Friday, January 10, 2014
Why species the world over sleep
However much some of us might crave some extra shut-eye, in the animal
kingdom, sleep can be a dangerous time. Snoozing leaves us more
vulnerable to predators and means we aren't up and around looking for
food or mates. Scientists at the University of Wisconsin-Madison have a
new hypothesis that might explain why species the world over sleep. A
new study in the journal Neuron presents evidence that sleep is the
price we pay for the ability to learn. Called the synaptic homeostasis
hypothesis of sleep or "SHY", the researchers argue that brain
connections may actually weaken during sleep. This allows the brain to
conserve energy and 'reset' itself, allowing for more learning the
following day. The scientists also cite evidence that sleep helps memory
by allowing the brain to forget unimportant details. Viewing the
primary function of sleep as decreasing the strength of connections
between synapse and increasing signal-to-noise ratio challenges many of
the existing theories on sleep and requires more testing to validate
several hypotheses, but scientists say it may help explain one of life's
most mysterious activities.
Focus on memory
Focus on memory
Nature Neuroscience 16, 111 (2013)
doi:10.1038/nn0213-111
Published online 28 January 2013
Nature Neuroscience presents a special focus issue highlighting recent
advances and discussing future directions in memory
research.
Whether remote or recent, blurred or vivid, conscious or hidden, memories
provide a link between the present and the past and allow us to project our
thoughts into the future. But memories are not immutable; instead, they
continually evolve throughout their lifetime. From the moment they are created,
they embark on a dynamic journey, during which they are consolidated, often
updated, but also sometimes distorted to the point that they falsify the past.
As our brain is constantly bombarded with newer information, memories may also
become suppressed by competing memories or experiences or seemingly disappear
into oblivion. In this issue, we present a focus on memory, comprising
Commentaries, Reviews and Perspectives discussing some of the most exciting
recent developments and emerging ideas in our understanding of the neurobiology
of learning and memory.
Are memories faithful snapshots of past experiences or can they become
insidiously deceitful? During its ruling on the Henderson case in 2011, the New
Jersey Supreme Court carefully considered the value of evidence based on
eyewitness memory. The decision showed some appreciation of the complexity of
memory processes and, in particular, the fact that memories can be tampered with
by suggestive influence. As a result of this case, instructions provided to
jurors on how to decide the fate of the accused in New Jersey now explicitly
state that memories do not replay like video recordings. In their Commentary on
page 119 of
this issue, Daniel Schacter and Elizabeth Loftus carefully discuss what
cognitive neuroscience can bring to the courtroom, focusing on the neural basis
of true and false memories and misinformation effects. Their commentary also
serves as a powerful case to illustrate how advances in understanding the
neurobiology of memory have immediate and direct consequences on society.
How are memories transformed by experience? Past experiences can persistently
modify gene expression by altering epigenetic marks on histones or DNA bases.
The possibility that this form of molecular memory could contribute to the
encoding, updating and persistence of long-term memories is very appealing, as
memory formation depends on changes in patterns of gene expression. This has
inspired memory researchers to investigate whether such mechanisms can
participate in shaping learning and memory. In a Perspective on page 124,
Matthew Lattal and Marcello Wood discuss recent progress on the epigenetics of
learning and memory. They argue that epigenetics can help to distinguish the
molecular mechanisms that mediate reconsolidation of memories and memory
extinction, and that epigenetics can provide a plausible molecular mechanism
that maintains the persistent change in behavior induced by extinction.
Of the many brain structures that are important for learning and memory, the
hippocampus has been widely studied as a central hub of this cognitive process.
The discovery in the early 1970s by O'Keefe and Dostrovsky that the position of
an animal in its environment can dictate the firing of hippocampal neurons, the
so-called place cells, prompted the burning question of whether memory and
navigation are part of a common system or simply functionally stand side by side
in the hippocampus. On page 130 of
this issue, György Buzsáki and Edvard Moser revisit this notion by discussing
recent evidence that the navigation and memory functions of the hippocampus and
the entorhinal cortex are supported by the same neuronal algorithms. In
addition, they propose that the mechanisms fueling the memory and mental travel
engines of the hippocampal-entorhinal system evolved from the mechanisms
supporting navigation in the physical world.
There is now converging and unequivocal experimental evidence supporting the
idea that memory consolidation takes place during sleep. Does sleep provide
passive protection from forgetting or does it actively shape the future of
memories? On page 139 of
this issue, Robert Stickgold and Matthew Walker offer a fresh perspective on
this question by introducing the concept of sleep-dependent memory triage. They
discuss recent findings in sleep research that support their view that
consolidation is not a monolithic process, but rather consists of a variety of
operations. They propose that offline consolidation during sleep sanctions what
information is ultimately retained or lost on the basis of salience tags and
acts as the architect of the evolution of memories during their integration into
existing implicit and explicit knowledge.
With a long and rich experimental history, learned fear is probably one of
the best understood forms of memory. In recent years, it has become clear that
aversive memories are shaped by distinct learning phases, and many of the
underlying molecular and circuit mechanisms have now been elucidated. On page 146 of
this issue, Ryan Parsons and Kerry Ressler review how the latest insights into
the biological basis of learned fear have provided a new strategic platform for
clinical approaches to fear and anxiety disorders. In particular, they discuss
the potential therapeutic value of targeting behavioral and pharmacological
interventions to different epochs of the fear learning process to treat
disorders such as phobias, panic and post-traumatic stress disorder.
Learning and memory is a very broad field. The handful of pieces in this
issue clearly cannot span the entire field; rather, we have simply highlighted
some of the topics that have received substantial attention and that have been
the focus of recent study. We express our gratitude to the authors, referees and
advisors who helped us to curate this special issue. We hope that these reviews
will inspire further research into unraveling the complex neuroscience of memory
and that they give our readers a glimpse of some of the exciting recent research
in this field.
Source: Nature Neuroscience
http://www.nature.com/neuro/journal/v16/n2/full/nn0213-111.html?WT.ec_id=NEURO-201302
http://www.nature.com/neuro/journal/v16/n2/full/nn0213-111.html?WT.ec_id=NEURO-201302
SIR LLEW EDWARDS BUILDING BY RICHARD KIRK ARCHITECT
The building was designed to respond to its immediate context in several respects. It addresses its largely landscaped setting by opening its interior out towards views over the University forecourt and by capturing an external landscaped courtyard between its two wings.
Its external form has been carefully modulated to respond to the varying scale and form of adjacent buildings. External materials have been selected to respond directly to the material palette of original University buildings, and given the University’s long term interests as a building owner, for their robustness and self- finished properties.
At peak times over 1,000 students can arrive and depart each hour to and from the building. In response to this, large public and circulation spaces have been provided, the generosity of which is reflective of similar spaces in some of the original University buildings. The building also provides the University with a new building typology that exemplifies significant advances in the inclusion of environmental features.
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