Mapping Connections

Mappings are the neural connections between cortical areas. They define how information flows through your genome, using connectivity rules to specify the exact wiring patterns.

What is a Mapping?

A mapping is a connection from one cortical area (source) to another (destination) that:

• Uses a connectivity rule to define connection structure
• Creates synapses between neurons
• Allows information flow during processing
• Can learn and adapt based on activity

Without mappings, cortical areas are isolated - mappings make them into an integrated neural network.

Mapping Components

Each mapping consists of:

Source and Destination

• Source (Afferent): The cortical area sending signals
• Destination (Efferent): The cortical area receiving signals
• Direction matters (A→B is different from B→A)

Connectivity Rule

• Defines which neurons connect to which
• Determines connection density and pattern
• Can be shared across multiple mappings

See [Connectivity Rules](connectivity rules.md) for details.

Parameters

• Postsynaptic Current: Strength of influence
• Plasticity: Whether connections learn
• Learning Rate: Speed of adaptation
• Weight Limits: Min/max connection strengths

Creating Mappings

Method 1: Drag in Circuit Builder

The most intuitive method:

1. Open Circuit Builder
2. Click and hold on output port (right side) of source area
3. Drag to input port (left side) of destination area
4. Release to open Mapping Editor
5. Configure connectivity rule and parameters
6. Click Create or Apply

Method 2: Quick Connect

From context menu:

1. Right-click source cortical area
2. Select Quick Connect
3. Choose destination from list
4. Mapping Editor opens
5. Configure and create

Method 3: Create Multiple

Connect one area to many:

1. Right-click source area
2. Select Quick Connect
3. Check multiple destinations
4. Set common connectivity rule
5. Create all mappings at once

Method 4: Bidirectional

Create two-way connection:

1. Create mapping A → B
2. Create mapping B → A
3. Or use bidirectional option if available
4. Each direction can use different connectivity rule

Mapping Editor

The Mapping Editor is your detailed interface for configuring connections.

Editor Sections

Header:

• Source area name and type
• Destination area name and type
• Direction indicator (→)

Connectivity Rule Selection:

• Dropdown of existing connectivity rules
• Preview of selected connectivity rule
• Button to create new connectivity rule

Parameters:

• Postsynaptic current
• Plasticity settings
• Learning parameters
• Weight configuration

Statistics:

• Estimated synapse count
• Connection density
• Memory usage estimate

Actions:

• Apply/Create button
• Cancel button
• Advanced options

Selecting Connectivity Rule

Use Existing:

1. Click connectivity rule dropdown
2. Browse available connectivity rules
3. Select appropriate pattern
4. Preview updates

Create New:

1. Click + New Connectivity Rule
2. Configure connectivity rule type and parameters
3. Name the connectivity rule
4. It becomes available in the list

Configuring Parameters

Postsynaptic Current (PSC):

• Strength of synaptic influence
• Higher values = stronger effect
• Can be positive (excitatory) or negative (inhibitory)
• Typical range: 0.1 to 10.0

Plasticity:

• Enabled: Connections strengthen/weaken based on activity
• Disabled: Fixed connection weights
• Enable for learning applications

Learning Rate:

• Speed of synaptic adaptation
• Higher = faster learning
• Too high = instability
• Typical range: 0.001 to 0.1

Weight Limits:

• Min Weight: Minimum synaptic strength
• Max Weight: Maximum synaptic strength
• Prevents runaway growth or decay

Creating the Mapping

Once configured:

1. Review parameters
2. Check synapse count estimate
3. Click Create or Apply
4. Mapping is created in FEAGI
5. Connection line appears in Circuit Builder
6. Connection is active in Brain Monitor

Viewing Existing Mappings

In Circuit Builder

Mappings appear as lines between cortical areas:

• Line Style: Indicates connection type
• Line Color: May indicate properties
• Arrows: Show direction of information flow

Click a line to view/edit its properties.

