limbic system pt 2

motivational neuroscience

• theories help us describe, explain, and predict behavior

  • (built on) assumptions: ideas that we think are true but cannot definitively be shown to be true or false (can be personal or theory-based)

  • (also built on) propositions (testable hypotheses): "formal statements about causes and effects or the nature of relationships among features of the world"

• neuroscience research can help generate and test hypotheses that inform and guide future development of theories of motivation (and occupation!)

key structures related to motivation

key structures for motivation

• prefrontal cortex (dorsolateral, ventromedial, orbitofrontal)

• anterior cingulate cortex

• striatum (dorsal, ventral)

• ventral tegmental area

• insula

• amygdala

• hypothalamus

• motor areas

• basal nuclei

key structures for motivation

• prefrontal cortex

essential for executive control and planning of motivated behavior

• dorsolateral prefrontal cortex (dlPFC)

  • involved in goal representation and attentional control

  • helps resist temptation in order to meet long-term goals (self-control)

    • e.g., resisting the urge to eat the cake you are making so that you can give it to your friend for their birthday

  • stores emotional memories that are used in decision making

    • e.g., you make this decision ^ by looking back on fond memories of that friendship

• ventromedial prefrontal cortex (vmPFC)

  • helps us assign emotional value to sensory rewards, social cues, and emotional inputs during decision-making

    • involved in making choices

      • e.g., while we may like eating cake, we may assign a higher value to the friendship —> don’t eat the cake

  • plays a role in risk assessment, decision-making, social judgements, and self-control

• orbitofrontal cortex (OFC)

  • stores and processes information about rewards from the environment

  • involved in developing preferences and choosing between options

  • inhibits inappropriate actions (involved with delay of gratification)

• orbitofrontal prefrontal cortex and and ventromedial prefrontal cortex have a similar location, but the ventromedial prefrontal cortex is a bit more medial

key structures for motivation

• anterior cingulate cortex (ACC) - part of the limbic lobe

• 2 regions

  • dorsal ACC:

    • associated with cognition

    • connected with PFC (pre-frontal cortex) and motor areas

  • ventral ACC:

    • associated with emotion

    • connected with the limbic system (amygdala, nucleus accumbens (ventral striatum), hypothalamus, and the anterior insula)

• helps calculate cost-benefit analysis (is the effort worth the reward?) and is activated when we detect conflict and/or errors during problem solving and in new situations

• helps to prioritize attention, make choices, and predict consequences

• uses information from both the cortex AND limbic areas to inform decision making and action selection

key structures for motivation

• insula

involved in intuitive feelings

• 2 regions

  • posterior insula:

    • monitors interoceptive information from the viscera (i.e., feelings from your organs/physiological information about how your body is feeling); can send this information to the anterior insula; creates a body-based “feeling state”

      • e.g., noticing rapid breathing, enticing increased heart rate, noticing sweaty palms

  • anterior insula:

    • integrates information from the posterior insula with contextual information (environment, task, people) to make conscious construction/representation of how we feel- emotional judgements

      • e.g., our gut feelings, like trust, anxiety, empathy

    • creates a global “feeling state” that guides decision-making

key structures for motivation

• amygdala

• receives sensory information from the thalamus and sends emotional information to cortical areas

• lateralization:

  • right amygdala: associated with negative emotions (fear, anger, anxiety), detects and responds to aversive events

  • left amygdala: associated with positive emotions and reward

• creates emotional associations with positive or negative stimuli in the environment

key structures for motivation

• hypothalamus

• regulates biological functions and responds to natural rewards (food)

• regulates the endocrine system (pituitary gland) and the ANS

• produces visceral responses to + physiological expression of emotions

  • e.g., racing heart rate, sweaty palms, trembling

    —> this information can be used to guide motivations

key structures for motivation

• ventral tegmental area (VTA)

• midbrain region that produces dopamine (involved in motivation/rewards)

• forms the beginning of the mesocorticolimbic pathways

  • —> sends dopaminergic projections to the prefrontal cortex and structures of the limbic system

• dopamine release based on reward anticipation and is greatest when rewards are unexpected

  • strongly involved in reward pathways, which helps to guide our motivated behaviors

key structures for motivation

• motor areas

motor areas of the brain are important for planning and executing motivated behavior

• premotor cortex and supplementary motor area: motor planning!

