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Consciousness in humans and non-human animals: recent advances and future directions.

Boly M, Seth AK, Wilke M, Ingmundson P, Baars B, Laureys S, Edelman DB, Tsuchiya N - Front Psychol (2013)

Bottom Line: In addition, much progress has been made in the understanding of non-vertebrate cognition relevant to possible conscious states.Finally, major advances have been made in theories of consciousness, and also in their comparison with the available evidence.Along with reviewing these findings, each author suggests future avenues for research in their field of investigation.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, University of Wisconsin Madison, WI, USA ; Department of Psychiatry, Center for Sleep and Consciousness, University of Wisconsin Madison, WI, USA ; Coma Science Group, Cyclotron Research Centre and Neurology Department, University of Liege and CHU Sart Tilman Hospital Liege, Belgium.

ABSTRACT
This joint article reflects the authors' personal views regarding noteworthy advances in the neuroscience of consciousness in the last 10 years, and suggests what we feel may be promising future directions. It is based on a small conference at the Samoset Resort in Rockport, Maine, USA, in July of 2012, organized by the Mind Science Foundation of San Antonio, Texas. Here, we summarize recent advances in our understanding of subjectivity in humans and other animals, including empirical, applied, technical, and conceptual insights. These include the evidence for the importance of fronto-parietal connectivity and of "top-down" processes, both of which enable information to travel across distant cortical areas effectively, as well as numerous dissociations between consciousness and cognitive functions, such as attention, in humans. In addition, we describe the development of mental imagery paradigms, which made it possible to identify covert awareness in non-responsive subjects. Non-human animal consciousness research has also witnessed substantial advances on the specific role of cortical areas and higher order thalamus for consciousness, thanks to important technological enhancements. In addition, much progress has been made in the understanding of non-vertebrate cognition relevant to possible conscious states. Finally, major advances have been made in theories of consciousness, and also in their comparison with the available evidence. Along with reviewing these findings, each author suggests future avenues for research in their field of investigation.

No MeSH data available.


Related in: MedlinePlus

PET studies reveal hypometabolism in similar fronto-parietal areas in vegetative and anesthesia (areas in blue, left panel). Recent dynamic causal modeling studies also suggest a loss of top-down (reentrant) connectivity in fronto-parietal cortices in both vegetative state (left panel, assessed for response to auditory stimuli) and propofol anesthesia (right panel, assessed from spontaneous EEG). Adapted from Boly et al. (2011, 2012a). *Significant difference between conditions (corrected p < 0.05).
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Figure 2: PET studies reveal hypometabolism in similar fronto-parietal areas in vegetative and anesthesia (areas in blue, left panel). Recent dynamic causal modeling studies also suggest a loss of top-down (reentrant) connectivity in fronto-parietal cortices in both vegetative state (left panel, assessed for response to auditory stimuli) and propofol anesthesia (right panel, assessed from spontaneous EEG). Adapted from Boly et al. (2011, 2012a). *Significant difference between conditions (corrected p < 0.05).

Mentions: Research on altered states of consciousness due to brain damage has greatly benefited from the definition of the minimally conscious state (MCS), provided by Giacino et al. (2002). Since the introduction of this definition, a number of studies have shown significant differences in brain function between vegetative and minimally conscious state patient populations (Boly, 2011). Brain function in patients in the vegetative state (VS) is very similar to that during sleep and anesthesia, and is characterized by an impaired function of thalamus and fronto-parietal cortical areas (Laureys et al., 2000a,b, 2002; Laureys, 2005). In contrast, brain function in MCS is much closer to that observed in HAVs, with the preservation of functional connectivity (temporal correlation patterns between cortical areas) and activation in frontal and parietal cortical areas (Boly et al., 2004, 2008a; Vanhaudenhuyse et al., 2010; Fernandez-Espejo et al., 2012). What makes conscious patients in MCS appear unconscious like VS patients is the lack of motor functions, including speech, which renders patients non-communicative. In addition to differences in brain activation and functional connectivity, recent electroencephalography (EEG) studies have revealed that MCS patients, in contrast to VS patients, show preserved “top-down” or recurrent processing in higher-order cortical areas (Boly et al., 2011) (Figure 2). Furthermore, the brains of the MCS patients and normal healthy people react to a single pulse of transcranial magnetic stimulation (TMS) in a similar way (Rosanova et al., 2012); TMS-evoked EEG response is variable across trials, spreads across widely distributed cortical areas and reveals much more complicated and sustained dynamics than those evoked in the VS patients' brains (also see Casali et al. (2013) the following section on anesthesia (Ferrarelli et al., 2010) and sleep (Massimini et al., 2005) on this TMS-EEG perturbational approach).