In Brain Monitor

Hover over cortical area to see:

• Outgoing connections (from this area)
• Incoming connections (to this area)
• Active data flow (if neuron activity present)

Connection Lines:

• Highlight when hovering
• Show direction with arrows or flow
• Intensity indicates activity level

Via Context Menu

Right-click cortical area:

1. Select Details
2. Navigate to Connections tab
3. View lists:
   • Afferent (incoming): Areas sending to this one
   • Efferent (outgoing): Areas this one sends to
   • Recursive: Connections to itself
4. Click connection to edit

Editing Mappings

Modifying Parameters

1. Click connection line in Circuit Builder OR
2. Right-click area → Details → Connections tab
3. Click mapping to edit
4. Mapping Editor opens
5. Modify parameters
6. Click Apply

Changes take effect immediately.

Changing Connectivity Rule

1. Open mapping in Mapping Editor
2. Select different connectivity rule from dropdown
3. Connection pattern updates
4. Synapse count may change
5. Click Apply

Caution: Major connectivity rule changes may dramatically alter behavior.

Copying Mappings

To replicate a mapping configuration:

1. Note the connectivity rule and parameters
2. Create new mapping
3. Apply same settings
4. Or use batch creation for efficiency

Deleting Mappings

Single Mapping

1. Click connection line in Circuit Builder
2. Press Delete key OR
3. Right-click line → Delete
4. Confirm deletion

OR

1. Right-click cortical area → Details
2. Go to Connections tab
3. Find mapping in list
4. Click Delete button
5. Confirm

Multiple Mappings

To delete all connections:

1. Select cortical area
2. Right-click → Reset (clears state but keeps connections)
3. OR manually delete each mapping

On Area Deletion

When deleting a cortical area:

• All mappings to/from it are automatically deleted
• You'll see a confirmation showing affected mappings
• This cannot be undone

Connection Patterns

Feedforward (Input → Processing → Output)

Typical flow:

IPU (Vision) → Custom (Edge Detection) → Custom (Object Recognition) → OPU (Action)

Best Practices:

• Use appropriate connectivity rules for each stage
• All-to-All for mixing and integration
• One-to-One for spatial preservation

Feedback (Higher → Lower)

Top-down modulation:

Memory (Context) → Custom (Visual Processing)

Use Cases:

• Attention and gating
• Expectations and predictions
• Context-dependent processing

Lateral (Within Layer)

Same-level integration:

Custom (Left Visual Field) ↔ Custom (Right Visual Field)

Use Cases:

• Information sharing
• Lateral inhibition
• Continuous representations

Recursive (Area to Itself)

Temporal processing:

Memory (Short Term) → Memory (Short Term)

Use Cases:

• Holding state over time
• Temporal integration
• Working memory

Multiple Mappings

You can create multiple mappings between the same two areas:

Why Multiple Mappings?

• Different connectivity rules for different purposes
• Excitatory and inhibitory connections
• Different learning rates
• Parallel pathways

Managing Multiple:

• Each mapping is independent
• Synaptic effects combine
• Can have different parameters
• Visualized as separate lines (or combined)

Mapping Direction

Direction is critical:

A → B:

• Neurons in A send to neurons in B
• Activity in A influences B
• Information flows A to B

B → A:

• Separate mapping (does NOT exist automatically)
• Must be created explicitly
• Can have different connectivity rule and parameters

Bidirectional:

• Create both A → B and B → A
• Allows information to flow both ways
• Each direction is independent

Connection Debugging

No Activity Flowing

If expected activity doesn't appear:

1. Verify Connection Exists: Check Circuit Builder for line
2. Check Source Activity: Ensure source area is active
3. Check Connectivity Rule: Verify appropriate pattern
4. Check PSC: Ensure postsynaptic current is not too weak
5. Check Path: Trace from inputs through all connections

Unexpected Behavior

If area behaves unexpectedly:

