Sylvain Gagnon

Preserved LTP and water maze learning in hyperglycaemic-hyperinsulinemic ZDF rats

Previous investigations have demonstrated that cognitive deficits as well as hippocampal dysfunctions are generated in animals presenting manifestations of Type 1 diabetes (T1D) mellitus. The present study examined whether such deficits can also be reproduced in the Zucker Diabetic Fatty (ZDF) rats after they developed symptoms of Type 2 diabetes (T2D). Learning and memory assessments were performed using the Morris water maze 5 weeks after the animals presented symptoms of Type 1 diabetes for Experiment 1 (Exp 1) and after 8 weeks for Experiment 2 (Exp 2). Testing in the water maze revealed that ZDF rats learned the task normally, although control rats were found to swim significantly faster after 5 or 8 weeks of untreated diabetes. From an electrophysiological perspective, we observed that the integrity of synaptic function was also preserved in ZDF rats as no alterations in long-term potentiation (LTP) were observed in the area CA1 of hippocampal slices. It is concluded that hyperglycaemia is not the only factor influencing water maze learning and LTP in this animal model of Type 2 diabetes (T2D). The experiments suggest that the resistance of ZDF rats to cognitive and electrophysiological dysfunctions might be related to the protective action of hyperinsulinemia. Indeed, measurements of the plasma insulin level at the end of testing were significantly superior in ZDF rats in comparison to control rats.

Comparative optimism among drivers: An intergenerational portrait

We describe a large cross-sectional study examining comparative optimism (CO) regarding the risk of car crash in three age cohorts (17-26, 27-64, 65 and older). The participants completed a questionnaire in which they were asked to indicate their personal risk of being in an at-fault crash over nine driving related events in comparison to young drivers, mid-aged drivers, and older drivers. The results indicated that all three age groups exhibited CO, but that the level varied according to the age group on which they had to base their comparative judgment. Interestingly, greater CO was constantly observed when the three age groups compared themselves to older drivers. Also, young males exhibited greater CO than female of the same age group.

Involvement of the hippocampus in implicit learning of supra-span sequences: The case of sj.

Learning of supra-span sequences was assessed in a densely amnesic individual (SJ) who suffers from a substantial circumscribed bilateral lesion to the hippocampus. SJs ability to lay down information originating from repetitive memory recall episodes was assessed using Hebbs supra-span procedure. After assessment of short-term memory span, 25 sequences of span +1 items were presented to SJ for immediate serial recall (ISR), one sequence being presented repeatedly eight times. Learning was deduced by the comparison of ISR scores on the repeated versus nonrepeated sequences of span +1 items. SJs learning capacity was examined using four different types of stimuli: digits, spatial locations (Corsi block tapping test), words, and pseudowords. Implicit learning of sensorimotor sequences was also assessed in SJ using a serial reaction time (SRT) paradigm. Findings with the supra-span ISR task revealed evidence of learning in SJ with all four types of stimuli. The learning magnitude, as well as learning rate, observed in SJ were comparable to those observed in matched control participants. SJ showed evidence of implicit learning on the SRT paradigm. We conclude that the hippocampus is not required to learn certain types of recurrent information, and that the supra-span ISR task can be considered as an implicit-based learning paradigm. These findings have significant implications for our conceptualisation of implicit learning, and for understanding of the role of the hippocampus in learning.

Driving difficulties of brain-injured drivers in reaction to high-crash-risk simulated road events: A question of impaired divided attention?

This study examined the role of impaired divided attention and speed of processing in traumatic brain injury (TBI) drivers in high-crash-risk simulated road events. A total of 17 TBI drivers and 16 healthy participants were exposed to four challenging simulated roadway events to which behavioral reactions were recorded. Participants were also asked to perform a dual task during portions of the driving task, and TBI individuals were administered standard measures of divided attention and reaction time. Results indicated that the TBI group crashed significantly more than controls (p < .05) and that dual-task performance correlated significantly with crash rate (r = .58, p = .05).

Fluctuating attentional demand in a simulated driving assessment: the roles of age and driving complexity.

Objective: The purpose of the study was to explore age differences in attentional demand in response to driving situations of varying complexity within the context of a simulated assessment protocol. It was hypothesized that as road complexity increased, an indicator of attentional demand (i.e., latency to respond to a secondary task) would increase and, independent of the road complexity, older adults would exhibit greater attentional demand in comparison with younger and middle-aged drivers. Methods: Drivers from 3 age categories (i.e., young, middle-aged, and older) completed an assessment protocol in a STISIM driving simulator (Systems Technology, Inc., Hawthorne, CA) during which participants responded to a series of strategically placed secondary tasks (i.e., peripheral detection tasks, PDTs). Situations where secondary tasks occurred were grouped according to whether they were straight-road, crossing-path, or lane-change events. Two global indices of driving safety as well as several cognitive measures external to the driving simulator were also collected. Results: The results supported the hypothesis in that complex driving situations elicited greater attentional demand among drivers of all ages. Older adults showed greater attentional demand in comparison to young and middle-aged adults even after controlling for baseline response time. Older drivers also scored poorer on a global measure of driving safety. Conclusions: The findings are highly consistent with the literature on road complexity and attention that show that increased driving complexity is associated with poorer performance on tasks designed to concurrently assess attention, an effect that is more pronounced for older drivers. The results point to intrinsic and extrinsic factors that contribute to motor vehicle collisions (MVCs) among older drivers. The relevance of these findings is discussed in relation to interventions and future research aimed at improving road safety.

