Unilateral Brain Lesions Research Articles

The Left-Right Side-Specific Neuroendocrine Signaling from Injured Brain: An Organizational Principle.

A neurological dogma is that the contralateral effects of brain injury are set through crossed descending neural tracts. We have recently identified a novel topographic neuroendocrine system (T-NES) that operates via a humoral pathway and mediates the left-right side-specific effects of unilateral brain lesions. In rats with completely transected thoracic spinal cords, unilateral injury to the sensorimotor cortex produced contralateral hindlimb flexion, a proxy for neurological deficit. Here, we investigated in acute experiments whether T-NES consists of left and right counterparts and whether they differ in neural and molecular mechanisms. We demonstrated that left- and right-sided hormonal signaling is differentially blocked by the δ-, κ- and µ-opioid antagonists. Left and right neurohormonal signaling differed in targeting the afferent spinal mechanisms. Bilateral deafferentation of the lumbar spinal cord abolished the hormone-mediated effects of the left-brain injury but not the right-sided lesion. The sympathetic nervous system was ruled out as a brain-to-spinal cord-signaling pathway since hindlimb responses were induced in rats with cervical spinal cord transections that were rostral to the preganglionic sympathetic neurons. Analysis of gene-gene co-expression patterns identified the left- and right-side-specific gene co-expression networks that were coordinated via the humoral pathway across the hypothalamus and lumbar spinal cord. The coordination was ipsilateral and disrupted by brain injury. These findings suggest that T-NES is bipartite and that its left and right counterparts contribute to contralateral neurological deficits through distinct neural mechanisms, and may enable ipsilateral regulation of molecular and neural processes across distant neural areas along the neuraxis.

Does right hemisphere compensate for the left in school-age children with large left middle fossa arachnoid cysts?

BackgroundTo assess the cognitive function changes and brain network neuroplasticity in school-age children having large (diameter > 5 cm) left middle fossa arachnoid cyst (MFACs).MethodsEleven patients and 22 normal controls (NC) between 6 and 14 years of age were included. The CNS Vital Signs (CNS VS) were administered for cognitive assessment. The differences of cognitive data and functional connectivity (FC) in resting-state functional magnetic resonance imaging (rs-fMRI) were compared between the patient group and the NC group. The correlations between the altered FC and cognitive data in the patient group were assessed.ResultsPatient group had significantly poorer attention (including Complex Attention, Sustained Attention, Simple Attention, Cognitive Flexibility, and Executive Function) and memory function (Visual Memory and Working Memory) than the NC group (uncorrected p-value, p-unc < 0.05). Whole-brain local correlation (LCOR) analysis showed an extensively lower LCOR in the patient group (voxel threshold p-unc < 0.001, cluster-size threshold of false discovery rate adjusted p (p-FDR) < 0.001). Functional connectivity (FC) analysis showed that bilateral frontal and temporal lobes connectivity in the patient group was significantly lower than the NC group (p-FDR < 0.05). Seed-based FC analysis indicated that there was altered FC between the right temporal lobe and the left temporal-parietal/temporal-occipital area (p-FDR < 0.05). In the patient group, most of the altered FC had a negative correlation to the cognitive score, while the FC in the right temporal lobe-left temporal-occipital area positively correlated to Verbal/Visual Memory (r = 0.41–0.60, p-FDR < 0.05). In correlation analysis between clinical data and cognitive score, the only significant result was a low correlation between cyst size and Reaction Time (-0.30–-0.36, P-FDR < 0.05).ConclusionsSchool-aged children with large left MFAC showed significantly lower cognitive performance primarily in attention and memory domains. Distinct from neuroplasticity in a unilateral brain lesion, compensation in the healthy hemisphere in MFAC patients was sparse.

88 REASmash: A serious game in immersive virtual reality for the evaluation of spatial and non-spatial attention impairments in post-stroke individuals.

