Where is the periaqueductal gray?
The periaqueductal gray, or PAG, is an area of gray matter found in the midbrain. The PAG surrounds the cerebral aqueduct (hence the name periaqueductal) and occupies a column of brainstem that stretches about 14 mm long. There are no obvious visible anatomical divisions within the PAG, but researchers have divided the PAG into four columns based on differences in connectivity and function: the dorsomedial, dorsolater........ Read more »
Behbehani, M. (1995) Functional characteristics of the midbrain periaqueductal gray. Progress in Neurobiology, 46(6), 575-605. DOI: 10.1016/0301-0082(95)00009-K
T. gondii cyst in a mouse brain.
For a simple protozoan, Toxoplasma gondii has experienced something of a meteoric rise in popularity over the past several years. Actually, to be fair T. gondii has garnered quite a bit of interest since the 1930s, when it was discovered the parasite could be transmitted from a mother to a fetus in the womb, sometimes resulting in severe congenital disorders. Curiosity about T. gondii grew significantly in the early 2000s, ........ Read more »
THE AMYGDALA SHOWN ALONG WITH OTHER LIMBIC SYSTEM STRUCTURES.
The amygdala---or, more appropriately, amygdalae, as there is one in each cerebral hemisphere---was not recognized as a distinct brain region until the 1800s, and it wasn't until the middle of the twentieth century that it began to be considered an especially significant area in mediating emotional responses. Specifics about the role of the amygdala in emotion remained somewhat unclear, however, ........ Read more »
LeDoux, Joseph. (2007) The Amygdala. Current Biology. info:/
While it may be difficult to imagine in a day and age when psychiatric medicines are advertised as a way to treat nearly every mental disorder, only 65 years ago targeted and effective psychiatric medicines were still just an unrealized aspiration. In fact, until the middle of the 20th century, the efficacy and safety of many common approaches to treating mental illness were highly questionable. For example, one method of treating schizophrenia that was common in the 1940s........ Read more »
López-Muñoz, F., Alamo, C., cuenca, E., Shen, W., Clervoy, P., & Rubio, G. (2005) History of the Discovery and Clinical Introduction of Chlorpromazine. Annals of Clinical Psychiatry, 17(3), 113-135. DOI: 10.1080/10401230591002002
Headaches are one of the most common neurological complaints; most people will experience headaches at some point in their life and close to 50% of the world's population is estimated to be suffering from a headache disorder at any point in time. The World Health Organization considers headaches to be one of the most disabling conditions people experience based on the impact chronic headaches can have on quality of life.There are more than 200 different types of headaches, which are broadly clas........ Read more »
Burstein, R., Noseda, R., & Borsook, D. (2015) Migraine: Multiple Processes, Complex Pathophysiology. Journal of Neuroscience, 35(17), 6619-6629. DOI: 10.1523/JNEUROSCI.0373-15.2015
In 1867, an archaeologist and diplomat named Ephraim George Squier sought out the help of Paul Pierre Broca, the esteemed anatomist and surgeon. He was trying to solve a mystery about an ancient Incan skull that had been given to him by a wealthy artifact collector in Peru. In addition to its age, the Neolithic skull had a unique feature: on the top of the cranium a rectangular piece of bone had been removed. The presence of several cross-cuts surrounding the hole suggested that it was not a sim........ Read more »
Clower, W., & Finger, S. (2001) Discovering Trepanation: The Contribution of Paul Broca. Neurosurgery, 49(6), 1417-1426. DOI: 10.1097/00006123-200112000-00021
Where is the vestibular system?The vestibular system is comprised of several structures and tracts, but the main components of the system are found in the inner ear in a system of interconnected compartments called the vestibular labyrinth. The vestibular labyrinth is made up of the semicircular canals and the otolith organs (all discussed below), and contains receptors for vestibular sensations. These receptors send vestibular information via the vestibulocochlear nerve to the cerebellum and to........ Read more »
Khan S, Chang R. (2013) Anatomy of the vestibular system: A review. NeuroRehabilitation, 32(3), 437-443. info:/
Think for a moment about the people in your life whom you are closest to and most familiar with---those whom you see, talk to, and maybe share intimate moments with on a regular basis. Perhaps this would be your spouse, partner, parents, siblings, or friends. Now, try to imagine waking up tomorrow and, upon seeing one of these people, being overcome with an unshakable feeling that it is not really them you are seeing. Even though you know it sounds crazy, you can't stop yourself from thinking th........ Read more »
The Centers for Disease Control and Prevention estimates that as many as 1.7 million people in the United States experience a traumatic brain injury (TBI) each year, over 15% of which are thought to be sports-related. Despite the relatively high prevalence of these injuries, however, it seems we are just beginning to appreciate the true extent of the effects they can have on the brain. Awareness of previously unrecognized consequences to TBI and repeated TBI--along with the realization that........ Read more »
Blennow, K., Hardy, J., & Zetterberg, H. (2012) The Neuropathology and Neurobiology of Traumatic Brain Injury. Neuron, 76(5), 886-899. DOI: 10.1016/j.neuron.2012.11.021
Where is the blood-brain barrier?The blood-brain barrier surrounds most of the blood vessels in the brain. It is a structure that is formed primarily due to the establishment of tight junctions between endothelial cells (i.e. cells that line the walls of blood vessels). There are also several other cells and proteins contributing to the blood-brain barrier complex; for example, processes called astrocytic end-feet extend from astrocytes to surround blood vessels and provide support to the endoth........ Read more »
Ballabh P, Braun A, & Nedergaard M. (2004) The blood-brain barrier: an overview: structure, regulation, and clinical implications. Neurobiology of disease, 16(1), 1-13. PMID: 15207256
