How can the dorsolateral prefrontal cortex (DLPFC), hippocampus, and other parts of the brain be activated through good design?

Activating the Dorsolateral Prefrontal Cortex, Hippocampus, and Other Brain Regions Through Design

Specific cognitive tasks and non-invasive brain stimulation techniques are the most effective methods to activate the dorsolateral prefrontal cortex (DLPFC), hippocampus, and other brain regions, with task-specific designs targeting executive functions showing the strongest evidence for DLPFC activation and spatial memory tasks for hippocampal engagement.

Brain Region Activation Through Cognitive Tasks

Dorsolateral Prefrontal Cortex (DLPFC) Activation

The DLPFC can be specifically activated through:

• Working memory tasks - The DLPFC shows selective activation during tasks requiring active maintenance and manipulation of information 1

  • N-back tasks (particularly two-back condition) strongly engage bilateral DLPFC (BA 46/9) 1
  • Tasks requiring manipulation of verbal and spatial knowledge, with left DLPFC necessary for manipulating information in working memory 2
  • Right DLPFC critical for manipulating information in broader reasoning contexts 2

• Sequence learning with spatial components - The DLPFC plays a critical role in sequence learning specifically related to spatial cues 3

  • Spatial working memory tasks engage DLPFC more effectively than non-spatial tasks 3
  • Position-based sequence learning tasks activate DLPFC more than color-based tasks 3

Hippocampal Activation

The hippocampus can be activated through:

• Category and letter fluency tasks - These engage hippocampal regions, particularly during memory retrieval 4

  • Animal Naming (category fluency) engages hippocampal networks 4
  • Letter fluency tasks (phonemic fluency) engage different but complementary networks 4

• Strategic learning tasks - The Hopkins Verbal Learning Test (HVLT-R) can provide measures of strategic learning that engage hippocampal regions 4

• Visuospatial tasks - The Rey-Osterreith Complex Figure copy and memory conditions activate visuospatial networks including hippocampal regions 4

Non-Invasive Brain Stimulation Techniques

Transcranial Direct Current Stimulation (tDCS)

tDCS can effectively activate the DLPFC with these parameters:

• Current intensity - 2 mA is the most frequently used and effective intensity 4

• Duration - 20 minutes or less is standard in 88% of trials 4

• Electrode placement for DLPFC targeting 4:

  • Anodal tDCS over left DLPFC with cathode on right supraorbital area
  • Anodal tDCS over right DLPFC with cathode on left DLPFC
  • Bilateral DLPFC stimulation

• Effects on cognition 5:

  • After single-session anodal tDCS (a-tDCS), participants respond faster and more accurately on cognitive tasks
  • Healthy subjects respond faster, while neuropsychiatric patients respond more accurately
  • Increasing current density and density charge results in improved accuracy, especially in females

Repetitive Transcranial Magnetic Stimulation (rTMS)

rTMS can effectively target the DLPFC with these parameters:

• Frequency - 10 Hz (49% of studies) or 20 Hz (24% of studies) are most effective 4
• Number of pulses - 2000 or fewer pulses per session in 82% of studies 4
• Target locations 4:
  • Left DLPFC is the most frequent anatomical target
  • Right DLPFC is the second most common target
  • Bilateral DLPFC stimulation is also effective

Design Elements That Engage Multiple Brain Regions

Task Design Principles

• Combine spatial and verbal components - Tasks that require both spatial processing and verbal manipulation engage multiple brain regions simultaneously 2, 3
• Include strategic learning elements - Tasks requiring strategic organization of information engage both DLPFC and hippocampal networks 4
• Incorporate executive function challenges - Tasks requiring response inhibition, set shifting, and planning engage frontostriatal networks 4

Environmental Design Considerations

• Spatial navigation elements - Designs requiring spatial navigation and memory engage hippocampal networks 4
• Goal-directed problem solving - Complex problem-solving tasks that involve managing multiple goals activate DLPFC 6
• Subgoal generation - Tasks requiring internally generated subgoals that modulate competition among posterior representations engage DLPFC 6

Clinical Applications and Considerations

• Therapeutic applications - Brain stimulation techniques targeting the DLPFC show promise for treating conditions like obsessive-compulsive disorder (OCD) 4

  • rTMS targeting the medial prefrontal cortex and anterior cingulate cortex with tailored symptom provocation can be effective 4
  • Deep rTMS has been approved by the FDA for OCD treatment 4

• Substance use disorders - Targeting the mesolimbic dopamine pathway through DLPFC stimulation may help address addiction 7

  • The DLPFC is involved in self-regulation and control, which are impaired in substance use disorders 7
  • Repeated drug exposure disrupts dopamine-modulated striatocortical pathways, impairing prefrontal cortical function 7

• Cognitive enhancement - DLPFC stimulation may improve cognitive performance in both healthy individuals and those with neuropsychiatric conditions 5

  • Task performance during a-tDCS results in stronger increases in accuracy rates compared to task performance following a-tDCS in neuropsychiatric patients 5

Practical Implementation

1. For cognitive tasks:

   • Implement working memory tasks (N-back)
   • Include spatial sequence learning components
   • Incorporate strategic learning elements
   • Design goal-directed problem solving with subgoal generation

2. For non-invasive brain stimulation:

   • Use anodal tDCS at 2 mA for 20 minutes targeting DLPFC
   • Apply high-frequency rTMS (10-20 Hz) to DLPFC
   • Consider bilateral stimulation for broader network effects

3. For environmental design:

   • Create spaces requiring spatial navigation
   • Incorporate elements requiring executive function
   • Design environments that challenge working memory and strategic planning

By implementing these evidence-based approaches, designers can create experiences and environments that effectively engage the DLPFC, hippocampus, and other key brain regions.