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VI. Cognitive Control
Concept of Executive Functions
- control processes that enable an individual to optimize performance in situations requiring the
operation and coordination of several more basic cognitive processes
- set of mechanisms use to meet situational demands, specially in novel situation or in the
presence or habitual routine to lead to opposing (action) tendencies
- supervisory, controlling or meta-cognitive, rather than specific to one domain (memory,
perception, language)—> applies to almost all regions
- linked to distinction between automatic & controlled behavior (latter requires EF)
- although EF have been classically linked to the PFC, not all of this region is involved in control &
also there are other key regions involved, such as the anterior insula/frontal operculum, parietal areas & basal ganglia circuits
- optimal parametrization of task processing to maximize rewards
- conscious, effortful, capacity-limited
- central role in human cognition: it interacts with many other cognitive processes
- field in need of mechanistic explanations to avoid the homunculus: avoid stipulating components
in seeks to explain (just another label if saying the PFC controls behavior)
- understanding control at different
levels of analysis (basic mechanistic way or control al higher level)
- what problems dies cognitive control
solve?
- adult human brain contains an
astonishing high number of neurons & connections, these are shaped by phylogeny & ontogeny; strong ballistic associations between stimuli (context) & response (action) —> depends on practice A simple Account: The SAS Model
- by Norman & Shallice identifies 5
general situations requiring EF —> set of tasks and behaviors (termed schemas) and a biasing mechanism that activated/ suppressed these schemas according to the individual’s current goals
- situations involving planning & decision making
- situations that require conflict solving (overcoming of a strong habitual response or resisting temptation)
- situations involving error correction
- situations where responses are not wll-learnded; novelty vs. practice effects: repeat vs. generate
- difficult & dangerous situations Evolutionary Development of the Frontal Lobe
- SAS Model & other early approaches linked control with the (pre)frontal cortex
- evolutionary the PFC developed among species —> human 1/3 of brain
Anatomy of PFC
- 3 surfaces: lateral, medial & orbital
- lateral surface lies anterior to premotor areas & frontal eye field, implicated in cognitive aspects
of EF, more associated with sensory inputs than orbitofrontal cortex, receives visual, somatosensory & auditory information & receiving inputs from multi-modal regions that integrate across senses (medial & orbital more connected with medial temporal lobe structures critical for long-term memory & processing emotion)
- medial lies between two hemispheres & to front of corpus callous & ACC (conflict detection &
description) more implicated in valuation, emotional/social regulation of behavior
- orbital lies above orbits of eyes & nasal cavity —> related to ventral part of medial surface
(evaluation & reward)
- lateral dorsal: manipulation & ventral:
- rostral PFC: most related to multi-tasking (most evolved part of the brain)
Brodmann´s areas other names possible functions (left hemisphere) possible functions (right hemisphere 45,47, [red] VLPFC retrieval & maintenance of semantic and/or linguistic information retrieval & maintenance of visual and/or spatial information 46, [green] DLPFC selecting possible range of response, & suppressing inappropriate ones; manipulating contents of working memory monitoring & checking of information held in mind, particularly in conditions of uncertainty; vigilance & sustained attention 10 [white] anterior PFC; frontal pole; rostral PFC multi-tasking, maintaining future intentions/goals whilst currently performing other tasks or sub-goals (the medial portion has been implicated in „TOM“) 24 (dorsal), 32 (dorsal) [yellow] ACC (dorsal), Pre-SMA moinitoring in situations of response conflict & error detection 11,12,13, [blue] orbito-frontal cortex executive processing of emotional stimuli (e.g. evaluating rewards & risks)
- interference from previous task („inhibition) —> to do with inhibiting old task than setting up new
one
- greater switch cost when switching from hard to easy
- from first language to a second language
- from word naming to color to naming the Stroop Multi-Tasking
- carrying out several tasks in succession; requires both task switching and maintaining future
goals while current goals are being dealt with
