Breaking News
May 3, 2019 - Vaping and Smoking May Signal Greater Motivation to Quit
May 3, 2019 - Dementia looks different in brains of Hispanics
May 3, 2019 - Short-Staffed Nursing Homes See Drop In Medicare Ratings
May 3, 2019 - Study of teens with eating disorders explores how substance users differ from non-substance users
May 3, 2019 - Scientists develop new video game that may help in the study of Alzheimer’s
May 3, 2019 - Arc Bio introduces Galileo Pathogen Solution product line at ASM Clinical Virology Symposium
May 3, 2019 - Cornell University study uncovers relationship between starch digestion gene and gut bacteria
May 3, 2019 - How to Safely Use Glucose Meters and Test Strips for Diabetes
May 3, 2019 - Anti-inflammatory drugs ineffective for prevention of Alzheimer’s disease
May 3, 2019 - Study tracks Pennsylvania’s oil and gas waste-disposal practices
May 3, 2019 - Creating a better radiation diagnostic test for astronauts
May 3, 2019 - Vegans are often deficient in these four nutrients
May 3, 2019 - PPDC announces seed grants to develop medical devices for children
May 3, 2019 - Study maps out the frequency and impact of water polo head injuries
May 3, 2019 - Research on Reddit identifies risks associated with unproven treatments for opioid addiction
May 3, 2019 - Good smells may help ease tobacco cravings
May 3, 2019 - Medical financial hardship found to be very common among people in the United States
May 3, 2019 - Researchers develop multimodal system for personalized post-stroke rehabilitation
May 3, 2019 - Study shows significant mortality benefit with CABG over percutaneous coronary intervention
May 3, 2019 - Will gene-editing of human embryos ever be justifiable?
May 3, 2019 - FDA Approves Dengvaxia (dengue vaccine) for the Prevention of Dengue Disease in Endemic Regions
May 3, 2019 - Why Tonsillitis Keeps Coming Back
May 3, 2019 - Fighting the opioid epidemic with data
May 3, 2019 - Maggot sausages may soon be a reality
May 3, 2019 - Deletion of ATDC gene prevents development of pancreatic cancer in mice
May 2, 2019 - Targeted Therapy Promising for Rare Hematologic Cancer
May 2, 2019 - Alzheimer’s disease is a ‘double-prion disorder,’ study shows
May 2, 2019 - Reservoir bugs: How one bacterial menace makes its home in the human stomach
May 2, 2019 - Clinical, Admin Staff From Cardiology Get Sneak Peek at Epic
May 2, 2019 - Depression increases hospital use and mortality in children
May 2, 2019 - Vicon and NOC support CURE International to create first gait lab in Ethiopia
May 2, 2019 - Researchers use 3D printer to make paper organs
May 2, 2019 - Viral infection in utero associated with behavioral abnormalities in offspring
May 2, 2019 - U.S. Teen Opioid Deaths Soaring
May 2, 2019 - Opioid distribution data should be public
May 2, 2019 - In the Spotlight: “I’m learning every single day”
May 2, 2019 - 2019 Schaefer Scholars Announced
May 2, 2019 - Podcast: KHN’s ‘What The Health?’ Bye-Bye, ACA, And Hello ‘Medicare-For-All’?
May 2, 2019 - Study describes new viral molecular evasion mechanism used by cytomegalovirus
May 2, 2019 - SLU study suggests a more equitable way for Medicare reimbursement
May 2, 2019 - Scientists discover first gene involved in lower urinary tract obstruction
May 2, 2019 - Researchers identify 34 genes associated with increased risk of ovarian cancer
May 2, 2019 - Many low-income infants receive formula in the first few days of life, finds study
May 2, 2019 - Global study finds high success rate for hip and knee replacements
May 2, 2019 - Taking depression seriously: What is it?
May 2, 2019 - With Head Injuries Mounting, Will Cities Put Their Feet Down On E-Scooters?
May 2, 2019 - Scientists develop small fluorophores for tracking metabolites in living cells
May 2, 2019 - Study casts new light into how mothers’ and babies’ genes influence birth weight
May 2, 2019 - Researchers uncover new brain mechanisms regulating body weight
May 2, 2019 - Organ-on-chip systems offered to Asia-Pacific regions by Sydney’s AXT
May 2, 2019 - Adoption of new rules drops readmission penalties against safety net hospitals
May 2, 2019 - Kids and teens who consume zero-calorie sweetened beverages do not save calories
May 2, 2019 - Improved procedure for cancer-related erectile dysfunction
May 2, 2019 - Hormone may improve social behavior in autism
May 2, 2019 - Alzheimer’s disease may be caused by infectious proteins called prions
May 2, 2019 - Even Doctors Can’t Navigate Our ‘Broken Health Care System’
May 2, 2019 - Study looks at the impact on criminal persistence of head injuries
May 2, 2019 - Honey ‘as high in sugars as table sugar’
May 2, 2019 - Innovations to U.S. food system could help consumers in choosing healthy foods
May 2, 2019 - FDA Approves Mavyret (glecaprevir and pibrentasvir) as First Treatment for All Genotypes of Hepatitis C in Pediatric Patients
May 2, 2019 - Women underreport prevalence and intensity of their own snoring
May 2, 2019 - Concussion summit focuses on science behind brain injury
May 2, 2019 - Booker’s Argument For Environmental Justice Stays Within The Lines
May 2, 2019 - Cornell research explains increased metastatic cancer risk in diabetics
May 2, 2019 - Mount Sinai study provides fresh insights into cellular pathways that cause cancer
May 2, 2019 - Researchers to study link between prenatal pesticide exposures and childhood ADHD
May 2, 2019 - CoGEN Congress 2019: Speakers’ overviews
May 2, 2019 - A new strategy for managing diabetic macular edema in people with good vision
May 2, 2019 - Sagent Pharmaceuticals Issues Voluntary Nationwide Recall of Ketorolac Tromethamine Injection, USP, 60mg/2mL (30mg per mL) Due to Lack of Sterility Assurance
May 2, 2019 - Screen time associated with behavioral problems in preschoolers
May 2, 2019 - Hormone reduces social impairment in kids with autism | News Center
May 2, 2019 - Researchers synthesize peroxidase-mimicking nanozyme with low cost and superior catalytic activity
May 2, 2019 - Study results of a potential drug to treat Type 2 diabetes in children announced
May 2, 2019 - Multigene test helps doctors to make effective treatment decisions for breast cancer patients
May 2, 2019 - UNC School of Medicine initiative providing unique care to dementia patients
May 2, 2019 - Nestlé Health Science and VHP join forces to launch innovative COPES program for cancer patients
May 2, 2019 - Study examines how our brain generates consciousness and loses it during anesthesia
May 2, 2019 - Transition Support Program May Aid Young Adults With Type 1 Diabetes
May 2, 2019 - Study shows how neutrophils exacerbate atherosclerosis by inducing smooth muscle-cell death
May 2, 2019 - Research reveals complexity of how we make decisions
Rewriting the brain pathway for consciousness

