Periodic Reporting for period 1 - BrainCrossTalk (Large-scale cortical communication: Brain oscillatory mechanisms of attention allocation and selective inhibition)
Período documentado: 2017-07-01 hasta 2019-06-30
The overall goal of this project is to understand the neuronal mechanisms supporting communication between and within frontal and posterior brain regions. Such communication is required when we operate in complex environments where attention has to be selectively allocated to the relevant sensory information while interfering input needs to be inhibited. While this sounds incredibly tricky, it is in fact what our brain does seemingly effortlessly at all times; for instance while driving a car or cooking dinner, remembering a phone number to call a friend, reading a book or simply having a conversation. We need to prioritise what is being processed at all times and thus allocate attention to relevant information and away from distracting or irrelevant input. Here the ability to maintain information that has been relayed to us but is no longer available in the environment plays a crucial role; this ability is called working memory. However, while we have come a long way in understanding how the human brain processes information, we are still far from truly understanding the basic underlying mechanisms. The present project was thus developed to investigate and draft a framework for dynamical information processing in working memory. Based on recent theories and empirical findings the focus was especially placed on rhythmic brain activity, spanning a vast range of frequencies, that allows the human brain to co-ordinate processes and different brain areas.
Knowledge gain from this research will not only inform our theoretical and mechanistic understanding of neuronal oscillations (rhythms) in the human brain. It will also lead to a better understanding of dysfunctional communication patterns in the brain. This is for instance the case in many psychiatric disorders like Schizophrenia or in pathological ageing, developmental disorders like attention deficit hyperactivity disorder, neurodegenerative diseases like Parkinson’s disease or spontaneously acquired disorders like Burnout syndrome. Understanding the mechanisms enabling effective information processing in the human brain will invariantly inform us what breaks down if something goes wrong; and ultimately lead to ways to protect these mechanisms and improve patient outcome in developing measures for prevention and treatment of mental and neurological disorders.
Knowledge gain from this research will not only inform our theoretical and mechanistic understanding of neuronal oscillations (rhythms) in the human brain. It will also lead to a better understanding of dysfunctional communication patterns in the brain. This is for instance the case in many psychiatric disorders like Schizophrenia or in pathological ageing, developmental disorders like attention deficit hyperactivity disorder, neurodegenerative diseases like Parkinson’s disease or spontaneously acquired disorders like Burnout syndrome. Understanding the mechanisms enabling effective information processing in the human brain will invariantly inform us what breaks down if something goes wrong; and ultimately lead to ways to protect these mechanisms and improve patient outcome in developing measures for prevention and treatment of mental and neurological disorders.
This project enabled the identification of an intricate neuronal mechanism read out with non-invasive recordings allowing the human brain to flexibly allocate and access cognitive resources in order to successfully maintain, manipulate and prioritise information in visual working memory. This mechanism of so called cross-frequency coupling connects posterior areas of the human brain thought to actively maintain and replay visual information held in working memory with frontal regions which are supposedly in charge of directing attention and cognitive resources. Specifically, fast oscillatory activity in posterior regions is locked to specific timepoints (i.e. phases) of a slow frontal oscillation (frontal midline theta) which is approximately 10 times faster than the posterior one. Depending on the amount of cognitive resources needed for the task, i.e. the difficulty level, different phases of the slow frontal rhythm are relevant. Moreover, when posterior areas are disrupted using non-invasive neurostimulation task performance drops to chance level only if the disruption occurs during this specific time window defined by the frontal rhythm; proofing that this cross-frequency coupling indeed is a relevant cortical mechanism enabling complex cognitive processing and flexible information processing (Berger et al., 2019 Nature Communications).
These results were achieved by recording electrophysiological brain signals and combining electroencephalography with transcranial magnetic stimulation, which is when short and reversible magnetic pulses are applied focally to a small area of the brain which is thought to be relevant for the cognitive operation. In the case of this project the area of the cortex which was stimulated was the parietal cortex relevant for visual working memory.
Results from this project are and will be published in open access peer reviewed scientific journals and presented at conferences (e.g. ICON, Helsinki) as well as appropriately communicated to the general public via news outlets and science festivals (e.g. Meet the Expert at the Thinktank Science Museum Birmingham, UK).
These results were achieved by recording electrophysiological brain signals and combining electroencephalography with transcranial magnetic stimulation, which is when short and reversible magnetic pulses are applied focally to a small area of the brain which is thought to be relevant for the cognitive operation. In the case of this project the area of the cortex which was stimulated was the parietal cortex relevant for visual working memory.
Results from this project are and will be published in open access peer reviewed scientific journals and presented at conferences (e.g. ICON, Helsinki) as well as appropriately communicated to the general public via news outlets and science festivals (e.g. Meet the Expert at the Thinktank Science Museum Birmingham, UK).
The project also enabled the collection of a huge dataset where magnetic brain activity was recorded while participants performed a visual working memory task during which different types of visual information (orientation vs faces) have to be flexibly prioritised. These types of information are represented in different areas of the human brain. Moreover, information was visually presented with a rapid flicker which was not perceived by the participant (faster than the refresh rate of a modern TV screen) but can still be read out from the areas of the human brain tracing the processing of visual information. Combined, the flicker and the different types of visual information, make it possible to further investigate the mechanism for flexible resource allocation by observing cross-frequency coupling between frontal areas and distinct posterior regions of the human brain; the primary visual regions relevant for processing of all visual input, the higher order regions relevant for visuo-spatial orientation (i.e. dorsal stream) and the higher order regions relevant for face processing (i.e. ventral stream).
Cummulative results from this project will ultimately bring us another step closer to understanding basic mechanisms of how the human brain integrates, processes and co-ordinates information processing across the whole cortex. This will lead to closer understanding not only of the brain oscillatory signatures of cognitive functioning but also dysfunctioning, i.e. what happens to these mechanisms when cognitive processes are impaired or vice versa. Ultimately, this will lead to better informed options for diagnosis, treatment and progress evaluation of patients suffering from a multitude of mental and neurological disorders.
Cummulative results from this project will ultimately bring us another step closer to understanding basic mechanisms of how the human brain integrates, processes and co-ordinates information processing across the whole cortex. This will lead to closer understanding not only of the brain oscillatory signatures of cognitive functioning but also dysfunctioning, i.e. what happens to these mechanisms when cognitive processes are impaired or vice versa. Ultimately, this will lead to better informed options for diagnosis, treatment and progress evaluation of patients suffering from a multitude of mental and neurological disorders.