  • creates a smooth, coordinated action plan to be able to carry out goal-directed actions

• primary motor cortex: initiates movement execution

  • encodes movement parameters (force, direction, distance, speed)

key structures for motivation

• basal nuclei

  • striatal complex

  • pallidal complex

striatal complex

• ventral striatum (nucleus accumbens)

  • pleasure center of the brain

  • activated by things we like, want, value, prefer, and enjoy

  • receives dopaminergic input from the VTA – mesolimbic pathway

  • sends projections to the ventral pallidum

• neostriatum or dorsal striatum (caudate nucleus, putamen)

  • input zone: pays an important role in selection of behavior based on value of goals

  • receives dopaminergic input from substantia nigra (pars compacta) – nigrostriatal pathway

pallidal complex

• ventral pallidum (substantia innominata)

  • receives input from the ventral striatum and other reward-related areas

  • helps translate reward-related motivation signals from the limbic system into motor output

• globus pallidus

  • output zone: energizes or inhibits action plans; informs motor output

== basai nuclei are very important for both motor output and the reward system

key pathways for motivation

• mesocorticolimbic pathway

• orbitofrontal-striatal circuit

• ventromedial prefrontal-amygdala pathway

• anterior insula-anterior cingulate cortex circuit

key pathways for motivation

• mesocorticolimbic pathway

• mesolimbic projections: VTA sends dopaminergic projections —> to the nucleus accumbens, amygdala, hippocampus

  • this dopamine pathway is involved in appraising the amount of reward a stimulus provides

• mesocortical projections: VTA sends dopaminergic projections —> to the PFC (orbitofrontal cortex)

  • this dopamine pathway helps to brings awareness to stimuli that produced past rewards and promotes goal-directed behaviors to seek out rewarding stimuli

key pathways for motivation

• orbitofrontal-striatal circuit

• circuit between the PFC (orbitofrontal cortex and dorsolateral PFC) and the ventral striatum (nucleus accumbens)

  • activation of the nucleus accumbens (associated with the reward system) increases focus on obtaining immediate rewards

  • the orbitofrontal cortex and dorsolateral PFC help to inhibit this ^ immediate gratification in order to achieve long term goals

• helps with choice of large delayed reward over small immediate reward

• delayed gratification

key pathways for motivation

• ventromedial prefrontal-amygdala pathway

• important for value-based decision-making and reward processing

• ventromedial prefrontal cortex (vmPFC) can suppress fear responses from the amygdala when it’s activated

  • pathway implicated in PTSD, where fear responses from the amygdala become overactivated and the vmPFC does not adequately inhibit these responses

• receiving feedback about failure may decrease vmPFC activation; however, making choices based on one’s preferences during a task can help maintain vmPFC activation, even when receiving failure feedback, leading to improved performance

key pathways for motivation

• anterior insula-anterior cingulate cortex circuit

• awareness of intuitive emotions (from the anterior insula) is used to make decisions about actions based on anticipated consequences (anterior cingulate cortex)

  • e.g., when you’re looking for a business partner, you’d rather pick someone you perceive as trustworthy than someone you perceive as sketchy

neural basis of key motivations

• homeostatic motivational processes

• homeostatic motivational processes (hunger, thirst)

  • involve a connection between the hypothalamus and the mesocorticolimbic pathway (i.e., the reward pathway)

  • both the orbitofrontal cortex and amygdala respond to rewards associated with fluid intake, activating the striatum (i.e., the dopaminergic reward system)

    • e.g., the enjoyment you feel when drinking a hot cup of tea on a cold day

neural basis of key motivations

• learned motivational states

• learned motivational states

  • incentives, reward

    • incentives: the amygdala evaluates if stimuli are associated with reward or punishment; memories are stored in the hippocampus, insula, and orbitofrontal cortex

      • incentive value is conveyed by the mesolimbic system to initiate action (to obtain the incentive!)

