Loss of hippocampal function impairs pattern separation on a mouse touch-screen operant paradigm

Area of Science:

• Neuroscience
• Cognitive Psychology
• Behavioral Neuroscience

Background:

• The hippocampus is vital for learning and memory, with its dysfunction linked to neuropsychiatric disorders.
• Current preclinical models require refined behavioral measures for hippocampal function.
• Automated tasks are being developed to better assess spatial memory and pattern separation.

Purpose of the Study:

• To evaluate a touchscreen-based delayed nonmatching-to-location (TUNL) task for assessing hippocampal-dependent pattern separation in mice.
• To investigate the impact of ventral hippocampus lesions on pattern separation performance in this automated paradigm.

Main Methods:

• Mice with ventral hippocampus lesions and control mice were trained on a touchscreen TUNL task.
• The task involved discriminating between initially presented and subsequently presented stimuli with varying spatial separations and delays.
• Performance was assessed based on acquisition rates and sensitivity to changes in stimulus separation and delay duration.

Main Results:

• Ventral hippocampus-lesioned mice showed impaired performance as stimulus separation decreased.
• Unlike in rats, consistently increasing delays did not significantly impair lesion mice.
• Variable delays within a session significantly impaired performance in lesioned mice.

Conclusions:

• The touchscreen TUNL paradigm is a sensitive measure of hippocampal-dependent pattern separation in mice.
• This automated task is valuable for studying the effects of hippocampal dysfunction in preclinical models of disease.
• The findings highlight the utility of refined behavioral assays for understanding memory deficits.