Excitotoxic lesions of the parafascicular nucleus produce deficits in a socially transmitted food preference

The parafascicular (PF) nucleus, a posterior component of the intralaminar nuclei of the thalamus, is considered to be an essential structure in the feedback circuits of basal ganglia-thalamo-cortical systems that critically participate in cognitive processes. To study the PF contribution to processing of behaviorally significant information during specific episodes of learning, we investigated the effects of damaging the PF nucleus in the acquisition of a natural form of social olfactory learning, the socially transmitted food preference (STFP) task. This task is a non-spatial paradigm that exhibits some of the characteristics of relational memory because it requires that animals use information obtained in one episode to guide later behavior in different circumstances. Adult male Wistar rats were submitted to pretraining bilateral N-methyl-D-aspartate (0.15 M, pH 7.4) lesions of the PF (0.4 microl/side, 0.2 microl/min). The behavioral effects of PF lesions were compared to vehicle- and sham-operated control groups and two retention delays were considered in separate groups: immediately (Lesion-I, Vehicle-I, and Sham-I groups) and 24h after training (Lesion-24, Vehicle-24, and Sham-24 groups). PF lesions produced delay-independent impairments in the STFP suggesting that this nucleus might modulate the acquisition of this odor-odor association task. Results are discussed in the context of medial prefrontal cortex deafferentation induced by PF damage.     

Embolie gazeuse cérébrale lors d’une séance d’hémodialyse : aspects médico-légaux : à propos d’une affaire judiciaire

Air embolism is a serious iatrogenic event, concerning many invasive medical therapies. It is a rare but life-threatening adverse event. We report a case of a cerebral air embolism occurring during a renal replacement therapy. We report the case of a court case analyzed in the Department of Legal Medicine of Farhat Hached University Hospital in Sousse, Tunisia, related to a cerebral gas embolism occurring during a session of renal replacement therapy. Then we discuss the medical liability of the medical team involved in this act. Through a draft organic law (law No. 41/2019 on patients’ rights and medical liability), Tunisian jurisprudence aims at resolving legal claims in the field of medical liability by providing more opportunities for an amicable solution and by guaranteeing an adequate and quick compensation of the damage suffered.     

Dynamic touch is affected in children with cerebral palsy

Children with developmental disorders such as cerebral palsy have limited opportunities for effortful interactions with objects and tools. The goal of the study was to investigate whether children with cerebral palsy have deficits in their ability to perceive object length by dynamic touch when compared to typically developing children. Fourteen children with typical development and 12 children with cerebral palsy were asked to report the length of hand-held rods after wielding them out of sight. Multilevel regression models indicated that I₁ (maximum principal moment of inertia) was a significant predictor of perceived length – L_P (p < .0001). The effect of I₁ on L_P was significantly different among children (p = .001) and the presence of cerebral palsy (group factor) partially explained such variance (p = .002). In addition, accuracy and reliability of the length judgments made by children with cerebral palsy were significantly lower than the typically developing children (p < .05). Theoretical and clinical implications of these results were identified and discussed.     

Functional cerebral changes in multiple sclerosis patients during an autobiographical memory test

Our aim was to investigate the functional underpinnings of autobiographical memory (AM) impairment in multiple sclerosis (MS) patients. To that end, 18 patients and 18 controls underwent the autobiographical interview (AI). Subsequently, the 36 participants underwent a functional magnetic resonance imaging (fMRI) session designed to assess the construction and elaboration of AMs. A categorical control task was also presented. Patients were trained in the fMRI procedure to optimise the procedural aspects accompanying the task itself. Although the patients obtained significantly poorer AI scores (p < .001), their performance on the easier AM fMRI task was efficiently carried out, allowing relevant comparisons with healthy controls. Relatively to healthy controls, the patients showed increased and bilateral cerebral activations (p < .005) during the construction and elaboration phases. The prefrontal, temporal and posterior cerebral region activations were located within the core network sustaining AM, with the bilateral prefrontal region being centrally involved. The parametric neural responses to the difficulty of access and amount of details of memories were also significantly different for the two groups, with the right hippocampal region showing a particularly increased recruitment (p < .005). The findings suggested the presence of functional cerebral changes during AM performance and supported the presence of AM retrieval deficit in MS patients.     

Predictors of Reading Comprehension in Children with Cerebral Palsy and Typically Developing Children

Predictors of reading comprehension were evaluated in 41 children with cerebral palsy and 74 typically developing children between the ages of 6 and 12 years. Regression analyses were conducted to determine the relative contributions of measures of phonemic awareness, receptive vocabulary, and general reasoning to variance in reading comprehension. All three independent variables were statistically significant predictors of reading comprehension in both groups of participants. The impact of phonemic awareness on reading comprehension was moderated by age, but only in the typically developing group. Within the group with cerebral palsy, there was an indirect effect of functional expressive ability on reading comprehension, mediated by phonemic awareness. It is concluded that largely the same variables predict reading comprehension in children with cerebral palsy as in typically developing children, but that children with cerebral palsy continue to rely on phonological processing for a more protracted period of time.     

