Rightward Bias Research Articles

Smartphones and rightward collisions.

People tend to deviate to the right when walking through a narrow aperture (e.g., a doorway), resulting in a rightward bias in collisions. This study examines the effects of smartphone use on rightward collisions while walking. When pedestrians walk through a narrow aperture, they usually head straight to the perceived centre of the aperture, which is shifted slightly to the right, without updating the estimates. The rightward shift of the perceived centre is attributable to the rightward attentional shift in the extrapersonal space. Pedestrians using smartphones tend to fixate on the phone most of the time and thus tend not to look at their surroundings (i.e., extrapersonal space). Therefore, we predict that smartphone use will reduce rightward collisions. To test this prediction, we used a narrow-doorway task in which participants walked through a narrow doorway either with or without a smartphone. The participants with smartphones used them to perform either verbal or spatial tasks. The number of rightward collisions decreased when the participants used smartphones. The type of task had no effect on the lateral collision biases. These results were interpreted in terms of lateral attentional bias in peripersonal and extrapersonal spaces.

Physically real and virtual reality exposed line bisection response patterns: visuospatial attention allocation in virtual reality.

To understand the nature of hemispatial attention allocation in virtual reality (VR), a line bisection task (LBT) was administered both in a real environment and a virtual environment to assess the rate of pseudoneglect. The mental construction of real and virtual environments was assumed to increase visuospatial activity in right hemisphere-related cognitive processes; an alteration in the activity that manifests in the direction and rate of line bisection lateral error. In the present study, fifty-one right-handed healthy college students were recruited. They performed a line bisection task in real and virtual environments. The obtained data showed that LBT errors in real and VR environments were correlated and individually consistent. Furthermore, a leftward LBT error was found in the physically real environment, however, in a VR the line bisection bias drifted towards the right hemispace. Participants with a lower right-handedness score showed a lower rate of left LBT bias in a real environment, but in VR, their LBT error showed a stronger rightwards error. Participants showed an individually consistent pattern in both real and VR environments, but VR-induced visuospatial reality construction was associated with rightward LBT bias in a virtual environment.

Passive Grouping Enhances Proto-Arithmetic Calculation for Leftward Correct Responses

Baby chicks and other animals including human infants master simple arithmetic. They discriminate 2 vs. 3 (1 + 1 vs. 1 + 1 + 1) but fail with 3 vs. 4 (1 + 1 + 1 vs. 1 + 1 + 1 + 1). Performance is restored when elements are grouped as 2 + 1 vs. 2 + 2. Here, we address whether grouping could lead to asymmetric response bias. We recoded behavioural data from a previous study, in which separate groups of four-day-old domestic chicks underwent an arithmetic task: when the objects were presented one-by-one (1 + 1 + 1 vs. 1 + 1 + 1 + 1), chicks failed in locating the larger group irrespective of its position and did not show any side bias; Experiment 1. When the objects were presented as grouped (2 + 1 vs. 2 + 2), chicks succeeded, performing better when the larger set was on their left; Experiment 2. A similar leftward bias was also observed with harder discriminations (4 vs. 5: 3 + 1 vs. 3 + 2), with baby chicks succeeding in the task only when the larger set was on the left (Experiments 3 and 4). A previous study showed a rightward bias, with tasks enhancing individual processing. Despite a similar effect in boosting proto-arithmetic calculations, individual processing (eliciting a right bias) and grouping (eliciting a left bias) seem to depend on distinct cognitive mechanisms.

No Sex Differences in the Attentional Bias for the Right Side of Human Bodies

Ambiguous silhouettes representing human individuals which perform unimanual actions are interpreted more often as right-handed. Such a preference might reflect a perceptual frequency effect, due to the fact that most social interactions occur with right-handers. As a consequence, observers would preferentially attend to the region in which others’ dominant hand usually falls, thus increasing the efficiency in monitoring both aggressive and communicative acts. Given that men can be more dangerous compared with women, the right-hand bias should be larger when observing male rather than female individuals, and given that aggressive interactions involve men more frequently than women, it should be larger in male rather than female observers. However, previous studies did not specifically test whether: (i) male—compared with female—observers pay more attention to the right side of others (regardless of the observed individuals’ sex), or (ii) observers (regardless of their sex) pay more attention to the right side of male—compared with female—individuals. Therefore, in the present study we used ambiguous human silhouettes rotating about their vertical axis with one arm extended in order to determine whether the rightward bias is larger for male rather than female figures and/or in male rather than female participants. According to our data, the bias toward the right side of human bodies was not significantly associated with either the figure’s or the participant’s sex.

