というと・といえば・といったら

If we talk about…
Noun + と言うと・と言えば・と言ったら

と＋言う in a conditional form is used to express “if you say X then…”.
It has 2 usages:

• To talk about something (I.e. change the topic). Expresses relation
• To express strong emotion (Surprise, annoyance..)

You can use というと、といえば、or といったら. 
というと is preferred for expressing relationship (If you say drumstick, that’s chicken). 

Note: do not use だ before と here. This is because it is an expression that functions like は (a particle).
It would be odd to say: 私だは先生だ

Examples

• トロというとマグロだ
  If (we) say “toro”,  it’s tuna.
  
  
• 猫と言えば、先見たんだ
  If you’re talking about a cat, I saw one earlier. 
  
  
• 勉強と言ったら、もう終わった。
  If you’re talking about homework, its already done. 
  
  
• 母と言ったら、今年は52歳だ。
  Speaking of mom, she’s 52 this year.
  
  
• フランスというと、アイフェル塔があるんだ
  Speaking of France, there’s the Eiffel tower. 
  
  
• パンというと、玉木亭があるん.
  Speaking of bread, there’s Tamakitei. 
  
  

Expressions

• どちらかというと
  If I had to choose…
  
  
• そういえば 
  Speaking of which…
  
  
• 何かと言うと
  Say something and X At every opportunity. 
  
  

Differences

The standard conditional differences apply here, though they are a little less pronounced with these phrases. 

• というと – If you say…Naturally, guaranteed.
  Used for things that naturally come to mind about a topic. 
  
  • トロというとマグロだ – If (we) say “toro”,  it’s tuna. 
    Toro is a type of tuna sushi. There’s no room for anything else here. 
    
    
• と言えば – If you say…Emphasis is on the preceding phrase, What you want to talk about comes first.
  • 猫と言えば、先見たんだ – If you’re talking about a cat, I saw one earlier. 
    Someone asked about a cat, they want to know about a cat, “cat” is the important thing here.
     
• と言ったら – In you say….Emphasis on last phrase. What you want to talk about comes later. 
  • 勉強と言ったら、もう終わった。- If you’re talking about homework, its already done. 
    Homework is already finished. You want to say “it’s done”, not talk about homework. 

If this is annoying to remember, You can probably default to というと in most cases.