scala weird symbol "_@" meaning

I am wondering what this scala symbol is: _@.

(Search engines have trouble with weird characters so it's hard to find anything on google...)

Here is the context:

def doNodeParse(json: JValue): TreeNode = {
    json match {
        case JObject(List(JField("Condition", JObject(List(JField("var", JString(variableName)), JField("Operation", JString("LT")), JField("Value", JDouble(threshold))))),
                JField("onTrue", _@ onTrue),
                JField("onFalse", _@ onFalse),
                JField("onMissing", _@ onMissing)
                )) =>
                LessThanNode(variableName, threshold, doNodeParse(onTrue), doNodeParse(onFalse), doNodeParse(onMissing))

        case _ => {
            throw new Error("failed parsing json!")
          }
    }
}

(The types of onTrue, onFalse, onMissing are JsonAST.JValue)