Intersession interval affects performance in the Morris Water Maze

Area of Science:

• Neuroscience
• Cognitive Psychology
• Animal Behavior

Background:

• The proximal perceptual style (PPS) effect, a sexually dimorphic difference in cognitive style, was previously identified in rats.
• This effect, where females navigate directly to a newly positioned platform, is modulated by factors like nicotine and ovariectomy.
• The PPS effect appears to be related to cognitive style rather than inherent ability, as no sex differences were noted during acquisition in prior studies.

Purpose of the Study:

• To investigate the impact of varied age and shortened acquisition training on the proximal perceptual style (PPS) effect in rats.
• To determine if modifications in training protocols influence the previously observed sex differences in spatial navigation strategies.

Main Methods:

• Rats underwent a shortened 6-day acquisition phase (two sessions daily) with a fixed platform position.
• Following acquisition, a probe trial shifted the platform to a proximal, visible location.
• The study incorporated variations in age and sex to assess their influence on the PPS effect and acquisition.

Main Results:

• Shortening the acquisition phase from 12 to 6 days eliminated the proximal perceptual style (PPS) effect in female rats.
• Sex- and age-related differences emerged during the modified acquisition phase: males showed an advantage, and prepubertal rats had longer escape latencies.
• No significant interaction between sex and age was observed during acquisition.

Conclusions:

• The duration and structure of initial training significantly influence the emergence of the proximal perceptual style (PPS) effect.
• Cognitive strategies, including the PPS effect, are sensitive to learning parameters and may not solely reflect stable cognitive styles.
• The study highlights the complex interplay between learning protocols, sex, and age in shaping cognitive behaviors in rats.