There are many examples throughout nature of microorganisms like bacteria, viruses, and parasites influencing the neurobiology and behavior of their hosts. For example, the rabies virus enters the nervous system almost immediately after a bite or scratch and travels to the brain, where it influences neural activity to make aggressive behavior more likely. This, of course, is beneficial for the virus as it increases the probability its infected host will make contact with another susceptible host........ Read more »
Cryan, J., & Dinan, T. (2012) Mind-altering microorganisms: the impact of the gut microbiota on brain and behaviour. Nature Reviews Neuroscience, 13(10), 701-712. DOI: 10.1038/nrn3346
The term placebo effect describes an improvement in the condition of a patient after being given a placebo--an inert substance (e.g. sugar pill) the patient expects may hold some benefit for him. The placebo effect has long been recognized as an unavoidable aspect of medical treatment. Physicians before the 1950s often took advantage of this knowledge by giving patients treatments like bread pills or injections of water with the understanding that patients had a tendency to feel better when they........ Read more »
Wager, T., & Atlas, L. (2015) The neuroscience of placebo effects: connecting context, learning and health. Nature Reviews Neuroscience, 16(7), 403-418. DOI: 10.1038/nrn3976
Where is the default mode network?The default mode network (sometimes called simply the default network) refers to an interconnected group of brain structures that are hypothesized to be part of a functional system. The default network is a relatively recent concept, and because of this there is not yet a complete consensus on which brain regions should be included in a definition of it. Regardless, some structures that are generally included are the medial prefrontal cortex, posterior cingulate........ Read more »
Buckner RL, Andrews-Hanna JR, & Schacter DL. (2008) The brain's default network: anatomy, function, and relevance to disease. Annals of the New York Academy of Sciences, 1-38. PMID: 18400922
Parkinson's disease (PD) belongs to a group of diseases that are referred to as neurodegenerative because they involve the degeneration and death of neurons. In PD a group of structures called the basal ganglia, which play a role in facilitating movement, are predominantly affected. The substantia nigra, one of the basal ganglia nuclei as well as one of the most dopamine-rich areas in the brain, is severely impacted; by the end stages of the disease patients have often lost 50-70% of the dopamin........ Read more »
de Hemptinne, C., Swann, N., Ostrem, J., Ryapolova-Webb, E., San Luciano, M., Galifianakis, N., & Starr, P. (2015) Therapeutic deep brain stimulation reduces cortical phase-amplitude coupling in Parkinson's disease. Nature Neuroscience, 18(5), 779-786. DOI: 10.1038/nn.3997
Orbitofrontal cortex (in green)
Where is the orbitofrontal cortex?The orbitofrontal cortex is the area of the prefrontal cortex that sits just above the orbits (also known as the eye sockets). It is thus found at the very front of the brain, and has extensive connections with sensory areas as well as limbic system structures involved in emotion and memory.What is the orbitofrontal cortex and what does it do?The orbitofrontal cortex (OFC) is a poorly underst........ Read more »
To those who believe strongly in the scientific method, it really is the only approach to understanding the relationship between two events or variables that allows us to make assertions about such relationships with any confidence. Due to the inherent flaws in human reasoning, our non-scientific conclusions are frequently riddled with bias, misunderstanding, and misattribution. Thus, it seems there is little that can be trusted if it hasn't been scientifically verified.The scientific method, ho........ Read more »
Moncrieff, J. (2009) A Critique of the Dopamine Hypothesis of Schizophrenia and Psychosis. Harvard Review of Psychiatry, 17(3), 214-225. DOI: 10.1080/10673220902979896
Where is the cochlea?
cochlea and cochlea in cross-section. image courtesy of openstax college.
The cochlea is a coiled structure that resembles a snail shell (cochlea comes from the Greek kochlos, which means "snail"); it is found within the inner ear. It is a small--yet complex--structure (about the size of a pea) that consists of three canals that run parallel to one another: the scala vestibuli, scala media, and scala tympani.What i........ Read more »
If you're looking for an indication of how intricately human physiology is tied to the environment our species evolved in, you need look no further than our circadian clock. For, the internal environment of our body is regulated by 24-hour cycles that closely mirror the time it takes for the earth to rotate once on its axis. Moreover, these cycles are shaped by changes in the external environment (e.g. fluctuating levels of daylight) associated with that rotation. Indeed, this 24-hour cycle regu........ Read more »
LeGates, T., Fernandez, D., & Hattar, S. (2014) Light as a central modulator of circadian rhythms, sleep and affect. Nature Reviews Neuroscience, 15(7), 443-454. DOI: 10.1038/nrn3743
When you consider that so much of our energy and such a large portion of our behavioral repertoire is devoted to ways of ensuring our survival, suicide appears to be perhaps the most inexplicable human behavior. What would make this human machine--which most of the time seems to be resolutely programmed to scratch, claw, and fight to endure through even the most dire situations--so easily decide to give it all up, even when the circumstances may not objectively seem all that desperate? Suicide i........ Read more »
Epilepsy refers to a group of disorders that are characterized by recurrent seizures. It is a relatively common neurological condition, and is considered the most common serious (implying that there is a risk of mortality) brain disorder, affecting around 2.2 million Americans.The seizures associated with epilepsy are not homogenous; they can have a drastically different presentation depending on the patient, the part of the brain the seizure originates in, and how much of the brain the seizure ........ Read more »
Krook-Magnuson, E., & Soltesz, I. (2015) Beyond the hammer and the scalpel: selective circuit control for the epilepsies. Nature Neuroscience, 18(3), 331-338. DOI: 10.1038/nn.3943
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