Brain-Inspired Cognitive Architectures
Working Memory + Attention

Prefrontal cortex working memory: maintain task-relevant information during multi-step reasoning. Claude Opus 4.1's 200K context holds intermediate results, hypotheses, constraints—like dorsolateral prefrontal cortex maintaining problem state across delays.

Sonnet 4.5's 1M context enables even larger working memory capacity: entire project context, API documentation, previous analysis results—all accessible during reasoning. No external memory store needed for medium-scale problems (unlike traditional RAG which fragments working memory).

For persistent long-term memory: hybrid architecture with vector databases (episodic memory), Claude's training (semantic memory), and context window (working memory). Mirrors hippocampal consolidation: working memory → hippocampus → neocortex storage.

Real deployment: debugging session keeping track of 15+ hypotheses, 40 code files, stack traces, variable states—Opus 4.1 maintained coherent investigation across 2-hour session without losing thread. Human-like sustained attention.

Parietal cortex attention: selective focus on task-relevant information. Claude's attention layers (transformer architecture) mirror top-down attention—prefrontal goals modulate sensory processing. In practice: prompt engineering directs attention ("focus on error handling", "ignore deprecated APIs").

Sustained attention for long documents: Sonnet 4.5's 1M context with attention optimization maintains focus across entire codebases. Like reading a novel—maintaining plot threads, character relationships, foreshadowing. No attentional blink for massive contexts.

Executive function reasoning loops: hypothesis → test → evaluate → refine. Claude Opus 4.1 excels at iterative reasoning: generate explanation → check against evidence → revise hypothesis → conclude. Mirrors scientific reasoning—Bayesian updating with evidence accumulation.

Claude Opus 4.1 (August 2025, 200K context): best for complex reasoning, multi-step problem-solving, nuanced analysis. Use when task requires deep thinking—architectural design, debugging complex systems, evaluating tradeoffs. Slower but more thorough than Sonnet. Like System 2 thinking (slow, deliberate, analytical).

Claude Sonnet 4.5 (September 2025, 1M context): best for orchestration, code generation, high-throughput reasoning. Faster than Opus, larger context than Opus. Use for multi-agent coordination, large codebase analysis, production workflows. Like System 1 thinking (fast, intuitive, pattern-based) but with massive context retention.