Spatial cognition and memory: a reversible lesion with lidocaine into the anteromedial/posterior parietal cortex (AM/PPC) affects differently working and long-term memory on two foraging tasks

Abstract

Place memory is relevant for exploration and forage behaviour. When food supply is dispersed, a win-shift has advantage over a win-stay strategy. In the Olton Octagonal Maze, the rat follows a win-shift strategy using working memory. However, in the Olton 4x4 version, the rat follows a win-stay strategy, using both working and long-term memories. It has been suggested that the neocortex is required for the resolution of tasks demanding long-term, but not for that demanding working memory alone. The role of anteromedial/posterior parietal cortex (AM/PPC) was investigated here, using a reversible lesion induced by intracerebral lidocaine infusion. Long-Evans rats were implanted with guide cannulae into the AM/PPC and trained in an Olton 4x4 maze, counting working and long-term memory errors after a delay. Then, the animals were infused with lidocaine or saline during the delay phase and tested for three days. Another series of animals, treated as before, was tested in an Olton Octagonal Maze and subjected to the same injection schedule. In the Olton 4x4 Maze, lidocaine produced a significant increase in working and long-term memory errors, compared to saline and post-lidocaine conditions. In contrast, in the Olton Octagonal Maze, lidocaine did not induce any effect on working memory errors. Thus, AM/PPC is required when both working with previous information and long-term memories are needed, but not when only working memory is required, as it happens under ethological conditions. Whenever food supply is dispersed, a win-shift strategy is preferable.

Functional Architecture and Encoding of Tactile Sensorimotor Behavior in Rat Posterior Parietal Cortex

“…In general, neuronal activity in PPC has been shown to correlate to a spectrum of behaviors, including motor behaviors that involve unrestricted exploration and motion/movement planning when subjects are head-fixed or navigate in a virtual reality setting (Espina-Marchant et al, 2006;Cui and Andersen, 2007;Harvey et al, 2012;Hauschild et al, 2012;Mimica et al, 2018;Crochet et al, 2019). We studied the functional architecture of PPC during tactile sensorimotor behavior in head-fixed rats, and the temporal dynamics of whisking and object touch resemble those observed in freely moving conditions (Carvell and Simons, 1990;Hobbs et al, 2015).…”

Posterior parietal cortex: An interface between attention and learning?

“…In contrast, the same lesion produced deficits in spatial learning; thus, the lesions were not without effect. Using two versions of a food foraging task, Espina-Marchant, Pinto-Hamuy, Bustamante, Morales, Robles, and Herrera-Marschitz (2006) examined the effects of temporarily inactivating the PPC with lidocaine during the delay period in a working memory procedure. The authors found that inactivating the PPC only had an effect when the task demands required both working memory and reliance on long-term memory, but not working memory alone.…”

Task phase‐specific involvement of the rat posterior parietal cortex in performance of the TUNL task

“…We have recently shown that the rat PPC is critical for performance of the TUNL task using temporary inactivations that lasted for the entire testing session 4 . Similarly, a number of previous studies show that the PPC is critical for visuospatial WM and memory‐guided perceptual decision making using visual stimuli 3,12,14,21 . In contrast, the PPC appears not to be necessary for WM tasks using odors or objects 18,32 .…”

“…The posterior parietal cortex (PPC) is an area of association cortex in the posterior cerebrum that is critical for a range of short‐term memory‐guided cognitive processes in primates and rodents including working memory (WM), 1‐12 perceptually guided decision making, 13 and sensory evidence accumulation 14,15 . Despite this evidence, however, the precise role of the rodent PPC in these cognitive processes is unclear.…”