    • rewards: activation of dopaminergic pathways

neural basis of key motivations

• person-generated motivational states

• person-generated motivational states

  • volition

  • self-regulation/ goals

  • intrinsic vs. extrinsic motivation

  • psychological needs

  • autonomous self-regulation

relationships between the structures involved in motivated action

• e.g., saw a chocolate cake and wanted to eat it

  • hypothalamus= indicates I am hungry

  • insula= communicates the feeling of hunger + positive feelings towards chocolate cake

  • ventral tegmental area= dopaminergic response is activated

  • —> communicates to the nucleus accumbens + amygdala (which is associated with rewards)

  • —> also communicates with the prefrontal cortex, which considers the value of the cupcake + but also may consider the reasons I should not eat the cupcake

    • e.g., am i on a diet? am i going to eat dinner soon? is it someone else’s cupcake?

  • anterior cingulate cortex= helps to navigate this conflict ^ to come up with a decision

  • motor system= is activated when we decide to eat the cupcake, enabling us to pick up and eat the cupcake

volition is a big part of the Model of Human Occupation and contributes to our ability to engage in meaningful occupations

volition

• mental control over action, or an ongoing effort to sustain motivated action

• model of human occupation:

  • making choices and decisions about what to do (choosing occupations)

  • anticipating options, choosing what to do, doing it, experiencing one's actions, interpreting that experience

• the anterior cingulate cortex is involved in exerting mental control and problem solving

• premotor and supplementary motor areas are activated in preparation for volitional actions

self-regulation/goals

• goal-setting and planning are key for occupational engagement

• the prefrontal cortex generates goals and intentions —> and then carries out the plans needed to meet our goals

• dorsolateral prefrontal cortex is involved in pursuing long term goals

  • this area allows us to maintain cognitive control, so that we can stay on task and persist in our goals

• anterior cingulate cortex is also involved in monitoring conflict, integrating our emotions, and making decisions about changing course of action

  • helps us adapt and make adjustments when things don’t go as planned

intrinsic vs. extrinsic motivation

• intrinsic motivation (interest, enjoyment):

  • “doing a behavior because the activity itself is interesting and spontaneously satisfying... positive feelings result from the activity itself”

  • anterior insula is activated by intrinsic rewards; may modulate the formation of rewarding memories through activation of the VTA!

    • anterior insula is involved in constructing how we feel

      • this relates to the positive emotions that we feel when we engage in something we enjoy doing

• extrinsic motivation (incentive motivation):

  • engaging in a behavior because it leads to some separate consequence, like gaining a reward or avoiding a punishment

  • associated with the dopaminergic reward system and the orbitofrontal-striatal circuit

  • anterior cingulate cortex helps determine if the reward is worth the effort needed to obtain it!

• providing extrinsic rewards can decrease intrinsic motivation!

  • once the external reward is drawn, it is less likely we’d want to continue the activity

intrinsic motivation

• intrinsic motivation increases positive affect, cognitive flexibility, and creativity, which are all supported by the dopamine system

• 2 types of dopaminergic neurons in VTA and substantial nigra (SN)

  • value-coding dopaminergic neurons: stimulated by reward and inhibited by punishment (rewards, feedback, learning, success)

    • stimulated by external rewards, but can also be activated by feedback about our success or failure on a given task; we learn from these experiences, and our future engagement is informed by them

      • unexpected success —> activated dopamine response

      • unexpected failure —> inhibited dopamine response

  • salience-coding dopaminergic neurons: activated by curiosity and interest in the environment or task (related to intrinsic motivation); curiosity has been associated with activation of the left VTA/SN and bilateral striata (including nucleus accumbens, caudate nucleus, putamen)

    • you must find a good balance of something interesting + challenging- but not too difficult- in order to learn best

• intrinsic motivation improves learning outcomes, by stimulating the dopamine system and is involved in self-directed learning

basic psychological needs

• self-determination theory assumptions

• 3 basic psychological needs support intrinsic motivation

• anterior insula and the rewards system are involved

• self-determination theory assumptions

  • people are naturally curious and motivated to explore their environments and succeed, which can either be supported or impeded by social environments

