Section 1 Flashcards
What is the diaphragm?
Forms the floor of the thorax and the roof of the abdomen. At rest, the diaphragm is dome shaped. It consists of a tough sheet of inelastic tissue at its centre (central tendon) and a sheet of muscle that rises as a broad rim from all around the lower portion of the inside of the rib cage and extends upwards to the edges of the central tendon.
What is the abdominal wall?
Provides a casing for the lower half of the torso; consists of two large sheets of connective tissue and several large muscles.
Name what controls respiration and differentiate tidal breathing, sustained tone, and speech.
The CNS and PNS control respiration.
Tidal breathing is the amount you typically breath in and out at rest (looks like a smooth wave). Sustained tone is what occurs when you are holding a sound, resulting in a sharp quick inhale with sustained exhale alone with phonation. Speech results in sharp quick inhales with extended bumpy exhales, sort of like a staircase.
Define vital capacity and tidal volume.
VC: The maximum amount you can breathe in and out. Depending on the size of your rib cage, this is usually 3.5-5 litres of air.
TV: the amount you typically breathe in and out at rest.
Define inspiratory and expiratory reserve volume.
IRV: the amount you can inspire if needed, beyond your end-inspiratory tidal volume.
ERV: the amount of air you can expire from your lunch after your end-expiratory lung volume in tidal breathing.
Describe what happens on inspiration, including muscles involved.
- External intercostals actively contract, pulling the ribcage upwards.
- Diaphagm actively flattens to accommodate expansion of the lungs.
Note that your abdominal muscles are always on during inspiration and exhalation.
Describe what happens on exhalation, including muscles involved.
- External intercostals passively recoil.
- Diagphragm massively returns to rest position
- Lungs passively recoil.
For active exhalation, the internal intercostals may be involved as they pull the ribs downwards to squeeze out air from your ERV. The abdominal muscles may also engage.
Describe breathing during speech.
Speech breathing has a short inspiration with a longer expiration with many fine adjustments made during the exhalation. We speak in the middle of our lung volume. Exhalation during speech is often an active process, requiring involvement from internal intercostals and abdominal muscles.
What is included in the articulatory system?
Includes the lips, teeth, alveolar ridge, hard palate, soft palate, velum and nasal cavity, tongue, and jaw; these structures (articulators) are used to shape the source signal generated at the glottis in order to generate speech.
Articulators can be active, passive, or both (i.e velum is active when producing nasals, but passive when approximated by the tongue, as in /k/ production)
What is included in the phonatory system?
Includes the larynx and vocal folds. In the source-filter model, the phonatory system is involved in generating the source signal from which speech is derived. The source signal will have its own fundamental frequency (f0) and will generate harmonics (multiples of the f0).
What two conditions need be met for vocal folds to be set in motion?
Vocal folds sufficiently approximated.
There is sufficient subglottal pressure.
How are vocal tract resonances created?
Vocal tract resonances will be created, corresponding to formant frequencies, which are properties of the filter.
F1 = Mostly determined by tongue height - vertical plane F2 = Mostly determined by tongue “backness” - horizontal plane
What is included in the resonatory system?
Also referred to as the vocal tract; includes the “throat” (area above and around the larynx), oral cavity, and nasal cavity. This is the area through which the source signal generated by the phonatory system travels and is filtered (in conjunction with the articulatory system) due, in part, to resonance frequencies and damping characteristics of the tract/system.
What is the larynx?
The larynx, commonly called the voice box or glottis, is the passageway for air between the pharynx above and the trachea below.
It extends from the fourth to the sixth vertebral levels. It is formed by cartilages that are connected to each other by muscles and ligaments.
Describe the skeletal framework of the larynx.
Hyoid bone: Considered “free-floating” (not attached to any other bone) Thyroid cartilage: Anterior prominence/ notch = Adam’s apple. Largest component; provides protection to other laryngeal structures Cricoid cartilage: Ring-like structure located above trachea. The cricoid is the only complete cartilaginous ring of the airway. Arytenoid cartilages (2): Sit atop the cricoid cartilage Corniculate cartilages (2): The corniculate and cuneiform cartilages have fibrous attachments to the arytenoids and are located on top of and anterior to the arytenoid cartilage, respectively. The true function of these structures is unknown, but they increase and stiffen the aryepiglottic fold and may therefore aid in prevention of aspiration during swallowing. Epiglottis: A single cartilage positioned behind hyoid bone and root of the tongue. Lingual surface attaches to hyoid bone; the lower part attaches to the inner part of the thyroid cartilage just below the thyroid notch.
