a) Firing rates of all 183 CA1 cells with at least one firing field
in the SMT that was confined to the sound presentation period (between the
press and the release of the joystick). Each row corresponds to one cell and
is normalized by the maximum firing rate during the sound presentation
period. Rows are sorted according to the frequency at which the maximum
firing rate occurred. Each trial was binned into 150 frequency bins, which
could vary in duration both within a trial and across trials. The firing
rate was calculated separately in each bin using that bin’s
duration, the firing rates were averaged across trials and smoothed with a
3-point square window. Note that fields in the SMT did not progressively
broaden during the delay period, as they typically do in time cells; this
may be due to the fact that an informative sensory variable (sound
frequency) was always available to the animal, preventing a drift in the
neural code. b) Firing rates of 141 MEC cells, calculated and plotted as in
(a). c) Distribution of CA1 firing field widths, only for those 122 cells
that were identified as “frequency-aligned” by the
electrophysiology model (Extended Data Fig.
8). Note that the entire trial was on average 3.1 octaves. d)
Distribution of 109 MEC firing field widths, plotted as in (c). Note that
the longer tail compared to the CA1 data is partially due to grid cells from
modules with wide spacing (Fig.
4e).