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suggest that sleep during the first postencoding night profoundly influences long-term systems-level consolidation of emotional memory and modifies the functional segregation and integration associated with recollection of affective memories in the long term (Sterpenich et al., 2009). Finally, using fMRI, it was recently demonstrated that SD amplifies reactivity throughout human mesolimbic reward brain networks in response to pleasureevoking stimuli. In addition, this amplified reactivity was associated with enhanced connectivity in the early primary visual processing pathways and extended limbic regions, yet with a reduction in coupling with medial frontal and orbitofrontal regions. These neural changes were accompanied by a biased increase in the number of emotional stimuli judged as pleasant in the sleep-deprived group, the extent of which exclusively correlated with activity in mesolimbic regions (Gujar et al., 2011b). These results may offer a neural foundation on which to consider interactions between sleep loss and emotional reactivity in

Collectively, the above findings demonstrate sleep-related mechanisms of emotional regulation and consolidation of affective memories that partially differ from those shown to be involved in emotionally neutral memory consolidation and in the cognitive functions of sleep. The emotional "fingerprint" seems to involve mostly connections between prefrontal cortices and amygdala. However, it still remains to be revealed which sleep portions or sleep stages might have contributed to the impaired brain activation patterns after SD

It is undeniable that highly specific sleep EEG rhythms and patterns of brain activation *actively* serve the memory, cognitive and psychological functions of sleep. The corresponding mechanisms involve brain plasticity at system, neural, synaptic, and genetic levels, and are closely related to the neurobiology of sleep. However, these mechanisms are *distinctly different* for certain memory, cognitive and psychological categories that sleep promotes, being *dissimilarly associated* with distinct sleep portions and sleep stages. Thus, both declarative and procedural memory consolidation and reconsolidation occur in earliest part of non-REM sleep/SWS by mechanisms of brain plasticity at system and neural levels, engaged in hippocampus-cortical relationships. Those, occurring during REM sleep appear more complex. Their pattern of brain activation engages a large set of areas, and possibly involves brain plasticity mechanisms at synaptic and genetic levels. The emotional 'fingerprint" of memory consolidation seems to be presented by connections between

Further, the mechanisms involved in other cognitive functions of sleep appear different from those involved specifically in its memorizing effects. Also, it seems that sleep contributes to cognitive processes in a state dependent rather than in a trait dependent manner, but a complex interaction between both also can be suggested. Thus, since some of the EEG data imply a trait dependent role for sleep in cognitive abilities, most of the neuroimaging data indicate a state dependent role. However, these conclusions need further

Importantly, different types of sleep mentality incorporated in different forms of dreaming production suggest a role for dreams in memory and cognitive processes. Data from such studies may open new perspectives of research and may provide new views about cognitive

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**9** 

*Italy* 

**Neuroimaging and Outcome Assessment in** 

Silvia Marino, Rosella Ciurleo, Annalisa Baglieri, Francesco Corallo, Rosaria De Luca, Simona De Salvo, Silvia Guerrera, Francesca Timpano,

*Dept. of Neurology, Neurosurgery & Behavioral Sciences, University of Siena, Siena,* 

Consciousness is a multifaceted concept that has two dimensions: arousal, or wakefulness (i.e., level of consciousness), and awareness (i.e., content of consciousness) (Laureys et al., 2004). An accurate and reliable assessment of the arousal and awareness of consciousness in patients with severe brain damage is of greatest importance for the differential diagnosis of low levels consciousness patients and for outcome evaluation. Following coma, some patients permanently lose all brainstem function (brain death), some progress to "wakeful unawareness" (vegetative state - VS), whereas others recover typically and progress through different stages before fully or partly recovering consciousness (minimally conscious state - MCS). Patients in VS can open their eyes and exhibit basic orienting responses, but show no conscious, purposeful activity. Reflex and other movements are seen, mediated by brainstem, spinal cord, and brainstem-diencephalic arousal systems (Laureys et al., 2004). VS can occur after patients emerge from an acute catastrophic brain insult causing coma, or can also be seen in degenerative or congenital nervous system disorders. The two common findings are necrosis of the cerebral cortex, thalamus and brainstem (usually after anoxic injury) and diffuse axonal injury (usually after trauma), although other pathological findings can be seen in degenerative and other disorders (Laureys, 2008). The MCS patients do not meet diagnostic criteria for coma or VS because they demonstrate some inconsistent but clear evidence of consciousness (Laureys et al., 2008; Giacino et al., 2002). In the MCS, there is variable impaired function of the cerebral cortex, diencephalons and upper brainstem. This allows occasional conscious behaviours to occur, unlike in VS or coma. Patients may enter the MCS as they emerge from coma or VS, or they can become minimally conscious as a result of acute injury or chronic degenerative diseases. Recent studies suggest a number of potential clinical and rehabilitative applications of magnetic resonance (MR) techniques. Although bedside clinical examination remains the criterion standard for establishing diagnosis, MR may provide an adjunctive diagnostic role when behavioural findings are very limited or ambiguous. The future of diagnostic and prognostic assessment of patients with disorders of consciousness (DOC) envisions a battery of neurobehavioral and neuroimaging techniques (such as structural and functional MR imaging (MRI and

**1. Introduction** 

**Vegetative and Minimally Conscious State** 

Placido Bramanti and Nicola De Stefano *IRCCS Centro Neurolesi "Bonino-Pulejo", Messina,* 

http://dx.plos.org/10.1371/journal.pone.0005675

Yordanova, J., Kolev, V., Wagner, U. & Verleger, R. (2010). Differential associations of earlyand late-night sleep with functional brain states promoting insight to abstract task regularity, *PLoS One*, 5(2):e9442. http://dx.plos.org/10.1371/journal.pone.0009442
