Development, reliability, validity, and acceptability of the remote administration of the Edinburgh Cognitive and Behavioural ALS Screen (ECAS).

BACKGROUND: ALS clinical care and research has changed dramatically since the COVID-19 pandemic, accelerating the need for cognitive assessments to be adapted for remote use. OBJECTIVES: To develop the remote administration method of the Edinburgh Cognitive and Behavioural ALS Screen (ECAS), and determine its reliability and validity. Methods: The validation process consisted of: (1) Two versions of the ECAS (A and B) were administered, one in-person and one remotely via video call in a randomized order to 27 people without ALS; (2) The ECAS was administered remotely to 24 pwALS, with a second rater independently scoring performance; and (3) Acceptability was assessed by gathering feedback from 17 pwALS and 19 clinicians and researchers about their experience of using the ECAS remotely. RESULTS: In the group without ALS, the remote and in-person ECAS total scores were found to be equivalent, and a Bland-Altman plot showed good agreement between the two administration methods. In pwALS, there was excellent agreement between two raters (ICC = 0.99). Positive feedback was gained from pwALS, researchers and clinicians with regards to ease of process, convenience, time, and the environment. CONCLUSIONS: These findings provide evidence of the reliability and validity of the remote administration of the ECAS for pwALS, with clinicians, researchers and pwALS viewing it as a good alternative to face-to-face administration.

Relearning in semantic dementia reflects contributions from both medial temporal lobe episodic and degraded neocortical semantic systems: evidence in support of the complementary learning systems theory.

When relearning words, patients with semantic dementia (SD) exhibit a characteristic rigidity, including a failure to generalise names to untrained exemplars of trained concepts. This has been attributed to an over-reliance on the medial temporal region which captures information in sparse, non-overlapping and therefore rigid representations. The current study extends previous investigations of SD relearning by re-examining the additional contribution made by the degraded cortical semantic system. The standard relearning protocol was modified by careful selection of foils to show that people with semantic dementia were sometimes able to extend their learning appropriately but that this correct generalisation was minimal (i.e. the patients under-generalised their learning). The revised assessment procedure highlighted the fact that, after relearning, the participants also incorrectly over-generalised the learned label to closely related concepts. It is unlikely that these behaviours would occur if the participants had only formed sparse hippocampal representations. These novel data build on the notion that people with semantic dementia engage both the degraded cortical semantic (neocortex) and the episodic (medial temporal) systems to learn. Because of neocortical damage to the anterior temporal lobes, relearning is disordered with a characteristic pattern of under- and over-generalisation.

At the edge of semantic space: the breakdown of coherent concepts in semantic dementia is constrained by typicality and severity but not modality.

Hub-and-spoke models of semantic representation suggest that coherent concepts are formed from the integration of multiple, modality-specific information sources with additional modality-invariant representations-most likely stored in the ventrolateral anterior temporal lobe (vATL). As well as providing the necessary computational mechanisms for the complexities of feature integration, these modality-invariant representations also license a key aspect of semantic memory-semantic-based generalization. Semantic dementia allows us to investigate this aspect of conceptual knowledge because (a) the patients have a selective and progressive semantic degradation and (b) this is associated with profound ventrolateral ATL atrophy. Specifically, the boundaries between concepts become degraded in semantic dementia and, when tested using the appropriate materials, the patients make simultaneous under- and overgeneralization errors. We found that the rate of these errors were a function of typicality and pseudotypicality of the items as well as the severity of the patients' semantic impairment. Following the modality-invariant nature of the vATL hub representation, we also confirmed that the patients were impaired on both verbal- and picture-based versions of the same task.

Coherent concepts are computed in the anterior temporal lobes.

In his Philosophical Investigations, Wittgenstein famously noted that the formation of semantic representations requires more than a simple combination of verbal and nonverbal features to generate conceptually based similarities and differences. Classical and contemporary neuroscience has tended to focus upon how different neocortical regions contribute to conceptualization through the summation of modality-specific information. The additional yet critical step of computing coherent concepts has received little attention. Some computational models of semantic memory are able to generate such concepts by the addition of modality-invariant information coded in a multidimensional semantic space. By studying patients with semantic dementia, we demonstrate that this aspect of semantic memory becomes compromised following atrophy of the anterior temporal lobes and, as a result, the patients become increasingly influenced by superficial rather than conceptual similarities.