Satellite Oceanographic Data Processing and Analysis: Correlation Between Nino 3.4 Sea Surface Temperature & Sea Surface High and Wind

El Nino Southern Oscillation (ENSO) is an irregular climate oscillation induced by sea surface temperature anomalies (SSTA) in the Equatorial Pacific Ocean. An anomalous warming in this area is known as El Nino, while an anomalous cooling bears the name of La Nina. The objectives of this study are to: reproduce Oceanic Nino Index (ONI) based on MW OISST; produce Nino Region 3.4 wind and Sea Surface High (SSH); analyze the correlation between SST and Wind & SSH; discuss Typhoon Soudelor based on SST, Wind, and SSH; and analyze the correlation of El Nino and Precipitation in specific area. MWOI-SST was used to produce monthly mean SST over Nino 3.4 region from January 1998 – May 2020. Monthly wind data was obtained from QuickScat. Daily Sea Surface High (SSH) was obtained from Copernicus Marine Environment Monitoring Service (CMEMS). Daily precipitation from TRMM 3B42 over Bandung City (Indonesia) was used to assess the correlation between El Nino and precipitation in specific area. The results show that in Nino 3.4 region, 2015 is the hottest year during 1998-2020 period with average SST of 28.5oC, and 1999 is the coldest year with average SST of 25.7oC. The result shows that the MWOI-SST Ocean Nino Index has very strong correlation with ERSST.v5 with coefficient of correlation is 0.92 and RMSE is 0.36oC. the wind speed of Nino 3.4 region is range from 5.23 m/s to 7.97 m/s. Unlike Sea Surface Temperature (SST), annual average wind speed is more stable with monthly variation. The wind speed is observed high in the beginning and the end of years. Sea Surface Height (SSH) over Nino 3.4 region varied from 65.8 cm to 106.8 cm. 2015 is the highest SSH with annual average of 96 cm, whereas 1999 is the lowest SSH with annual average of 71.4 cm. It is observed that Sea Surface Temperature (SST) has negative correlation with wind speed with coefficient of correlation of 0.28. Conversely, Sea Surface Temperature (SST) over Nino 3.4 region has positive correlation with Sea Surface High (SSH) with coefficient of correlation of 0.30. which mean the higher temperature, the higher Sea Surface Height. During the passage of Typhoon Soudelor, there is evident cool trail along its track with rightward bias. We can assume that the decreasing precipitation in Bandung City might be affected by strong El Nino occurrence in 2015.

Temporopolar regions of the human brain.

Following prolonged neglect during the formative decades of behavioural neurology, the temporopolar region has become a site of vibrant research on the neurobiology of cognition and conduct. This turnaround can be attributed to increasing recognition of neurodegenerative diseases that target temporopolar regions for peak destruction. The resultant syndromes include behavioural dementia, associative agnosia, semantic forms of primary progressive aphasia and semantic dementia. Clinicopathological correlations show that object naming and word comprehension are critically dependent on the language-dominant (usually left) temporopolar region, whereas behavioural control and non-verbal object recognition display a more bilateral representation with a rightward bias. Neuroanatomical experiments in macaques and neuroimaging in humans show that the temporoparietal region sits at the confluence of auditory, visual and limbic streams of processing at the downstream (deep) pole of the 'what' pathway. The functional neuroanatomy of this region revolves around three axes, an anterograde horizontal axis from unimodal to heteromodal and paralimbic cortex; a radial axis where visual (ventral), auditory (dorsal) and paralimbic (medial) territories encircle temporopolar cortex and display hemispheric asymmetry; and a vertical depth-of-processing axis for the associative elaboration of words, objects and interoceptive states. One function of this neural matrix is to support the transformation of object and word representations from unimodal percepts to multimodal concepts. The underlying process is likely to start at canonical gateways that successively lead to generic (superordinate), specific (basic) and unique levels of recognition. A first sign of left temporopolar dysfunction takes the form of taxonomic blurring where boundaries among categories are preserved but not boundaries among exemplars of a category. Semantic paraphasias and coordinate errors in word-picture verification tests are consequences of this phenomenon. Eventually, boundaries among categories are also blurred and comprehension impairments become more profound. The medial temporopolar region belongs to the amygdalocentric component of the limbic system and stands to integrate exteroceptive information with interoceptive states underlying social interactions. Review of the pertinent literature shows that word comprehension and conduct impairments caused by temporopolar strokes and temporal lobectomy are far less severe than those seen in temporopolar atrophies. One explanation for this unexpected discrepancy invokes the miswiring of residual temporopolar neurons during the many years of indolently progressive neurodegeneration. According to this hypothesis, the temporopolar regions become not only dysfunctional but also sources of aberrant outputs that interfere with the function of areas elsewhere in the language and paralimbic networks, a juxtaposition not seen in lobectomy or stroke.