What is the pharynx?
The pharynx, commonly called the throat, is a passageway that extends from the base of the skull to the level of the sixth cervical vertebra.
Inferiorly, it opens into the larynx and esophagus. The pharynx is divided into three regions according to location: the nasopharynx,
the oropharynx, and the laryngopharynx (hypopharynx).
Name the intrinsic laryngeal muscles, their action, and their effect.
Cricothyroid: (A) pulls thyroid forward and downward when contracting (stretching vocal ligament). (E) Increases vocal pitch.
Posterior cricoarytenoid muscle: (A) rocks arytenoid away from midline to open VF. (E) moves VF out of the airway, stopping sound via abduction of VF.
Lateral cricoarytenoid: 9A) rocks arytenoid towards midline and backwards to close VF. (E) Adducts VF into the airway; voicing posture.
Transverse arytenoid: (A) pulls arytenoid cartilages together. (E) adducts VF.
Oblique arytenoid: (A) pulls cartilages together in a tipping motion. (E) adducts VF.
Thyroarytenoid: (A) causes arytenoids to pull towards thyroid and towards the midline, relaxes and shortens VF (agnostic to criocothyroid). (E) Makes up VF.
Name the extrinsic laryngeal muscles, their function, and their innervation.
Thyrohyoid: contraction decreases the distanced between the thyroid cartilage and the hyoid. (I) Cervical spinal nerves.
Sternothyroid: pulls the thyroid cartilage downwards and may enlarge the pharynx. (I) cervical spinal nerves.
Inferior pharyngeal constrictor: moves the sidewall of the lower pharynx inwards and decreases size of pharyngeal lumen. Stabilizes position of the laryngeal housing. (I) CN X (Vagus)
Name the intrinsic muscles of the tongue and their function.
I & S longitudinal muscles: moves tip up and down, can shorten tongue.
Transverse: narrows and lengthens tongue
Vertical: flattens and depresses the tongue.
What innervated the intrinsic tongue muscles?
CN XII (Hypoglossal)
Name the extrinsic tongue muscles and their functions.
Genioglossus: forms bulk of the tongue, sticks tongue out, presses against teeth/alveolar ridge, pulls tongue tip back, troughs the tongue.
Styloglossus: pulls tongue up and back.
Hyoglossus: retracts and depresses, elevates hyoid.
Palatoglossus: pulls tongue back to groove the tongue.
What muscles make up the vocal folds and cords?
Folds: exterior part made up of external and internal thyroarytenoid muscles and the vocal ligament
Vocal cord: interior thyroarytenoid and vocal ligament.
Where do the vocal folds attach to?
Anterior: inner surface of the thyroid.
Posterior: Arytenoids.
Name the five layers of the vocal folds.
Cover: (1) epithelium & (2) superficial lamina propria (SLP)
Transition: (3) intermediate lamina propria (ILP) & (4) deep lamina propria (DLP)
Body: (5) vocalist/thyroarytenoid.
Describe the myoelstic aerodynamic theory.
Vocal folds move towards the midline
Subglottal air pressure builds and blows VF apart
Muscle recoil (elasticity) and Bernoulli Effect (increase in velocity decreases pressure between the VF and sucks them back together again) creates vibration
Name and describe the parts that make up the outer ear.
Auricle (pinna): a flap of thin elastic cartilage covered by skin which is continuous with the cartilage of the external auditory meatus; role = sound localization and amplification
Concha (the bowl at the entrance to the ear canal) - has a resonating frequency of 4.5 kHz and amplifies this frequency by 10-15 dB
External Auditory Meatus aka EAM (Ear canal)
Outer part of tympanic membrane (eardrum)
Name and describe the parts that make up the middle ear.
