neurological science

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Here’s a clearer version of my ADHD info graphic
Happy ADHD awareness month everyone!!

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Phineas Gage is one of the most famous patients in the history of neuroscience. He was 25 years old when he experienced a serious accident at his work place, where a tamping iron was shot through his head - entering under his eye socket at exiting through the top of his head - after an explosive charge went off. The tamping iron was over a metre long, and after exiting Gage’s head landed 25m away. 

Initially Gage collapsed and went into minor convlusions, but recovered quickly and was able to speak after a few minutes. He walked with little assistance to an ox-cart and was brought to a nearby physician. Initially the physician did not believe his story because he was in such good condition, but was convinced when: 

Mr. G. got up and vomited; the effort of vomiting pressed out about half a teacupful of the brain, which fell upon the floor.

Gage exhibited a number of dramatic behavioural changes following the accident. Harlow, the physician who initially treated Gage, described this change “He is fitful, irreverent, indulging at times in the grossest profanity (which was not pre­vi­ous­ly his custom), manifesting but little deference for his fellows, impatient of restraint or advice when it conflicts with his desires”. However the surgeon Henry Jacob Bigelow described his condition as improving over the course of recovery, stated he was “quite recovered in faculties of body and mind”. This may have been early evidence of neural plasticity. This recovery was also reported by a physician who knew Gage while he lived in Chile, who described his ability to hold on a full time job as a Concord coach driver, a job that required exceptional social skills.

Gage’s neurological deficits following his traumatic brain injury is thought to have been exaggerated and distorted over the course of history, to the point that he is often portrayed as a ‘psychopath’. Scientific analysis of the historical accounts of Gage’s life following his accident, namely by the psychologist Malcolm Macmillan, find that these distorted accounts are most likely untrue, and that Gage made a very good recovery.

Post-mortem analysis of the Gage case concluded that it was the left frontal lobe that was damaged in the accident, although further neurological damage may have resulted from infection. Combined examination of the Phineas Gage case with the other famous cases of Tan and H.M. have concluded that social behaviour, memory, and language are dependent on the co-ordination of a number of different brain areas rather than a single region.

A Collection Of Books By Neurologist Oliver Sacks

If you’re interested in neuroscience or psychology, I’d highly reccomend any book by Oliver Sacks! I get asked a lot about books to read so you can also check out this video I made with my top 7 and this masterpost which includes websites where you can learn more!

1. Migrane

For centuries, physicians have been fascinated by the many manifestations of migraine, and especially by the visual hallucinations or auras- similar in some ways to those induced by hallucinogenic drugs or deliria–which often precede a migraine. Dr. Sacks describes these hallucinatory constants, and what they reveal about the working of the brain. 

2. Awakenings

Awakenings is the remarkable account of a group of patients who contracted sleeping-sickness during the great epidemic just after World War I. Frozen in a decades-long sleep, these men and women were given up as hopeless until 1969, when Dr. Sacks gave them the then-new drug L-DOPA, which had an astonishing, explosive, “awakening” effect. Dr. Sacks recounts the moving case histories of these individuals, the stories of their lives, and the extraordinary transformations they underwent with treatment.

3. The Island of The Color Blind

Oliver Sacks has always been fascinated by islands, and this book is an account of his work with an isolated community of islanders born totally colorblind.  He listens to these achromatopic islanders describe their colorless world in rich terms of pattern and tone, luminance and shadow.

4. Uncle Tungsten

A book about Sacks’ childood;  his discovery of biology, his departure from his childhood love of chemistry and, at age 14, a new understanding that he would become a doctor.

5. An Anthropologist on Mars

This book talks about 7 seemingly paradoxical neurological conditions: including a surgeon consumed by the compulsive tics of Tourette’s Syndrome except when he is operating; an artist who loses all sense of color in a car accident, but finds a new sensibility and creative power in black and white; and an autistic professor who has great difficulty deciphering the simplest social exchange between humans, but has built a career out of her intuitive understanding of animal behavior. 