Assessment of Drivers with Alzheimer’s Disease in High Demand Driving Situations: Coping with Intersections in a Driving Simulator

Intersections are one of the most complex and cognitively demanding driving situations. Individuals with dementia and, more precisely, Alzheimer’s disease (AD), may face additional challenges negotiating intersections given the nature of their cognitive decline, which often includes deficits of attention. We developed a comprehensive evaluation scheme to assess simulated driving performance at intersections. The evaluation scheme captured all types of errors that could occur during preparation (i.e., prior to the intersection), execution (i.e., during the intersection), and recovery (i.e., after the intersection). Using the evaluation scheme, intersection behaviour in a driving simulator among 17 drivers with mild AD was compared to that of 21 healthy controls. The results indicated that across all types of intersections, mild AD drivers exhibited a greater number of errors relative to controls. Drivers with mild AD made the most errors during the preparation period leading up to the intersection. These findings present a novel approach to analyzing intersection behaviour and contribute to the growing body of research on dementia and driving.

The effect of old age on supra-span learning of visuo-spatial sequences under incidental and intentional encoding instructions.

Recent findings [Turcotte, Gagnon, & Poirier, 2005. The effect of old age on the learning of supra-span sequences. Psychology and Aging, 20, 251-260.] indicate that incidental learning of visuo-spatial supra-span sequences through immediate serial recall declines with old age (Hebbs paradigm). In this study, we examined whether strategies induced by awareness of the repeated sequence might explain age differences. Young (18-35 years old) and older (65-80 years old) participants underwent either incidental or intentional learning instructions. Results indicated that older adults demonstrated reduced learning of the repeated sequence under both incidental and intentional instructions. In comparison, young adults showed superior learning of the repeated sequence in both conditions but intentional instructions triggered faster and greater learning in this age group. The results strongly indicated that knowledge of the repeated sequence enhanced learning only in the group of young adults. Older adults were unable to translate the knowledge of the repetition into elaborate strategies that would increase recall of the repeated sequence. Other findings suggest that incidental learning in young adults was mediated by both non-conscious and conscious recollection processes.

Crash avoidance in response to challenging driving events: The roles of age, serialization, and driving simulator platform

We examined the crash avoidance behaviors of older and middle-aged drivers in reaction to six simulated challenging road events using two different driving simulator platforms. Thirty-five healthy adults aged 21-36 years old (M=28.9±3.96) and 35 healthy adults aged 65-83 years old (M=72.1±4.34) were tested using a mid-level simulator, and 27 adults aged 21-38 years old (M=28.6±6.63) and 27 healthy adults aged 65-83 years old (M=72.7±5.39) were tested on a low-cost desktop simulator. Participants completed a set of six challenging events varying in terms of the maneuvers required, avoiding space given, directional avoidance cues, and time pressure. Results indicated that older drivers showed higher crash risk when events required multiple synchronized reactions. In situations that required simultaneous use of steering and braking, older adults tended to crash significantly more frequently. As for middle-aged drivers, their crashes were attributable to faster driving speed. The same age-related driving patterns were observed across simulator platforms. Our findings support the hypothesis that older adults tend to react serially while engaging in cognitively challenging road maneuvers.

Driving Competence in Mild Dementia with Lewy Bodies: In Search of Cognitive Predictors Using Driving Simulation

Driving is a multifactorial behaviour drawing on multiple cognitive, sensory, and physical systems. Dementia is a progressive and degenerative neurological condition that impacts the cognitive processes necessary for safe driving. While a number of studies have examined driving among individuals with Alzheimers disease, less is known about the impact of Dementia with Lewy Bodies (DLB) on driving safety. The present study compared simulated driving performance of 15 older drivers with mild DLB with that of 21 neurologically healthy control drivers. DLB drivers showed poorer performance on all indicators of simulated driving including an increased number of collisions in the simulator and poorer composite indicators of overall driving performance. A measure of global cognitive function (i.e., the Mini Mental State Exam) was found to be related to the overall driving performance. In addition, measures of attention (i.e., Useful Field of View, UFOV) and space processing (Visual Object and Space Perception, VOSP, Test) correlated significantly with a raters assessment of driving performance.

Deficits in Attention and Visual Processing but not Global Cognition Predict Simulated Driving Errors in Drivers Diagnosed With Mild Alzheimer's Disease.

This study sought to predict driving performance of drivers with Alzheimer’s disease (AD) using measures of attention, visual processing, and global cognition. Simulated driving performance of individuals with mild AD (n = 20) was contrasted with performance of a group of healthy controls (n = 21). Performance on measures of global cognitive function and specific tests of attention and visual processing were examined in relation to simulated driving performance. Strong associations were observed between measures of attention, notably the Test of Everyday Attention (sustained attention; r = −.651, P = .002) and the Useful Field of View (r = .563, P = .010), and driving performance among drivers with mild AD. The Visual Object and Space Perception Test–object was significantly correlated with the occurrence of crashes (r = .652, P = .002). Tests of global cognition did not correlate with simulated driving outcomes. The results suggest that professionals exercise caution when extrapolating driving performance based on global cognitive indicators.