1Center for the Study of Children at Risk, Alpert Medical School, Brown University, 2Women & Infants Hospital of Rhode Island, 3University of Massachusetts, Boston
Source: Laboratories of Jonas T. Kaplan and Sarah I. Gimbel—University of Southern California
The autonomic nervous system (ANS) controls the activity of the body's internal organs and regulates changes in their activity depending on the current environment. The vagus nerve, which innervates many of the internal organs, is an important part of the system. When our brain senses danger, vagal tone is inhibited, leading to a set of changes in the body designed to make us more prepared to fight or flee; for example, our heart rate increases, our pupils dilate, and we breath more quickly. Conversely, when the vagal system is activated, these physiological responses are inhibited, leading to a calmer state. The vagus nerve, then, acts as a kind of "brake" on our arousal. One interesting consequence of this calmer state is that it tends to promote social interaction-when we are not tensed and afraid of our immediate environment we are instead receptive to interacting with others. Poor functioning of this regulatory mechanism, therefore, may be associated with difficulties in social behavior.
One index of autonomic regulation is heart rate variability (HRV). HRV is a measure of how much the gap between one beat and the next varies over time. High HRV means there are continual fluctuations in the …
Source: Jaideep S. Talwalkar, MD, Internal Medicine and Pediatrics, Yale School of Medicine, New Haven, CT
Observation and inspection is fundamental to physical examination and begins at the first point of contact with a patient. While observation and inspection are often used interchangeably, observation is a general term that refers to the careful use of one's senses to gain information. Inspection is an act limited to what one can observe visually, and when referring to physical examination, typically refers to findings on the surface of the body, rather than to behaviors. Skilled clinicians utilize all of their senses to assist with gaining an understanding of their patients, relying on vision, touch (percussion and palpation), and hearing (percussion and auscultation) primarily. Smell can also provide important diagnostic information during the patient encounter (e.g., personal hygiene, substance use, or metabolic diseases). Fortunately the sense of taste is largely a historical relic in medicine, though it is interesting to note that diabetes mellitus was diagnosed for many centuries by the sweet taste of the urine. Through experience, clinicians develop an important sixth sense - the gut instinct - that can only be gained through deliberate practice of clinical skills on thousands of pati…
Physical Examinations I
Source: Laboratory of Jonathan Flombaum—Johns Hopkins University
In order for recognition of a certain stimulus to take place, visual attention needs to be directed towards said stimulus. To the earliest parts of the visual system, objects are not objects, they are collections of visual features-lines, corners, changes in texture, color, and light. Attention is the resource that is necessary for later processing in order to recognize what a given bundle of features adds up to. This makes attention a central focus of research. One especially important set of questions concerns how people sustain attention, that is, the extent to which they can continuously maintain a focus of attention from moment-to-moment. It is now known that sustained attention takes great effort. When attention needs to be focused very rapidly on something that is moving or changing very quickly, the effort involved causes a momentary lapse in attention once it is disengaged. This kind of lapse in attention is called an attentional blink. It is like the brain blinks for a moment, shutting down attention for a rest. Stimuli that appear during an attentional blink will not be perceived.
In 1992, a group of researchers devised a paradigm to study the attentional blink, and the paradigm has come to be known by the same nam…
Sensation and Perception
1Biomedical Sciences, Tufts University Cummings School of Veterinary Medicine, 2School of Healthcare Sciences, Manchester Metropolitan University