Objective:Stroke results in various cognitive and motor impairments. The most frequent cognitive problem is spatial and non-spatial attention, typically caused by unilateral brain lesion. Attention is typically assessed with several different paper-and-pencil tests, which have long been criticized for their lack of theoretical basis, their limited ecological validity to deficits experienced in daily life, and their lack of measurement sensitivity (Appelros et al., 2004; Azouvi, 2017). Here, our global aim was to develop an innovative integrative serious game in an immersive environment. The REASmash, combines the evaluation of spatial attention, non-spatial attention, and motor performance. We present the spatial and non-spatial cognitive attention evaluation results.Participants and Methods:Eighteen first stroke individuals and 40 age-match healthy controls were assessed on the REASmash. They were instructed to find a target mole presented amongst distractor moles. The stimulus array consisted of a grid of 6 columns and 4 rows of molehills, from which the target and 11, 17 and 23 distractors moles could randomly appear, in two search conditions (single feature condition and saliency condition). Responses were made with the ipsilesional hand for individuals with stroke and with the dominant hand for the healthy controls. Participants were evaluated also with two standardized clinical tests of attention; the hearts cancellation task of the Oxford Cognitive Screen, and the visual scanning subtest of the Test for Attentional Performance.Results:Validation results showed significant and strong correlations between the REASmash and the two reference tests, with the REASmash showing high sensitivity and specificity (i.e., the correct identification of the post-stroke vs. control individuals). The REASmash also showed significant and strong test/re-test reliability. We additionally evaluated user experience using the UEQ, and the results showed excellent attractiveness and novelty, and good stimulation and efficiency.Conclusions:In conclusion, the REASmash is a novel immersive virtual environment serious game that is valid, sensitive, and usable. It provides a new diagnosis measure spatial and non-spatial attention impairment.

Monocular eye patching modulates reorienting of covert attention in patients with unilateral middle cerebral artery stroke

Unilateral brain lesions can lead to impaired contralesional attention and reduced ipsilesional and enhanced contralesional superior colliculus (SC) activity. We aimed to investigate whether modulation of SC activation via monocular eye patching can improve contralesional attention. Twenty left-hemispheric (LH) and 20 right-hemispheric (RH) patients with an acute or subacute middle cerebral artery (MCA) stroke completed an endogenous version of the Posner cueing task twice, while the left or right eye was covered with an eye patch. The LH and RH patients showed significantly slower reactions to contralesional than to ipsilesional stimuli. In addition, the eye patch modulated responses to invalidly but not those to validly cued stimuli. Post hoc analyses could not discriminate whether this effect pertained to a particular target side or eye patch position. However, exploratory analyses indicated that the observed eye patch effect might affect the RH group more than the LH group. As predicted 36 years ago, monocular eye patching modulates visuospatial attention, presumably due to differences in SC activation between the two eye patch conditions. However, this modulation seems too weak and unspecific, and therefore possibly not strong enough to be a treatment option for patients with visuospatial attention impairments.

Action Observation Training to Improve Upper Limb Function in Infants with Unilateral Brain Lesion – a Feasibility Study

ABSTRACT In this study, the feasibility of Action Observation Training (AOT) in combination with sensor-based measurements in infants at high risk of Unilateral Spastic Cerebral Palsy (UCP) were evaluated. Over a four-week period, eight infants at high risk of UCP performed AOT at home while wearing sensors with assistance of caregivers. Sensor data were compared to clinical assessments of upper limb function, the Hand Assessment for Infants (HAI) and the Mini-Assisting Hand Assessment (Mini-AHA). AOT training time and acceptance by the caregivers were considered as indicators for feasibility. The excellent training adherence and positive feedback of the caregivers showed that the AOT was feasible in this patient group and setting. Sensor measurements were accepted and displayed significant correlations with hand function. These preliminary results indicate the potential of wearable sensors to record upper limb function over the course of AOT for infants at high risk of UCP. Thus, AOT in combination with sensor measurements are proposed as a feasible training tool to complement usual care.

