Neurolecture Seminar Series
Imagery is everything
Thomas Naselaris, Medical University of South Carolina
- November 15, 2019
- 11:00 am
- Reynolds School of Journalism, Room 101
Many of us spend much of our waking life generating and inspecting mental images. We know from neuroimaging studies that mental imagery excites the same broad network of cortical areas that are excited during vision. Yet there are few models of visual cortex that explain how or why mental imagery emerges alongside seeing. We propose that mental imagery arises because the visual system relentlessly queries relationships between the visual features it represents. According to this view, the existence of mental imagery is an essential fact about how visual cortex makes sense of the world. We formalize this idea by modeling imagery as inference in a deep generative network. We present fMRI evidence in support of the model from imagery experiments that permit estimates of the regions of imagined space and the imagined visual features that most excite individual voxels in the visual cortex. We then describe ongoing work toward an ambitious test of the model in which we estimate network architectures directly from a massive database of brain responses to natural scenes.
Perceiving Faces and Making Faces
Richard Russell, Gettysburg College (Psychology)
- October 18, 2019
- 2:00 pm
- Reynolds School of Journalism, Room 101
Our visual perception of the world relies on contrast between adjacent regions. In this talk, I describe work demonstrating the importance of contrast for the perception of faces, skin, and people. First I show that the contrast between the facial features and the surrounding skin, termed ‘facial contrast', plays a role in perceiving gender, age, health, and beauty from faces. Facial contrast is also modified by typical makeup use. I then demonstrate how contrast between the skin and adjacent surfaces such as hair or facial features modulates the appearance of skin evenness and wrinkles. This modulation is due to a lower-level mechanism, likely contrast gain control. Finally, I discuss how makeup and other methods of personal adornment can and could modify the appearance of skin and faces.
The Cognitive Neuroscience of Episodic Memory Retrieval Across the Adult Lifespan
Michael Rugg, University of Texas at Dallas, Behavioral and Brain Sciences
- October 11, 2019
- 1:00 pm
- Reynolds School of Journalism, Room 101
I will describe findings from a series of fMRI studies that examine the neural regions, networks, and patterns of cortical activity that accompany successful episodic memory retrieval (recollection). I will present evidence that recollection is associated with a consistent pattern of enhanced activity in a ‘core recollection network' as well as enhanced functional connectivity between the network and a domain-general executive control network. I will also describe findings indicating that recollection is associated with reinstatement in the brain of processes and representations that were active when the recollected event was first experienced. Each of these neural correlates of recollection is largely impervious to the effects of age, at least when older participant samples comprise healthy individuals at low risk for neurodegenerative disease. The implications of these findings for understanding the neural bases of both recollection and age-related episodic memory decline will be discussed.