Tympanic membrane: concave oval cone-like disc, that appears pearly gray in colour and translucent. The apex lies at the umbo which corresponds to the bottom end of the malleus handle
Umbo - area of slightly rounded elevation where malleus attaches to TM (point of maximal convexity/greatest retraction)
Ossicles:
Malleus = largest and most lateral and attached to the eardrum and the incus
Incus = middle bone
Stapes = attaches to the oval window of the cochlea by ligament
Stapedial muscle: attaches to the neck of the stapes; contracts bilaterally to loud sound and tenses the membrane in the oval window. This reduces some of the signal passed onto the cochlea (acts as a protective mechanism for loud, startling sounds)
Tensor tympani: inserts into the manubrium of the malleus and contracts bilaterally to non-auditory stimulation ( i.e., touching the ear canal or introducing air into the ear canal)
Eustachian tube: This mucous lined tube is about 25 mm long and provides communication of the middle ear cavity with the nasopharynx (above and behind the soft palate) and permits equalization on both sides of the TM. It’s usually closed → opens when a mismatch in air pressure is detected between the middle ear cavity and ear canal.
What is the general function of the inner ear?
Overall function: transduction of mechanical energy to electrical.
Cochlea (hearing)
Vestibular system (balance)
What functions do the outer and middle ear serve.
Transformation of sound into mechanical energy.
Outer ear: Sound waves reach the outer ear and are localized and amplified by the pinna and EAM. Sound reaches the external part of the tympanic membrane at the end of the EAM.
Middle ear: The eardrum is the first movable link in the chain of auditory events. Acoustic pressure waves, which hit the eardrum, cause it to vibrate, reproducing the same spectrum of sounds that enter the eardrum. Sound pressure changes at the TM cause it to move.
Name and describe the functions and parts of the inner ear.
Fluid-filled series of canals called the “labyrinth”.
The outer duct is called the bony (osseous) labyrinth (spaces/cavities) because walls are made from temporal bone.
It is divided into three sections:
the vestibule
the semicircular canals
the cochlea.
Within the bony labyrinth is a membranous labyrinth.
It is also divided into three parts:
the semicircular ducts;
two saclike structures, the saccule and utricle, located in the vestibule
the cochlear duct ( the only part of the inner ear involved in hearing).
The entire inner ear is bathed in a cushioning fluid, called the endolymph when it lies within the membranous labyrinth and the perilymph when it separates the bony and membranous labyrinths.
The cochlea is a spiral chamber that resembles a shell of a snail (~ 35mm long tube). It is subdivided into 3 chambers (upper, middle and lower). The scala vestibuli is the superior duct that begins at the oval window and extends to the apex of the cochlea. The inferior duct, called the scala tympani, begins at the apex and ends at the round window.
The organ of Corti, a sensory mechanism of hearing, is located in the scala media and rests on the basilar membrane. It is the site of sensory transduction, containing the sensory cells responsible for transducing mechanical motion into electrical (neuronal) activity, and nerve fibres which transmit the electrical activity to the brain where it is perceived as auditory signals. It is the beginning of tonotopic organization within the auditory system (the frequency of a sound is coded or mapped to a place on the basilar membrane) and each hair cell has a characteristic frequency.
Two types of sensory cells:
1 row of inner hair (3500) cells lined up side by side along the length of the organ of Corti
3-5 rows of outer hair cells (12,000). The OHC have hairs (modified microvilli) that project into the tectorial membrane which form a W pattern
Hair cells synapse with nerve fibres which form the cochlear nerve (branch of CNVIII)
How does the cochlear work (physiology)?
The stapes pushes in the oval window which moves the fluid in the scala vestibuli (aka vestibular duct) and scala tympani (aka tympanic duct). The motion is referred to as a travelling wave.
The wave travels the length of the cochlea, growing in strength until it reaches a place of maximum displacement. At this point, hair cells embedded in the tectorial membrane experience a shearing force and begin to bend
This causes a release of a neurotransmitter from the base of the hair cells that stimulates the nerve ending of the cochlear branch of the VIII nerve, causing an action potential which travels up the auditory pathway.
The direction of the travelling wave is from the base (high frequencies) to the apex
Low tones cause a vibration of the basilar membrane in the apex where the membrane is the widest but the cochlea is the narrowest (i.e in the center)
Describe the ascending auditory pathway.
