The California Cognitive Assessment Battery (CCAB).

INTRODUCTION: We are developing the California Cognitive Assessment Battery (CCAB) to provide neuropsychological assessments to patients who lack test access due to cost, capacity, mobility, and transportation barriers. METHODS: The CCAB consists of 15 non-verbal and 17 verbal subtests normed for telemedical assessment. The CCAB runs on calibrated tablet computers over cellular or Wi-Fi connections either in a laboratory or in participants homes. Spoken instructions and verbal stimuli are delivered through headphones using naturalistic text-to-speech voices. Verbal responses are scored in real time and recorded and transcribed offline using consensus automatic speech recognition which combines the transcripts from seven commercial ASR engines to produce timestamped transcripts more accurate than those of any single ASR engine. The CCAB is designed for supervised self-administration using a web-browser application, the Examiner. The Examiner permits examiners to record observations, view subtest performance in real time, initiate video chats, and correct potential error conditions (e.g., training and performance failures, etc.,) for multiple participants concurrently. RESULTS: Here we describe (1) CCAB usability with older (ages 50 to 89) participants; (2) CCAB psychometric properties based on normative data from 415 older participants; (3) Comparisons of the results of at-home vs. in-lab CCAB testing; (4) We also present preliminary analyses of the effects of COVID-19 infection on performance. Mean z-scores averaged over CCAB subtests showed impaired performance of COVID+ compared to COVID- participants after factoring out the contributions of Age, Education, and Gender (AEG). However, inter-cohort differences were no longer significant when performance was analyzed with a comprehensive model that factored out the influences of additional pre-existing demographic factors that distinguished COVID+ and COVID- cohorts (e.g., vocabulary, depression, race, etc.,). In contrast, unlike AEG scores, comprehensive scores correlated significantly with the severity of COVID infection. (5) Finally, we found that scoring models influenced the classification of individual participants with Mild Cognitive Impairment (MCI, z-scores < -1.50) where the comprehensive model accounted for more than twice as much variance as the AEG model and reduced racial bias in MCI classification. DISCUSSION: The CCAB holds the promise of providing scalable laboratory-quality neurodiagnostic assessments to underserved urban, exurban, and rural populations

Shifting attention in viewer- and object-based reference frames after unilateral brain injury

The aims of the present study were to investigate the respective roles that object- and viewer-based reference frames play in reorienting visual attention, and to assess their influence after unilateral brain injury. To do so, we studied 16 right hemisphere injured (RHI) and 13 left hemisphere injured (LHI) patients. We used a cueing design that manipulates the location of cues and targets relative to a display comprised of two rectangles (i.e., objects). Unlike previous studies with patients, we presented all cues at midline rather than in the left or right visual fields. Thus, in the critical conditions in which targets were presented laterally, reorienting of attention was always from a midline cue. Performance was measured for lateralized target detection as a function of viewer-based (contra- and ipsilesional sides) and object-based (requiring reorienting within or between objects) reference frames. As expected, contralesional detection was slower than ipsilesional detection for the patients. More importantly, objects influenced target detection differently in the contralesional and ipsilesional fields. Contralesionally, reorienting to a target within the cued object took longer than reorienting to a target in the same location but in the uncued object. This finding is consistent with object-based neglect. Ipsilesionally, the means were in the opposite direction. Furthermore, no significant difference was found in object-based influences between the patient groups (RHI vs. LHI). These findings are discussed in the context of reference frames used in reorienting attention for target detection

White matter pathways critical for language are also critical for resolving proactive interference in working memory

Background White matter pathways connecting brain regions involved in language processing in the left prefrontal (PFC) and temporal cortices have been found to play a critical role in language comprehension (Turken and Dronkers, 2011). Among the frontal brain regions associated with language processing, the left inferior frontal gyrus (lIFG) has also been strongly associated with resolving proactive interference in working memory (Jonides and Nee, 2006). Here we investigated whether the white matter pathways connecting the lIFG to the left temporal lobe found to be important in language comprehension were also critical for resolving proactive interference in working memory. Methods We tested 4 patients with left PFC damage involving the lIFG, 5 with left temporal damage and 6 age-matched controls. Critically, 2 left PFC patients and 1 left temporal patient had lesions involving a complete disconnection between the lIFG and the left temporal cortex and the remaining patients had partial disconnection only. Performance was assessed using the Recent Probes test (Monsell, 1978): 4 visually-presented letters are followed by a probe: one central letter. The task was to decide whether or not the probe was part of the immediately preceding set of letters. Whether or not the probe was also part of the previous trial and elicited a positive or negative response was then manipulated and created recent negative (RN) and recent positive trials, respectively. RN trials generated interference in trial n compared to non-recent negative (NN) trials. Behavioral results were reported using error rates as the dependent variable. Results When the groups were separated based on which cortical lobe was damaged, there was a significant main interference effect (F(1,12)=24.94, p <.001), where RN trials were associated with worse performance than NN trials, and a main effect of group (F(2,12)=4.65, p <.05), where performance was worse for patients than for controls, but there was no interaction between the size of the interference effect and group (F(2,12)=1.86, p =.198). Critically, when the left temporal patient who had a total disconnection with the left IFG was included in the left PFC group, there were still main effects of interference and group but there was also a significant interaction between the size of the interference effect and group (F(2,12)=5.31, p<.05), the interference effect was larger for patients having left IFG lesions and/or a total disconnection between the lIFG and the temporal lobe than for controls or for temporal patients without total disconnection (see table 1). Conclusions Our results are in agreement with the idea that the lIFG plays a critical role in resolving proactive interference in working memory (Jonides and Nee, 2006). However, our results also suggest that the lIFG may not be the only critical structure needed for such a mechanism. Indeed, similarly as in language processing, white matter pathways connecting the lIFG to the left temporal lobe seem to be critical for resolving proactive interference in working memory. This further suggests that a common underlying mechanism may be involved in both cognitive functions