How can I create a loop that will generate the amount of points that exist in between specific values?

I have a dataset of event times that is generated in 1 row in an array. Essentially, the appearance of a -1 in this row signifies the end of that trial, and each other number is an event in that trial. For example,

FSpks = [4, 5, 6, 6.5, -1, 2, 4, 5, 6, -1, 1, 3, 4, -1, 4, 5, 6, -1]

How would I be able to generate a loop, or a function, that would generate the amount of events that occurred in each trial?

Thanks

Answer 1

[Walter Roberson]

FSpks = [4, 5, 6, 6.5, -1, 2, 4, 5, 6, -1, 1, 3, 4, -1, 4, 5, 6, -1];
numevents_in_trial = diff([0 find(FSpks == -1)]) - 1;

[James Baldassano]

this works as well, thank you so much!