Vestibulocochlear nerve (VIII CN) - enters brainstem where its fibres bifurcate to synapses in the ventral and dorsal cochlear nuclei (cranial nerve nuclei)
Some fibres decussate (cross over) the midline and synapse in the superior olivary complex ( first site of binaural representation from ipsilateral and contralateral input from CN,
Role: localization through information on time and intensity) on the opposite side.
Information travels to the nucleus of the lateral lemniscus
Inferior colliculus AKA IC (relay station). The two IC are connected by fibres to allow crossover from both sides of the brainstem
From the IC, pathway travels ipsilaterally and contralaterally, then continues to the medial geniculate body (MGB)
The MGB is located in the thalamus and is the last subcortical relay station for auditory impulses. It:
maintains and directs auditory attention (dorsal MGB)
tells the brain to pay attention to what is going on (medial MGB)
integrates information about the source, location, frequency and intensity of sound (ventral MGB)
After the MGB, the central auditory tract fans out into multiple small fibres (auditory radiations) which run from MGB to the auditory cortex
Describe the primary auditory cortex.
Located in the temporal lobes on both sides of the cortex in an area called superior temporal gyrus (Heschl’s gyrus)
The tonotopic organization continues in the cortex
Information is finally processed at this level
Loudness perception and pitch are controlled at the brainstem, but higher-level behaviours (understanding speech and processing complex signals) is at the auditory cortex
Speech is primarily processed in the LEFT Auditory Cortex.
This means speech information from the right AC (information from left cochlea) crosses to the left AC, via the corpus callosum to be processed by the brain.
Discuss the basic embryology and development of the auditory system.
The outer, middle and inner ears develop from different embryological tissue, and therefore one can have an abnormality in one part of the ear and not the other (usually abnormalities of the outer and middle ear are seen in combination with a normal inner ear)
Outer and middle ear development starts around 3 weeks gestation; the pinna develops between 5th and 18th-week gestation, the tympanic membrane is formed by 4 months gestation, and the middle ear ossicles (adult size at birth) are correctly positioned/ formed by the 8th month (This means that most babies can “hear” in utero by 8 months gestation)
The eustachian tubes are more horizontal in babies/young children, which often results in poor drainage; this is the reason young children are so susceptible to ear infections (as are individuals with Down Syndrome) due to fluid build up
The brainstem and auditory cortex are not mature at birth;
Brainstem response is adult-like by 18-24 months
Auditory cortex is ½ the thickness at birth; development continues until age 2-3
Undetected hearing loss stunts auditory cortex development
What are neurons?
Cells specialized to transport information throughout the body.
Consist of a cell body (soma) with one axon (projecting segment), and one or more dendrite(s) (receptor segments).
Grey matter; primary found on the outside of the brain and in the middle of the spinal cord (for protection)
What are glial cells?
Surround neurons and provide support for and insulation between them, which increases the speed at which impulses travel through the neural system.
Support neuronal function by regulating the environment of the nervous system and providing protection against harmful agents.
White matter; on the inside of the brain and the outside of the spinal cord.
What is the diancephlon?
Refers to 4 structures together: Thalamus (Relay station for all sensory and motor tracts, except olfaction; seems to regulate cortical activity for alertness), Subthalamic nucleus (STN -Tiny nucleus that sits under the thalamus; part of basal ganglia circuits or motor and cognitive functions), Hypothalamus (Controls the autonomic nervous system - heart rate, digestion, respiration, stress response, blood pressure, temperature regulation, fluid balance in the body), and the Epithalamus (Contains the pineal gland which secretes melatonin - involved in sleep/wake cycles).
Describe the limbic system.
The part of the brain involved in our behavioural and emotional responses, especially when it comes to behaviours we need for survival: feeding, reproduction and caring for our young, and fight or flight responses. Includes the hippocampus, the amygdala, and the hypothalamus.
What is the amygdala?
A roughly almond-shaped mass of gray matter inside each cerebral hemisphere, involved with the experiencing of emotions and drives.
Name the four different lobes of the brain and their main function
Frontal: Higher order reasoning, planning, organization, inhibitory control, focusing attention, executive functions, decision making, motor control (mainly motor functions and higher-level functions)
Occipital: Vision
Temporal: Auditory, comprehension of language, some parts of taste, memory
Pariatal: Somatosensory (touch, pressure, etc.)