Perception of object motion during self-motion: Correlated biases in judgments of heading direction and object motion.

This study investigated the relationship between perceived heading direction and perceived motion of an independently moving object during self-motion. Using a dual task paradigm, we tested whether object motion judgments showed biases consistent with heading perception, both across conditions and from trial to trial. Subjects viewed simulated self-motion and estimated their heading direction (Experiment 1), or walked toward a target in virtual reality with conflicting physical and visual cues (Experiment 2). During self-motion, an independently moving object briefly appeared, with varied horizontal velocity, and observers judged whether the object was moving leftward or rightward. In Experiment 1, heading estimates showed an expected center bias, and object motion judgments showed corresponding biases. Trial-to-trial variations were also correlated: on trials with a more rightward heading bias, object motion judgments were consistent with a more rightward heading, and vice versa. In Experiment 2, we estimated the relative weighting of visual and physical cues in control of walking and object motion judgments. Both were strongly influenced by nonvisual cues, with less weighting for object motion (86% vs. 63%). There were also trial-to-trial correlations between biases in walking direction and object motion judgments. The results provide evidence that shared mechanisms contribute to heading perception and perception of object motion.

Study of storm-induced changes in circulation and temperature over the northern South China Sea during Typhoon Linfa

Hydrodynamic responses of the northern South China Sea (nSCS) to Typhoon Linfa in 2009 are examined using observations and model results. A shelf circulation model based on the Regional Ocean Modelling System (ROMS-nSCS) is used in quantifying the important physical processes affecting the storm-induced changes in circulation and hydrography in the upper ocean during Linfa. The ROMS-nSCS is forced by atmospheric forcing taken from the Climate Forecast System Reanalysis (CFSR). A parametric vortex is inserted into the CFSR atmospheric forcing to improve winds and sea-level air pressures associated with Linfa. The lateral open boundary condition of ROMS-nSCS is specified based on the global ocean circulation reanalysis produced by the Hybrid Coordinate Ocean Model (HYCOM). The simulated upper ocean circulation produced by ROMS-nSCS is characterized by strong wind-driven currents over the area affected directly by Linfa and intense near-inertial oscillations (NIOs) in the wake of Linfa. The simulated cooling in the wake of the storm is biased to the right of the storm track and agrees well with satellite-derived analysis data. The simulated NIOs also have significant rightward biases. The rotary spectral analysis of model currents demonstrates that the peak frequency fp of NIOs is about 9% greater than the local inertial frequency, which can be explained mostly by the vorticity of the background circulation. Analysis of model results also reveal that different dynamics are responsible for storm-induced cooling at different stages of Linfa. In the early development stage of Linfa, the cooling in the wake of the storm is affected mostly by the storm-induced advection in the vertical. In the mature stage of Linfa, the cooling in the wake of the storm is dominated by the joint effect of the storm-induced mixing and advection. Storm-induced warming occurs outside the wake of Linfa, due to downwelling generated by the storm.

