimotor interference during anticipatory control of bimanual actions.

Traditional approaches to research on bimanual coordination focus on sensorimotor interference, motor programming, and effects of perception and feedback guidance; surprisingly, little is known about high-level conceptual constraints that might unify separate movements into coordinated actions. We investigated two possible forms of high-level unifying representations on anticipatory control (i.e., reaction time: RT) in two-limb (bimanual) movements. Specifically, we adapted a paradigmatic bimanual task involving reaching to targets by adding two novel manipulations. One involved a visual-perceptual manipulation in which target-objects were presented either separately (i.e., two circles) or as a unified object (i.e., two circles connected by a bar). The other involved variants on language representation to elicit separate action plans (i.e., separate instructional commands joined by 'and') or unified action plans (i.e., a single verb applying to both hands). Typical forms of sensorimotor interference were virtually abolished when these unifying constraints were available. These findings provide strong support for the theoretical account that unifying conceptual representations are primary forms of bimanual constraint. Findings further suggest that the organization and content of the language used to form action representations can strongly influence anticipatory planning of bimanual actions.

Viewer perspective affects central bottleneck requirements in spatial translation tasks.

A psychological refractory period (PRP) approach and the locus of slack logic were applied to examine the novel question of whether spatial translation processes can begin before the central bottleneck when effector or noneffector stimuli are processed from an egocentric (viewer-centered) perspective. In single tasks, trials requiring spatial translations were considerably slower than trials without translations (Experiment 1). Dual tasks consisted of tone discriminations (Task 1) and spatial translations (Task 2) using PRP methods with different manipulations on perceptual and response demands. When a viewer-centered perspective was used, the effect of spatial translation was reduced at short compared with long stimulus onset asynchronies (SOAs) when the potential for code overlap between tasks was removed (Experiments 2, 3, and 4); this finding supports the view that translation processes can begin before the central bottleneck. When an allocentric (non-viewer-centered) perspective was used (Experiment 5), the slowing associated with spatial translation was additive with SOA, suggesting that the processes of spatial translation cannot begin before the bottleneck. These findings highlight the importance of viewer perspective on central bottleneck requirements. Findings are further discussed in relation to the dorsal-ventral model of action and perception.

Goal-related planning constraints in bimanual grasping and placing of objects.

Our primary objective was to examine the possible interplay of the end-state comfort effect and bimanual temporal and spatial coupling constraints in a grasp-to-place task. Unimanual and bimanual grasping and placing tasks were employed with manipulations on initial comfort (by use of potentially interfering obstacles) and target goals (using various demands on end goal object orientations). Confirming previous temporal findings, incongruent bimanual tasks were considerably slower in initiation time and movement time than congruent ones, reflecting costs in conceptualizing, planning, and completion of the task. With respect to spatial constraints, when the same goal was present for both hands there was strong evidence of the influence of both end-state comfort and bimanual constraints. This was often not the case when the task demands differed for the two hands, although the primary task goals were still attained. We suggest that the implementation of constraints is not based on a strict hierarchy; rather, certain constraints become dominant depending on the task and situation.

The "sweet" effect: Comparative assessments of dietary sugars on cognitive performance.

In recent years there has been increasing interest in studying cognitive effects associated with sugar consumption. Neuro-cognitive research has confirmed that glucose, as a main energy substrate for the brain, can momentarily benefit cognitive performances, particularly for memory functioning. However, there is still limited understanding of relative effects of other common sugars (e.g., fructose and sucrose) on cognitive performance. The present study tested in 49 people the effects of three common dietary sugars against a placebo sweetener (i.e., sucralose), on performance of three well-studied cognitive tasks - simple response time, arithmetic, and Stroop interference, all of which are suggested to rely on the prefrontal lobe. A double-blind, placebo-controlled, cross-over experimental design was used. Results revealed that ingestion of glucose and sucrose led to poorer performances on the assessed tasks as opposed to fructose and the placebo (p<0.05); these effects were particularly pronounced under the fasting condition in comparison to the non-fasting condition (p<0.001). Overall, these results indicate that cognitive effects of sugar are unlikely to be mediated by the perception of sweetness. Rather, the effects are mediated by glucose. Further research should systematically assess effects of dietary sugars on other cognitive domains, such as memory, to give further insights on general cognitive effects of sugar consumption.

Response inhibition in patients with functional neurological symptom disorder.

Abnormal response inhibition has been demonstrated in psychogenic movement disorders (PMD) and is a plausible mechanism for other forms of functional neurological symptom disorder (FNSD), in which response inhibition has not yet been investigated. Response inhibition was therefore studied in patients with FNSD, including patients with psychogenic non-epileptic seizures (PNES), functional weakness (FW) or both. Twenty-nine patients with FNSD and 29 age and sex-matched healthy volunteers underwent a go-nogo task, a stop-signal reaction time (SSRT) task, and a negative priming flanker task. The Attentional Resource Allocation Scale, the Beck Depression Inventory and the Spielberger State and Trait Anxiety Inventory were also administered. Mean hit rates on nogo trials, miss rates on go signals and discriminability index were higher and go signal reaction times were significantly longer in the FNSD group than in healthy controls. The presence of FW was associated with increased hit rates on nogo trials, suggesting a bias toward responding to nogo signals rather than missed go signals. SSRT and negative priming were not significantly different from healthy controls. It is unclear whether impaired performance on the go-nogo task reflects dysfunctional inhibitory processes, disordered attention, or impaired ability to discriminate between stimuli.

Brain and cognitive processes of imitation in bimanual situations: Making inferences about mirror neuron systems.

The relationship between mirror neuron systems and imitation is being widely studied. However, most if not all, studies on imitation have investigated only the mirror mode. The present study examined whether imitation in a mirror (specular) mode is likely to reflect similar or distinct neural processes and psychological principles as imitation in a non-mirror (anatomical) mode. Experiment 1 examined whether altering sensory information may reverse the typical mirror mode advantage, resulting in superior performance in the non-mirror mode. Experiment 2 examined whether the two different modes of imitation rely differentially on target selection (goals) and effector selection (means). Experiment 3 examined whether spatial translations are likely to occur in a typical non-mirror imitation mode. Experiment 4 examined whether non-mirror imitation would be the naturally selected mode of imitation under some situations. Findings from all experiments demonstrated marked differences between mirror and non-mirror modes of imitation. The implications of these findings may raise challenges for theories and models of mirror neurons.