Friday, May 27, 2011
Neurosciences Seminar Series
UCSD Neurosciences Graduate Program
Center for Neural Circuits and Behavior Large Conference Room (formerly CMG)
Jill Leutgeb, UCSD
Hippocampal circuits for memory encoding
Dr. Jill Leutgeb’s research is aimed at understanding the neural basis of memory formation at the systems level. Although there is consensus that the hippocampus is required for episodic memories, it remains poorly understood how neuronal computations within its circuitry contribute to memory formation and retrieval. Dr. Leutgeb investigates how the various subregions of the medial temporal lobe, including the hippocampus and the parahippocampal cortices, contribute to memory encoding. She will present research describing how distinct networks of medial temporal lobe neurons encode a combination of temporal, spatial, and non-spatial information. The computations these circuits perform are thought to be essential for the encoding of episodic memories. Dr. Leutgeb's work has advanced our understanding of the neural mechanisms underlying memory formation-- please join us for an exciting talk from a star of the home team.
Thursday, May 26, 2011
Probing the flexibility of selection when attention fails
UC Santa Barbara
Abstract Selective attention is often conceived of as a dynamic, flexible mechanism that helps us cope with a complex environment, in which multiple sources of information compete for the control of behavior and representation in awareness. Despite this common notion, dual task studies that measure the temporal distribution of attention, such as studies of the attentional blink (AB), paint an entirely different picture consistently demonstrating that selective attention is more rigid and operates a relatively late stage of processing. I will present a series of studies that investigate whether these latter findings are indicative of the operation of a unique and rigid attentional mechanism or whether they represent the operation of a mechanism that is more general. I will argue that there is clear evidence of flexibility of selection during the AB, and that this flexibility represents the perceptual and cognitive dynamics of a more general attention mechanism.
Wednesday, May 25, 2011
Hiroshi Abe & Daeyeol Lee
SummaryKnowledge about hypothetical outcomes from unchosen actions is beneficial only when such outcomes can be correctly attributed to specific actions. Here we show that during a simulated rock-paper-scissors game, rhesus monkeys can adjust their choice behaviors according to both actual and hypothetical outcomes from their chosen and unchosen actions, respectively. In addition, neurons in both dorsolateral prefrontal cortex and orbitofrontal cortex encoded the signals related to actual and hypothetical outcomes immediately after they were revealed to the animal. Moreover, compared to the neurons in the orbitofrontal cortex, those in the dorsolateral prefrontal cortex were more likely to change their activity according to the hypothetical outcomes from specific actions. Conjunctive and parallel coding of multiple actions and their outcomes in the prefrontal cortex might enhance the efficiency of reinforcement learning and also contribute to their context-dependent memory.
Tuesday, May 24, 2011
Friday, May 20, 2011
Addition and Memory
ABSTRACT In the last decade the theory that memory and addiction are interrelated has gained tremendous traction. Along with reviewing the definition for addiction, I will discuss the different flavors of this theory and review the evidence for or against them. I will also discuss work from our lab, using a variety of amnesic treatments in rodent models of addiction, to test this theory. The end goal of the talk will be to reach a better specified (and testable) version of the overall “memory=addiction” theory.
more info here
Wednesday, May 18, 2011
Silvia A. Bunge, Ph.D.
Associate Professor, Department of Psychology &
Helen Wills Neuroscience Institute
University of California at Berkeley
Reasoning Ability: Neural Mechanisms, Development, and Plasticity
Abstract The capacity to reason with complex information and to solve novel problems, often referred to as fluid reasoning, is a central characteristic of human cognition. During childhood, the emerging capacity to reason supports learning across multiple domains. I will argue, based on a series of neuroscientific studies in adults, that a key component of fluid reasoning is the ability to jointly consider multiple relations between mental representations, or relational integration. I will then discuss the changes in brain structure and function that support reasoning development over childhood and adolescence. Finally, I will present evidence for improved reasoning ability after intensive training, both in children and in college students.