Neuro-imaging characteristics of sensory impairment in cerebral palsy; a systematic review.

Objective: To identify and examine neural reorganization of the sensory network in terms of lesion type, somatotopic organization of the primary somatosensory area, and functional connectivity in relation to sensory function in children and young adults with cerebral palsy (CP). Design: systematic review, Prospero registration ID 342570. Data sources: PubMed; Cochrane; Web of Science; Embase; CINAHL and PEDro from inception to March 13, 2021. Eligibility criteria: All types of original studies, concerning sensory connectivity in relation to sensory outcome in patients with spastic CP, <30 years of age. No publication status or date restrictions were applied. Data extraction and synthesis: Two authors independently determined the eligibility of studies. Quality assessment was performed by a third author. Neuro-imaging/neurophysiological techniques, sensory outcomes and patient characteristics were extracted. Children and young adults with periventricular leucomalacia (PVL) lesions have significantly better hand function and sensation scores than patients with cortical-subcortical/middle cerebral artery (MCA) lesions. Ipsilesional reorganization of the S1 (primary somatosensory cortex) area appears to be the primary compensation mechanism after a unilateral early brain lesion, regardless of the timing of the lesion. Interhemispheric reorganization of the sensory system after early brain lesions is rare and, when it occurs, poorly effective. Diffusion tractography shows a positive correlation between the ascending sensory tract (AST) diffusivity metrics of the more affected hemisphere and sensory test outcomes. Because of the large variability in study design, patient characteristics, neuroimaging/neurophysiological techniques and parameters as well as sensory assessment methods used, it is difficult to draw definite inferences on the relationship between the reorganization of the sensory network following early brain damage and sensory function in children and young adults with CP. In general, sensory function seems to be worse in cortical as opposed to white matter tract (PVL) lesions. International consensus on a clinically relevant sensory test battery is needed to enhance understanding of the intriguing compensatory mechanisms of sensory network following early brain damage and potential consequences for rehabilitation strategies. https://www.crd.york.ac.uk/prospero/.

Multisensory Stimulation and Priming (MuSSAP) in 4-10 Months Old Infants with a Unilateral Brain Lesion: A Pilot Randomised Clinical Trial.

To explore the effect of an Early Intensive-Upper Limb intervention (EI-UL) compared to EI-UL with integrated Multisensory Stimulation And Priming (MuSSAP) training on improving manual ability in infants with a unilateral brain lesion. A pilot randomised clinical trial with pre- and postintervention and follow-up measurements (T0, T1, and T2) was conducted. Sixteen infants with a unilateral brain lesion (corrected age is 4-10 months) received home-based intervention with video coaching. Eight infants received EI-UL and eight infants received EI-UL with integrated MuSSAP training. Primary outcome was the Hand Assessment for Infants (HAI) score. Additionally, effects were explored on initiation of goal-directed movements in both groups and on attention in the EI-UL with integrated MuSSAP training group. No significant group differences in HAI scores were found. Overall, HAI 'Affected hand score' increased between T0 and T1 (p = 0.001, Cohen's d = 1.04) and between T0 and T2 (p < 0.001, Cohen's d = 1.28); and the HAI 'Both Hands Measure' increased between T0 and T1 (p < 0.001, Cohen's d = 1.72) and between T0 and T2 (p < 0.001, Cohen's d = 1.81). At the start of the intervention, six infants (three in both groups) did not demonstrate initiation of goal-directed contralesional upper limb movements. During the intervention one infant receiving EI-UL and all three infants receiving EI-UL with integrated MuSSAP training started to initiate goal-directed movements. The results suggest manual ability of infants with unilateral brain lesion improved with both interventions. We hypothesize that the integrated MuSSAP training may facilitate attention and initiation of contralesional upper limb goal-directed movements. This trial is registered with NCT05533476).

