Table 1.

Numbers of reward-related responses

	No. of cells	Total recorded cells (%)	Reward-related responses (%)
Total no. of recorded cells	385	100
No. of reward-related units	66	17.1	100
Firing rate response
Increase	61		92.4
Decrease	5		7.6
Response timing relative to reward site arrival
Prior to arrival	20		30.3
After arrival	20		30.3
During both phases	26		39.3
Reward availability
Reward present	39		59.1
Reward absent	9		13.6
Differential responses between conditions	5		7.6
Reward sites
1 site	21		31.8
2 sites	9		13.6
3 sites	6		9.1
Differential responses between sites	9/15		60.0
Reward availability and reward sites
Differential firing to presence and sites	26		39.3
Firing pattern not specific for any condition	8		12.1

Shown is an overview of the number of significant reward-related correlates. A total of 66 reward-related correlates were identified from 385 units (Wilcoxon's matched-pairs signed rank test, p < 0.01). Subsets of reward-related correlates, classified under ″Reward availability″ and ″Reward sites,″ responded differentially to the presence/absence of reward or to the reward sites, respectively, whereas the remaining neurons were less selective in their firing profiles. The term ″differential responses″ between reward presence and reward absence indicates that, in both conditions, a significant response was observed but the amplitude of the responses was significantly different (Kruskall–Wallis, p < 0.05; Mann–Whitney U test, p < 0.05). The same specification holds for differential responses between reward sites. Some neurons discriminated between reward presence/absence and between reward sites. These are listed under ″Differential firing to presence and sites.″