Memory and the Brain • 193that the parahippocampal area responds
to places, such as pictures of buildings
or rooms), and the enthorhinal area,
like the perirhinal area, is involved with
recognition memory. But LTM extends
beyond the MTL, to other areas in the
parietal and frontal lobes, as well as to
the amygdala (see Figure 7.17) which
is important for emotional memo-
ries. We will return to the amygdala in
Chapter 8 when we consider memory
for emotional events such as the terror-
ist attacks of 9/11.
What’s important about the widely
distributed nature of memory in the brain
is that although specifi c areas may have
specifi c functions, different areas inter-
act and communicate with each other.
One aspect of memory that involves this
interaction between areas is consolida-
tion, the process that transforms newly
formed memories from a fragile state to
a more permanent state.FORMING MEMORIES IN THE BRAIN:
THE PROCESS OF CONSOLIDATION
Every experience creates the potential for a new memory. But new memories are fragile
and can therefore be easily disrupted.New Memories Are Fragile but Become Stabilized by Consolidation A well-known
observation is that very recent memories can be eliminated by trauma to the head.
Examples are easy to fi nd in football. A recent instance occurred on September 26, 2009,
when Tim Tebow, the Heisman Trophy quarterback from the University of Florida, suf-
fered a concussion when his head hit another player’s knee as he was being sacked. Upon
regaining consciousness, the fi rst words he said to his coach were “Did I hold onto the
ball?” Typically, players suffering a concussion not only are unaware of what happened
during and right after the concussion, but also don’t remember events that occurred just
prior to the concussion (see Chapter 1, page 15).
Amnesia caused by trauma or brain damage
can affect both the ability to form new memories
(anterograde amnesia, see page 149) and the abil-
ity to remember events that occurred prior to the
injury (retrograde amnesia). Retrograde amnesia
due to concussions is typically less severe for remote
memories—memory for events that occurred long
ago (Frankland & Bontempi, 2005). This effect,
which occurs because memory for recent events is
more fragile than memory for remote events, is called
graded amnesia (● Figure 7.20). As time passes after
an event, a process called consolidation stabilizes
memory for the event so it is less likely to be affected
by trauma.
Consolidation is the process that transforms new
memories from a fragile state, in which they can be
disrupted, to a more permanent state, in which they
are resistant to disruption (Frankland & Bontempi,● FIGURE 7.19 Results of Davachi’s experiment. (a) Response in perirhinal cortex
measured during encoding for items that were recognized and forgotten in the
retrieval test. (b) Response of the hippocampus for recognized and forgotten items.
Percent change in brain activityRecognizedPerirhinal cortexResult of memory testForgotten00.200.150.100.05(a)
RecognizedHippocampusResult of memory testForgotten00.200.150.100.05(b)● FIGURE 7.20 Anterograde amnesia is amnesia for events that
occur after an injury (the inability to form new memories). Retrograde
amnesia is amnesia for events that happened before the injury (the
inability to remember information from the past). The vertical lines,
which symbolize the amount of retrograde amnesia, indicate that
amnesia is more severe for events or learning that was closer in time to
the injury. This is the graded nature of retrograde amnesia.
PAST FUTURE
Gradedamnesia InjuryRemote
memoryRetrograde AnterogradeCopyright 2011 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.