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observed in patients in a vegetative state (Laureys et al., 2002). The minimally conscious state is distinguished from the vegetative state by the presence of inconsistent behavioral evidence of consciousness and partial awareness (Giacino et al., 2013). Patients in minimally conscious states are characterized by sleep/wake cycles and purposeful movements. They are able to maintain visual fixations, localize auditory stimuli, verbalize and gesture, follow commands, and may give emotional responses (Davis, 2007). However, a patient’s health and cognitive abilities can influence their motor, visual, and auditory abilities, as these abilities may deteriorate in patients with poor health or reduced cognition. Although few brain imaging studies have been done on patients in the minimally conscious state, it has been revealed that the cingulate cortex and parietal cortex remain functional (Davis, 2007). This suggests that the neurological networks that are involved in consciousness retain their functionality. Despite current knowledge concerning these states of consciousness, questions still arise about how these states of consciousness emerge and are maintained biologically. This review will investigate both the vegetative and minimally conscious states by considering biological and neurological pathways that can result in either states of consciousness and current advancements that aim to treat these conditions.

Genetic Implications

Although there are neurological underpinnings that determine the progression and emergence of the vegetative and minimally conscious states, genetic factors can increase the susceptibility to the vegetative and minimally conscious states and influence the neural networks associated with these states of consciousness. The most common cause of disorders of consciousness is traumatic brain injury. The severity and brain regions affected in the event can determine a patient’s outcome, while post-injury neuronal repair can determine the recovery of their outcome (Bennett et al., 2016). Genes that influence the severity of the injury and the repair post-injury are pro- and anti-inflammatory cytokines and neurotrophic genes (Bennett et al., 2016). During the initial phases of a brain injury, cytokines may act to prematurely exacerbate the injury or may offer neuroprotective properties (Bennett et al., 2016). Tumor necro