Graph lesion-deficit mapping of fluid intelligence.

Fluid intelligence is arguably the defining feature of human cognition. Yet the nature of its relationship with the brain remains a contentious topic. Influential proposals drawing primarily on functional imaging data have implicated 'multiple demand' frontoparietal and more widely distributed cortical networks, but extant lesion-deficit studies with greater causal power are almost all small, methodologically constrained, and inconclusive. The task demands large samples of patients, comprehensive investigation of performance, fine-grained anatomical mapping, and robust lesion-deficit inference, yet to be brought to bear on it. We assessed 165 healthy controls and 227 frontal or non-frontal patients with unilateral brain lesions on the best-established test of fluid intelligence, Raven's Advanced Progressive Matrices, employing an array of lesion-deficit inferential models responsive to the potentially distributed nature of fluid intelligence. Non-parametric Bayesian stochastic block models were used to reveal the community structure of lesion deficit networks, disentangling functional from confounding pathological distributed effects. Impaired performance was confined to patients with frontal lesions [F(2,387) = 18.491; P < 0.001; frontal worse than non-frontal and healthy participants P < 0.01, P <0.001], more marked on the right than left [F(4,385) = 12.237; P < 0.001; right worse than left and healthy participants P < 0.01, P < 0.001]. Patients with non-frontal lesions were indistinguishable from controls and showed no modulation by laterality. Neither the presence nor the extent of multiple demand network involvement affected performance. Both conventional network-based statistics and non-parametric Bayesian stochastic block modelling heavily implicated the right frontal lobe. Crucially, this localization was confirmed on explicitly disentangling functional from pathology-driven effects within a layered stochastic block model, prominently highlighting a right frontal network involving middle and inferior frontal gyrus, pre- and post-central gyri, with a weak contribution from right superior parietal lobule. Similar results were obtained with standard lesion-deficit analyses. Our study represents the first large-scale investigation of the distributed neural substrates of fluid intelligence in the focally injured brain. Combining novel graph-based lesion-deficit mapping with detailed investigation of cognitive performance in a large sample of patients provides crucial information about the neural basis of intelligence. Our findings indicate that a set of predominantly right frontal regions, rather than a more widely distributed network, is critical to the high-level functions involved in fluid intelligence. Further they suggest that Raven's Advanced Progressive Matrices is a useful clinical index of fluid intelligence and a sensitive marker of right frontal lobe dysfunction.

Temporal judgments of actions following unilateral brain damage

Sense of time is a complex construct, and its neural correlates remain to date in most part unknown. To complicate the frame, physical attributes of the stimulus, such as its intensity or movement, influence temporal perception. Although previous studies have shown that time perception can be compromised after a brain lesion, the evidence on the role of the left and right hemispheres are meager. In two experiments, the study explores the ability of temporal estimation of multi-second actions and non-biological movements in 33 patients suffering from unilateral brain lesion. Furthermore, the modulatory role of induced embodiment processes is investigated. The results reveal a joint contribution of the two hemispheres depending not only on different durations but also on the presence of actions. Indeed, the left hemisphere damaged patients find it difficult to estimate 4500 ms or longer durations, while the right hemisphere damaged patients fail in 3000 ms durations. Furthermore, the former fail when a biological action is shown, while the latter fail in non-biological movement. Embodiment processes have a modulatory effect only after right hemisphere lesions. Among neuropsychological variables, only spatial neglect influences estimation of non-biological movement.

Production and Comprehension of Prosodic Boundary Marking in Persons With Unilateral Brain Lesions.

