NameError: global name 'v_rest_e' is not defined

i am trying to run the Mnist repository but got the following error.need your help to resolve this issue.
NameError                                 Traceback (most recent call last)
<ipython-input-2-1052c970edd9> in <module>()
    349 
    350 neuron_groups['e'] = b.NeuronGroup(n_e*len(population_names), neuron_eqs_e, threshold= v_thresh_e, refractory= refrac_e, reset= scr_e, 
--> 351                                    compile = True, freeze = True)
    352 neuron_groups['i'] = b.NeuronGroup(n_i*len(population_names), neuron_eqs_i, threshold= v_thresh_i, refractory= refrac_i, reset= v_reset_i, 
    353                                    compile = True, freeze = True)

C:\ProgramData\Anaconda5\envs\py27\lib\site-packages\brian\fundamentalunits.pyc in new_f(*args, **kwds)
   1406                                                      str(au[k]),
   1407                                                      get_dimensions(newkeyset[k]))
-> 1408             result = f(*args, **kwds)
   1409             if "result" in au:
   1410                 assert have_same_dimensions(result, au["result"]), \

C:\ProgramData\Anaconda5\envs\py27\lib\site-packages\brian\neurongroup.pyc in __init__(self, N, model, threshold, reset, init, refractory, level, clock, order, implicit, unit_checking, max_delay, compile, freeze, method, max_refractory)
    283         if isinstance(threshold, str):
    284             if isinstance(model, Equations):
--> 285                 threshold = select_threshold(threshold, model, level=level + 1)
    286             else:
    287                 threshold = StringThreshold(threshold, level=level + 1)

C:\ProgramData\Anaconda5\envs\py27\lib\site-packages\brian\threshold.pyc in select_threshold(expr, eqs, level)
    101     # non-constant.
    102     expr = expr.strip()
--> 103     eqs.prepare()
    104     ns = namespace(expr, level=level + 1)
    105     s = re.search(r'^\s*(\w+)\s*>=?(.+)', expr)

C:\ProgramData\Anaconda5\envs\py27\lib\site-packages\brian\equations.pyc in prepare(self, check_units)
    371         self.compile_functions()
    372         # Check units
--> 373         if check_units: self.check_units()
    374         # Set the update order of (static) variables
    375         self.set_eq_order()

C:\ProgramData\Anaconda5\envs\py27\lib\site-packages\brian\equations.pyc in check_units(self)
    457                 f.func_globals.update(namespace_replace_quantity_with_pure(f.func_globals))
    458                 units = namespace_replace_quantity_with_pure(self._units)
--> 459                 self.apply(var, units) + (self._units[var] / second) # Check that the two terms have the same dimension
    460                 f.func_globals.update(old_func_globals)
    461         except DimensionMismatchError, inst:

C:\ProgramData\Anaconda5\envs\py27\lib\site-packages\brian\equations.pyc in apply(self, state, vardict)
    590             # could add something like: if var not in vardict: this would allow you to override the dependencies if you wanted to - worth doing?
    591             vardict[var] = call_with_dict(self._function[var], vardict)
--> 592         return f(*[vardict[var] for var in f.func_code.co_varnames])
    593 
    594     """

<string> in <lambda>(v, I_synE, I_synI)

NameError: global name 'v_rest_e' is not defined
brian-team / brian

NameError: global name 'v_rest_e' is not defined #5
