We proposed four new deviation indices for angle and distance (Fig. This degree may consist of several parameters including angle, distance, or some derived index. The new deviation indices refer to the deviation degree of the subject’s trajectory relative to the optimal route in unit time. Thus, we proposed an alternative model that measures deviation indices. Another aim of the present study is to form a comprehensive evaluation system that combines summative and dynamic evaluation for the MWM.Īccording to map cognition 12, experimental subjects can determine their own location and the direction of the platform by establishing a relatively perfect cognitive map, and they can search the platform according to the optimal route. The aim of the present study is to explore dynamic evaluation indicators based on behavioral processes of animal learning and memory, and to make up for the lack of summative evaluation that only pays attention to the final results in a limited time. The new indices reported here are based upon sufficient trajectory information, and they use the accumulation of real-time deviations to quantitatively describe the dynamic processes of animal learning behavior. In order to resolve such contradictions, Maei et al., suggested that using the P measure may reveal more efficient detection of spatial learning 9.
For example, if the subject used less time (escape latency) to find the platform, the target quadrant time spent by the subject cannot support this data. These parameters compensate for deficiencies in escape latency measures, but there is a clear separation between these indices and escape latency. Therefore, total distance, target quadrant activity time, searching strategies and other indices are also used as common reference indices to comprehensively evaluate the learning and memory abilities of the experimental subjects 9, 10, 11. Several recent studies suggested that using escape latency to evaluate learning and memory is not comprehensive 7, 8. Therefore, the low escape latency in a single training does not reflect the ability of the subject to use spatial cues to find the platform. The faster they swim, the more likely they are to encounter the platform randomly. Rodents that suffer from vascular dementia swim along the wall randomly searching for escape routes until they happen to swim away from the wall and find the hidden platform. Reductions in escape latency suggest that the experimental subjects focused on searching strategies, but in fact, reduced escape latencies may also reflect the adoption of non-spatial strategies 9. For example, escape latency, one of the most common parameters, was widely used in the MWM 7, 8. These measures are convenient to observe and record, but they rarely examine the dynamic behavior of the animal while searching for the platform 7, missing key parameters that could provide valuable insights into learning and memory. Many of the metrics currently used in the MWM are based on simple summaries of the rodent’s path, such as path-length, the percent of time spent away from walls, escape latency, angles of approach to the platform, and quadrant time, etc. The Morris water maze (MWM) evaluates the spatial learning and memory ability of rodents 1, 2, 3, and it is widely used to examine hippocampal-dependent memory 4. Therefore, including these new evaluation indices in MWM experiments provided a more effective analysis of cognitive function compared to using escape latency. From the receiver operating characteristic curve, the diagnostic values of the new deviation indices are higher than those of escape latency. Further, the new measures displayed higher sensitivity and specificity compared to what escape latency displayed in the Monte Carlo simulation. We compared the four new deviation indices to the classically used escape latency measures in a vascular dementia model and demonstrated a higher consistency in the normal distribution between the vascular dementia group and the control rats. These include the sum of the lateral deviation vectors, the sum of the offset angles, the sum of the correction vectors, and the sum of the lateral deviation vectors to the initial optimal route. Utilizing the graph cognition hypothesis, we proposed four new deviation indices to evaluate cognitive function in the MWM that compared the optimal swim track to the actual track taken. However, current evaluation measures are not comprehensive because there is a wide distribution in the measured response.
The Morris water maze (MWM) is widely used to evaluate rodent spatial learning and memory.