Source: Laboratory of Jonathan Flombaum—Johns Hopkins University
Human color vision is impressive. People with normal color vision can tell apart millions of individual hues. Most amazingly, this ability is achieved with fairly simple hardware.
Part of the power of human color vision comes from a clever bit of engineering in the human brain. There, color perception relies on what is known as an 'opponent system.' This means that the presence of one kind of stimulus is treated as evidence for the absence of another, and vice versa; absence of one kind of stimulus is taken as evidence for the presence of the other. In particular, in the human brain there are cells that fire both when they receive signals to suggest that blue light is present, or when they do not receive signals suggesting yellow light. Similarly, there are cells that fire in the presence of yellow or the absence of blue. Blue and yellow are thus treated as opponent values in one dimension, and can be thought of as negative versus positive values on one axis of a Cartesian plane. If a stimulus is characterized as having a negative value on that axis, it can't also have a positive value. So, if it is characterized as yellow, it can't also be characterized as blue. Similarly, green and red (or really, magenta), o…
Sensation and Perception
EEG is a non-invasive technique that can measure brain activity. The neural activity generates electrical signals that are recorded by EEG electrodes placed on the scalp. When an individual is engaged in performing a cognitive task, brain activity changes and these changes can be recorded on the EEG graph. Therefore, it is a powerful tool for cognitive scientist aiming to better understand the neural correlates associated with different aspects of cognition, which will ultimately help them devise improved treatments for patients with cognitive deficits.
Here, JoVE presents a brief overview of EEG and its applications in cognitive research. First, we discuss where and how EEG signals are generated. Then, we explain the use of EEG in studying cognition along with a detailed step-by-step protocol to perform an EEG experiment. Lastly, the video reviews some specific cognitive experiments that use EEG in combination with other techniques such as functional Magnetic Resonance imaging (fMRI) or transcranial direct current stimulation (tDCS).…
Source: Laboratories of Jonas T. Kaplan and Sarah I. Gimbel—University of Southern California
Decision-making is an important component of human executive function, in which a choice about a course of action or cognition is made from many possibilities. Damage to the inferior parts of the frontal lobes can affect a person's ability to make good decisions. However, while decision-making deficits can have a large impact on one's life, these deficits can be difficult to quantify in the laboratory. In the mid-1990s, a task was designed to mimic real life decision-making in the laboratory. This task, known as the Iowa Gambling Task (IGT), is a cognitively complex task used widely in research and clinical studies as a highly sensitive measure of decision-making ability.1-3
In the IGT, a participant is shown four decks of cards and chooses to reveal a card from one deck on each turn. When a card is turned over, the participant will receive some money, but sometimes will also be required to pay a penalty. Two of the decks have higher payoffs, but also have high penalties such that choosing from these decks leads to a net loss in the long term. The other two decks have lower payoffs, but also present smaller penalties, so that choosing from these decks leads to a net gain. Thus, to make an a…
Source: Laboratories of Jonas T. Kaplan and Sarah I. Gimbel— University of Southern California
The human visual system is incredibly sophisticated and capable of processing large amounts of information very quickly. However, the brain's capacity to process information is not an unlimited resource. Attention, the ability to selectively process information that is relevant to current goals and to ignore information that is not, is therefore an essential part of visual perception. Some aspects of attention are automatic, while others are subject to voluntary, conscious control. In this experiment we explore the mechanisms of voluntary, or "top-down" attentional control on visual processing.
This experiment leverages the orderly organization of visual cortex to examine how top-down attention can selectively modulate the processing of visual stimuli. Certain regions of the visual cortex appear to be specialized for processing specific visual items. Specifically, work by Kanwisher et al.1 has identified an area in the fusiform gyrus of the inferior temporal lobe that is significantly more active when subjects view faces compared to when they observe other common objects. This area has come to be known as the Fusiform Face Area (FFA). Another brain region, known as the Para…
Neuroanatomy is the study of nervous system structures and how they relate to function. One focus of neuroanatomists is the macroscopic structures within the central and peripheral nervous systems, like the cortical folds on the surface of the brain. However, scientists in this field are also interested in the microscopic relationships between neurons and glia - the two major cell types of the nervous system. This video provides a brief overview of the history of neuroanatomical research, which dates back to the 4th century BC, when philosophers first proposed that the soul resides in the brain rather than the heart. Key questions asked by neuroanatomists are also reviewed, including topics like the role cytoarchitecture, or the arrangement of neurons and glia, plays in brain function; and how neuroanatomy changes as a result of experience or disease. Next, some of the tools available to answer these questions, such as histology and magnetic resonance imaging, are described. Finally, the video provides several applications of neuroanatomical research, demonstrating how the field lives on in today’s neuroscience labs.…
1Laboratory of Neuromodulation, Department of Physical Medicine & Rehabilitation, Spaulding Rehabilitation Hospital and Massachusetts General Hospital, Harvard Medical School, 2School of Medicine, Pontifical Catholic University of Ecuador, 3Charité University Medicine Berlin, 4The City College of The City University of New York, 5Headache & Orofacial Pain Effort (H.O.P.E.), Biologic & Materials Sciences, School of Dentistry, University of Michigan
1Department of Psychology, University of New Mexico, 2Department of Neurology, University of California, San Francisco, 3Department of Physiology, Center for Integrative Neuroscience, University of California, San Francisco, 4Department of Psychiatry, University of California, San Francisco