What impairs subitizing in cerebral palsied children?

The goal of this study was to investigate the factors responsible for the low subitizing limit of cerebral palsied (CP) children. For this purpose, 44 CPs were tested on two tasks involving the rapid recognition of dot configurations. The answer was either a number (subitizing task) or the name of a pattern (pattern recognition task). The CPs were compared to controls of the same age. All children were evaluated for visual and visuospatial short-term memory. The results showed that CPs with a low subitizing limit did not do better with a canonical arrangement than the random one, were impaired to the same extent on the pattern recognition task as on the subitizing task, and had a short visuospatial short-term memory span. These results suggest that the low subitizing limit of CPs stems from a (non-number-dependent) lesser capacity to perceive a dot configuration as a gestalt. A low subitizing limit was almost always associated with a right-hemisphere lesion.     

Using psychometric ability to improve education in ultrasound-guided regional anaesthesia: a multicentre randomised controlled trial

The learning curve for novices developing regional anaesthesia skills, such as real-time ultrasound-guided needle manipulation, may be affected by innate visuospatial ability, as this influences spatial cognition and motor co-ordination. We conducted a multinational randomised controlled trial to test if novices with low visuospatial ability would perform better at an ultrasound-guided needling task with deliberate practice training than with discovery learning. Visuospatial ability was evaluated using the mental rotations test-A. We recruited 140 medical students and randomly allocated them into low-ability control (discovery learning), low-ability intervention (received deliberate practice), high-ability control, and high-ability intervention groups. Primary outcome was the time taken to complete the needling task, and there was no significant difference between groups: median (IQR [range]) low-ability control 125 s (69–237 [43–600 s]); low-ability intervention 163 s (116–276 [44–600 s]); high-ability control 130 s (80–210 [41–384 s]); and high-ability intervention 177 s (113–285 [43–547 s]), p = 0.06. No difference was found using the global rating scale: mean (95%CI) low-ability control 53% (95%CI 46–60%); low-ability intervention 61% (95%CI 53–68%); high-ability control 63% (95%CI 56–70%); and high-ability intervention 66% (95%CI 60–72%), p = 0.05. For overall procedure pass/fail, the low-ability control group pass rate of 42% (14/33) was significantly less than the other three groups: low-ability intervention 69% (25/36); high-ability control 68% (25/37); and high-ability intervention 85% (29/34) p = 0.003. Further research is required to determine the role of visuospatial ability screening in training for ultrasound-guided needle skills.     

Visuospatial representation in patients with mild cognitive impairment: Implication for rehabilitation

Behavioral and neurophysiological experiments have demonstrated that distinct and common cognitive processes and associated neural substrates maintain allocentric and egocentric spatial representations. This review aimed to provide evidence from previous behavioral and neurophysiological studies on collating cognitive processes and associated neural substrates and linking them to the state of visuospatial representations in patients with mild cognitive impairment (MCI). Even though MCI patients showed impaired visuospatial attentional processing and working memory, previous neuropsychological experiments in MCI largely emphasized memory impairment and lacked substantiating evidence of whether memory impairment could be associated with how patients with MCI encode objects in space. The present review suggests that impaired memory capacity is linked to impaired allocentric representation in MCI patients. This review indicates that further research is needed to examine how the decline in visuospatial attentional resources during allocentric coding of space could be linked to working memory impairment.     

帕金森病患者视空间能力损害研究

目的：探讨早、中期帕金森病（parkinson’s disease,PD）患者的视空间感知能力和视空间物体组织能力损害特点。方法选取早、中期 PD 患者19例以及人口学资料与其相匹配的18例健康对照组作为研究被试,神经心理学背景测试采用简易精神状态评价量表（MMSE）、汉密顿抑郁量表（HAMD）、数字广度、词汇流畅性,Stroop 字色干扰实验以及听觉词汇学习等测试被试的总体认知、情绪、记忆以及执行功能。采用视觉线段方向判断测试被试视空间的感知能力,采用 Hooper 视觉组织任务测试被试的视空间物体的组织能力。结果相对于正常对照组,早、中期 PD 患者在词汇流畅性,Stroop 字色干扰实验,听觉词汇的延迟再认差异均有统计学意义（P ＜0．05）。在视空间能力方面,PD 组在视觉线段方向能力与对照组差异无统计学意义（P ＞0．05）;而在 Hooper 视觉组织任务中,PD 组的视空间物体的组织能力较对照组明显下降,差异有统计学意义（P ＜0．05）;经 Pearson 相关分析,我们发现 PD 患者的视空间物体的组织能力与其疾病的严重程度并没有明显相关性（P ＞0．05）。结论早、中期 PD 患者不仅存在记忆及执行功能损害,同时视空间能力损害,而这种视空间能力损害可能主要表现为视空间物体的组织和重建能力。     

Visual-Spatial Memory and Recall Test (V-SMART): validity and reliability*

Abstract

Objective: Nonverbal memory decline is a concern associated with aging. Visuospatial memory tests often do not distinguish between learning, recall, or retrieval, yet such distinctions may help clarify the nature of memory difficulties. Further, many visuospatial tests rely on abilities not directly related to memory (e.g. graphomotor skill). The present study examined the feasibility and initial psychometric evidence of the Visual-Spatial Memory and Recall Test (V-SMART). Method: Ninety-nine adults (71% women) were recruited from two sources: undergraduate students (n = 37) and healthy older adults (n = 62). Volunteers completed a brief battery of cognitive tests. Results: Internal consistency and interrater reliability were strong. Principal Components Analysis supported the hypothesized learning and recall structure, and correlations with other memory tests supported external validity of the V-SMART as a visuospatial learning measure. Correlations with recall scores were less compelling yet likely reflected the intact recall among this generally healthy sample. Conclusions: These preliminary findings support the V-SMART as a visuospatial memory test. Evidence for validity was acceptable for learning indices; further examination of recall measures is needed.     

