Antonova I, Arancio O, Trillat AC, Wang HG, Zablow L, Udo H, Kandel ER, Hawkins RD.
Rapid increase in clusters of presynaptic proteins at onset of long-lasting potentiation.
Science. 2001 Nov 16;294(5546):1547-50.
PubMed.
Although these results are
intriguing, the authors' interpretation of them seems to go beyond what
the data actually might support. Briefly, the pattern of results they
report is that as you look at activation of older memories, both the
hippocampal and entorhinal cortex (EC) activation decreases. The
authors claim this supports the idea that the EC is responsible for
consolidating older memories. But if this were true, might not the
older memories show higher EC activations, not lower, since they have
been strengthened over the years.
More broadly, it appears the experiment was designed to test the
consolidation hypothesis against the multiple trace hypothesis. The
data should be examined with this in mind. The data in this paper show
that only 1990s faces significantly activated hippocampus. Faces from
1940s to 1980s were not significantly over baseline activation. One
other point that makes interpretations difficult is that activations for
1990s and the rest were not statistically significant. EC activations,
on the other hand, showed a linear decreasing function from 1990s to
1970s (then the 3 data points from 70s, 60s, and 50s plateaued with
another drop below baseline for faces from 1940s).
The authors concluded that MTL activation (at least EC) was time-limited
and not time-invariant, thus supporting consolidation but not multiple
trace. The fact that the EC but not hippocampus showed a linear function
suggested that hippocampus plays a role in the shorter time frame ( 10 years). But the data
might also be interpreted as EC playing a longer term and time-dependent
role in retrieval while hippocampus plays a short term one. If encoding
(and consolidation) and retrieval are separate processes, it is not
clear how this data provide clear information about consolidation.
Comments
Comment by Mark Gluck, Kin Ho Chan, M. Todd Allen
Although these results are
intriguing, the authors' interpretation of them seems to go beyond what
the data actually might support. Briefly, the pattern of results they
report is that as you look at activation of older memories, both the
hippocampal and entorhinal cortex (EC) activation decreases. The
authors claim this supports the idea that the EC is responsible for
consolidating older memories. But if this were true, might not the
older memories show higher EC activations, not lower, since they have
been strengthened over the years.
More broadly, it appears the experiment was designed to test the
consolidation hypothesis against the multiple trace hypothesis. The
data should be examined with this in mind. The data in this paper show
that only 1990s faces significantly activated hippocampus. Faces from
1940s to 1980s were not significantly over baseline activation. One
other point that makes interpretations difficult is that activations for
1990s and the rest were not statistically significant. EC activations,
on the other hand, showed a linear decreasing function from 1990s to
1970s (then the 3 data points from 70s, 60s, and 50s plateaued with
another drop below baseline for faces from 1940s).
The authors concluded that MTL activation (at least EC) was time-limited
View all comments by Mark Gluckand not time-invariant, thus supporting consolidation but not multiple
trace. The fact that the EC but not hippocampus showed a linear function
suggested that hippocampus plays a role in the shorter time frame ( 10 years). But the data
might also be interpreted as EC playing a longer term and time-dependent
role in retrieval while hippocampus plays a short term one. If encoding
(and consolidation) and retrieval are separate processes, it is not
clear how this data provide clear information about consolidation.
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