fix for #1227

also see
- NeurodataWithoutBorders/pynwb#1300
- NeurodataWithoutBorders/pynwb#1596

Author: apdavison

neo/io/nwbio.py

@@ -564,12 +564,22 @@ def _write_signal(self, nwbfile, signal, electrodes):
         if hasattr(signal, 'proxy_for') and signal.proxy_for in [AnalogSignal,
                                                                  IrregularlySampledSignal]:
             signal = signal.load()
+        if issubclass(timeseries_class, pynwb.icephys.PatchClampSeries):
+            if signal.shape[1] != 1:
+                raise ValueError(
+                    "To store patch clamp data in NWB, please ensure that each AnalogSignal"
+                    f"contains only one channel. The current signal has {signal.shape[1]} channels."
+                )
+            # see https://github.com/NeurodataWithoutBorders/pynwb/issues/1300
+            data = signal.ravel()  # convert to 1D
+        else:
+            data = signal
         if isinstance(signal, AnalogSignal):
             sampling_rate = signal.sampling_rate.rescale("Hz")
             tS = timeseries_class(
                 name=signal.name,
                 starting_time=time_in_seconds(signal.t_start),
-                data=signal,
+                data=data,
                 unit=units.dimensionality.string,
                 rate=float(sampling_rate),
                 comments=json.dumps(hierarchy),
@@ -578,7 +588,7 @@ def _write_signal(self, nwbfile, signal, electrodes):
         elif isinstance(signal, IrregularlySampledSignal):
             tS = timeseries_class(
                 name=signal.name,
-                data=signal,
+                data=data,
                 unit=units.dimensionality.string,
                 timestamps=signal.times.rescale('second').magnitude,
                 comments=json.dumps(hierarchy),