# Multicompartmental models (Brian 1 –> 2 conversion)¶

Brian 1 offered support for simple multi-compartmental models in the
`compartments`

module. This module allowed you to combine the equations for
several compartments into a single `Equations`

object. This is only a suitable
solution for simple morphologies (e.g. “ball-and-stick” models) but has the
advantage over using `SpatialNeuron`

that you can have several of such neurons
in a `NeuronGroup`

.

If you already have a definition of a model using Brian 1’s `compartments`

module, then you can simply print out the equations and use them directly in
Brian 2. For simple models, writing the equations without that help is rather
straightforward anyway:

Brian 1 | Brian 2 |
---|---|

```
V0 = 10*mV
C = 200*pF
Ra = 150*kohm
R = 50*Mohm
soma_eqs = (MembraneEquation(C) +
IonicCurrent('I=(vm-V0)/R : amp'))
dend_eqs = MembraneEquation(C)
neuron_eqs = Compartments({'soma': soma_eqs,
'dend': dend_eqs})
neuron = NeuronGroup(N, neuron_eqs)
``` |
```
V0 = 10*mV
C = 200*pF
Ra = 150*kohm
R = 50*Mohm
neuron_eqs = '''
dvm_soma/dt = (I_soma + I_soma_dend)/C : volt
I_soma = (V0 - vm_soma)/R : amp
I_soma_dend = (vm_dend - vm_soma)/Ra : amp
dvm_dend/dt = -I_soma_dend/C : volt'''
neuron = NeuronGroup(N, neuron_eqs)
``` |