How to Determine if a Reflection Type is a Type Parameter

In Scala I am using reflection to examine method signatures. Some of these methods are parametrized, like in the following example:

implicit def toOption[T](x:T):Option[T] = Some(x)

When I use reflection to get a Symbol that represents toOption, say sym, and do

sym.typeSignature.paramLists.head.head.typeSignature

I get the type named T (it’s the type of x, the first argument in the first argument list). If I have some value y, it can’t be of type T but I can pass it into toOption anyway because T is actually a type parameter, not a normal type.

So my question is the following: how can I tell if a given Type is a generic type parameter (like T in the above example) or a specific type?

Ideally I’d like to determine this at runtime, but if the information is available only at compile time I’d also like to hear how to get it then.