Consciousness in humans and non-human animals: recent advances and future directions.

Boly M, Seth AK, Wilke M, Ingmundson P, Baars B, Laureys S, Edelman DB, Tsuchiya N - Front Psychol (2013)

PET studies reveal hypometabolism in similar fronto-parietal areas in vegetative and anesthesia (areas in blue, left panel). Recent dynamic causal modeling studies also suggest a loss of top-down (reentrant) connectivity in fronto-parietal cortices in both vegetative state (left panel, assessed for response to auditory stimuli) and propofol anesthesia (right panel, assessed from spontaneous EEG). Adapted from Boly et al. (2011, 2012a). *Significant difference between conditions (corrected p < 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3814086&req=5

Figure 2: PET studies reveal hypometabolism in similar fronto-parietal areas in vegetative and anesthesia (areas in blue, left panel). Recent dynamic causal modeling studies also suggest a loss of top-down (reentrant) connectivity in fronto-parietal cortices in both vegetative state (left panel, assessed for response to auditory stimuli) and propofol anesthesia (right panel, assessed from spontaneous EEG). Adapted from Boly et al. (2011, 2012a). *Significant difference between conditions (corrected p < 0.05).
Mentions: Research on altered states of consciousness due to brain damage has greatly benefited from the definition of the minimally conscious state (MCS), provided by Giacino et al. (2002). Since the introduction of this definition, a number of studies have shown significant differences in brain function between vegetative and minimally conscious state patient populations (Boly, 2011). Brain function in patients in the vegetative state (VS) is very similar to that during sleep and anesthesia, and is characterized by an impaired function of thalamus and fronto-parietal cortical areas (Laureys et al., 2000a,b, 2002; Laureys, 2005). In contrast, brain function in MCS is much closer to that observed in HAVs, with the preservation of functional connectivity (temporal correlation patterns between cortical areas) and activation in frontal and parietal cortical areas (Boly et al., 2004, 2008a; Vanhaudenhuyse et al., 2010; Fernandez-Espejo et al., 2012). What makes conscious patients in MCS appear unconscious like VS patients is the lack of motor functions, including speech, which renders patients non-communicative. In addition to differences in brain activation and functional connectivity, recent electroencephalography (EEG) studies have revealed that MCS patients, in contrast to VS patients, show preserved “top-down” or recurrent processing in higher-order cortical areas (Boly et al., 2011) (Figure 2). Furthermore, the brains of the MCS patients and normal healthy people react to a single pulse of transcranial magnetic stimulation (TMS) in a similar way (Rosanova et al., 2012); TMS-evoked EEG response is variable across trials, spreads across widely distributed cortical areas and reveals much more complicated and sustained dynamics than those evoked in the VS patients' brains (also see Casali et al. (2013) the following section on anesthesia (Ferrarelli et al., 2010) and sleep (Massimini et al., 2005) on this TMS-EEG perturbational approach).

Bottom Line: In addition, much progress has been made in the understanding of non-vertebrate cognition relevant to possible conscious states.Finally, major advances have been made in theories of consciousness, and also in their comparison with the available evidence.Along with reviewing these findings, each author suggests future avenues for research in their field of investigation.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, University of Wisconsin Madison, WI, USA ; Department of Psychiatry, Center for Sleep and Consciousness, University of Wisconsin Madison, WI, USA ; Coma Science Group, Cyclotron Research Centre and Neurology Department, University of Liege and CHU Sart Tilman Hospital Liege, Belgium.

ABSTRACT
This joint article reflects the authors' personal views regarding noteworthy advances in the neuroscience of consciousness in the last 10 years, and suggests what we feel may be promising future directions. It is based on a small conference at the Samoset Resort in Rockport, Maine, USA, in July of 2012, organized by the Mind Science Foundation of San Antonio, Texas. Here, we summarize recent advances in our understanding of subjectivity in humans and other animals, including empirical, applied, technical, and conceptual insights. These include the evidence for the importance of fronto-parietal connectivity and of "top-down" processes, both of which enable information to travel across distant cortical areas effectively, as well as numerous dissociations between consciousness and cognitive functions, such as attention, in humans. In addition, we describe the development of mental imagery paradigms, which made it possible to identify covert awareness in non-responsive subjects. Non-human animal consciousness research has also witnessed substantial advances on the specific role of cortical areas and higher order thalamus for consciousness, thanks to important technological enhancements. In addition, much progress has been made in the understanding of non-vertebrate cognition relevant to possible conscious states. Finally, major advances have been made in theories of consciousness, and also in their comparison with the available evidence. Along with reviewing these findings, each author suggests future avenues for research in their field of investigation.

No MeSH data available.


Related in: MedlinePlus