A comprehensive analysis of variability in the sulci that define the inferior frontal gyrus in the chimpanzee (Pan troglodytes) brain

AbstractObjectivesIn the human brain, the inferior frontal gyrus (IFG) is comprised of three morphological regions, which include the pars opercularis, pars triangularis, and pars orbitalis. These brains regions are implicated in a number of cognitive and linguistic functions, and the pars opercularis and pars triangularis of the language dominant hemisphere are collectively referred to as Broca's area. Evolution of the morphology of the IFG has been a topic of study in comparative neuroscience.Materials and MethodsUsing magnetic resonance images (MRI) from 294 chimpanzees with known pedigrees, we quantified the folding patterns, surface area, and depth of three sulci and their subdivisions that define the IFG.ResultsChimpanzees show considerable individual variation in IFG sulci. A higher proportion of males and chimpanzees with better orofacial motor control had a bifurcation in the dorsal limb of the fronto‐orbital sulcus. For surface area and depth, chimpanzees with better orofacial motor control had greater leftward asymmetries in surface area and increased gyrification for the fronto‐orbital sulcus and greater rightward biases for the inferior precentral sulcus. Quantitative genetic analyses revealed that the average surface area and depth for three of the five sulci subdivisions were significantly heritable. By contrast, we found no evidence for heritability in asymmetries for any of the sulci.DiscussionThese findings provide context to understanding evolutionary selection for increasing motor, cognitive and linguistic functions among primates, and contribute an essential comparative framework for interpreting IFG evolution in the human lineage.

Biases of Temporal Duration Judgements in Visual and Auditory System

Background: There is evidence that temporal duration is spatially represented on a horizontal mental timeline (MTL) with relatively short durations represented on the left and long duration on the right side. Most of this evidence comes from the visual domain. Objective: With the present study, we investigated whether temporal duration judgements of visual and auditory stimuli might be affected by spatial biases in time representation. Methods: Participants were asked to estimate the temporal duration of a target with respect to a reference stimulus. Two different exposure times were used for the reference (fast and slow), and three exposure times for the target with respect to the reference (shorter, equal, longer). Two versions of the task were implemented to probe visual and auditory temporal processing. Results: Participants showed enhanced performance when the target had longer duration than the reference independently of the type of task, but they were affected in opposite ways by the reference exposure time, in the two tasks. Best performance was observed for the fast reference in the visual domain and for the slow reference in the auditory one. Discussion: We argue that these findings provide evidence that temporal judgments of visual and auditory stimuli are affected by the duration of the reference stimulus, besides the duration of the target stimulus. Interestingly, they suggest putative leftward and rightward spatial biases in time representation for the visual and auditory domains, respectively, although future studies are necessary to further investigate these initial findings.

Asymmetric Lévy Flights Are More Efficient in Random Search

We study the first-arrival (first-hitting) dynamics and efficiency of a one-dimensional random search model performing asymmetric Lévy flights by leveraging the Fokker–Planck equation with a δ-sink and an asymmetric space-fractional derivative operator with stable index α and asymmetry (skewness) parameter β. We find exact analytical results for the probability density of first-arrival times and the search efficiency, and we analyse their behaviour within the limits of short and long times. We find that when the starting point of the searcher is to the right of the target, random search by Brownian motion is more efficient than Lévy flights with β≤0 (with a rightward bias) for short initial distances, while for β>0 (with a leftward bias) Lévy flights with α→1 are more efficient. When increasing the initial distance of the searcher to the target, Lévy flight search (except for α=1 with β=0) is more efficient than the Brownian search. Moreover, the asymmetry in jumps leads to essentially higher efficiency of the Lévy search compared to symmetric Lévy flights at both short and long distances, and the effect is more pronounced for stable indices α close to unity.

