Introduction & Basics of Neuro

Introduction to Neurology

Brain Mapping

Through time, scientists and researchers have developed ways to map the brain. The term “mapping” refers to discovering ways to place and mark anatomical structures of the brain.

Phrenology

Developed by Francis Joseph Gall, a neuroanatomist and physiologist, derived from Greek with (phren) meaning “mind” and (logos) meaning “knowledge”

Have you ever thought a bump on your head could give you an idea about your personality?

The pseudoscience phrenology was a method derived around this idea, that bumps on a person’s head was a link to that person’s personality and character.

-So if you were a robber, a bump on the side of your head, according to phrenology, could mean you had a tendency to deceive, lie, and be clever. Or maybe if you were a dancer, a bump on the base of your neck could mean you were graceful, delicate and patient.

Gall proposed the following basic tenets of his system:
1) moral and intellectual faculties are innate
2) manifestation depends on organization
3) the brain is the organ of propensities, sentiments, and faculties
4) the brain is composed of as many particular organs as there are propensities, sentiments, and faculties which differ essentially from each other
5) the form of the skull represented and reflected the form and development of the brain’s organs

Although this method was largely disagreed upon, the basis and general idea of Gall’s method remained: the human brain was the center of cognition, intellect, emotion, perception and character and that different areas of the brain were responsible for different and specific mental capacities.

Brain Behavior Associations

Probably the most famous names associated with mapping language areas of the brain were Paul Broca and Carl Wernicke, the masters behind the discovery of Broca’s and Wernicke’s areas.

Paul Broca and Broca’s Area

Paul Broca was a French surgeon, anatomist, and anthropologist. His interest in the brain and language arose when he was working with a patient Leborgne, formally known as Tan, age 51.

Tan had no meaningful speech for 21 years, he had many neurological problems, he repeated the word “tan” (which is where his nickname came from) and other emotional utterances, and he had paralysis of the right sides, or right hemiplegia. Although Tan presented with all these problems, his muscles of articulation and phonation were intact and he had no issues with hearing.

Another one of Broca’s patients, Lelong, who was 84 years old, had suffered a stroke a year before meeting Broca. He was only able to produce five words (all in French): oui (yes), non (no), trois (three), toujour (all the time), and lelo (variation of his name).

Broca deduced that the damage must’ve occurred within an area involved with production of articulation or fluent speech production. This area, located in the inferior frontal lobe, mapped in the brain as Brodmann’s area (BA) 44,45 (pars triangularis and pars opercularis), later became known as Broca’s area, the site for speech production. A patient who has damage to this area, like Broca’s aphasia, has problems producing fluent speech, yet their comprehension is intact.

Carl Wernicke and Wernicke’s Area

Carl Wernicke was a German physician, psychiatrist, neuropathologist and anatomist. His interest in brain and language also arose with one of his patients, Susan Rother, age 75 years old.

Susan presented with an “expression of suffering”, yet a large enough vocabulary that a motor aphasia couldn’t be a possibility. She had “intact sensation”, and she had intact words but confused meanings. He later found out that patients with comprehension problems had: partial lesions of the sensory speech center, a large vocabulary, a loss in the ability to communicate via writing (agraphia), an inability to see and read words (alexia), but had no hemiplegia.

Wernicke deduced that the damage must’ve occurred within an area involved in language comprehension. This area, located in the superior temporal lobe, mapped in the brain as BA 22, later became known as Wernicke’s area, the site for language comprehension. Damage to this area, like Wernicke’s aphasia, will leave a patient with otherwise fluent and grammatical speech production but an impairment in language comprehension.

Here's a quick clip to give you an idea of what Broca's Aphasia is:

Here's a quick video to give you an idea of what Wernicke's Apasia is:

Brain Mapping Instruments

Thankfully, because we are living in a technologically advanced age, scientists and engineers have developed instruments used in visually viewing areas of the brain. This is especially important because anyone in a health science field (like speech-language pathologists) needs to be able to see where activity, or lack of, is occurring in the brain in order to diagnose and devise a treatment plan. (Think: where would Dr. Derek Shepherd be without his MRI scans! He wouldn’t have been the brilliant neurosurgeon that he was!)

Electroencephalogram (EEG)

used to detect and record electrical activity in the brain
small metal discs with electrodes are placed on the scalp and signals are sent to a computer to record results
measures event related potentials (ERP) or brain wave patterns

Positron Emission Tomography (PET)

Cortical Stimulation

normally used in epileptic patients
physically invasive procedure
patient is under local anesthesia and awake during the procedure
aim is to localize functions of specific brain regions through electrical stimulation of the cerebral cortex
language is assessed during name line drawings (so while a surgeon is marking different areas of the brain, they will have a patient, for example, count backwards from 10 to 1 to denote location of language area)

type of imaging test
uses a radioactive substance, known as a tracer, to detect disease in the body (this scan can detect the early onset of a disease before it’s evident, as compared to any other imaging test)
shows how organ and tissues are working
can be used in conjunction with computerized (or computed) tomography (commonly refereed to as CT or CAT scan)

Functional Magnetic Resonance Imaging (fMRI)

imaging technique that uses MRI machinery
measures brain activity
detects changes associated with blood oxygenation and flow that occur due to a response in neural activity
can be used to produce activation maps, showing which parts of the brain are involved in a particular mental process

Diffusion Tensor Imaging (DTI)

image based technique also using MRI technology
identifies structural connections between regions
detects how water travels along the white matter tracts (which connect different parts of the brain, so must they remain protected)
able to visualize location, orientation and directional dependence of brain’s white matter tracts

Magnetoencephalography (MEG)

neuroimaging technique for mapping brain activity
direct measure of brain function
measures ongoing brain activity on a millisecond–to-millisecond basis (which allows for reasonable accuracy)
records magnetic fields produced by electrical currents occurring naturally in the brain
shows where brain activity is produced, which part of the brain are undergoing which tasks, and how the brain works

Brain Orientation

There are various ways of looking at the brain as well as different terms used to navigate your way around the brain. Because this is neurology, we use science-based terms. So instead of referencing the front, back, top, and bottom of the brain, you would say: anterior, posterior, superior and inferior sections of the brain, respectively.

The same applies for the planes of the brain, which are: sagittal, horizontal (also can be called axial or transverse), coronal (think of how you would put on Beats headphones) and lateral (which would just be the sides of the brain)

SLP528 Neurology

Guide to neurology for clinicians and students in speech-language pathology