Robert Stickgold
Sleep, Memory, and Dreams: A Cognitive Neuroscience Perspective
The concept of "sleeping on a problem" is familiar to most of us. But with myriad stages of sleep, forms of
memory and processes of memory encoding and consolidation, sorting out how sleep contributes to memory
has been anything but straightforward. Nevertheless, converging evidence, from the molecular to the
phenomenological, leaves little doubt that offline memory reprocessing during sleep is an important
component of how our memories are formed and ultimately shaped.
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Massimo Piattelli-Palmarini
Rethinking language, evolution and the evolution of language
In this talk, I will present a re-conceptualization of several core issues
in the biology and evolution of language. An appropriate sub-title could,
then, be (paraphrasing a classic 1961 paper by Warren Sturgis McCulloch):
What is language, that it may have evolved, and what is biological
evolution, that it may apply to language? New promising
avenues of inquiry (in mainstream biology, but decidedly still a minority
view in language evolution) have emerged towards new biological foundations
of language. I think one has many reasons to be dissatisfied with the
attempts to explain language evolution in terms of gradualist neo-Darwinian
adaptations. Such dissatisfaction is justified by the frequent neglect, or
the denial, of central properties of language (unlimited recursion,
computational compactness at the expense of communicability,
parametrization, strict compositionality, headedness, endocentricty,
conservativity etc.). The Evo-Devo approach now offers a powerful unifying
perspective with a common plan in all the "bilateral" body forms, along over
550 million years, with what we are entitled to see as minor "parametric"
genetic variations. Some lessons from the "new biology" towards rethinking
the evolution of language will be suggested.
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Jason Mitchell
Inferring the mental states of similar and dissimilar others
Unlike most other things in the world, human beings are driven by their
internal mental states - what they think, feel, and desire. Accordingly,
successful social interaction requires that we be capable of inferring the
content of another person's mind, an ability known as "mentalizing." But
by what cognitive processes does one go about inferring others' mental
states? One possibility is that perceivers may sometimes be able to
"simulate" another person's mental states by imagining themselves in the
same situation and assuming that others would share the same thoughts and
feelings that they experience themselves. However, this simulationist
strategy would only be appropriate if one is willing to assume that the
other person is sufficiently similar to self that he or she would indeed
experience the same mental states as oneself. A recent series of
neuroimaging and behavioral experiments has provided initial evidence in
support of this prediction of simulation theory. First, we have observed
that a brain region previously linked to self-referential thought
(ventromedial prefrontal cortex) activates selectively for mentalizing
about similar others. Second, we have demonstrated that perceivers more
rapidly judge their own mental states after making the same judgment about
a similar (relative to dissimilar) other. Finally, our most recent work
has shown "repetition suppression" in the functional activation during
self-reference following judgments of a similar other, suggesting that the
same processing accompanies judgments of self and similar others.
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Kyle Cave
When Top-Down Attentional Control Turns Off
When a visual object that is attended is partially occluded by a distractor object, the occluded region
is inhibited, but only under certain conditions. This distractor region is apparently inhibited only
when the display is fairly simple. If the configuration of objects is too complex, it may be too
difficult to determine which regions belong to which objects. In a different set of experments,
subjects search for a single target or for two targets simultaneously. The two targets have different
colors. In single-target search, color is used effectively to prevent fixations of nontargets. During
dual-target search, however, distractors with nontarget colors are fixated more often, indicating a
partial break-down in top-down attentional control. These two findings demonstrate very different
aspects of attention, but both show how top-down attentional control can be overwhelmed by complexity
in the stimulus or in the task. Together they help to define the limits of top-down attentional
control.
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Justin Wood
Remembering actions and events in visual working memory
Humans depend on the ability to remember the actions of other
individuals, information which needs to be stored in a temporary
buffer to guide behavior after actions have been observed. To date,
however, the storage capacity, contents, and architecture of visual
working memory (VWM) for observed actions are unknown. In this talk,
I present a series of studies which characterize the storage capacity
and contents of VWM for actions and other types of events. Further,
I investigate the architecture of VWM more generally, by asking how
memory for actions and events interacts with other VWM systems, such
as those used to store information about objects and spatial locations.
