Obsessive Compulsive Disorder

action selection, energization

deciding what is worth doing

reinforcement learning

doing something based on what has worked before

where do dopamine cells tend to live?

midbrain

input nucleus

striatum

output nucleus

SNr

obsessions

recurrent and persistent thoughts, urges

compulsions

repetitive behaviors or mental acts

disorder

time-consuming or clinically significant distress or functional impairment

cortico-basal ganglia circuit

connects cortex with basal ganglia and thalamus with cortex; is refined by rewards

locus of arbitration

cortico-basal ganglia circuit

process in cortico-basal ganglia circuit

proposal → vote → accept/reject

what refines arbitration?

rewards

which neurotransmitter controls 100% of plasticity in the striatum?

dopamine

flexible behaviors

meet demands of a changing world, learn how world changes, perform/execute knowledge one has about world

key roles of cortico-basal-ganglia

reward learning, decision making, movement, motivation/effort, executive functions, working memory, cognitive effort/focus

disorders cortico-basal-ganglia is implicated in

addiction, gambling, binge-eating, Parkinson’s, depression, schizophrenia, bipolar disorders, OCD, ADHD

when does the cortico-basal-ganglia flag and use a corrective action?

catching errors online or learning from errors

hierarchy

circuits identify errors in elementary circuits

procedural memory examples

baking, biking

obsession role in cortico-basal-ganglia

error detection mechanism, flag

compulsion role in cortico-basal-ganglia

error resolution mechanism, corrective action

caudal (direction)

forward

medial (direction)

middle

dorsal (direction)

up

lateral (direction)

away from middle

brain regions are implicated in OCD

dorsal-lateral prefrontal cortex, orbito frontal cortex, anterior cingulate cortex (all in a loop with cortico-basal ganglia), and caudate (dorsal-medial-striatum; deep brain structure that receives inputs from cortical areas)

dorsal-lateral prefrontal cortex (DLPFC) roles

domain-general executive control, operator or planner/schedule, planning, task-switching, task-set reconfiguration, inhibitory control, working memory regulation and load management

how does the dorsal-lateral prefrontal cortex (DLPFC) perform its roles?

tracks sequence “order” and “hierarchy” of events, tracks progress in this order/hierarchy

orbito frontal cortex (OFC) roles

rule book, stores causal structures of task space, cognitive map of ‘what if’ trajectories (rules), helps refine ‘plans’ of what to do next

how does the orbito frontal cortex (OFC) perform its roles?

learns transition probability of world, especially when conditioned on my actions

anterior cingulate cortex (ACC) roles

error detector, conflict/error monitoring, compare what happened w/ plan, affects motivation to perform/continue plan, strong coupling w/ amygdala (anxiety) and ventral striatum (motivation to correct behavior)

how does the anterior cingulate cortex (ACC) perform its roles?

computes ‘expected value of control (EVC)’, forecasts what plan achieves (rewards?) and costs of plans

caudate (dorsal-medial-striatum) roles

integrator, stores casual associations (a→b→c etc.), stores agency (how do I affect the world?), ‘procedural’ memory

how does the caudate (dorsal-medial-striatum) perform its roles?

arbitrates cortical proposal related to its roles, sequences plans to pursue goals (goal directed behaviors)

how do genome wide association studies (GWAS) find any patterns of variation in genes that could explain OCD diagnosis or traits?

assess heritable single nucleotide polymorphisms (SNPs; change in gene locations)

which neurotransmitters are associated with variations in genes related to OCD?

serotonin, dopamine, glutamate

how is optogenetic stimulation of lateral orbito fronto striatal pathway used to treat OCD?

suppresses compulsive behaviors

role of selective serotonin reuptake inhibitors (SSRIs) in treating OCD

increases serotonin levels, takes weeks for therapeutic function, unknown mechanism of action but many guesses

Brain Locked-Unlocked method of treating OCD

cognitive behavioral therapy with two steps

1. relabel the problem (there is a problem, but that is my OCD)

2. refocus the problem (do something else rewarding)

how is exposure used to treat OCD?

immerse person in fear to create response prevention

transcranial magnetic stimulation (TMS)

a method to affect electrical activity in the brain using alternating electro-magnetic fields

deep brain stimulation (DBS)

a method to affect electrical activity in the brain using implanted electrodes and programmed stimulator