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Conditioning learning in an attentional task relates to age and ventricular expansion in a nonhuman primate
Jennifer Wittkowski1, Rebecca G Fritz1, Martin Meier2
1Institute of Zoology, University of Veterinary Medicine Hannover, Hannover, Germany.
Abstract:
The grey mouse lemur (Microcebus murinus) is a promising nonhuman primate model for brain ageing and neurodegenerative diseases. Age-related cognitive decline in this model is well described, however, data on possible relations between attention and age, as they are known from humans, are missing. We tested 10 mouse lemurs in a touchscreen-based version of the 5-choice-serial-reaction-time-task (5CSRTT) on visuo-spatial attention: subjects had to interact with a briefly presented stimulus occurring unpredictably in one out of five locations on the touchscreen. Animals were trained to an 80 % performance at a four seconds stimulus presentation duration (SPD) and subsequently challenged by a SPD of two seconds. Additionally, ventricular expansion was assessed using structural magnetic resonance imaging. Trials to the 80 % criterion at four seconds SPD correlated significantly with age and with ventricular expansion, especially around the occipital lobe. Once criterion performance was reached, two seconds challenge performance was independent of age. In four subjects that were additionally challenged with 1.5, 1.0, 0.8, or 0.6 s SPDs or variable delays preceding stimulus presentation, performance linearly declined with decreasing SPD, i.e. increasing attentional demand. In conclusion, this is the first report of 5CSRTT data in mouse lemurs and demonstrates the general applicability of this task of visuo-spatial attention to this nonhuman primate model. Results further demonstrate age-related deficits in learning during acquisition of the 5CSRTT and suggest that both may be linked through age-related atrophy of occipital structures and a resulting deficit in central visual processes.
Insights
Grey mouse lemurs show age-related learning deficits in a visuo-spatial attention task (5CSRTT). Performance correlated with age and occipital lobe changes, suggesting visual processing deficits contribute to cognitive decline.
Area of Science:
- Neuroscience
- Primate Cognition
- Aging Research
Background:
- The grey mouse lemur (Microcebus murinus) is a valuable nonhuman primate model for studying brain aging and neurodegenerative diseases.
- While age-related cognitive decline is documented, specific attention-age relationships are not well understood in this species.
Purpose of the Study:
- To investigate visuo-spatial attention in grey mouse lemurs using a touchscreen-based 5-choice-serial-reaction-time-task (5CSRTT).
- To explore the relationship between age, cognitive performance, and structural brain changes (ventricular expansion) in this primate model.
Main Methods:
- Ten grey mouse lemurs were trained on a touchscreen 5CSRTT, assessing performance at varying stimulus presentation durations (SPD).
- Structural magnetic resonance imaging (MRI) was used to measure ventricular expansion.
- Correlation analyses examined relationships between task acquisition, performance, age, and ventricular size.
Main Results:
- Learning acquisition (reaching 80% performance at 4s SPD) significantly correlated with age and occipital lobe ventricular expansion.
- Performance during a 2s SPD challenge was independent of age once criterion was met.
- Further challenges revealed a linear decline in performance with decreasing SPD, indicating increased attentional demand.
Conclusions:
- The 5CSRTT is applicable for assessing visuo-spatial attention in grey mouse lemurs.
- Age-related deficits in learning the 5CSRTT were observed.
- These deficits may be linked to age-related occipital structure atrophy and impaired central visual processing.
