How channels for sodium (na+) control the neuron impulse and depolarization and how changes to these channels would affect neuron function?

The opening of channels that let positive ions flow out of the cell (or negative ions flow in) can cause hyperpolarization. Examples: Opening of channels that let
+
K
​+
​​ K, start superscript, plus, end superscript out of the cell or
−
Cl
​−
​​ C, l, start superscript, minus, end superscript into the cell.
The opening of channels that let positive ions flow into the cell can cause depolarization. Example: Opening of channels that let
+
Na
​+
​​ N, a, start superscript, plus, end superscript into the cell.
The opening and closing of these channels may depend on the binding of signaling molecules such as neurotransmitters (ligand-gated ion channels), or on the voltage across the membrane (voltage-gated ion channels).

The answer is observations and interpreting.