Name the four primary cortex of the brain.
Primary motor
Primary somatosensory
Primary auditory
Primary visual
What is the function of the temporal gyri (Superior, middle and inferior)?
Processing eye movements, analysis of visual social information, semantic memory processing, language processes, visual perception, and integrating information from different senses
Differentiate Broca’s and wernicke’s area.
Brocas: expressive language; Production of speech and written language.
Wernickes: Receptive language; Language comprehension, creates plans for meaningful speech.
What is the function of the prefrontal cortex?
Executive functions; Attention, planning, impulse control, making predictions, cognitive flexibility
What are the functions of the association cortex?
Coordinates brain functions that require more than basic primary sensory or motor functions.
Can include language, attention, memory, visuospatial functions, mathematical functions, social cognition, reasoning, problem-solving, personality, critical thinking.
Main purpose = Appropriate use of muscles (QUALITY; planning, sequencing) in context
Describe the ‘what’ pathway.
Runs from the primary occipital lobe in the occipital cortex to the temporal lobe. Supports object identification – Images will start in the visual cortex, then move to the association cortex
Describe the ‘where’ pathway.
Runs from the primary occipital lobe in the occipital cortex to the parietal lobe. Supports navigating space and understanding where you are in space
Describe the function of the brainstem.
Corridor for all major sensory, motor, cerebellar and cranial nerve pathways
Location of cranial nerve nuclei
Location of other nuclei with unique functions that do not exist in the spinal cord (ex. critical for consciousness, cerebellar circuits, muscle tone, cardiac functions, & respiratory functions)
Describe the function of the medulla.
Transmits motor and sensory signals from the spinal cord to higher parts of the brain.
Regulation of heartbeat, respiration, and hormone release
Describe the function of the pons.
Relays information from the cerebral cortex to the cerebellum; motor and sensory function of face, head, & eyes; hearing & balance; salivation
Describe the function of the midbrain.
Associated with vision, hearing, motor control, sleep and wakefulness, arousal (alertness), and temperature regulation
Describe the function of the cerebellum.
Responsible for the smooth coordination of movement.
One of the “big three” responsible for the quality of movement.
What is the function of the thalamus?
All sensory roads connecting the outside world to the cortex go through the thalamus (except smell). A relay for the pathway between the cerebellum and primary motor cortex,as well as between the basal ganglia and primary motor cortex. Also regulates cortical activity for alertness.
What is the function of the hypothalamus?
Controls autonomic nervous system. Responsible for homeostatic functions including autonomic and neuroendocrine functions.
What is the subthalamic nucleus?
Part of basal ganglia circuits for motor and cognitive functions
What is the epithalamus?
Pineal gland secretes melatonin, epithalamus connects diencephalon to limbic system and cortex
What is the function of the basal ganglia?
Made up of the caudate and putamen nuclei, the globus pallidus, the subthalamic nucleus, and the substantia nigra.
Refines motor commands from the cortex by receiving and processing information from the cortex, then sending it back to the cortex through the thalamus.
Involved in the initiation (and inhibition) of movement
What is the function of the hippocampus.
Memory.
What are upper motor neurons?
Nerve cells that have cell bodies in the cerebral cortex and axons which run to the brainstem and spinal cord to synapse with interneurons and lower motor neurons, which in turn signal muscles to contract or relax
What are lower motor neurons?
Nerve cells that have cell bodies in the spinal cord or brainstem (CNS) and axons that go into the PNS to synapse with interneurons or muscles
Final common pathway
What is a neuromuscular junction?
A synapse formed by the contact between a motor neuron and a muscle fibre
Describe a peripheral nerve.
Contains lower motor neurons but can also contain sensory nerves.
There can be a peripheral nerve that is only sensory, a peripheral nerve that is only motor, or a peripheral nerve that is a combination of the two.
Describe a motor unit.
Made up of a motor neuron and the muscle fibres innervated by that motor neuron’s axonal terminal
What functions do spinal nerves serve?
Only carry motor and somatosensory information (don’t carry smell, taste, vision, hearing)
Carry information between the spinal cord and the body
All spinal nerves carry both sensory and motor information together
What functions to cranial nerves serve?
