# Visuospatial Working Memory for Autonomous UAVs: A Bio-Inspired Computational Model
## 2 A Bio-Inspired Computational Model for Autonomous UAVs
### Visuospatial Working Memory  
* LPFC module. This module represents the lateral prefrontal cortex (LPFC). Findings in neuroscience indicate that broadly, but strictly within the domain of vision, the entire LPFC is involved in maintenance and manipulation tasks such as attention, working memory, and switching task sets [24]. The LPFC module includes the dlPFC and vlPFC modules. Therefore, this module integrates visual and spatial information coming from the dlPFC and vlPFC modules, respectively, to create visuospatial maps.  
Figure 6 shows an example of visuospatial maps created by the LPFC module. These maps offer a coherent and continuous representation of interest objects that have been identified, along with their spatial relationship in the environment. For instance, Figure 6 shows a first scene where a vehicle and a person have been identified and labeled as vehicle 1 and person 1, respectively. Spatial information indicates that vehicle 1 is located in front, but to the left side of the UAV, and person 1 is located in front, but to the right side of the UAV. On the other hand, Figure 6 shows a second scene, where two additional persons (labeled person 2 and person 3, respectively) have appeared and they are close to each other. In this case, when two or more interest objects are close to each other, additional spatial information is generated and included. This spatial information indicates the spatial relationship between these objects. Additionally, Figure 6 shows what happens when an object has gone out of the UAV's visual field. In this case, a selective removal process is activated. However, this process can be stopped if the object reappears in the environment.  
Therefore, whereas the VSWM tries to maintain information about the objects that are no longer present in the environment, the selective removal process operates on outdated information to limit the VSWM's load and hence facilitates the maintenance of relevant information [37; 38]. To implement this behavior in the bio-inspired VSWM computational model, Equation (7) was coded as part of the selective removal process:  
\[R=e^{\frac{-t}{s}} \tag{7}\]  
where \(R\) is retrievability (a measure of how easy it is to retrieve a piece of information from the VSWM), \(s\) is stability of memory (how fast \(R\) falls over time in the absence of a relevant stimulus), and \(t\) is time. As shown in Figure 6b, when a stimulus that has been previously identified is no longer present in the environment, its representation in the VSWM is degraded until it disappears. The graph represents this process by fading its node until it dissipates, simulating how irrelevant stimuli that are no longer present in the environment are removed from the UAV's VSWM.  
* dlPFC module. This module represents the dorsolateral prefrontal cortex. There is neuroscientific evidence that shows that the dorsolateral prefrontal cortex is responsible for spatial selectivity [24]. The dlPFC has also been associated with planning, problem solving [39] and top-down executive control [21]. Currently, the dlPFC module is responsible for integrating spatial information coming from the IPS module on the visuospatial maps and sending motor commands to the FEF and MC modules in order to exhibit top-down behavior.
* vlPFC module. This module represents the ventrolateral prefrontal cortex. Neuroscientific evidence shows that the vlPFC is responsible for object selectivity [24]. Currently, the vlPFC module is responsible for integrating visual information coming from the ITC module on the visuospatial maps.