Table 2.

Changes of MSN firing rates with different types of dopamine responses

	Off	On	Dysk
Unidirectional responses (50%)
↑↑ (36%)	21.1 (1.6)	33.3* (2)	44.1* (2.2)
↓↓ (14%)	33.6 (2.6)	22.6* (2.2)	16.5* (2.3)
Bidirectional responses (47%)
↑↓ (27%)	29.9 (2)	47.9* (2.4)	32.9* (2.6)
↓↑ (20%)	33.5 (2.4)	20* (2)	35.2* (2.8)

Data derived from caudate and putamen MSNs pooled together. Units are grouped according to their response to dopamine stimulation as unidirectional [same direction of rate changes in the transition from the Off to the On and to the On-with-dyskinesias (Dysk) states] and bidirectional (inversion of the previous rate changes in the transition to the On-with-dyskinesias state). The successive changes of rate from one state to another are indicated by the arrows, and the percentage of neurons showing such a response is given in parenthesis. In each group, the mean rate (in hertz) is provided for each motor state (Off, On, and On with dyskinesias). Data are mean ± SEM.

*p < 0.0001 versus the previous state.