In addition to what spinal nerves carry, cranial carry smell, taste, vision, hearing
Carry information between the head & neck and the body
Can carry sensory information, motor information, or both
Name the 12 cranial nerves in order with their major function.
Olfactory - smell
Optic - vision
Oculomotor - eye movement, pupil size, accommodation
Trochlear - Eye movement, looking down
Trigeminal - sensation (TTPP in face), motor (muscles of mastication)
Abducens - eye movement, looking temporally
Facial - sensation (taste), motor (muscles of facial expression)
Vestibulocochlear - Sensation (sound, balance)
glossopharyngeal - sensation (taste), motor (muscles of pharynx)
Vagus - motor (larynx, parasympathetic to viscera)
Hypoglossal - motor (muscles of the tongue)
What are the key concepts that characterize neural development?
Neural development is characterized by over-development followed by pruning
Neurons are born biased for certain functions but uncommitted
The ultimate function of cells depends on what other cells they connect with and what input they receive
Nervous system develops on a use-it-or-lose-it basis
- Developmental plasticity permits correction of “minor mistakes”
- Reorganized cortex may end up being somewhat different from the typical pattern
Define gastrulation, neurulation, and embryonic folding.
Gastrulation: The process by which the three germ layers of the trilaminar embryonic disc are formed (Ectoderm, mesoderm, endoderm)
Neurulation: The beginning of the formation of the nervous system– the process by which the neural plate forms into the neural tube
Embryonic folding: Process by which the trilaminar disc creates a basic three-dimensional human body plan. See section 1.3 for more details.
Name the three layers present after gastrulation and what they form.
Ectoderm: skin and nervous system.
Mesoderm: bone, muscles, and connective tissue
Endoderm: lining of organs such as gastrointestinal tract and airways
What do the notochord and neural tube become?
Notochord: neucleus of the backbone
Neural tube: comes off ectoderm and forms CNS`
How does the brain change after birth?
At birth there is over-proliferation of neurons
After birth, there is over-proliferation of connections
- Programmed cell death
- Pruning of connections
Second wave of synaptogenesis and pruning in the pre-adolescent years
Within the first few months of life, ventricles continue to grow and myelin coated axons begin connecting.
When does myelination occur?
Myelination and formation of connections continues well after birth. For example, there is dramatic growth of neural connections between birth and 24 months in Broca’s area (and other brain regions).
Different motor, sensory, and cognitive systems “come online” at different points throughout life as the neurons in the associated areas become myelinated and transmit information more effectively. Although MOST areas become myelinated in early childhood, several areas do not become myelinated until adolescence or even adulthood.
What are the key principles of neuroplasticity?
Use it or lose it Use it and improve it Repetition matters Time matters Intensity matters Specificity matters Salience matters Difficulty matters Transference Interference Age matters
Describe the steps of responding “no” to a question.
In order to respond “no” to a question, the auditory cortex will first receive information.
From the auditory cortex, the prefrontal cortex makes the decision to respond.
Muscle actions are planned in the premotor and supplementary motor area, which is connected to Broca’s area (“broken tongue” – expression is impaired).
Then, info is sent to basal ganglia to decide if and how to proceed with action.
Muscle actions begin to be planned in the premotor area, then are sent to basal ganglia that decides whether to initiate movement based on previous experiences
Info goes back to the thalamus, which directs info to the primary motor cortex, which sends info to the brainstem and spinal cord, as well as a copy being sent to the cerebellum (allows the cortex to make adjustments)
Name the different types memory and name the associated brain structures.
Sensory memory: peripheral receptors
Working: frontal lobes and anterior structures of the limbic system
Long-term (declarative): association cortex, medial temporal lobe, hippocampal formation, adjacent cortex of parahippocampal gyrus, medialdiencephalic memory areas, thalamus, mammillary bodies, other diencephalic nuclei lining 3rd ventrical
Long-term (non-declarative): subcortical structures and cerebellum
Name the three types of declarative memory and their associated structures.
