PSYC327: Motivation and Resource Allocation

The Prefrontal Cortex (PFC)

Frontal lobes, excluding primary and secondary motor cortex

- All regions: goal-driven, internally directed behaviour

Dorsomedial PFC

Dorsal portion of anterior cingulate cortex (dACC) + surrounding medial PFC regions

These regions work closely together, but most research focuses on the dACC

Dorsal Portion of Anterior Cingulate Cortex (dACC)

Dorsal anterior cingulate strongly activated whenever a task gets difficult and it seems to be activated before the lateral PFC

EEG Evidence of dACC in Planning

Dorsal Anterior Cingulate is active just after a person makes an error

- Electrical signal in dorsal Anterior Cingulate occurs 100ms after a mistake

Conflict Monitoring Hypothesis (Botvinick et al., 2004)

When seeing the word, activate mental representation of both possibilities (congruent and incongruent). There's always competition between the habitual world and the correct choice. This conflict involves the Lateral PFC & ACC

Conflict Monitoring Hypothesis: Lateral PFC

Competition between words is monitored by the Lateral PFC

Conflict Monitoring Hypothesis: ACC

ACC keeps an eye on task performance and the level of competition to redirect more energy to lateral PFC

- High conflict or errors = signals back to Lateral PFC to try harder and provide more resources

- Answer correct = ACC not activated

Detects possible conflict based on:

- Internal cues (competition)

- External feedback (errors)

Conflict Monitoring Hypothesis (Botvinick et al., 2004): Limitations

People with damage the anterior cingulate:

- don't make lots of errors on Stroop task

- when they do, they slow down to improve accuracy

- Don't have spontaneous activity or behaviour

Effects of Damage to dACC/Surrounding PFC

- Apathy: lack of interest, enthusiasm, or concern Lack of intuition

- Aboulia: more marked apathy, person initiates speech/actions only when prompted

- Akinetic Mutism: by a lack of voluntary/self-directed movement and speech, despite the patient appearing awake and having a preserved level of consciousness, vision, and comprehension

Measuring Damage to dACC

- Cingulotomy

- Poor performance on ALL tasks with some generative component (sensitive measure), Letter (phonemic), or Alternate uses task

- The NPI Apathy scale

- Degenerative disease

Measuring Damage to dACC: Degenerative Disease

medial surface of the frontal lobe and dACC regions with low grey matter volume predicts high scores on the NPI apathy scale

Measuring Damage to dACC: Cingulotomy

involves creating targeted lesions in the brain's cingulate gyrus

Critchley et al. (2003): ACC's Role

Measured peoples blood pressure and rate during a hard task

- Healthy people → change in heart rate, blood pressure just before a challenging task

- ACC damage: → little or no change in heart rate/blood pressure Suggests a lack of autonomic arousal for hard tasks

Suggests the ACC's role is to communicate with both lateral PFC and the autonomic nervous system to maximise performance and allocate resources according to values and priorities

Resource Allocation Theory (Koechlin et al. 2021)

ACC/dmPFC monitor two factors:

- Level of difficulty

- Value of succeeding

It signals and allocates effort according to the outcome and these two factors and we need it to change from a current behaviour to a different one