Spontaneous object recognition: a promising approach to the comparative study of memory

Abstract

Spontaneous recognition of a novel object is a popular measure of exploratory behavior, perception and recognition memory in rodent models. Because of its relative simplicity and speed of testing, the variety of stimuli that can be used, and its ecological validity across species, it is also an attractive task for comparative research. To date, variants of this test have been used with vertebrate and invertebrate species, but the methods have seldom been sufficiently standardized to allow cross-species comparison. Here, we review the methods necessary for the study of novel object recognition in mammalian and non-mammalian models, as well as the results of these experiments. Critical to the use of this test is an understanding of the organism’s initial response to a novel object, the modulation of exploration by context, and species differences in object perception and exploratory behaviors. We argue that with appropriate consideration of species differences in perception, object affordances, and natural exploratory behaviors, the spontaneous object recognition test can be a valid and versatile tool for translational research with non-mammalian models.

Effects of Moderate Prenatal Alcohol Exposure during Early Gestation in Rats on Inflammation across the Maternal-Fetal-Immune Interface and Later-Life Immune Function in the Offspring

“…Exploration of each object was defined as actively sniffing, pawing at, or whisking with its snout directed toward the object and less than approximately 2 cm away from the object (Ennaceur 2010). The percent of time spent exploring the novel object was taken as a ratio of the time spent exploring both objects combined (“discrimination ratio”) as described in (Blaser and Heyser 2015). …”

The olfactory bulbectomized rat as a model of depression: The hippocampal pathway

“…Different versions of this test measure learning or memory in rodents and the hippocampus seems to be an important area involved in these processes [112]. A validation of this tests is based in humans with amnesia not being able to discriminate between new and familiar objects [111]. In the NORT, while sham animals can discriminate between the novel versus the familiar object, OBX animals fail at this task [70].…”

“…The novel object recognition test (NORT) is a recognized test to measure learning and memory in rodent models [111,112]. Different versions of this test measure learning or memory in rodents and the hippocampus seems to be an important area involved in these processes [112].…”

RECOLLECTION OF WHAT-WHERE-WHICH MEMORY IN DEGUS (<i>OCTODON DEGUS</i>)

“…We obtained basically the same results in degus, which implies that the ability to recall What-Where-Which episodic-like memories may be shared among rodents. It could be informative to use the same task not only with other rodents but also various species that show novelty preferences (Blaser & Heyser, 2015). Alternatively, by replacing objects with food rewards, for example, other species could be tested, as long as they show specific satiety.…”