Well, your brain would make more connections than that one:

%brain = (
  programming => {
    'things to buy' => { 'doohickey' => undef, },
    # ...,
  },
  things_to_buy => {'milk' => '1 gallon',
                    'eggs' => {'amount' => 'dozen',
                               'color' => 'brown',
                               'size' => 'Large grade A'
                               }
                    'doohickey' => undef
                    },
  doohickey => (\$brain{programming}, \$brain{things_to_buy}),
   etc...

  # ...,
);
[download]

So, you would recall it in various ways. You may be at the store buying milk, you may be programming again etc... So, not that I disagree here, but the brain is more complex than any simple hash structure could illustrate.. it has triggers which will fill in other relations, according to various relations you have already made, and create new ones, remove some, blah blah blah.

Cheers,
KM