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Angela Gutchess
Memory Specificity with Age
Young adults exhibit highly specific neural responses to certain
types of information, such as object categories or social stimuli. This
specificity is also present in the domain of memory, distinguishing
between encoding processes or to the relatedness of information at the
time of retrieval. In contrast, aging is marked by more generalized
responses. For example, there is a less distinct neural response to
classes of objects with age, and older adults activate both hemispheres
for tasks on which young activate only one. To date, there has been
little research addressing the degree to which specificity in memory is
preserved with age. I will present three lines of work that address this
question across stimulus features (background contexts vs. objects),
modalities (self vs. other), and encoding processes (perceived vs.
self-generated images). Although elderly adults show some preservation of
distinct responses, age-related changes occur in the processes engaged
during encoding and recognition. These changes may explain the
pervasiveness of memory impairments with age in that, compared to young,
older adults fail to engage cognitive control processes and access less
specific information about the memory trace during retrieval.
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David Somers
Visual, Tactile and Spatial Attentional Processing in Human Occipital
and Parietal Cortex
fMRI has proven a very useful tool for localizing the neural substrates of human
cognition and perception; however, the spatial resolution is limited by
inter-subject averaging methods. We have employed within-subject methods to gain
a clearer picture. We are now able to observe 14 distinct visual hemifield maps
in human cerebral cortex. This includes five areas, V7, IPS1, IPS2, IPS3 and IPS4
that tile the medial bank of the intraparietal sulcus (IPS), an area of the brain
known to support visual attention, visual STM, and multisensory interactions.
These visual maps are consistent within individuals, but there are important
differences across individuals. Although group-analysis of tactile and visual
activation patterns suggests a region of overlapping multisensory activation in
IPS, our within-subject analysis reveals that visual and tactile activations in
IPS fit together like interlocking puzzle pieces within minimal overlap.
Surprisingly, we find evidence for a degree of multimodal integration in primary
visual cortex, as V1 is activated during tactile perception in blindfolded
subjects. We have also investigated the mechanisms which support visual attention
to more than one object location. We find that the attentional spotlight can be
split to attend to multiple objects and that this divided spotlight modulates all
visual cortical areas. The spotlight can be split within and across hemifields.
Splitting the attentional spotlight can be an efficient strategy as it conserves
attentional resources, withholding attention from irrelevant regions of the visual
field. This Resource Conservation benefit is observed in Occipital Lobe BOLD
signal. However, splitting the spotlight places a burden on attentional control
circuitry in parietal and frontal lobes. BOLD signal activation in occipital and
parietal cortex predicts overall behavioral performance via a two-stage model.
Finally, our results conflict with the notion of independent hemispheric
processing in visual attention: occipital hemispheres compete for attentional
resources and IPS hemispheres cooperate.
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Samuel Moulton
The psychological effects of meditation
Although recent reviews of meditation research have focused on its
physiological, psychophysiological, or therapeutic effects, the claim that
meditation improves cognitive functioning has not been systematically
examined. I will present preliminary results from a meta-analysis of the
relationship between meditative experience and cognitive abilities in an
attempt to answer the question: does meditation make you smarter? I will
also present results from several original studies assessing the
relationship between meditative practice and emotional processing.
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Jacob Beck
The language of thought reconsidered
According to the Language of Thought Hypothesis, cognition is dominated by representations
that are structurally analogous to the sentences of a language. In my presentation, I
will argue against this Hypothesis on both philosophical and empirical grounds. I will
raise objections to three prominent arguments that philosophers and cognitive scientists
have advanced in favor of the Language of Thought Hypothesis, and marshal empirical
evidence that cognitive representations come in a variety of formats, many of which do not
resemble sentences. The resulting view is that cognition is subserved by a plurality of
representational kinds.
