large scale networks

white matter fibres / tracts

• arcate fasciculus= key language tract

• white matter tracts helps us understand the anatomical interconnections between regions

• structural connectivity

• the roadways of the brain = cant have good communication without good ways to connect areas

diffusion tensor imaging (DTI) 

• tracks the direction of movement of water molecules

• systematic flow in one direction indicates a large white matter tract

DTI clinical applications

• identifying diseases that affect long axons e.g multiple sclerosis

• psychologically; if basic scans down show anything but there are cognitive problems

• diffuse axonal injury in head injury and concussion, twisting and tearing large white matter tracts 

• know a lot more from these methods about structural problems that underlie amnesia

corpus colosseum 

• people experiencing significant amnesia tend to have lower white matter fibre volume

• corpus colosseum damage itself is occurring, but also predictive of greater amnesia, along with many other areas

functional connectivity

• the crosstalk between interconnected regions during a particular activity

• traffic on the road

• degree of cross talk between regions varies depending on the task

• can measure the degree of synchrony between activity in different regions - how does the bold signal change over time to map connection and communication between areas 

dynamic networks

• Lots of large scale networks operate as inhibitors of each other, so the networks will ebb and flow as the brain moves between thought and focus 

default mode network

• ‘day dreaming’ network

• active at rest 

• active when focused on internal thoughts 

• deactivated when focus shifts to external stimuli 

• inner reflection exploring ideas / solutions

• super portion of the

  prefrontal cortex

• number of lateral structures, but lots of key ones on the medial surface

• temporoparietal cortex, hippocampus, ventromedial PFC, posterior cingulate cortex 

DMN activities

• retrieving memories for past experiences, reliving mentally (hippocampus) 

• making judgements about themselves relative to others (VMPFC, social cognition and judgments on others) 

• mind wandering 

mind wandering

• button press tasks 

• greater activation of the DMN when day dreaming 

• able to measure beyond activities that require an external focus 

frontoparietal control network

• activated when performing a demanding task

• highly externally focused cognitive control & effortful tasks 

• controlling behaviour to achieve a goal

• large portion of the lateral PFC 

• parietal lobe 

• interparietal sulcus 

  

the salience network 

• signals when something is aversive or emotionally salient

• can respond to a thought or emotion

• helps to initiate rapid switches between networks

• dorsal anterior cingulate= signals when we need to exert effort on a task

• anterior insula= evaluates emotional and bodily states

anterior PFC

• the hotel task & complex problem solving

• real life problems & multi tasking involve dynamic switching between modes 

• damage to the anterior PFC; people get fixed in one network and then cannot switch to the other one 

depression

• increased connectivity, synchronicity, and overall activation within the default mode network 

• more time being introspective, more time ruminating 

• unclear as to wether cause or effect 

creativity in healthy people

• high scorers: tightly synchronised activity in parts of the default mode and fronto parietal control networks 

• low scorers: primarily posterior cross talk 

• suggests that creative thought involves flexible interplay between; 

1. Default mode network (internal thoughts, reflection, imagining, remembering)

2. Frontoparietal control network (goal directed top-down control of cognition, evaluation of ideas, etc.)