Persons with unilateral brain damage in the right hemisphere (RH) or left hemisphere (LH) show limitations in processing linguistic prosody, with yet inconclusive results on their ability to process prosodically marked structural boundaries for syntactic ambiguity resolution. We aimed at systematically investigating production and comprehension of three prosodic cues (f 0 range, final lengthening, and pause) at structural boundaries in coordinate sequences in participants with right hemisphere brain damage (RHDP) and participants with left hemisphere brain damage (LHDP). Twenty RHDP and 15 LHDP participated in our study. Comprehension experiment: Participants and a control group listened to coordinate name sequences with internal grouping by a prosodically marked structural boundary (grouped condition, e.g., "(Gabi und Leni) # und Nina") or without internal grouping (ungrouped condition, e.g., "Gabi und Leni und Nina") and had to identify the target condition. The strength and combinations of prosodic cues in the stimuli were manipulated. Production experiment: Participants were asked to produce coordinate sequences in the two conditions (grouped, ungrouped) in two different tasks: a Reading Aloud and a Repetition experiment. Accuracy of participants' productions was subsequently assessed in a rating study and productions were analyzed with respect to use of prosodic cues. In the Comprehension experiment, RHDP and LHDP had overall lower identification accuracies than unimpaired control participants and LHDP were found to have particular problems with boundary identification when the pause cue was reduced. In production, LHDP and RHDP employed all three prosodic cues for boundary marking, but struggled to clearly mark prosodic boundaries in 28% of all productions. Both groups showed better performance in reading aloud than in repetition. LHDP relied more on using f 0 range and pause duration to prosodically mark structural boundaries, whereas RHDP employed final lengthening more vigorously than LHDP in reading aloud. We conclude that processing of linguistic prosody is affected in RHDP and LHDP, but not completely impaired. Therefore, prosody can serve as a relevant communicative resource. However, it should also be considered as a target area for assessment and treatment in both groups. https://doi.org/10.23641/asha.21637505.

The challenge of neuropsychological assessment of visual/visuo-spatial memory: A critical, historical review, and lessons for the present and future.

A proliferation of tests exists for the assessment of auditory-verbal memory processes. However, from a clinical practice perspective, the situation is less clear when it comes to the ready availability of reliable and valid tests for the evaluation of visual/visuo-spatial memory processes. While, at face value, there appear to be a wide range of available tests of visual/visuo-spatial memory, utilizing different types of materials and assessment strategies, a number of criticisms have been, and arguably should be, leveled at the majority of these tests. The criticisms that have been directed toward what are typically considered to be visual/visuo-spatial memory tests, such as (1) the potential for verbal mediation, (2) over-abstraction of stimuli, (3) the requirement of a drawing response, and (4) the lack of sensitivity to unilateral brain lesions, mean that, in reality, the number of readily available valid tests of visual/visuo-spatial memory is, at best, limited. This article offers a critical, historical review on the existing measures and resources for the neuropsychological assessment of visual/visuo-spatial memory, and it showcases some examples of newer tests that have aimed to overcome the challenges of assessing these important aspects of memory. The article also identifies new trends and examples of how technological advances such as virtual reality may add value to overcome previous obstacles to assessment, thereby offering professionals more reliable, accurate means to evaluate visual/visuo-spatial memory in clinical practice.

Contralateral Limb Specificity for Movement Preparation in the Parietal Reach Region.