Rewriting the brain pathway for consciousness

Credit: University of Iowa

With a finding that will “rewrite neuroanatomy textbooks,” University of Iowa neurologist Aaron Boes, MD, Ph.D., and his colleagues show that the thalamus is not a critical part of the brain pathway involved in keeping humans awake and conscious.

The finding upends decades of medical dogma that placed the thalamus as a critical relay point for the signals originating in the brainstem and ending in the cortex that maintain consciousness (wakefulness). The new study, published online Nov. 12 as a preprint in the Annals of Neurology, provides the first systematic evidence from humans that questions the routing of this critical pathway. The study evaluates patients with strokes of the thalamus and shows that even extensive injury to the thalamus does not severely impair consciousness.

“Beyond just challenging a long-standing dogma that has persisted for decades, what’s really exciting about this finding is that it has implications for clinical care for patients,” says Boes, UI assistant professor of pediatrics and neurology and a member of the Iowa Neuroscience Institute. “Based on the old understanding, people have tried to stimulate the thalamus for disorders of consciousness without much success. Our results suggest that was the wrong target to go after and that the hypothalamus or basal forebrain would be better targets.”

Consciousness has two main elements—wakefulness and awareness. The more basic of the two, keeping the brain in a state of wakefulness, is what the UI team focused on in the current study. When this basic function is lost the result is coma, or loss of consciousness.

The idea that the wakefulness pathway runs from the brainstem to thalamus to cortex came from influential studies done in the 1940s-50s that correctly identified the brainstem as a critical area for arousing the cortex. The researchers suggested that projections from the brainstem likely passed through the thalamus to reach the cerebral cortex. Because the brainstem evidence was so strong, the assumption was that the thalamus evidence was strong, too.

Despite a lack of concrete evidence, this pathway subsequently became textbook knowledge for students learning neuroanatomy. However, recent work in animals has shown that the thalamus may not be a critical part of the pathway, challenging the model.

To evaluate the role of the thalamus in the neural circuitry of arousal in humans, the UI team led by Boes and Joel Geerling, MD, Ph.D., assistant professor of neurology, searched medical records to identify 33 patients who had had a stroke that affected the thalamus. They used the patients’ MRI images to map the precise brain areas damaged by the stroke and assessed the level of consciousness for each patient within the first 12 hours of the stroke.

There were four patients with severely impaired arousal (coma, or stupor), all of whom had damage that extended beyond the thalamus into the hypothalamus and brainstem. In contrast, none of the patients with damage confined purely to the thalamus experienced severe impairment of arousal (wakefulness).

“It looks like the pathway most critical for maintaining consciousness runs from the brainstem through the hypothalamus and basal forebrain into the cortex,” Boes says. “I hope future studies will now focus on this new pathway. I think that could change the management of patients in a coma, and those with other disorders of consciousness.”

The new study is part of a larger effort by Boes and Geerling to investigate the brain pathways critical for maintaining consciousness. The researchers think that the other pathway (brainstem to thalamus to cortex) might have more of a role in attention and awareness.

“A key aspect of our study is identifying a similarity between the human brain and basic neuroscience findings in other mammals, mice included,” says Geerling, who also is a member of the Iowa Neuroscience Institute. “This means human wakefulness probably emerges from a network with the same basic wiring principles that evolved in other mammals, which suggests that our detailed studies of this network in mice or other model species will help identify new ways to treat human patients.”

An accompanying editorial written by Nicholas Schiff, professor of neuroscience at Weill Cornell Medical College, suggests that other neurologists also find the study convincing. Boes is hopeful this might mean that the next edition of neuroanatomy textbooks explaining disorders of consciousness will update the pathway to account for the new findings.

“Usually that kind of change takes years, but we are hopeful this time might be much faster,” he says.


Explore further:
Study reveals a network within the brain that plays a role maintaining consciousness

More information:
Joseph Hindman et al, Thalamic Strokes that Severely Impair Arousal Extend into the Brainstem, Annals of Neurology (2018). DOI: 10.1002/ana.25377

Journal reference:
Annals of Neurology

Provided by:
University of Iowa

About author

Related Articles