Exploring Object Discrimination in Zebrafish: Behavioral Performance and Scopolamine-Induced Cognitive Deficits at Different Retention Intervals

Abstract

The object discrimination test allows the testing of different memory retention periods. However, few behavioral endpoints have been measured in fish species such that retention is often assessed using a single parameter (time spent in object area). Here, we aimed to explore the object discrimination test in zebrafish by assessing their behavioral performance after 1 h or 24 h retention interval periods. To characterize putative interaction-like behaviors, fish were tested in the absence or presence of scopolamine (1 h before test session). Zebrafish were habituated for three consecutive days in the experimental tank and training session was performed for 10 min using two identical nonpreferred objects (black cube or sphere). After the retention intervals, a familiar object was replaced by a novel object (test session, 10 min). Fish were also exposed to the novel tank diving test to assess locomotion and anxiety-like behaviors. At 1 h retention interval, animals performed more circular-like investigation near the familiar object, whereas 24 h after training session, a prominent rapid investigation was observed when animals explore the non-familiar object. Because scopolamine abolished these phenotypes, as well as the increased time spent in the novel object area during the test without changing locomotion and anxiety-related parameters, the behavioral responses described here may predictively reflect interaction-like behaviors involved in object discrimination memory in zebrafish models.

Effects of the Hydroethanolic Extract of Lycopodium selago L. on Scopolamine-Induced Memory Deficits in Zebrafish

“…According to Figure 6B, all three doses of LS, but especially the doses of 1 mg/L and 3 mg/L, significantly reversed the recognition memory impairment caused by the SCOP administration (p < 0.01), increasing zebrafish preference for the new object. Because scopolamine changes transitions to the object areas, locomotion, and anxiety-related responses, the interaction-like behaviors described here may predictably reflect a distinct behavioral performance associated with an object, which has been described by other authors [29,30]. However, the exact significance of such behaviors, as well as the neurochemical mechanisms involved in these responses, still require further scrutiny.…”

“…The NOR test evaluates the short-and long-term memory of the fish. The test is based on the ability to recognize an unfamiliar object when placed in its area [30]. The parameter that was estimated in this test conducted by our research group focused on highlighting the preference regarding the newly identified object of the zebrafish taken in the study.…”

Baicalein 5,6-Dimethyl Ether Prevents Memory Deficits in the Scopolamine Zebrafish Model by Regulating Cholinergic and Antioxidant Systems

“…To explore whether baicalein 5,6-dimethyl ether treatment affects locomotion or anxiety-like behavior, the animals were submitted to NTT, according to a previously described method by Levin et al [ 58 ]. NTT is widely used to measure exploratory behavior and novelty stress habituation [ 59 ]. Zebrafish ( n = 10 per group) were individually introduced in the apparatus filled with 1.5 L of home tank water and their behaviors were recorded for 6 min.…”

The Promise of the Zebrafish Model for Parkinson’s Disease: Today’s Science and Tomorrow’s Treatment

“…For example, the object discrimination test measures the ability of a zebrafish to retain a memory (Figure 1). Zebrafish are introduced to a novel object to test whether they are still able to recognize the object after 1-or 24-h post-introduction (Stefanello et al, 2019). One study revealed that the zebrafish telencephalon and thalamus are the major brain regions that are involved in processing visual discrimination (Messina et al, 2020).…”