The canonical view of motor control is that distal musculature is controlled primarily by the contralateral cerebral hemisphere; unilateral brain lesions typically affect contralateral but not ipsilateral musculature. Contralateral-only limb deficits following a unilateral lesion suggest but do not prove that control is strictly contralateral: the loss of a contribution of the lesioned hemisphere to the control of the ipsilesional limb could be masked by the intact contralateral drive from the nonlesioned hemisphere. To distinguish between these possibilities, we serially inactivated the parietal reach region, comprising the posterior portion of medial intraparietal area, the anterior portion of V6a, and portions of the lateral occipital parietal area, in each hemisphere of 2 monkeys (23 experimental sessions, 46 injections total) to evaluate parietal reach region's contribution to the contralateral reaching deficits observed following lateralized brain lesions. Following unilateral inactivation, reach reaction times with the contralesional limb were slowed compared with matched blocks of control behavioral data; there was no effect of unilateral inactivation on the reaction time of either ipsilesional limb reaches or saccadic eye movements. Following bilateral inactivation, reaching was slowed in both limbs, with an effect size in each no different from that produced by unilateral inactivation. These findings indicate contralateral organization of reach preparation in posterior parietal cortex.SIGNIFICANCE STATEMENT Unilateral brain lesions typically affect contralateral but not ipsilateral musculature. Contralateral-only limb deficits following a unilateral lesion suggest but do not prove that control is strictly contralateral: the loss of a contribution of the lesioned hemisphere to the control of the ipsilesional limb could be masked by the intact contralateral drive from the nonlesioned hemisphere. Unilateral lesions cannot distinguish between contralateral and bilateral control, but bilateral lesions can. Here we show similar movement initiation deficits after combined unilateral and bilateral inactivation of the parietal reach region, indicating contralateral organization of reach preparation.

Apperceptive and associative visual object agnosia in patients with acute ischemic stroke

Visual object agnosia (VOA) is a loss of the ability to recognize visible objects in patients with the intact primary visual functions and in the absence of dementia. The apperceptive and associative variants of VOA are marked out. The apperceptive VOA is thought to be due to «pre-semantic» impairment of visual information processing. The associative VOA is caused by the loss of access to knowledge about the objects, and its semantic subtype is due to the disintegration of this knowledge itself. It is important to diagnose VOA and its variants in time to provide individualized approaches to medical rehabilitation of patients. Case reports of apperceptive and associative VOA in acute ischemic stroke are presented in this paper. These case reports indicate the possibility of the development of apperceptive and associative VOA in unilateral acute ischemic brain lesion. The variants of VOA can be recognized only by a detailed neuropsychological examination.

Simultaneously stimulating both brain hemispheres by rTMS in patients with unilateral brain lesions decreases interhemispheric asymmetry.

Interhemispheric asymmetry caused by brain lesions is an adverse factor in the recovery of patients with neurological deficits. Repetitive transcranial magnetic stimulation (rTMS) has been shown to modulate cortical oscillation and proposed as an approach to rebalance the symmetry, which has not been documented well. In this study, we investigated the influence of repetitive transcranial magnetic stimulation (rTMS) on EEG power in patients with unilateral brain lesions by simultaneously stimulating both brain hemispheres and to elucidate asymmetrical changes in rTMS-induced neurophysiological activity. Fourteen patients with unilateral brain lesions were treated with one active and one sham session of 10 Hz rTMS over the vertex (Cz position). Resting-state EEGs were recorded before and immediately after rTMS. The brain symmetry index (BSI), calculated from a fast Fourier transform, was employed to quantify the power asymmetry in both hemispheres and paired channels over the entire range and five frequency bands (delta, theta, alpha, beta and gamma bands). Comparison between active and sham sessions demonstrated rTMS-induced EEG after-effects. rTMS in the active session significantly reduced the BSI in patients with unilateral brain lesions over the entire frequency range (t = 2.767, P = 0.016). Among the five frequency bands, rTMS only induced a noticeable decrease in the BSI in the delta band (t = 2.254, P = 0.042). Furthermore, analysis of different brain regions showed that significant changes in the BSI of the alpha band were only demonstrated in the posterior parietal lobe. In addition, EEG topographic mapping showed a decreased power of delta oscillations in the ipsilesional hemisphere, whereas distinct cortical oscillations were observed in the alpha band around the parietal-occipital lobe in the contralesional hemisphere. When both brain hemispheres were simultaneously activated, rTMS decreased interhemispheric asymmetry primarily via reducing the delta band in the lesioned hemisphere.

Is There a Causal Link between the Left Lateralization of Language and Other Brain Asymmetries? A Review of Data Gathered in Patients with Focal Brain Lesions.

