According to a recent research, dehydration alters human brain shape and activity and even slackens task performance.A Georgia Institute of Technology study suggests that when dehydration strikes, part of the brain can swell, neural signaling can intensify, and doing monotonous tasks can get harder.The researchers also found that even without dehydration, exertion and heat put a dent in test subjects’ performance, but water loss made the dent about twice as deep.”We wanted to tease out whether exercise and heat stress alone have an impact on your cognitive function and study the effect of dehydration on top of that,” said Mindy Millard-Stafford, the study’s principal investigator.In the experiments, when participants exercised, sweated and drank water, fluid-filled spaces called ventricles in the center of their brains contracted. But with exertion plus dehydration, the ventricles did the opposite; they expanded.
Functional magnetic resonance imaging (fMRI) revealed the differences. Oddly, the ventricle expansion in dehydrated test subjects may not have had much to do with their deeper slumps in task performance.
“The structural changes were remarkably consistent across individuals,” said Millard-Stafford. “But performance differences in the tasks could not be explained by changes in the size of those brain areas.”The cerebrum is connected by the brainstem to the spinal cord. The brainstem consists of the midbrain, the pons, and the medulla oblongata. The cerebellum is connected to the brainstem by pairs of tracts. Within the cerebrum is the ventricular system, consisting of four interconnected ventricles in which cerebrospinal fluid is produced and circulated. Underneath the cerebral cortex are several important structures, including the thalamus, the epithalamus, the pineal gland, the hypothalamus, the pituitary gland, and the subthalamus; the limbic structures, including the amygdala and the hippocampus; the claustrum, the various nuclei of the basal ganglia; the basal forebrain structures, and the three circumventricular organs. The cells of the brain include neurons and supportive glial cells. There are more than 86 billion neurons in the brain, and a more or less equal number of other cells. Brain activity is made possible by the interconnections of neurons and their release of neurotransmitters in response to nerve impulses. Neurons connect to form neural pathways, neural circuits, and elaborate network systems. The whole circuitry is driven by the process of neurotransmission.In culture, the philosophy of mind has for centuries attempted to address the question of the nature of consciousness and the mind-body problem. The pseudoscience of phrenology attempted to localise personality attributes to regions of the cortex in the 19th century. In science fiction, brain transplants are imagined in tales such as the 1942 Donovan’s Brain.
“The areas in the brain required for doing the task appeared to activate more intensely than before, and also, areas lit up that were not necessarily involved in completing the task,” said the study’s first author Matt Wittbrodt.
“We think the latter may be in response to the physiological state: the body signaling, ‘I’m dehydrated’.”
Mind-Numbing TaskThe task the subjects completed was mindless and repetitive.For 20 straight minutes, they were expected to punch a button every time a yellow square appeared on a monitor. Sometimes, the square appeared in a regular pattern, and sometimes it appeared randomly. The task was dull for a reason.
“It helped us to avoid the cognitive complexity behind elaborate tasks and strip cognition down to simple motor output,” Wittbrodt said. “It was designed to hit essential neural processing one would use to make straightforward, repetitive movements.”The study has been published in Physiological Reports.
