Mon29May201711hSalle de réunion du LPP, H432, 4ème étage, Centre Biomédical des Saints Pères 45 rue des Sts Pères, 75006 ParisLPP seminarShow details
Fifty years without free will
How are actions initiated by the human brain when there is no external sensory cue or other immediate imperative? Much is understood about how the brain decides between competing alternatives, leading to different behavioral responses. But far less is known about how the brain decides "when" to perform an action, or "whether" to perform an action in the first place, especially in a context where there is no sensory cue to act such as during foraging. More than fifty years ago, in 1965, scientists discovered a slow buildup of neural activity that precedes the onset of spontaneous self-initiated movements (movements made without any cue telling you when to move). This buildup was dubbed the "readiness potential" (RP) or bereitschaftspotential, and has since been confirmed at the single-neuron level. For decades it has been assumed to reflect a process of "planning and preparation for movement". In the 1980s the RP was used to argue that we do not have conscious free will, because it appears to begin even before we are aware of our own conscious decision to act. Now we and others have challenged the long-standing interpretation of the RP by showing that the early part of the RP might reflect sub-threshold random fluctuations in brain activity that have an influence on the precise moment that the movement begins. These fluctuations thus appear as part of the "signal" when we analyze the data time-locked to the time of movement onset. This insight leads to novel and testable predictions concerning both objective (brain signals and behavior) and subjective (the perceived time of the conscious intention) phenomena, and also exposes serious limitations of the age-old practice of working with movement-locked data epochs.
Invited by the AVoC team
Mon12Jun201711hSalle de Conférence R229, Centre Biomédical des Saints Pères 45 rue des Sts Pères, 75006 ParisShow details
Imaging Pain, Analgesia and Anaesthesia induced altered states of Consciousness
The ability to experience pain is old and shared across species. Acute pain is the body’s alarm and warning system, and as such a good thing. Chronic pain is the system gone wrong and now one of the largest medical health problems worldwide. The brain is key to these experiences and relating specific neurophysiologic measures from advanced brain imaging to perceptual or non-perceptual changes in pain perception induced by peripheral or central sensitisation, psychological or pharmacological mechanisms has tremendous value. Identifying non-invasively where functional and structural plasticity, sensitisation and other amplification or attenuation processes occur along the pain neuraxis for an individual and relating these neural mechanisms to specific pain experiences, measures of pain relief, persistence of pain states, degree of injury and the subject's underlying genetics, has neuroscientific and potential diagnostic relevance.
As such, advanced neuroimaging methods can powerfully aid explanation of a subject’s multidimensional pain experience, analgesia and even what makes them vulnerable to developing chronic pain.
Relatively far less work has been directed at understanding what changes in the brain occur during altered states of consciousness induced either endogenously (e.g. sleep) or exogenously (e.g. anaesthesia). However, that situation is changing rapidly. For example, our recent multimodal neuroimaging work explores how anaesthetic agents produce altered states of consciousness such that perceptual experiences of pain and awareness are degraded. This is bringing us fascinating insights into the complex phenomenon of anaesthesia.
- The basic neuroanatomy of pain processing in the human brain – concept of a flexibly accessible network
- How different neuroimaging techniques provide insight into chronic and acute pain (and analgesia)
- How neuroimaging tools are being used to unravel how anaesthetics produce altered states of consciousness
Invited by the Vision team
Mon26Jun201711hSalle de réunion du LPP, H432, 4ème étage, Centre Biomédical des Saints Pères 45 rue des Sts Pères, 75006 ParisLPP seminarShow details
Invited by the AVOC team