Effect of cooperative care training on physiological parameters and compliance in dogs undergoing a veterinary examination – A pilot study

One way to reduce fear and lack of compliance during veterinary procedures is ‘cooperative care training’, training animals to voluntarily participate in husbandry and medical care. Here we assessed the effects of cooperative care training on heart rate (HR), heart rate variability (HRV), tympanic membrane temperature (TMT) and compliance (i.e., all steps of the examination completed) of dogs during a veterinary examination. A blinded controlled trial with 47 dogs (training group (TG): 26; control group (CG): 21) was carried out. Forty dogs completed the study (TG: 22, CG:18). Dogs and their owners took part in a standardized veterinary visit twice (visit interval: 140 ± 23 days). In between, the TG took part in cooperative care training (10 ± 2 group training sessions, additional training at home). Linear mixed models were calculated (fixed effects HR/HRV: group* visit* period, TMT: group* visit; random effect: dogID). Compliance (completed steps of exam) was analyzed using McNemar tests. HR/HRV was higher/lower during the veterinary examination compared to the waiting room (period: p < 0.001), indicating that the examination was more stressful. No significant differences in HR/HRV regarding group*visit were found. TMT, taken at the end of each examination, resulted in a significant group*visit interaction (p = 0.008); stress appeared increased during visit 2 in the CG whereas in the TG a heterogeneous pattern, with 42% of dogs with reduced rightward bias, was observed. Compliance was lower in the TG during the second visit (p = 0.04). Trainer and owners claimed observable improvement of behavior during training and a decrease in HR between visits correlated significantly with trainer perception of high training success (rs = −0.52, p = 0.049). Overall, transfer of trained skills to the veterinary examination performed by a team blinded to the group allocation was poor. TMT analyses and HR/HRV data within the training group, suggest that the training had differing effects on the dogs based on their previous tolerance of handling and their progress made during training. Further research how to optimize training programs, including desensitization and counterconditioning, and their outcomes is needed.

“Broadband Alpha Transcranial Alternating Current Stimulation”: Exploring a new biologically calibrated brain stimulation protocol

Transcranial alternating current stimulation (tACS) can be used to study causal contributions of oscillatory brain mechanisms to cognition and behavior. For instance, individual alpha frequency (IAF) tACS was reported to enhance alpha power and impact visuospatial attention performance. Unfortunately, such results have been inconsistent and difficult to replicate. In tACS, stimulation generally involves one frequency, sometimes individually calibrated to a peak value observed in an M/EEG power spectrum. Yet, the ‘peak’ actually observed in such power spectra often contains a broader range of frequencies, raising the question whether a biologically calibrated tACS protocol containing this fuller range of alpha-band frequencies might be more effective. Here, we introduce ‘Broadband-alpha-tACS’, a complex individually calibrated electrical stimulation protocol. We band-pass filtered left posterior resting-state EEG data around the IAF (± 2 Hz), and converted that time series into an electrical waveform for tACS stimulation of that same left posterior parietal cortex location. In other words, we stimulated a brain region with a ‘replay’ of its own alpha-band frequency content, based on spontaneous activity. Within-subjects (N = 24), we compared to a sham tACS session the effects of broadband-alpha tACS, power-matched spectral inverse (‘alpha-removed’) control tACS, and individual alpha frequency (IAF) tACS, on EEG alpha power and performance in an endogenous attention task previously reported to be affected by alpha tACS. Broadband-alpha-tACS significantly modulated attention task performance (i.e., reduced the rightward visuospatial attention bias in trials without distractors, and reduced attention benefits). Alpha-removed tACS also reduced the rightward visuospatial attention bias. IAF-tACS did not significantly modulate attention task performance compared to sham tACS, but also did not statistically significantly differ from broadband-alpha-tACS. This new broadband-alpha-tACS approach seems promising, but should be further explored and validated in future studies.

The directionality of reduplicative plurality

One instantiation of the well-known suffixing preference is the strong predominance of suffixes over prefixes in nominal-plural marking. Plurality may also be expressed by (partial) reduplication. In contradistinction to the rightward bias of affixes, reduplication in general exhibits a leftward bias. These opposite effects lead to a notable prediction regarding the directionality of reduplicative plurals, which are expected to show a compromise between the rightward bias of affixing and the leftward bias of reduplication. This prediction is not borne out in a sizeable sample of languages with reduplicative plurals. Almost all these languages put the reduplicant in word-initial position. That is, the leftward bias in reduplicative plurals is even more pronounced than that in reduplication generally. The explanation of this striking set of results revolves around a conspiracy of several factors which render the occurrence of word-final reduplicative plurals extremely unlikely. Thus, word-initial and word-final sites are much more unequal competitors in reduplicative plurality than prefixes and suffixes are in affixal plural marking.

