Cortex Club Presents: Professor Marcello Massimini

We are excited to welcome Professor Marcello Massimini, from the University of Milan, on Tuesday 19th November, at 4 pm in the Small Lecture Theatre, Sherrington Building, Off Parks Road, OX1 3PT.

Professor Massimini will be giving a talk on ‘OFF-periods, causality and complexity in cortical networks during loss and recovery of Consciousness‘.

All Welcome! If you would like to attend the talk, please sign up at: https://cortex-club-massimini.eventbrite.co.uk .

Abstract:
Theoretical neuroscience suggest that consciousness depends on the ability of neural elements to engage in complex activity patterns that are, at once, distributed within a system of interacting cortical areas (integrated) and differentiated in space and time (information-rich) (i.e. brain complexity). Based on this principle, we have been developing and testing a theory-driven empirical method to assess brain complexity based on a combination of transcranial magnetic stimulation (TMS) and electroencephalography (EEG). Overall, the estimation of brain complexity provides a reliable measuring scale along the unconsciousness/consciousness spectrum and allows a robust assessment of unresponsive individuals (such as locked-in, minimally conscious and vegetative state patients) whose level of consciousness cannot be assessed behaviorally.
Starting from the experimental evidence of a link between consciousness and complexity, we moved on to explore the mechanisms by which brain complexity collapses and recovers in the human brain. Specifically, we wanted to test the hypothesis that neuronal bistability – the intrinsic tendency of cortical neurons to fall into a silent OFF-period after an initial activation – may play an important role in impairing the brain’s capacity to engage in complex patterns of causal interactions not only during NREM sleep but also in anesthesia and in brain-injured patients. We address this question at multiple scales (macro, meso and micro) of investigation, by recording brain responses to direct cortical stimulations using (1) TMS/EEG, (2) intracranial electrical stimulation/recordings in neurosurgical patients as well as (3) in cortical slices. These measurements provide convergence evidence that bistability and neuronal OFF periods may play an important role in disrupting causality and in preventing the build-up of brain complexity. Since bistability is, in principle, a reversible dynamics, this finding may point to novel strategies to promote recovery of consciousness after brain injury.

Circuits for Care – Deconstructing Parental Behavior

Circuits for Care – Deconstructing Parental Behavior

On Monday, 11th Nov in Sherrington Library, Dr Johannes Kohl, from the Francis Crick Institute, will give a talk on ‘Circuits for care – deconstructing parental behaviour’.
If you would like to join us for after-talk pub with the speaker, please sign up at: https://forms.gle/hjpq1cvWSyJZXM399.

Abstract:
Parenting is essential for the survival and wellbeing of offspring in many species, but we lack a circuit-level understanding of how this social behaviour is orchestrated. Using viral tracing, in vivo imaging, optogenetic manipulations and behavioural profiling in mice, we recently discovered that a genetically specified class of hypothalamic neurons forms projection-defined subpopulations which are each tuned to, and control, specific aspects of parenting. This functional organisation provides a new model for how discrete elements of an instinctive behaviour are generated at the circuit level. Our current goal is to understand how physiological states (such as pregnancy, hunger and sleep) alter the form and function of this parenting circuit.

Assessing Cortical Dynamics and Function despite the Subsampling Problem

Assessing Cortical Dynamics and Function despite the Subsampling Problem

Dr Viola Priesemann, from the Max Planck Institute for Dynamics and Self-Organization, on Thursday 7th November at 4 pm in the Sherrington Library will be giving a talk on “Assessing Cortical Dynamics and Function despite the Subsampling Problem”.

All Welcome! If you would like to join us for after-talk pub with the speaker, please sign up at: https://forms.gle/xEidEY6ighdPaYfs8

ABSTRACT:
Neural networks, both in the human brain as well as artificial ones, show intriguing information processing capacities. Nonetheless, we lack a principled understanding how their functions emerge. A major challenge when assessing cortical processing lies in the subsampling problem: Despite rapid technological advances, we are still far from recording all neurons in an area with millisecond precision. Thus, one records either a subset of the neurons, or some spatial average of their activity, like LFP or EEG. We showed that such spatial subsampling can strongly bias inference about collective properties like clusters or neural avalanches. It even biases measures as basic as the correlation, thus any measure of effective connectivity or coupling between areas. We derived approaches to overcome the subsampling bias, and now have the toolset to make unbiased inferences. This has enabled us to revisit a long-standing debate about the nature of collective dynamics: Instead of the well-known asynchronous-irregular (AI) or critical dynamics, we find a novel, reverberating regime. Experimental evidence for that regime is now accumulating from cortical spike recordings in rat, cat, monkey and even human. The novel regime unifies a large body of contradictory, past results; it combines the advantages of the AI and critical state; and it enables each cortical circuit to tune its compute properties to task requirements by small adjustments of synaptic strength. Thereby each cortical circuit might be able to tune itself into the distributed computation of cortex in a flexible manner – and importantly also to tune-out if not needed.

Envisioning The Reward: Contextual Signals in Mouse Visual Cortex

Envisioning The Reward: Contextual Signals in Mouse Visual Cortex

We are delighted to host Dr Nathalie Rochefort, from the University of Edinburgh, on Thursday 31st October at 4pm in the Sherrington Library, Sherrington Building, Parks Road, OX1 3PT.

Dr Rochefort will deliver a talk on “Envisioning The Reward: Contextual Signals in Mouse Visual Cortex”.

If you would like to join us for after-talk pub with the speaker, please sign up at: https://forms.gle/BwQrFqm8thJEDcRUA