What spontaneous neural activity reveals about the brain

You look at a photograph of a hiker in an alpine landscape. The hiker, her dog, the trees in the background, and the houses of a village in the distance are vividly reconstructed by your brain from the shades of light and color on the paper. The subjects of the picture are so distinct and clear that it is hard to see how difficult it was for your visual system to reconstruct it. A closer examination highlights some of the problems our brain has to overcome: The hiker in the foreground is higher and occupies a larger area than the houses and the trees in the background, yet you perceive her as being smaller. The dog is partially hidden by one of the legs of its master, yet you perceive it as a single animal, rather than two half-dogs. Theoretical models and psychological experiments led researchers to think that, in these examples and in countless other everyday situations, your brain makes use of an internal model of the world, built over a lifetime of experiences, to correctly interpret the image.

By analyzing the mathematical equivalents of the internal model, researchers in Jozsef Fiser’s lab in the Volen Center for Complex Systems at Brandeis and colleagues at Cambridge University (UK) deduce that, if the internal model works as hypothesized by theoreticians, traces of its functioning would be seen in neural activity recorded in complete darkness. Intuitively, an internal model would use its understanding of typical natural images to “fill-in” noisy and incomplete parts of a visual scene. As the brightness of an image is reduced, the visual system increasingly relies on prior expectations, until most of the neural activity is dominated by the internal model. This intuition is compatible with previous observations of neural data showing strong and coordinated activity in the visual system in the absence of visual stimulation, whose significance had remained unexplained.

Figure 1: The two panels show the distribution of all possible instantaneous activity patterns on 16 electrodes, in response to natural movies (M, x-axis) and during spontaneous activity in the dark (S, y-axis). Colors represent the number of electrodes detecting activity in each pattern, as shown in the legend on the left. In a young ferret, just after eye opening, the frequency with which the patterns occur is very different in the two conditions (left panel); instead, for an adult animal of about 4 months of age, the two distributions are very similar, as indicated by the patterns clustering around the diagonal.

In a paper published this week in Science, the authors analyzed neural activity in the primary visual cortex of ferrets watching natural scenes or artificial patterns, or just sitting in darkness. They found that, as predicted by the model, when the animal is in darkness the recorded patterns of neural activity closely resemble those recorded in response to natural visual scenes, but not those recorded in response to artificial stimuli. The fact that the similarity was specific to natural scenes indicates that the neural activity was due to the model’s expectations about the environment, and not to some other secondary effects. The authors repeated the measurements on animals at different stages of development, and found that the match of neural activity in the dark and in natural images was not present at birth, but rather gradually developed over the first four months of visual experience, as the internal model adapted to the statistics of the external world.

These results provide neural evidence for the internal models theorized by computational neuroscientists, and allow us to take a glance at the computations performed by the visual areas of the brain.

GSA 2010: an eye-opening experience

What happens when you organize a conference based on a population rather than a field of study? Everybody gets an eye-opening experience! At the end of November, members of Brandeis Psychology and Neuroscience community presented research at the 63rd annual Gerontological Society of America conference. Members from Art Wingfield’s Memory and Cognition Lab, Derek Isaacowitz’s Emotion Lab, and Margie Lachman’s Lifespan Developmental Psychology Lab all presented research at this conference.
This conference includes research on a wide area of aging topics from many different disciplines: behavioral and social sciences, health sciences, biological sciences, and social policy and practice.

To give an idea of the variety of ideas discussed at the conference, here is a sampling of session titles:

  • “Introduction to medicare part d data for research”
  • “Differences in Stroke Care Settings: Findings from the Patient Preference for Stroke Study”
  • “Age-related Differences and Similarities in Learning and Memory”
  • “Followed to extinction: Predictors of exceptional Survival in Very Long Term Cohort Studies”
  • “Composition Changes and Muscle Function: Targets for Preserving Health and Function”

This conference allowed members of the Brandeis scientific community to share their research with peers in their field and members of their academic family, as well as scientists and professionals from other fields. Although sharing research with your peers is always a productive experience, interacting with those from completely other fields also proved to be an invaluable exercise. It allowed attendees to be reminded of the assumptions that are made within any given discipline or paradigm, and allowed practice in communicating results to a broader audience.

All of this took place in the great city of New Orleans. The Cajun was music and food was enjoyed by many, and a great great time was had by all!

Wingfield Receives 2010 Baltes Distinguished Research Achievement Award

Update; BrandeisNOW has a in-depth profile on Prof. Wingfield.

