Fig. 6.

Distribution of spine lengths in fixed or live (time-lapse imaged) slices (2 weeks in vitro). The lengths of all spiny protrusions on dendrites in a live slice were determined at the beginning (PRE-TIME LAPSE) and end (POST-TIME LAPSE) of a standard 3 hr time-lapse imaging sequence (experiment shown in Fig. 5). There was no significant difference in the mean length or length distribution of spines before or after the imaging session, indicating that the time-lapse imaging did not induce changes in spine structure. Also, the mean length of spines on live cells was very similar to the distribution of spine lengths on dendrites in comparable slices fixed before labeling and imaging (FIXED). See Results for more details.