Update README.md

README.md

@@ -53,7 +53,7 @@ and display the first data row:
 }
 ```
 where:
-* `spike_counts` is a `uint8` array containing the spike count data.
+* `spike_counts` is a `uint8` array containing the spike count data. Its shape is `(n,t)` where `n` is the number of simultaneously recorded neurons in that session and `t` is the number of time bins (20 ms bins).
 * `source_dataset` is an identifier string indicating the source dataset from which that particular row of data came from.
 * `subject_id` is an identifier string indicating the subject the data were recorded from.
 * `session_id` is an identifier string indicating the recording session.