6.  Seeing Voices

 A journey into the world of deaf culture, and the neurological and social underpinnings of the remarkable visual language of the congenitally deaf. Sacks writes “The existence of a visual language, Sign, and the visual intelligence that goes with its acquisition, shows us that the brain is rich in potentials we would scarcely have guessed of, shows us the almost unlimited resource of the human organism when it is faced with the new and must adapt.”

Neurotransmitters

Central nervous system

  • Glutamate 
  • GABA 
  • Glycine 
  • Dopamine 
  • Serotonin 
  • Noradrenaline 
  • Histamine 
  • Orexin 
  • Endorphins 

Peripheral nervous system 

  • Noradrenaline 
  • Acetylcholine 

Neurotransmitter synthesis/packaging 

  • Some neurotransmitters are readily available amino acids eg Glutamate, glycine 
  • Some are synthesised by the cells that secrete them eg GABA, noradrenaline, dopamine 

Noradrenaline synthesis:

Packaging

  • In the presynapse, neurotransmitter is contained in vesicles 
  • The neurotransmitter must be packaged into the vesicle ready for release 
  • Uses transporters and proton gradients to package 

[packaging and release - above]

  • Neurotransmitter release is quantal – Each vesicle contains the same amount of neurotransmitter 
  • Therefore it is the number of vesicles fusing which determines the post synaptic potentials 
  • membranes must fuse for release - membrane fusion is energetically unfavourable so must be catalysed by something

SNARE Hypothesis 

  • Proteins on the presynaptic membrane ‘grab’ proteins on the vesicle membrane 
  • These SNARE proteins pull the two membranes close together 
  • SNARE proteins provide most of the energy for membrane fusion
  • v-SNARE (VAMP2) – on vesicle membrane 
  • t-SNAREs (syntaxin1A, SNAP-25) on target membrane 
  • Bind together to make SNARE complex 
  •  SNARE ‘zippering’ forces the membranes close together 
  • Spontaneous, highly energetically favourable 
  • Once assembled, they require ATP hydrolysis to separate them 
  •  Ca2+ binding to synaptotagmin provides extra energy to fuse the membranes

Neurotransmitter release

  • synaptic vesicle release sites are highly organised and regulated
  • exocytose into synaptic cleft

presynaptic active zone:


Neurotransmitter detection

  • Ionotropic (ion channel coupled) – Glutamate, GABA, Glycine 
  • Metabotropic (G-protein coupled) – monoamines, histamine etc. 
  • Some have both kinds, e.g. glutamate, GABA 
  • Ionotropic responses are faster 
  • Metabotropic responses can have more diverse effects 

Glutamate receptors

  • Glutamate is the main excitatory neurotransmitter in the brain 
  • Three classes of ionotropic receptor – AMPA – NMDA – Kainate 
  •  Named after pharmacological agonists 
  • All let in positive ions when they bind glutamate 
  • Glutamate also has a family of metabotropic receptors – mGluRs – These modulate neurotransmission 

AMPA Receptors 

  •  Main fast excitatory receptor 
  • Strength of a synapse is largely determined by its complement of AMPARs
  •  More AMPAR in the post-synaptic membrane = stronger synaptic transmission 

NMDA Receptors 

  • Minor role in postsynaptic firing 
  • Major role is in synaptic plasticity 
  • NMDA receptors are calcium permeable 
  • require strong neurotransmitter release to open 

So I sat the GAMSAT yesterday 💉 And today (after a substantial amount of sleep) I started my day by reading this wonderful novel. 

For those of you who haven’t read it, I’d 100% recommend! For anyone wondering, the flash cards are called Moore’s Clinical Anatomy Flash Cards ☀️☀️

P.S. You can follow my Instagram here: taylamaree7

bbc.com
Experts excited by brain 'wonder-drug' - BBC News
A drug for depression could stop all neurodegenerative diseases, including dementia, scientists hope.

Scientists hope they have found a drug to stop all neurodegenerative brain diseases, including dementia.

In 2013, a UK Medical Research Council team stopped brain cells dying in an animal for the first time, creating headline news around the world.

But the compound used was unsuitable for people, as it caused organ damage.

Now two drugs have been found that should have the same protective effect on the brain and are already safely used in people.

“It’s really exciting,” said Prof Giovanna Mallucci, from the MRC Toxicology Unit in Leicester.

