Cognitive Neuropsychology最新文献

We examined the effects of context bias and target exposure duration on error rates (ERR) and response times (RTs) in letter choice task within context. Surface Electromyography (sEMG) was recorded in both hands during context presentation, as a measure of readiness to respond. The goal was to affect the outcome of the task by manipulating relative schemata activation levels prior to target onset, as per the Supervisory Attentional System model. At short exposures, context bias and sEMG activity affected ERR, whereas at longer durations, RTs were affected. Context bias mediated the effect of sEMG activity. Increasing activity in both hands led to higher ERR and RTs in incongruent context. Non-increasing activity in the non-responding lead to lack of relationship between sEMG activity and behavior, irrespective of context. sEMG activity in both hands was found to be interrelated and context-sensitive. These results conform to the predictions of the Supervisory Attentional Model.

Working memory (WM) is critical for many cognitive functions including language production. A key feature of WM is its capacity limitation. Two models have been proposed to account for such capacity limitation: slot models and resource models. In recent years, resource models have found support in both visual and auditory perception, but do they also extend to production? We investigate this by analyzing sublexical errors from four individuals with aphasia. Using tools from computational linguistics, we first define the concept of "precision" of sublexical errors. We then demonstrate that such precision decreases with increased working memory load, i.e., word length, as predicted by resource models. Finally, we rule out alternative accounts of this effect, such as articulatory simplification. These data provide the first evidence for the applicability of the resource model to production and further point to the generalizability of this account as a model of resource division in WM.

Visuo-imitative apraxia has been consistently reported in patients with dementia, yet there have been substantial methodological differences between studies, while multiple, sometimes competing hypotheses have been put forward to explain this syndrome. Our goals were to study specific imitation deficits in groups of patients who have been selected and assigned to a group solely based on clinical criteria. We tested the effects of body part, bimanual imitation, asymmetry of the model, and body midline crossing, in patients with cortical atrophy of the temporal lobes (semantic dementia, SD), frontal-parietal networks (FPN, i.e., posterior cortical atrophy and corticobasal syndrome) or both (Alzheimer's disease, AD). Sixty-three patients and 32 healthy controls were asked to imitate 45 meaningless finger/hand, uni-/bimanual, asymmetrical/symmetrical, and crossed/uncrossed postures. SD patients had subnormal imitation scores. FPN patients showed frequent and marked deficits in most conditions, better performance with hand than finger postures (probably because of visuo-constructive deficits), and better performance with uncrossed than crossed configurations (probably because of body schema disorganization). Bimanual configurations were difficult for AD patients, not because of bimanual activity in itself, but rather because of the complexity of the model. The finding of dissociations in 34/63 cases (54%) suggests that some patients, even within the same clinical category, can have variable performance in imitation tests as a function of the abovementioned factors. Clinicians are advised to use tests with a large array of items to properly capture patients' imitation skills. This provides a new basis for future research to unpack which neurocognitive mechanisms are disrupted to cause specific patterns of impaired imitation.

The visual word form area (VWFA), a region canonically located within left ventral temporal cortex (VTC), is specialized for orthography in literate adults presumbly due to its connectivity with frontotemporal language regions. But is a typical, left-lateralized language network critical for the VWFA's emergence? We investigated this question in an individual (EG) born without the left superior temporal lobe but who has normal reading ability. EG showed canonical typical face-selectivity bilateraly but no wordselectivity either in right VWFA or in the spared left VWFA. Moreover, in contrast with the idea that the VWFA is simply part of the language network, no part of EG's VTC showed selectivity to higher-level linguistic processing. Interestingly, EG's VWFA showed reliable multivariate patterns that distinguished words from other categories. These results suggest that a typical left-hemisphere language network is necessary for acanonical VWFA, and that orthographic processing can otherwise be supported by a distributed neural code.

Intuitive Physics, the ability to anticipate how the physical events involving mass objects unfold in time and space, is a central component of intelligent systems. Intuitive physics is a promising tool for gaining insight into mechanisms that generalize across species because both humans and non-human primates are subject to the same physical constraints when engaging with the environment. Physical reasoning abilities are widely present within the animal kingdom, but monkeys, with acute 3D vision and a high level of dexterity, appreciate and manipulate the physical world in much the same way humans do.

We report the reading performance of an Italian speaker with egocentric Neglect Dyslexia on sentences with Negative Concord structures, which contain a linguistic cue to the presence of a preceding negative marker and compare it to sentences with no such cue. As predicted, the frequency of reading the whole sentence, including the initial negative marker non, was higher in Negative Concord structures than in sentences which also started with non, but crucially, lacked the medially positioned linguistic cue to the presence of non. These data support the claim that the presence of linguistic cues to sentence structure modulates attention during reading in Neglect Dyslexia.

ABSTRACTNeuropsychological case studies have provided evidence that individuals with semantic, but not phonological, working memory (WM) deficits have difficulty producing phrases containing several content words. These findings supported the claim of a phrasal scope of planning at the grammatical formulation stage of production, where semantic WM supports the maintenance of lexical-semantic representations as they are inserted into slots in phrasal constituents. Recent narrative production results for individuals at the acute stage of stroke supported the role for semantic WM in phrasal elaboration while suggesting a role for phonological WM at a subsequent phonological encoding stage in supporting fluent, rapid speech. In the present study, we employed a larger participant sample while controlling for single word production abilities at semantic and phonological levels. Results confirmed the relations between semantic WM and phrasal elaboration whereas the relation between phonological WM and speech rate was eliminated. There was, however, evidence that both impaired phonological retrieval and restricted phonological WM were related to the tendency to produce short, highly frequent words such as pronouns rather than longer, less frequent words. Future research is needed to address whether the results relating to phonological WM depend on damage specific to an output rather than an input phonological capacity.

We assessed effects of semantic interference in people with aphasia (PWA). Two naming tasks (continuous naming and cyclic blocking) were contrasted with tasks which required suppression of competitors but minimized lexical access (probe task) or required extra-lexical mechanisms of control (Stroop task). In continuous naming, some PWA showed increased interference compared to control participants, with slower RTs and increased omissions. Others showed normal or weaker interference effects in terms of RTs but increased semantic errors. Patterns were consistent only between naming tasks. We explain results by assuming that some PWA are slow at implementing mechanisms of control/selection which weed-out competitors. Others, instead, will have activation difficulties which will induce them to lower the threshold needed for selection. Results highlight how different kinds of brain damage may induce different compensatory strategies and how semantic relatedness may induce both interference and facilitation. Implications for models of lexical selection are discussed.

The present study explores the extent to which properties of abstract graphemic representations are maintained at the post-graphemic level of graphic motor plans, where the sequences of writing strokes for producing the letters in a word are represented. On the basis of results from a stroke patient (NGN) who has a deficit affecting the activation of graphic motor plans, we explore the post-graphemic representation of 1) consonant/vowel status of letters; 2) geminate (double) letters, such as the BB in RABBIT; and 3) digraphs, such as the SH in SHIP. Through analyses of NGN's letter substitution errors, we conclude that 1) consonant-vowel status is not represented at the level of graphic motor plans; 2) geminates have special representations at the motor-plan level, as at the graphemic level; and 3) digraphs are represented by two separate single-letter graphic motor plans, and not by unitary digraph motor plans.