Visuospatial Bias in Children with Autism Spectrum Disorder: Evidence from Line Bisection Tasks.

Previous studies have found reduced leftward bias of facial processing in individuals with Autism Spectrum Disorder (ASD). However, it is not clear whether they manifest a leftward bias in general visual processing. To shed light on this issue, the current study used the manual line bisection task to assess children 5 to 15years of age with ASD as well as typically developing (TD) children. Results showed that children with ASD, similar to TD children, demonstrate a leftward bias in general visual processing, especially for bisecting long lines (≧80mm). In both groups, participant performance in line bisection was affected by the hand used, the length of the line, the cueing symbol, and the location of the symbol. The ASD group showed a rightward bias when bisecting short lines (30mm) with their left hands, which slightly differed from the TD group. These results indicate that while ASD individuals and TD individuals share a similar leftward bias in general visual processing, when using their left hands to bisect short lines, ASD individuals may show an atypical bias pattern.

Representation of Body Orientation in Vestibular-Defective Patients Before and After Unilateral Vestibular Loss.

Introduction: The unilateral vestibular syndrome results in postural, oculomotor, perceptive, and cognitive symptoms. This study was designed to investigate the role of vestibular signals in body orientation representation, which remains poorly considered in vestibular patients.Methods: The subjective straight ahead (SSA) was investigated using a method disentangling translation and rotation components of error. Participants were required to align a rod with their body midline in the horizontal plane. Patients with right vestibular neurotomy (RVN; n =8) or left vestibular neurotomy (LVN; n = 13) or vestibular schwannoma resection were compared with 12 healthy controls. Patients were tested the day before surgery and during the recovery period, 7 days and 2 months after the surgery.Results: Before and after unilateral vestibular neurotomy, i.e., in the chronic phases, patients showed a rightward translation bias of their SSA, without rotation bias, whatever the side of the vestibular loss. However, the data show that the lower the translation error before neurotomy, the greater its increase 2 months after a total unilateral vestibular loss, therefore leading to a rightward translation of similar amplitude in the two groups of patients. In the early phase after surgery, SSA moved toward the operated side both in translation and in rotation, as typically found for biases occurring after unilateral vestibular loss, such as the subjective visual vertical (SVV) bias.Discussion and Conclusion: This study gives the first description of the immediate consequences and of the recovery time course of body orientation representation after a complete unilateral vestibular loss. The overall evolution differed according to the side of the lesion with more extensive changes over time before and after left vestibular loss. It is noteworthy that representational disturbances of self-orientation were highly unusual in the chronic stage after vestibular loss and similar to those reported after hemispheric lesions causing spatial neglect, while classical ipsilesional biases were reported in the acute stage. This study strongly supports the notion that the vestibular system plays a major role in body representation processes and more broadly in spatial cognition. From a clinical point of view, SSA appeared to be a reliable indicator for the presence of a vestibular disorder.

Response of the Bay of Bengal to super cyclone Amphan examined using synergistic satellite and in-situ observations

Tropical cyclone Amphan is the first super cyclone that happened in the north Indian Ocean in the last 20 years. In this work, multi-platform datasets were used to investigate the responses of the upper ocean to cyclone Amphan. The most striking response was the cold wake left by the cyclone spanning the entire Bay of Bengal with an amplitude up to ∼4°C. Satellite salinity observations revealed that the maximum increase in surface salinity was ∼1.5 PSU on the right side of the track of Amphan. Surface circulation was also observed to be modulated with the passage of a cyclone with a rightward bias in the change in its speed and direction. The currents observed from a moored buoy showed strong inertial oscillations. Argo observations showed that changes induced by the cyclone occurred up to 150 m depth of the cyclone and ocean heat content in the upper 150 m depth decreased due to the passage of the cyclone. There was an enhancement of surface chlorophyll concentration (∼1.5 mg/m3) after the passage of the cyclone, which was centred along the track of the cyclone where the winds were the highest. Mixed layer heat and salinity budget analysis showed that the sea surface cooling and increase in salinity was primarily driven by vertical mixing processes, though horizontal advection contributed meagrely. This study also brings forward the fact that regional differences exist in the responses of the ocean to the forcing of cyclones.

