BI 243 Alison Barth: Learning as a Window to Cortex
Alison Barth discusses how learning experiments in mice reveal the contributions of different neuron types to cortical function, including how sensory-cortex cell types change as animals learn reward associations.
Interacting spiral wave patterns underlie complex brain dynamics and are related to cognitive processing
The large-scale activity of the human brain exhibits rich and complex patterns, but the spatiotemporal dynamics of these patterns and their functional roles in cognition remain unclear. Here by characterizing moment-by-moment fluctuations of human cortical functional magnetic resonance imaging signals, we show that spiral-like, rotational wave patterns (brain spirals) are widespread during both resting and cognitive task states. These brain spirals propagate across the cortex while rotating around their phase singularity centres, giving rise to spatiotemporal activity dynamics with non-stationary features. The properties of these brain spirals, such as their rotational directions and locations, are task relevant and can be used to classify different cognitive tasks. We also demonstrate that multiple, interacting brain spirals are involved in coordinating the correlated activations and de-activations of distributed functional regions; this mechanism enables flexible reconfiguration of task-driven activity flow between bottom-up and top-down directions during cognitive processing. Our findings suggest that brain spirals organize complex spatiotemporal dynamics of the human brain and have functional correlates to cognitive processing.
Modeling shared and variable information encoded in fine-scale cortical topographies
Information is encoded in fine-scale functional topographies that vary from brain to brain. Hyperalignment models information that is shared across brain in a high-dimensional common information space. Hyperalignment transformations project idiosyncratic individual topographies into the common model information space. These transformations contain topographic basis functions, affording estimates of how shared information in the common model space is instantiated in the idiosyncratic functional topographies of individual brains. This new model of the functional organization of cortex – as multiplexed, overlapping basis functions – captures the idiosyncratic conformations of both coarse-scale topographies, such as retinotopy and category-selectivity, and fine-scale topographies. Hyperalignment also makes it possible to investigate how information that is encoded in fine-scale topographies differs across brains. These individual differences in fine-grained cortical function were not accessible with previous methods.
CNStalk: Anatomo-functional organisation of the grasping network in the primate brain
Cortical functions result from the conjoint activity of different, reciprocally connected areas working together as large-scale functionally specialized networks. In the macaque brain, neural tracers and functional data have provided evidence for functionally specialized large-scale cortical networks involving temporal, parietal, and frontal areas. One of these networks, the lateral grasping network, appears to play a primary role in controlling hand action organization and recognition. Available functional and tractograpy data suggest the existence of a human counterpart of this network.