## 1 Introduction
In particular, the attentional (DAN/VAN) and salience (SN) networks represent brain activities that are of relevance to depression when it is conceived as behavioural withdrawal. The dorsal and ventral attention networks (DAN/VAN) have been described as having multiple nodes located throughout the grey matter, each of which is related to specific aspects of attention [23]. These are (1) alerting (increases and maintains response readiness in response to a specific stimulus; located in the frontal and parietal regions, mostly in the right hemisphere); (2) orienting (selecting pertinent information; located in the pulvinar, superior colliculus, superior parietal lobe, temporoparietal junction, superior temporal lobe, and frontal eye fields); and (3) executive attention (the monitoring and resolution of conflict between information from different neural regions; the dorsal anterior cingulate cortex (ACC) in cognitive conflict tasks, and activation in the rostral ACC after the commission of errors. Whether the ACC monitors or resolves conflict is not clear, but the ACC function seems to preferentially relate to conflict at the response level [24]). The salience network (SN; [24; 25]) is mostly located in the cortical and subcortical prominent nodes of the anterior cingulate cortex, as well as the rostral prefrontal cortex and the supramarginal gyrus. The SN has a major role in emotional control [26]. Altered SN function has been associated with reduced motivation to engage with the external environments of depressed patients [27]. It has been suggested that the primary function of the SN is to identify the most relevant stimuli that reach the brain, including both the cognitive and affective aspects of the stimulus [28]. If these were associated with the emotional and cognitive aspects of MDD, then the SN may well be conceptualised as helping the depressed patient identify which stimuli held the most emotional and/or cognitive valence vis a vis the MDD symptomatology and the individual's response to those stimuli. With relevance to the attentional networks, the SN may assist in deciding if the information identified by the DAN or VAN requires a behavioural response from the individual. That response may differ across depressed and non-depressed individuals and reflect the underlying propensity towards behavioural withdrawal from stressful stimuli that is a hallmark of MDD. Connectivity between the DAN, VAN, and SN might provide a confirmation of the behavioural withdrawal model of MDD, and assist in the development of effective treatment models for depression or its subtypes. Therefore, the aim of the study was to examine the DAN, VAN, and SN network activity (and their connectivity with each other), and their association with MDD as well as the four MDD subtypes (Anhedonic, Cognitive, Somatic, and Mood) described by [PERSON] and [PERSON] [15]. Although the lack of previous conclusive research findings on these issues prevented the raising of specific directional hypotheses, it was expected that high depression scores (characterised by behavioural withdrawal in the form of MDD symptoms) would be associated with lowered activity in frequency bands associated with cognitive activation such as beta and gamma. That is, the depressed individual would exert neurological energy on the environmental cues that contributed to their depression but fail to find them sufficiently relevant to initiate behavioural activity.