A comparison of discrimination and reversal learning for olfactory and visual stimuli in aged rats.

Abstract

The present study investigated age-related differences in discrimination and reversal learning for olfactory and visual stimuli in 6 mo and 24 mo old rats. Rats were trained to discriminate between two pseudo-randomly selected odors or objects. Once each animal reached a criterion on discrimination trials, the reward contingencies were reversed. Young and aged rats acquired the olfactory and visual discrimination tasks at similar rates. However, on reversal trials, aged rats required significantly more trials to reach the learning criterion on both the olfactory and visual reversal tasks than young rats. The deficit in reversal learning was comparable for odors and objects. Furthermore, the results showed that rats acquired the olfactory task more readily than the visual task. The present study represents the first examination of age-related differences in reversal learning using the same paradigm for odors and objects to facilitate cross-modal comparisons. The results may have important implications for the selection of memory paradigms for future research studies on aging.

Age-related changes in detection of spatial novelty

“…Therefore, the rats in the present study showed significant memory impairments at 25-mo of age despite having longer average longevity than other strains of aged rats used in prior spatial exploratory studies [33]. The present finding is consistent with other studies that have reported age-related behavioral deficits in F344/BN rats 24–25-mo of age on various cognitive tasks [12,25,26,40–42]. However, 24-mo-old F344/BN rats have been shown to match young rats on some behavioral measures such as trace and delayed eyeblink conditioning paradigms [43].…”

The Organization of Behavior over Time: Insights from Mid-session Reversal

“…This allows them to be more sensitive to reinforcement cues and reduce their reliance on using time as the main switching cue in MSR. That said, a reliable finding with T-maze procedures in rats is that of spontaneous alternation (Brushfield, Luu, Callahan, & Gilbert, 2008; Dudchenko, 2004). Rats tend not to repeat a previous response in spatially constructed apparatuses, such as the T-maze, Y-maze, and radial arm maze, even with lengthy delays between trials (Dudchenko, 2004; Evenden & Robbins, 1984).…”

Willingness to Wait and Altered Encoding of Time-Discounted Reward in the Orbitofrontal Cortex with Normal Aging

“…The prefrontal cortex and OFC in particular has been implicated in aging related changes in decision-making in a variety of contexts (Rapp & Heindel, 1994; Zyzak et al ., 1995; Rypma & D’Esposito, 2000; Barense et al ., 2002; Lamar et al ., 2004; Smith et al ., 2004; Gazzaley et al ., 2005; Marschner et al ., 2005; Moore et al ., 2006; Brushfield et al ., 2008; Lasarge et al ., 2009; Mizoguchi et al ., 2009; Wang et al ., 2011). For example, aged rats are slower to acquire reversals, and these impairments have been linked to changes in processing in the OFC (Schoenbaum et al ., 2002; Schoenbaum et al ., 2006).…”