Patients with highly (chemically) sensitive discs appear to achieve significantly better long-term outcomes with interbody/combined fusion than with intertransverse fusion. Patients without disc surgery have the least favorable outcome. Precise prospective categorization of positive discographic diagnoses may predict outcomes from treatment, surgical or otherwise, thereby greatly facilitating therapeutic decision-making.

The classic finding from short-term relative JOR tasks is that correct response time (RT) depends on the lag to the more recent item but not to the less recent item (Hacker, 1980). For decades, researchers have argued that this finding is consistent with a self-terminating backward scanning model (Muter, 1979;Hacker, 1980;Hockley, 1984;McElree & Dosher, 1993). This finding has taken on new importance in light of recent proposal that many forms of memory depend on a compressed representation of the past (Howard, Shankar, Aue, & Criss, 2015). This paper replicates and extends the results of the classic papers. A Bayesian t-test showed substantial evidence for the null e↵ect of lag to the less recent item on correct RT. In addition, this paper reports that correct RT is a sub-linear function of lag to the more recent probe and replicates the classic finding that error RT depends on lag to the less recent probe. These findings place new constraints on models of short-term memory scanning.In a relative judgment of recency (JOR) task participants choose which of two probes from a list was presented more recently. Recency in this task is traditionally measured in units of lag, which is the number of time steps in the past at which the probe was presented. That is, if the last item in the list was presented as a probe, it would be associated with a lag of one. The classic finding from short-term relative JOR tasks is that correct response time (RT) depends on the lag to the more recent item but not to the less recent item (see Fig. 1, Muter, 1979;Hacker, 1980;Hockley, 1984). For decades, researchers have argued that this finding is consistent with a self-terminating backward scan (Muter, 1979;Hacker, 1980;Hockley, 1984;McElree & Dosher, 1993). Because the scan starts at the present and proceeds backwards in time, RTs show a recency e↵ect. Because the scan is self-terminating this naturally accounts for the finding that correct RTs do not depend on the lag of the less-

Neurons in the hippocampus fire in consistent sequence over the timescale of seconds during the delay period of some memory experiments. For longer timescales, firing of hippocampal neurons also changes slowly over minutes within experimental sessions. It was thought that these slow dynamics are caused by stochastic drift or a continuous change in the representation of the episode, rather than consistent sequences unfolding over minutes. This paper studies the consistency of contextual drift in three chronic calcium imaging recordings from the hippocampus CA1 region in mice. Computational measures of consistency show reliable sequences within experimental trials at the scale of seconds as one would expect from time cells or place cells during the trial, as well as across experimental trials on the scale of minutes within a recording session. Consistent sequences in the hippocampus are observed over a wide range of time scales, from seconds to minutes. Hippocampal activity could reflect a scale-invariant spatiotemporal context as suggested by theories of memory from cognitive psychology.

Several authors have suggested a deep symmetry between the psychological processes that underlie our ability to remember the past and make predictions about the future. The judgment of recency (JOR) task measures temporal order judgments for the past by presenting pairs of probe stimuli; participants choose the probe that was presented more recently. We performed a short-term relative JOR task and introduced a novel judgment of imminence (JOI) task to study temporal order judgments for the future. In the JOI task, participants were trained on a probabilistic sequence. During a test phase, the sequence was occasionally interrupted with pairs of probes. Participants chose the probe that they expected would be presented sooner. Replicating prior work, we found that in JOR the correct RT depended only on the recency of the more recent probe. This suggests that memory for the past was supported by a backward self-terminating search model operating on a temporally-organized representation of the past. Analogously, in the JOI task we find that correct RT depended only on the imminence of the more imminent probe. By analogy to the JOR results, this suggests a forward self-terminating search model operating on a temporally-organized representation of the future. Critically, in both JOR and JOI the increase in RT with recency/imminence was sublinear, suggesting that both the timeline for the future and the timeline of the past are compressed. These results place strong constraints on computational models for constructing the predicted future.