This review evaluated if the hypothesis of a causal link between the left lateralization of language and other brain asymmetries could be supported by a careful review of data gathered in patients with unilateral brain lesions. In a short introduction a distinction was made between brain activities that could: (a) benefit from the shaping influences of language (such as the capacity to solve non-verbal cognitive tasks and the increased levels of consciousness and of intentionality); (b) be incompatible with the properties and the shaping activities of language (e.g., the relations between language and the automatic orienting of visual-spatial attention or between cognition and emotion) and (c) be more represented on the right hemisphere due to competition for cortical space. The correspondence between predictions based on the theoretical impact of language on other brain functions and data obtained in patients with lesions of the right and left hemisphere was then assessed. The reviewed data suggest that different kinds of hemispheric asymmetries observed in patients with unilateral brain lesions could be subsumed by common mechanisms, more or less directly linked to the left lateralization of language.

Story reading with incidental comprehension and memory: left hemisphere dominance.

There are no studies on adults with unilateral brain lesions regarding story reading with incidental/implicit comprehension and memory, in which memory is only assessed through delayed recall. There is a need for validation of cerebral laterality in this type of verbal recall, which includes spontaneous performance (free or uncued condition (UC)), and induced-through-question performance regarding the forgotten units (cued condition (CC)). To explore the effects of unilateral brain lesions, of oral reading with expression (RE) and comprehension (RC) on delayed recall of a story, as either UC or CC; and to validate the ability of UC and CC to discriminate the side of brain injury. Data were obtained from 200 right-handed volunteers, among whom 42 had left-hemisphere injury (LHI), 49 had right-hemisphere injury (RHI) and 109 were demographically-matched healthy participants (HP). Patients who were unable to read, understand or speak were excluded. LHI individuals presented impairment of both UC and CC, in relation to the other two groups (non-LHI) with sensitivity and specificity above 70%. LHI and RHI individuals were not significantly different in RE and RC, but they were both different from HP in all the assessments except CC, in which RHI individuals resembled HP. Despite this lack of abnormality in RHI individuals during CC, about half of this group showed impairment in UC. Additionally, whereas RE had a significant effect on UC, the moral of the story (RC) had a significant effect on both UC and CC. The left hemisphere was dominant for this memory task involving implicit processing.

Unilateral brain injury to pregnant rats induces asymmetric neurological deficits in the offspring

Effects of environmental factors may be transmitted to the following generation, and cause neuropsychiatric disorders including depression, anxiety and posttraumatic stress disorder in the offspring. Enhanced synaptic plasticity induced by environmental enrichment may be also transmitted. We here test the hypothesis that the effects of brain injury in pregnant animals may produce neurological deficits in the offspring. Unilateral brain injury (UBI) by ablation of the hindlimb sensorimotor cortex in pregnant rats resulted in the development of hindlimb postural asymmetry (HL-PA), and impairment of balance and coordination in beam walking test in the offspring. The offspring of rats with the left UBI exhibited HL-PA before and after spinal cord transection with the contralesional (i.e. right) hindlimb flexion. The right UBI caused the offspring to develop HL-PA that however was cryptic and not-lateralized; it was evident only after spinalization, and was characterized by similar occurrence of the ipsi- and contralesional hindlimb flexion. The HL-PA persisted after spinalization suggesting that the asymmetry was encoded in lumbar spinal neurocircuits that control hindlimb muscles. Balance and coordination were affected by the right UBI but not the left UBI. Thus, the effects of a unilateral brain lesion in pregnant animals may be intergenerationally transmitted, and this process may depend on the side of brain injury. The results suggest the existence of left-right side specific mechanisms that mediate transmission of the lateralized effects of brain trauma from mother to fetus.

Hemispheric asymmetries in visual mental imagery.