1. Review Connections: Check all afferent mappings
2. Check Connectivity Rules: Verify connection patterns
3. Check Parameters: Look for unusual PSC or learning rates
4. Check for Loops: Recursive or feedback loops can cause issues
5. Isolate: Temporarily remove connections to identify culprit

Performance Issues

If too many connections slow the system:

1. Reduce Density: Use sparser connectivity rules
2. Limit Connections: Set max connections per neuron
3. Remove Unused: Delete unnecessary mappings
4. Optimize Connectivity Rules: Use efficient patterns

Advanced Mapping Techniques

Gating

Use one area to control another:

Context Area (modulation) → Processing Area (modulated)

Low PSC or conditional connections act as gates.

Ensembles

Connect multiple areas to one target for voting/integration:

Evidence A → Decision
Evidence B → Decision
Evidence C → Decision

Hierarchical

Build processing hierarchies:

Low-Level Features → Mid-Level Features → High-Level Features

Attentional

Use feedback to enhance relevant processing:

Task Area (what to attend) → Sensory Area (what's attended)

Synapse Budget

Mappings consume synapses:

• Check current vs max synapse count in top toolbar
• All-to-All mappings use the most
• Sparse patterns conserve synapses
• Plan ahead for large genomes

Estimating Synapse Count:

• Small areas, All-to-All: (M × N) synapses
• Large areas, sparse: Much fewer
• Mapping Editor shows estimate

Best Practices

Start Simple

1. Create minimal connections first
2. Test functionality
3. Add complexity incrementally
4. Verify each addition

Use Appropriate Connectivity Rules

• One-to-One: Spatial tasks
• All-to-All: Integration and mixing
• Lateral: Context and smoothing
• Sparse: Efficiency

Name and Document

• Use meaningful cortical area names
• Document connection purposes
• Note unusual parameter choices
• Explain design decisions

Test Incrementally

• Create one mapping at a time
• Verify expected behavior
• Check activity flow
• Then add next connection

Monitor Performance

• Watch synapse count
• Check processing speed
• Optimize as needed
• Remove unnecessary connections

Common Workflows

Creating a Simple Circuit

1. Create Input (IPU) cortical area
2. Create Processing (Custom) area
3. Create Output (OPU) area
4. Connect IPU → Custom with All-to-All
5. Connect Custom → OPU with All-to-All
6. Test with data

Building a Vision Pipeline

1. Vision IPU (camera input)
2. Edge Detection Custom (lateral connectivity rule)
3. Feature Extraction Custom (All-to-All)
4. Object Recognition Custom (All-to-All)
5. Motor Control OPU (One-to-One or All-to-All)

Adding Memory

1. Existing circuit: Input → Processing → Output
2. Create Memory area
3. Connect Processing → Memory (storage)
4. Connect Memory → Processing (recall)
5. Adjust parameters for learning

Troubleshooting

"Can't create mapping"

• Verify both areas exist
• Check you're dragging to input port
• Ensure areas are in same FEAGI instance
• Try Quick Connect instead

"Synapse count exceeds limit"

• Use sparser connectivity rule
• Reduce cortical area dimensions
• Limit connections per neuron
• Increase genome synapse limit (if possible)

"Activity not propagating"

• Check connection exists and direction is correct
• Verify source area is active
• Check PSC is not too small
• Look for blocking connections (inhibitory)

"Mapping line disappeared"

• May be hidden (check visualization settings)
• Might have been deleted accidentally
• Verify in cortical area Details → Connections

"Too many connections are confusing"

• Use Split View to focus on sub-circuits
• Hover to highlight specific connections
• Hide global connections toggle
• Work on one region at a time

Related Topics

• [Connectivity Rules](connectivity rules.md) - Connection structure templates
• Cortical Areas - What gets connected
• Circuit Builder - Visual connection creation
• Brain Monitor - Visualizing active connections
• Quick Menu - Quick Connect operations

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