Dialectal differences in hemispheric specialization for Japanese lexical pitch accent

Language experience can alter perceptual abilities and the neural specialization for phonological contrasts. Here we investigated whether dialectal differences in the lexical use of pitch information lead to differences in functional lateralization for pitch processing. We measured cortical hemodynamic responses to pitch pattern changes in native speakers of Standard (Tokyo) Japanese, which has a lexical pitch accent system, and native speakers of ‘accentless’ dialects, which do not have any lexical tonal phenomena. While the Standard Japanese speakers showed left-dominant responses in temporal regions to pitch pattern changes within words, the accentless dialects speakers did not show such left-dominance. Pitch pattern changes within harmonic-complex tones also elicited different brain activation patterns between the two groups. These results indicate that the neural processing of pitch information differs depending on the listener’s native dialect, and that listeners’ linguistic experiences may further affect the processing of pitch changes even for non-linguistic sounds.     

Anomalous global effects induced by ‘blind’ distractors in visual hemifield defects

Previous research has revealed that a stimulus presented in the blind visual field of participants with visual hemifield defects can evoke oculomotor competition, in the absence of awareness. Here we studied three cases to determine whether a distractor in a blind hemifield would be capable of inducing a global effect, a shift of saccade endpoint when target and distractor are close to each other, in participants with lesions of the optic radiations or striate cortex. We found that blind field distractors significantly shifted saccadic endpoints in two of three participants with lesions of either the striate cortex or distal optic radiations. The direction of the effect was paradoxical, however, in that saccadic endpoints shifted away from blind field distractors, whereas endpoints shifted towards distractors in the visible hemifields, which is the normal global effect. These results provide further evidence that elements presented in the blind visual field can generate modulatory interactions in the oculomotor system, which may differ from interactions in normal vision.     

Right–left approach and reaching arm movements of 4-month infants in free and constrained conditions

Recent theories on the evolution of language (e.g. Corballis, 2009) emphazise the interest of early manifestations of manual laterality and manual specialization in human infants. In the present study, left- and right-hand movements towards a midline object were observed in 24 infants aged 4 months in a constrained condition, in which the hands were maintained closed, and in a free condition. A left-hand dominance for approach movements without contact with the object, and a right-hand dominance for reaching movements with object contact was observed in the free condition. In the constrained condition reaching movements of the right hand decreased dramatically. These results are interpreted as strong evidence of manual specialization in 4-month olds, with approach movements having a localization role and reaching movements announcing future right-hand dominance for prehension and object manipulation.     

Consciousness wanted,attention found: Reasons for the advantage of the left visual field in identifying T2 among rapidly presented series

Everyday experience suggests that people are equally aware of events in both hemi-fields. However, when two streams of stimuli are rapidly presented left and right containing two targets, the second target is better identified in the left than in the right visual field.This might be considered evidence for a right-hemisphere advantage in generating conscious percepts. However, this putative asymmetry of conscious perception cannot be measured independently of participants’ access to their conscious percepts, and there is actually evidence from split-brain patients for the reverse, left-hemisphere advantage in having access to conscious percepts. Several other topics were studied in search of the responsible mechanism, among others: Mutual inhibition of hemispheres, cooperation of hemispheres in perceiving midline stimuli, and asymmetries in processing various perceptual inputs. Directing attention by salient cues turned out to be one of the few mechanisms capable of modifying the left visual-field advantage in this paradigm. Thus, this left visual-field advantage is best explained by the notion of a right-hemisphere advantage in directing attention to salient events. Dovetailing with the pathological asymmetries of attention after right-hemisphere lesions and with asymmetries of brain activation when healthy participants shift their attention, the present results extend that body of evidence by demonstrating unusually large and reliable behavioral asymmetries for attention-directing processes in healthy participants.     

Effects of Temporal Lobe Lesions on Retrograde Memory: A Critical Review

Scientific interest in retrograde memory has grown considerably over the last two decades. Studies have demonstrated that several brain regions, including the temporal lobes, participate in the formation, maintenance and storage of past memories. Different patterns and extents of retrograde memory deficits have been recorded in patients with temporal lobe lesions. It has been argued that the pattern of retrograde memory deficits is determined not only by the side and specific location of lesion within this region, but also by methodology, medical variables (such as etiology or seizure history), and coexisting cognitive deficits. In this paper we will review published case and group studies of patients with temporal lobe lesions to evaluate the impact of these factors on retrograde memory.