She wants to start human clinical trials on dementia patients soon and expects to know whether the drugs work within two to three years.

Continue Reading.

Neurologic emergencies

´Cause lack of awareness is not an excuse.

Head injury

Seizure

Stroke

Spinal injury

Last but not least is acute neuromuscular weakness, which is nonspecific and common sign of several possible life-threatening causes: 

Unilateral weakness: Ischemic stroke,  Intracerebral hemorrhage,  Subarachnoid hemorrhage

Bilateral weakness: Brainstem stroke, Spinal cord disease, Peripheral nerve disease ( Guillain-Barré syndrome , Tick paralysis), Neuromuscular junction disease (Myasthenia Gravis, Organophospate poisioning, Botulism), Muscle disease (Alcoholic myopathy, Myositis)

Focal findings: Hypoglycemia, Periodic paralysis

Generalized weakness: Sepsis, Acute coronary syndrome, CO poisoning, Adrenal insufficiency

Other neurologic causes: Multiple sclerosis, Todd´s paralysis, Hemiplegic migrane

Other non-neurological causes: Hypothyroidism, Infection, Anemia, Dehydration or hypovolemia, Presyncope, Medication, Rheumatologic disease

“If you press somewhere, and the dog turns around and bites you, that’s usually a pretty good indicator that it hurts.”
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A 5 month old girl with alobar holoprosenceohaly. This condition was diagnosed prenatally in utero and understandably resulted in severe enlargement of the child’s head. The child was oriented to sound, able to move all extremities and responded to external stimuli, however the long term prognosis for this condition is poor as it is typically fatal in the neonatal period.

Neuro chip records brain cell activity at higher resolution

Brain functions are controlled by millions of brain cells. However, in order to understand how the brain controls functions, such as simple reflexes or learning and memory, we must be able to record the activity of large networks and groups of neurons. Conventional methods have allowed scientists to record the activity of neurons for minutes, but a new technology, developed by University of Calgary researchers, known as a bionic hybrid neuro chip, is able to record activity in animal brain cells for weeks at a much higher resolution. The technological advancement was published in the journal Scientific Reports.

“These chips are 15 times more sensitive than conventional neuro chips,” says Naweed Syed, PhD, scientific director of the University of Calgary, Cumming School of Medicine’s Alberta Children’s Hospital Research Institute, member of the Hotchkiss Brain Institute and senior author on the study. “This allows brain cell signals to be amplified more easily and to see real time recordings of brain cell activity at a resolution that has never been achieved before.”

The development of this technology will allow researchers to investigate and understand in greater depth, in animal models, the origins of neurological diseases and conditions such as epilepsy, as well as other cognitive functions such as learning and memory.

“Recording this activity over a long period of time allows you to see changes that occur over time, in the activity itself,” says Pierre Wijdenes, a PhD student in the Biomedical Engineering Graduate Program and the study’s first author. “This helps to understand why certain neurons form connections with each other and why others won’t.”

The cross-faculty team created the chip to mimic the natural biological contact between brain cells, essentially tricking the brain cells into believing that they are connecting with other brain cells. As a result, the cells immediately connect with the chip, thereby allowing researchers to view and record the two-way communication that would go on between two normal functioning brain cells.

“We simulated what Mother Nature does in nature and provided brain cells with an environment where they feel as if they are at home,” says Syed. “This has allowed us to increase the sensitivity of our readings and help neurons build a long-term relationship with our electronic chip.”

While the chip is currently used to analyze animal brain cells, this increased resolution and the ability to make long-term recordings is bringing the technology one step closer to being effective in the recording of human brain cell activity.

“Human brain cell signals are smaller and therefore require more sensitive electronic tools to be designed to pick up the signals,” says Colin Dalton, adjunct professor in the Department of Electrical and Computer Engineering at the Schulich School of Engineering and a co-author on this study. Dalton is also the facility manager of the University of Calgary’s Advanced Micro/nanosystems Integration Facility (AMIF), where the chips were designed and fabricated.

Researchers hope the technology will one day be used as a tool to bring personalized therapeutic options to patients facing neurological disease.