UCSD Cognitive Science Distinguished Speaker Lecture Series
Monday, May 16, 2011
Friday, May 13, 2011
Tuesday @ Noon
Learning to Attend Induces an Increased Response to Unattended Stimuli
Anna Byers - UCSD
Traditional perceptual learning tasks employ just a single stimulus feature, making it difficult to parse out the differential effects of low-level sensory plasticity (i.e. Seitz et al., 2009) and top-down attentional gain modulations (i.e. Fahle, 2009) on observed changes in behavior and neural activity. Here, we evaluated the relationship between learning and top-down attentional gain using feature-selective fMRI techniques and a task that required discriminating one of ten possible orientations (instead of only a single orientation, as is typically employed in perceptual learning studies). Given that perceptual learning has been documented to occur without attention (Seitz et al., 2009), we expected to see an increase in the amplitude of orientation-selective response profiles in V1 after training on both an orientation-attended and an orientation-unattended task. Five subjects participated in an initial fMRI scan session, 10 behavioral training sessions, and a final scan session. For all sessions, subjects performed four blocks of an orientation discrimination task and four blocks of a rapid serial visual presentation (RSVP) letter task. Before training, the orientation-selective response profile in V1 had higher amplitude during the orientation-attended task compared to the orientation-unattended (RSVP) task. However, after training, the amplitude of the orientation-selective response profile increased, particularly when orientation was ignored (i.e. during the RSVP task). These results indicate that practice improves feature-selective representations of stimuli in early visual cortex, even when the stimulus is not being actively attended. Moreover, since our experiment involved multiple orientations, our subjects must have been learning to modulate sensory gain in a general sense, as opposed to optimizing gain to process a single, highly trained stimulus feature.
The effects of task engagement on neural responses in the songbird auditory forebrain.
Dan Knudsen - UCSD
Sensory systems in the brain evolved to provide a representation of the external world for use in behavior. Though it has traditionally been thought that these representations are static in adult vertebrates, it is becoming increasingly clear that neural representations in sensory areas can be modified by exposure to or training with behaviorally meaningful stimuli, and by changes in motivational and attentional states. The songbird auditory system provides an powerful model for studying this type of behaviorally modifiable sensory representation. A major feature of this system is the ability to modify representations at all levels of the ascending auditory pathway in response to behavioral demands placed on a bird. While these findings have been exposed at the relatively long timescale of song recognition learning, it is unknown if or how the auditory system modifies stimulus representations at shorter timescales, such as changes in behavioral state. In order to determine the relationship between neural response and behavioral state, we have developed methods to record from single units in the auditory forebrain of freely moving starlings as they perform auditory recognition tasks on segments of conspecific song. By comparing neural responses to these songs when a bird is engaged in the task to responses when the bird is not performing the task, we can see the effects of task-engagement on stimulus representation. I will present current findings, including changes in trial-to-trial firing rate variability and stimulus selectivity, and discuss how these types of changes might allow a sensory system to more reliably represent those features in the environment that are relevant to an organism.
check it out here
Tuesday, May 10, 2011
here is a rather depressing quote from Tom Insel (Director of NIMH)
'Currently, with the focus on reducing US discretionary spending, we expect Congressional appropriations for NIH in 2011 and 2012 to be flat or possibly reduced to below the 2010 budget. Because most of our funding is committed to the out-years (years following the first year of funding) of 4- and 5-year grants, any reduction is taken from the 20 to 25% of the budget that turns over each year. As a result, the National Institute of Mental Health (NIMH) expects to fund fewer than 500 new grants this year, the lowest number of new awards since 1999.'
check out the full article here
Monday, May 9, 2011
and Kavli Institute for Brain and Mind Sixth Annual Symposium on Innovative Research
Saturday, May 14, 2011
9:00 am - 4:00 pm
Continental Breakfast served at 8:30 am
University of California, San Diego
10100 John Jay Hopkins Drive
San Diego Supercomputer Center (Auditorium- Room B211)
San Diego, CA 92093-0523
Wednesday, May 4, 2011
The spatial periodicity of grid cells is not sustained during reduced theta oscillations
Koenig et al.
Abstract Grid cells in parahippocampal cortices fire at vertices of a periodic triangular grid that spans the entire recording environment. Such precise neural computations in space have been proposed to emerge from equally precise temporal oscillations within cells or within the local neural circuitry. We found that grid-like firing patterns in the entorhinal cortex vanished when theta oscillations were reduced after intraseptal lidocaine infusions in rats. Other spatially modulated cells in the same cortical region and place cells in the hippocampus retained their spatial firing patterns to a larger extent during these periods without well-organized oscillatory neuronal activity. Precisely timed neural activity within single cells or local networks is thus required for periodic spatial firing but not for single place fields.
Carlson et al.
Abstract Communication can contribute to the evolution of biodiversity by promoting speciation and reinforcing reproductive isolation between existing species. The evolution of species-specific signals depends on the ability of individuals to detect signal variation, which in turn relies on the capability of the brain to process signal information. Here, we show that evolutionary change in a region of the brain devoted to the analysis of communication signals in mormyrid electric fishes improved detection of subtle signal variation and resulted in enhanced rates of signal evolution and species diversification. These results show that neural innovations can drive the diversification of signals and promote speciation.
Monday, May 2, 2011
Merck Neurosciences Seminar Series
UCSD Neurosciences Graduate Program
Center for Neural Circuits and Behavior Large Conference Room (formerly CMG)
Michael Brainard, UCSF School of Medicine
"Mechanisms of vocal learning in the songbird"