Table 1.

Latencies, durations, and magnitudes of reward responses in the two behavioral situations

Behavioral situation	N	Latency (msec)	Duration (msec)	Magnitude (% decrease)
Instrumental task condition
Immediate	35	171  ± 83	160  ± 74	50  ± 17
Fixed delay	40	188  ± 68	143  ± 74	55  ± 16
Variable delay	23	193  ± 59	126  ± 86	53  ± 20
Free reward condition
Irregular	92	169  ± 42	147  ± 56	63  ± 18
Regular 4 sec	89	179  ± 37	143  ± 57	60  ± 16
Regular 2 sec	70	175  ± 51	143  ± 64	53  ± 16

Values are means ± SD. N, numbers of TANs. Magnitudes are indicated as decreases in percentage below baseline activity during the control period (see Materials and Methods). For quantitative analysis, some recorded neurons were discarded if noise artifact caused by jerky movements by the monkeys contaminated the data, thus explaining the lower number of neurons used for the response parameters analysis, compared with the size of the samples of responding neurons.