• 3 basic psychological needs support intrinsic motivation

  • competence: feeling effective in one’s ability to develop mastery in activities that are optimally challenging and that further develop one’s capacities; confidence in abilities and capacity to achieve goals

    • support perceptions of competence by providing feedback about success + making sure the task is the right level of challenge (where success is possible)

  • autonomy: exercising choice in one's behavior out of their own volition/will; "an experience of volition and integrity, the sense that one’s behavior is authentic and self-organized, rather than internally conflicted and pressured or externally coerced"

    • studying because you value the information vs studying to get a good grade, or to avoid embarrassment

  • relatedness: feeling connected with others and having satisfying social relationships improves intrinsic motivation

• anterior insula (relates to how we feel about ourselves within our environment) and the rewards system are both activated when our basic psychological needs are met

autonomous self-regulation

• volitional decision-making (making personal choices) that are based on one’s sense of autonomy activates the ventromedial prefrontal cortex (vmPFC)

  • can help resolve internal conflicts identified by the anterior cingulate cortex

• vmPFC interacts with both the ventral striatum and amygdala during value-based decision making

  • co-activated with the ventral striatum during rewarding decisions

  • suppresses fear response from amygdala

    • having a sense of control can help extinguish fear and anxiety generated by the amygdala

• making self-determined choices when engaging in a task can increase resilience when receiving feedback about failure, thereby improving performance

  • vmPFC activation may reduce stress responses from the brainstem and reduce cortisol levels, increasing active coping

    • failure is a natural part of learning; making mistakes is essential for growth and improvement! —> achievement of goals

motivation and motor learning

OPTIMAL Theory: “optimizing performance through intrinsic motivation and attention for learning”: i.e., supporting intrinsic motivation can improve motor learning

• motor learning influenced by:

  • autonomy (active participation in determining one’s behavior)

  • enhanced expectancies for future success (increase in perceived competence)

  • external focus of attention (concentration on the movement's intended effect)

• response of dopamine to the anticipation of positive experience leads to improved performance

• expected success leads to further success and aids memory consolidation

• dopamine from the VTA promotes neuroplasticity in the primary motor cortex leading to —> new motor learning, formation of new motor memories

limbic system and the *vagus nerve

• the vagus nerve appears to connect to limbic system structures via the solitary nucleus

  • the solitary nucleus sends direct projections to the amygdala and appears to mediates emotional responses to respiration

• amygdala is implicated in stress-related disorders, including PTSD

  • overactivity in the amygdala can occur after exposure to traumatic stress

  • —> stress can lead to maladaptive breathing patterns (hyperventilation), which can —> further induce anxiety and panic

  • decreased vmPFC control over the amygdala, leading to overactive fear responses

  • hippocampal functioning is also impaired, which may lead to re-experiencing of trauma-related symptoms

• vagus nerve stimulation is a treatment for chronic depression and PTSD

  • electrical stimulation of the vagus nerve appears to alter cortical and subcortical brain regions such as the amygdala and hippocampus (although the mechanisms are unclear)

  • shown to reduce symptoms of depression and anxiety

  • may inhibit the sympathetic nervous system, reducing “fight or flight” responses, which may explain the reduction of ^ depression and anxiety symptoms

• mind-body interventions are also thought to increase parasympathetic tone
  through activation of the vagus nerve, leading to reduced stress

  • slow breathing with long exhalation, yoga, mindfulness-based stress reduction techniques

  • benefits are associated with connections between the autonomic nervous system and the limbic system (amygdala, hippocampus, PFC)

  • increased PFC activation is associated with increased parasympathetic activity (which may improve inhibitory control over the amygdala)

  • however, much is still unknown!

• therapeutic breathing techniques and mind-body interventions can help reduce stress and anxiety through connections between the autonomic nervous system (vagus nerve) and the limbic system

*vagus nerve= part of the parasympathetic division of the autonomic nervous system; related to our ability to manage stress and anxiety