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. 2011 Feb 15;6(2):e17047. doi: 10.1371/journal.pone.0017047

Figure 3. Firing patterns and pharmacology characterizations.

Figure 3

(A–C) Three examples of tetrode-recorded putative dopamine neurons (type-1, type-2, and type-3) and their representative spike waveforms. PC1 and PC2 represent the first and second principal components in the principal component analysis, respectively. Blue dots represent individual spikes for the isolated dopamine neurons; black dots indicate individual spikes for other unsorted VTA neurons. (D) Inter-spike intervals of three examples of putative dopamine neurons (type-1, type-2, and type-3). (E) Percentages of burst firing for the three types of putative dopamine neurons. Error bars, s.e.m.; ***P<0.001, Student's t-test. (F) Baseline firing rates of the three types of putative dopamine neurons. Error bars, s.e.m.; ***P<0.001, Student's t-test. (G) Cumulative spike activity of thee examples of putative dopamine neurons (type-1, type-2, and type-3) in response to the dopamine receptor agonist apomorphine. It was noted that the type-1 and type-3 putative dopamine neurons were recorded simultaneously from one tetrode. (H and I) Baseline and post-drug firing rates of putative dopamine (H) and non-dopamine (I) neurons. Mice were injected with the dopamine receptor agonist apomorphine (1 mg/kg, i.p.) and the firing rates were averaged 30 min before and 30 min after apomorphine injection.