Professor Arthur Wingfield is the 2010 recipient of the Baltes Distinguished Research Achievement Award. The $5000 award, given annually by the Margaret M. and Paul B. Baltes Foundation and Division 20 (Adult Development and Aging) of the American Psychological Association (APA), recognizes outstanding contributions to our understanding of adult development and aging. As part of the award, Wingfield will deliver a keynote address at the next annual meeting of the APA.

The number of adults age 65 or older in the US is expected to grow from 35 million in the year 2000, to 70.3 million in 2030.  Among this group, hearing loss is the third most prevalent chronic medical condition, exceeded only by arthritis and hypertension.  The hearing loss associated with adult aging, or presbycusis (literally, “old hearing”) presents a more complex picture than many realize. Whether the loss is mild or more severe, the source is a thinning of hair cells located in the cochlea, a spiral-shaped structure about only the size of the nail on your little finger. There are also “higher level” effects that include the pathways from the cochea to the brain, and age-related changes in the auditory receiving areas of the brain itself. These biological changes result in the older listener expending attentional effort that is not only tiring, but can draw on resources that would ordinarily be available for encoding what has been heard in memory.

This recent award recognizes Wingfield and his Brandeis colleagues’ contributions to understanding this complex interaction between sensory and cognitive changes in adult aging.  Arthur Wingfield is the Nancy Lurie Marks Professor of Neuroscience and director of the Volen National Center for Complex Systems at Brandeis.  His work has also been recognized by the American Speech, Language and Hearing Association, and two successive MERIT Awards from the NIH’s National Institute on Aging.

Re-vamped course for Spring 2011 — PSYC 213a: Social Neuroscience and Culture

This course combines two current topics in Psychology, exploring how the social interactions of humans are processed by the brain and the ways that culture can shape social, as well as cognitive, processes.  Topics include the self, stereotyping, empathy, neuroeconomics, and biculturalism.  In addition to a focus on fMRI research, Dr. Janelle Beadle, a postdoctoral trainee in Neuroscience, will serve as a co-Instructor, lending her expertise in patient research.

Previously taught three years ago as PSYC 180a, this course has been re-listed as a graduate course (although advanced undergraduates are welcome to enroll, pending instructor approval) to allow for more hands-on work, such as the design of cross-cultural research studies.  Prof. Angela Gutchess notes that both social neuroscience and cross-cultural research (and even “cultural neuroscience”, the combination of the two) have grown tremendously in the short time since the course was last offered, and that she is particularly excited to be teaching this course upon return from her semester in Istanbul, Turkey as a Fulbright Scholar.

Control beliefs, social support, and physical exercise are probably good for you

In a paper recently publised in PLoS One entitled Promoting functional health in midlife and old age: long-term protective effects of control beliefs, social support, and physical exercise, Margie Lachman, Minnie and Harold Fierman Professor of Psychology, and Brandeis postdoc Stefan Agrigoroaei analyzed data from MIDUS, a national longitudinal study of “Midlife in the US”. Controlling for other risks, the authors found significant positive contributions from three additional factors in the functional health outcome in these older adults:

  1. Control beliefs (the perception that one can influence what happens in one’s life)
  2. Social support (feeling support, not strain, in relationships with family, friends, and spouse)
  3. Physical exercise

Since I’ll be healthier if I believe I can control my health this way, why not give it a try? The popular press is also picking up on these ideas.

Connecting with underrepresented minorities in the sciences

For the past six years, Brandeis has been participating yearly at two undergraduate-oriented conferences in an effort to recruit the best minority students for the life sciences graduate programs. These two conferences are: SACNAS (Society for advancing Hispanics/chicanos and Native American in science) and ABRCMS (Annual Biomedical research conference for minority students).

This year SACNAS was held at Anaheim, CA during September 30 and October 3. Professor Jim Morris and 2 graduate students represented Brandeis and interacted with post-docs, graduate students, pre college teachers, undergrads and other 300 exhibitors. The theme of this year conference was Science, Technology & Diversity for a Sustainable Future. In addition, SACNAS combined efforts with MAES (Society for Mexican American engineers and scientists) in order to make the experience more interdisciplinary.

For the past 30 years SACNAS has been holding this conference to enforce the underrepresented minority population in science to pursue advanced degrees, careers, and positions of leadership. A Brandeis SACNAS chapter was created over a year ago, in order to provide information and give access to professional tools to all the undergrads interested in pursuing careers in science. This year, the Brandeis SACNAS chapter was recognized during the meeting as a new chapter, and 9 of our undergraduates participated in the conference; 2 of them Angel Garcia and Kerwin Vega, presented their research in the poster sessions. You can also connect with the Brandeis chapter on Facebook.

– Yaihara Fortis

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