Visual mental imagery is the faculty whereby we can "visualize" objects that are not in our line of sight. Longstanding evidence dating back over thirty years has shown that unilateral brain lesions, especially in the left temporal lobe, can impair aspects of this ability. Yet, there is currently no attempt to identify analogies between these neuropsychological findings of hemispheric asymmetry and those from other neuroscientific approaches. Here, we present a critical review of the available literature on the hemispheric laterality of visual mental imagery, by looking at cross-method patterns of evidence in the domains of lesion neuropsychology, neuroimaging, and direct cortical stimulation. Results can be summarized under three main axes. First, frontoparietal networks in both hemispheres appear to be associated with visual mental imagery. Second, lateralization patterns emerge in the temporal lobes, with the left inferior temporal lobe being the most common finding in the literature for endogenously generated images, especially, but not exclusively, when orthographic material is used to ignite imagery. Third, an opposite pattern of hemispheric laterality emerges when visual mental images are induced by exogenous stimulation; direct cortical electrical stimulation tends to produce visual imagery experiences predominantly when applied to the right temporal lobe. These patterns of hemispheric asymmetry are difficult to reconcile with the dominant model of visual mental imagery, which emphasizes the implication of early sensory cortices. They suggest instead that visual mental imagery relies on large-scale brain networks, with a crucial participation of high-level visual regions in the temporal lobes.

The importance of the insular cortex for vestibular and spatial syndromes.

The aim of the study was to identify the neuroanatomical correlates and associations of neuropsychological syndromes after acute unilateral right-hemisphere brain lesions. The neuropsychological syndromes considered were orientation in three-dimensional space such as tilts of the subjective visual vertical or of the subjective haptic vertical, pusher syndrome, visual neglect and unawareness of paresis (anosognosia for hemiparesis). These neuropsychological phenomena have been found to occur separately or in different combinations after lesions to the right insular cortex. Magnetic resonance imaging scans were obtained from 82 patients with acute right-hemispheric stroke. A lesion-behavior mapping analysis was conducted to specify the neuroanatomical correlates of the above-mentioned neuropsychological syndromes. In all analyses of the individual neuropsychological syndromes the insular cortex was affected. Thus, the insular cortex is involved in (self-)perception and orientation within a three-dimensional space. Since isolated lesions of the insular cortex did not induce the above neuropsychological phenomena, there have to be other regions involved.

Relationship between Increased Intracranial Pressure and Mastoid Effusion.

ObjectiveThis study aimed to assess the relationship between increased intracranial pressure (ICP) and mastoid effusions (ME). MethodsBetween January 2015 and October 2018, patients who underwent intracranial surgery and had ICP monitoring catheters placed were enrolled. ICP was recorded hourly for at least 3 days. ME was determined by the emergence of opacification in mastoid air cells on follow-up brain imaging. C-reactive protein (CRP) levels, presence of endotracheal tube (ETT) and nasogastric tube (NGT), duration of intensive care unit (ICU) stay, duration of mechanical ventilator application, diagnosis, surgical modalities, and presence of sinusitis were recorded. Each factor’s effect on the occurrence of ME was analyzed by binary logistic regression analyses. To analyze the independent effects of ICP as a predictor of ME a multivariable logistic regression analysis was performed. ResultsTotal of 61 (53%) out of 115 patients had ME. Among the patients who had unilateral brain lesions, 94% of subject (43/50) revealed the ipsilateral development of ME. ME developed at a mean of 11.1±6.2 days. The variables including mean ICP, peak ICP, age, trauma, CRP, ICU stays, application of mechanical ventilators and presence of ETT and NGT showed statistically significant difference between ME groups and non-ME groups in univariate analysis. Sex and the occurrence of sinusitis did not differ between two groups. Adding the ICP variables significantly improved the prediction of ME in multivariable logistic regression analysis. ConclusionWhile multiple factors affect ME, this study demonstrates that ICP and ME are probably related. Further studies are needed to determine the mechanistic relationship between ICP and middle ear pressure.