Investigating visuo-spatial neglect and visual extinction during intracranial electrical stimulations: The role of the right inferior parietal cortex

Both visuo-spatial neglect and visual extinction may occur following right-brain damage. So far, studies on brain-damaged patients have not provided definite evidence about which lesion patterns may lead to the association or dissociation of these deficits. This study was set out to address this issue using Intracranial Electrical Stimulation (IES) in a group of nine patients affected by refractory epilepsy. Cerebral regions associated with visuo-spatial neglect and visual extinction were stimulated, including the right frontal, temporal, and posterior parietal areas. During IES, patients with intracranial implantation involving at least one of these cortical regions were administered with a manual line bisection task (N = 9) to assess visuo-spatial neglect, and a computerized task (N = 8) assessing visual extinction. Results showed that parietal IES induced a rightward bias at the manual bisection task, together with a general improvement in reaction times at bilateral and unilateral visual stimuli detection at the extinction task. The occurrence of visual extinction did not vary across stimulations. By adopting a complementary approach to anatomo-clinical correlation studies, our work corroborates the notion that lesions to the right inferior parietal lobule play a pivotal role in the pathogenesis of visuo-spatial neglect. Importantly, our results also suggest that temporarily interfering with the activity of this region is not sufficient per se to generate visual extinction, which instead may involve a broader and/or different network, possibly extending beyond the cerebral regions considered here, posing important theoretical and clinical implications.

Revisiting the attentional bias in the split brain

Previous research has revealed a strong right bias in allocation of attention in split brain subjects, suggesting that a pathological attention bias occurs not only after unilateral (usually right-hemispheric) damage but also after functional disconnection of intact right-hemispheric areas involved in allocation of attention from those in the left hemisphere. Here, we investigated the laterality bias in spatial attention, as measured with the greyscales task, in two split-brain subjects (D.D.C. and D.D.V.) who had undergone complete callosotomy. The greyscales task requires participants to judge the darker (or brighter) of two left-right mirror-reversed luminance gradients under conditions of free viewing, and offers an efficient means of quantifying pathological attentional biases in patients with unilateral lesions. As predicted, the results of the two split-brain subjects revealed a pathological rightward bias in allocation of attention, suggesting strong dependence on a single hemisphere (the left) in spatial attention, which is opposite to what one expects from people with intact commissures, and is remarkable in that it occurs in free viewing. In that sense both split-brain patients are behaving as though the brain is indeed split, especially in D.D.C. who had undergone partial resection of the anterior commissure in addition to complete callosotomy, whereas the anterior commissure is still intact in D.D.V. The findings support the view that the commissural pathways play a significant role in integration of attentional processes across cerebral hemispheres.

Effects of Gold Nanoparticles on the Stepping Trajectories of Kinesin.

A substantial increase in the temporal resolution of the stepping of dimeric molecular motors is possible by tracking the position of a large gold nanoparticle (GNP) attached to a labeled site on one of the heads. This technique was employed to measure the stepping trajectories of conventional kinesin (Kin1) using the time-dependent position of the GNP as a proxy. The trajectories revealed that the detached head always passes to the right of the head that is tightly bound to the microtubule (MT) during a step. In interpreting the results of such experiments, it is assumed that the GNP does not significantly alter the diffusive motion of the detached head. We used coarse-grained simulations of a system consisting of the MT-Kin1 complex with and without attached GNP to investigate how the stepping trajectories are affected. The two significant findings are: (1) The GNP does not faithfully track the position of the stepping head, and (2) the rightward bias is typically exaggerated by the GNP. Both these findings depend on the precise residue position to which the GNP is attached. Surprisingly, the stepping trajectories of kinesin are not significantly affected if, in addition to the GNP, a 1 μm diameter cargo is attached to the coiled coil. Our simulations suggest the effects of the large probe have to be considered when inferring the stepping mechanisms using GNP tracking experiments.