Multiple sessions of transcranial direct current stimulation to the intact hemisphere improves visual function after unilateral ablation of visual cortex

Damage to cerebral systems is frequently followed by the emergence of compensatory mechanisms, which serve to reduce the effects of brain damage and allow recovery of function. Intrinsic recovery, however, is rarely complete. Non‐invasive brain stimulation technologies have the potential to actively shape neural circuits and enhance recovery from brain damage. In this study, a stable deficit for detecting and orienting to visual stimuli presented in the contralesional visual hemifield was generated by producing unilateral brain damage of the right posterior parietal and contiguous visual cortical areas. A long regimen of inhibitory non‐invasive transcranial direct‐current stimulation (cathodal tDCS, 2 mA, 20 min) was applied to the contralateral (intact) posterior parietal cortex over 14 weeks (total of 70 sessions, one per day, 5 days per week) and behavioral outcomes were periodically assessed. In three out of four stimulated cats, lasting recovery of visuospatial function was observed. Recovery started after 2–3 weeks of stimulation, and recovered targets were located first in the periphery, and moved to more central visual field locations with the accrual of stimulation sessions. Recovery for moving tasks followed a biphasic pattern before reaching plateau levels. Recovery did not occur for more difficult visual tasks. These findings highlight the ability of multiple sessions of transcranial direct‐current stimulation to produce recovery of visuospatial function after unilateral brain damage.     

Impairment of simultaneous-spatial working memory in nonverbal (visuospatial) learning disability: A treatment case study

We report the case of B.A., an 11-year-old child with a nonverbal (visuospatial) learning disability (NLD). Detailed psychometric and neuropsychological assessment on visuospatial working memory (VSWM) revealed specific simultaneous-spatial working memory impairment. A treatment targeting simultaneous-spatial working memory was given to B.A. for seven sessions (over one month); this resulted in improvement of simultaneous-spatial working memory, with the benefit that the training was maintained after six months.

Discussion of clinical and theoretical implications is given, taking account of the distinctions that can be made between the different components of visuospatial working memory and different subtypes of NLD, thus allowing the tailoring of specific training to target the impaired VSWM component.     

Game theoretical mapping of white matter contributions to visuospatial attention in stroke patients with hemineglect

White matter bundles linking gray matter nodes are key anatomical players to fully characterize associations between brain systems and cognitive functions. Here we used a multivariate lesion inference approach grounded in coalitional game theory (multiperturbation Shapley value analysis, MSA) to infer causal contributions of white matter bundles to visuospatial orienting of attention. Our work is based on the characterization of the lesion patterns of 25 right hemisphere stroke patients and the causal analysis of their impact on three neuropsychological tasks: line bisection, letter cancellation, and bells cancellation. We report that, out of the 11 white matter bundles included in our MSA coalitions, the optic radiations, the inferior fronto‐occipital fasciculus and the anterior cingulum were the only tracts to display task‐invariant contributions (positive, positive, and negative, respectively) to the tasks. We also report task‐dependent influences for the branches of the superior longitudinal fasciculus and the posterior cingulum. By extending prior findings to white matter tracts linking key gray matter nodes, we further characterize from a network perspective the anatomical basis of visual and attentional orienting processes. The knowledge about interactions patterns mediated by white matter tracts linking cortical nodes of attention orienting networks, consolidated by further studies, may help develop and customize brain stimulation approaches for the rehabilitation of visuospatial neglect.     

Human ventral parietal cortex plays a functional role on visuospatial attention and primary consciousness. A repetitive transcranial magnetic stimulation study

In this paper, we used repetitive transcranial magnetic stimulation (rTMS) in 18 normal subjects to investigate whether the ventral posterior parietal cortex (PPC) plays a causal role on visuospatial attention and primary consciousness and whether these 2 functions are linearly correlated with each other. Two distinct experimental conditions involved a similar visual stimuli recognition paradigm. In "Consciousness" experiment, number of consciously perceived visual stimuli was lower by about 10% after rTMS (300 ms, 20 Hz, motor threshold intensity) on left or right PPC than after sham (pseudo) rTMS. In "Attentional" Posner's experiment, these stimuli were always consciously perceived. Compared with sham condition, parietal rTMS slowed of about 25 ms reaction time to go stimuli, thus disclosing effects on endogenous covert spatial attention. No linear correlation was observed between the rTMS-induced impairment on attention and conscious perception. Results suggest that PPC plays a slight but significant causal role in both visuospatial attention and primary consciousness. Furthermore, these high-level cognitive functions, as modulated by parietal rTMS, do not seem to share either linear or simple relationships.     

Exploring the cognitive phenotype of autism: weak "central coherence" in parents and siblings of children with autism: I. Experimental tests

Previous twin and family studies have indicated that there are strong genetic influences in the etiology of autism, and provide support for the notion of a broader phenotype in first-degree relatives. The present study explored this phenotype in terms of one current cognitive theory of autism. Parents and brothers of boys with autism, boys with dyslexia, and normal boys were given tests of "central coherence", on which children with autism perform unusually well due to an information-processing bias favouring part/detail processing over processing of wholes/meaning. Results indicated that fathers of boys with autism, as a group, showed piecemeal processing across four tests of central coherence. This was not true for any other group. These findings raise the possibility that the broader autism phenotype may include a "cognitive style" (weak central coherence) that can confer information-processing advantages.