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Ramakrishna Chakravarthi
Mechanisms in Visual Crowding
When a target is surrounded by distracters, it can no longer be easily identified. This phenomenon - known as Visual Crowding - is quite common in our visual
experience. An understanding of crowding might shed light on several essential visual processes such as attention, search, reading, and awareness, among
others. In a series of three studies I explore the mechanisms that underlie this phenomenon. Study 1, which looks at the temporal properties of a specific
aspect of crowding, shows that crowding is not a low-level interaction but has features of attention. Study 2 demonstrates that crowding exhibits a signature
of selective attention. Finally, Study 3 indicates that signal integrity of the distracters, but not their representation, is crucial for crowding to occur.
That is, crowding seems to be a mid level interaction between the target and the distracters. In conclusion, current evidence strongly supports, although it
does not confirm, an attentional hypothesis of crowding: crowding is due to a limitation in the resolution of attention. According to this hypothesis,
attention cannot zoom in beyond a lower bound and if several objects happen to fall within this limit, their individual identities cannot be resolved crowding.
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Ryan Bogdan
The Contributions of Stress and Genetics to Reward Processing:
Implications for Depression
The heterogeneity of depression has hindered progress in identifying
and understanding the genetic and environmental factors that contribute to
this debilitating disorder. To reduce this heterogeneity and improve our
etiological understanding it has been suggested that researchers target specific
phenotypes of depression rather than investigate the overall disorder. Anhedonia, the
loss of pleasure or lack of reactivity to pleasurable stimuli, is a promising
phenotype to investigate as it is hypothesized to be a trait marker for
depression and has been associated with dysfunction in the brain's reward
system in preclinical models. Three studies will be presented that investigate
how hedonic capacity is affected by 1) stress, 2) broad genetics and 3) the
interaction of serotonin transporter genotype and stress.
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Joshua Greene
What Pushes Your Moral Buttons?
In recent years, many hypothetical people have been killed by
hypothetical runaway trolleys. This is not necessarily a bad thing,
since the sacrifice of these victims was, in each case, offset by the
saving of five other people's lives. In some cases people judge
these trade-offs to be morally acceptable, while in other cases they
don't. Why? A dual-process theory of moral judgment (supported by
fMRI, neuropsychological, and behavioral data) offers a partial
answer: People say "No" when they have an alarm-like emotional
response that inclines them to disapprove of the action in question.
In the absence of such responses, people tend toward a more
"cognitive," utilitarian (cost-benefit) mode of moral judgment that
inclines them to say "Yes." This is a partial answer because it
doesn't explain why people respond more emotionally to some cases
rather than others. I will discuss a series of behavioral
experiments involving a number of "trolley variations" aimed at (a)
isolating the features of harmful actions that trigger the
aforementioned emotional responses and (b) understanding the
cognitive mechanisms that govern these responses.
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Sheila Blumstein
Phonetic Category Structure and the Mapping of Sound Structure to the Lexicon: Evidence from Lesion Studies and Functional Neuroimaging
This research investigates how the functional architecture of the speech-lexical processing system maps on to the neural systems underlying it. To this end, we will first examine the nature of phonetic category structure and the influence of top-down lexical information on phonetic processing (the lexical effect).
Evidence from studies of aphasia and functional neuroimaging suggests that
∗the phonetic processing stream is a distributed network that includes temporal, parietal, and frontal structures with details of phonetic category structure retained throughout the stream
∗modulation of activation in frontal areas emerges as a function of acoustic-phonetic competition, not phonetic quality, whereas modulation of activation in posterior areas appears to reflect ´goodness of fit´ to a phonetic category.
∗the influence of lexicality on phonetic category structure reflects both perceptual and decision-related, post-lexical processes
We will then explore the mapping of sound structure to lexical form and the lexical-semantic network by investigating the effects of phonological-lexical competition and lexical density on lexical access. Results suggest that:
∗both anterior (inferior frontal gyrus) and posterior (superior temporal gyrus) structures are influenced by phonological-lexical competition but in different ways
∗effects of phonological lexical density emerge in the supramarginal gyrus for both perception and production, suggesting that there is a common lexicon accessed for both perception and production and that this parietal area is recruited when increased processing demands are required for accessing phonological form
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