- much worse when trying to do several things simultaneously than focusing on one task because
of losing efficiency
- six element Test: several tasks to do pictures of two decks, mathematical tasks —> have 10min
to do as many tasks as possible, at least one of every kind of task —> coordination and planning is required
- hotel task: as receptionist you have to do several tasks as efficient as possible
- frontal patients are greatly impaired at this tasks, which also reflects differences in fluid
intelligence —> fail often to switch tasks, send too long panning but never execute plans and so on, could easily perform isolated task, but their difficulties ware only apparent when they had to coordinate between them Duncan´s Multiple Demand Network
- set of brain regions in lateral prefrontal and parietal lobes activated by a large range of tasks
relative to baseline
- wide variety of tasks engaging cognitive control engage the same brain network, termed the
Multiple Demand Network
- MDN: L & R lateral PFC (including frontal opercolum/insula), ACC, IPS
- tests of EF & fluid intelligence (e.g. Raven´s matrices) rely on very similar brain regions
- damaging PFC impairs performance on both measures but
NOT crystallized intelligence (e.g. WAIS)
- high overlap in concepts of cognitive control & fluid intelligence
according to cerebral activity
- DMN regions mainly represent task-relevant rules & stimulus
dimensions
- regions of the MDN only represent cue-relevant information
(as instructed at beginning of blocks of of trials) which indicates the high flexibility in the information coded by these control-related regions —> has
been termed „adaptive coding“ (neurons can depending on goal of person represent different things - needs a lot of flexibility)
- how is cognitive control implemented?
task relevant regions show increased activity when information they represent is relevant for task goal; region in LPFC, the inferior frontal junction [control region], synchronizes in a coherent fashion with the task-relevant region (either FFA or PPA) depending on the focus of attention (Neural Mechanisms of Object-Based Attention, Baldaul & Desimone, 2014) Dividing Executive Control?
- emotional (hot) vs. cognitive (cold) control (orbital/ventro-medial vs. lateral PFC)
- left vs. right LPFC (evidence is highly inconclusive)
- posterior & anterior LPFC (the more frontal you go the more complex & abstract „tasks“ are processed)
- control vs. monitoring (ACC vs. LPFC)
1. Emotional (hot) vs. Cognitive (cold) Control Switching Rewards vs. Switching Tasks — Dias et al. (1996)
- test similar to WCST in marmosets (primates)
- compounds of black loved superimposed on blue shapes
- monkeys trained to respond to only one of these dimensions
(shapes or lines) & had to remember which shapes pr line were correct which were rewarded
- neurotoxic lesions to LPFC or OFC
- reverse learning condition: presentation of same stimuli but
such that previously rewarded stimuli were no longer rewarded
- dimensional-shift condition: presentation of new lines & shapes, monkeys
had to learn that lines were now rewarded & not shapes
- OFC lesions: poor reversal learning, disruption of ability to respond to fact
that reward had been switched (but not that relevant cognitive dimension had switched)
- lPFC lesions: poor shifting between dimensions, disruption of ability to
respond to fact that relative cognitive dimension had switched from shapes to lines (but were able to learn that previously rewarded shapes were no longer rewarded)
- evidence due to double dissociation for tow separate inhibitory control
processes: one reward-related & another related to stimulus dimensions The Somatic Marker Hypothesis - Damasio et al.
- proposal that emotional and bodily states associated with previous
behaviors are used to influence decision making a) emotional events (e.g. risky situation) store „somatic markers“ in memory b) somatic markers are believed to be stored in orbitofrontal & ventromedial frontal cortex c) retrieving that event reinstates the somatic marker & this guides behavior (e.g. making a response more or less likely) d) somatic markers may be unconscious or conscious
- Iowa Gambling task: task in which participants must learn to avoid risky choices (generating a
net loss) in favor of less risky (and more rewarding) choices
- before being aware of „rules“, but our system already recognizes and shows reactions
(sweat), system is already anticipating emotional consequences
- patients fail to show anticipatory skin conductance response SCR, but show one in other
circumstances (e.g. after loss)
- double dissociation with working memory deficits and „cold“ tests of EF (following lateral PFC
damage)