Episodic: temporal neocortex
Lexical: angular gyrus
Semantic: temporal parietal, frontal association cortex
Name the three types of non-declaratice memory and their associated structures
Skills and habits: cerebellum, basal ganglia (debated)
Emotional associations: interactions among the limbic system, prefrontal cortex, subcortical structures (debated)
Conditioned reflexes: cerebellum (debated)
Discuss the evidence for a localization view of the brain.
The structure of our brains—from the time the brain begins to develop, neurons grow outwards from the middle in columns (which also differentiate into layers); this supports the idea that one column does one distinct thing, while a different column does something else.
Existence of primary cortices and a variety of cell types
Connections and dendritic arborization patterns across brain regions
Lesion-behaviour correlations (especially for basic sensorimotor functions; i.e. a lesion in Broca’s area affects fluent speech output)
Discuss the evidence against a localization view of the brain.
How interconnected and interdependent the brain is—when completing many functions (ex. reading, having a conversation, etc.), areas all over the brain are affected, and it is currently impossible to determine what sections of the brain do what
It’s oversimplified
Doesn’t account for individual variability
A lot of data comes from patients with lesions (i.e difference between brains with and without lesions - different organization)
Doesn’t account for dynamic changes in the brain over time
What is lateralization?
A special kind of localization; function is primarily controlled by one hemisphere relative to the other
Using the lateralization view, what functions are associated with the left hemisphere?
Language & verbal ability Logic Sequential things Details Fast temporal processing: acoustic timing and integration of information over time
Using the lateralization view, what functions are associated with the right hemisphere?
Spectral processing: acoustic pitch and integration of information over space
Big picture (gestalt)
Musical ability
Emotion recognition
Attention to extrapersonal space (paying attention to the space around you- this is why right hemisphere strokes lead to spatial neglect far more often than left hemisphere strokes)
Name the different structural imaging types.
Angiography: blood vessels over time
CT: structural images collected over time via multi-angle x-ray (show tissue density)
MRI: structural images collected via exposure to magnetic field (reflects density of hydrogen ions)
MRA: blood vessels at one moment in time
Name the different functional imaging techniques
PET: radiation emitted by radioisotopes injected into artery, measures metabolism of glucose
EEG: brain electrical activity via electrodes on the scalp or on brain
Compare UMN and LMN damage based on strength, reflexes and the presence of atrophy and fasciculations.
Strength: reduced weakness (UMN), weakness (LMN)
Reflexes: hyperreflexia, hyporeflexia
Atrophy: N/A, present
Fasciculations: N/A, present.
Describe the four major events of embryologic development.
1) Formation of embryonic disc: Differentiation into endoderm, mesoderm, ectoderm (aka gastrulation)
2) Formation of the neural plate: Notochord (structure that derives from embryonic disc) secretes growth factors that induce development of ectoderm layer into the neural plate → folds in and edges fuse to become neural tube → develops into brain and spinal cord with hollowed-out center that will become central canal and ventricles. Neural plate is formed during gastrulation
3) Migration of neural crest cells to become cranial nerves: Neural crest cells originate in the ectoderm and the settle down in various parts of the body. Cranial neural crest that gives rise to the head, connective skeletal structures and nerves
4) Development and fusion of pharyngeal arches
What do the different pharyngeal arches form into?
The first arch gives rise to the mandible
The second arch gives rise to the hyoid
The third arch gives rise to the stylopharyngeus
The fourth arch gives rise to the cricothyroid and soft palate
The fifth doesn’t really form in humans
The sixth arch gives rise to the intrinsic muscles of the larynx (except for the cricothyroid)
Discuss how cleft palate arises.
Cleft palate forms if facial ridges don’t fuse properly in embryological development from sides and top of head. Cleft palate can lead to a variety of issues, including feeding/swallowing and nasal air emissions impacting speech intelligibility.
How does substance consumption impact embryological development?
Early in embryological development, there are many processes that could be impacted by consuming substances like alcohol and drugs. These may impact the development before a pregnant person even knows they are pregnant (e.g., FASD), which may in turn impact speech or language development.
How does premature birth impact development?
Risks of a lack of folds in the brain; the brain cortex is not developed fully and prepared for birth. White matter is not fully developed in premature children.
Define chromosome and gene.
Chromosome: a thread-like (x like) structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes
Gene: section of chromosomes that are the basic unit of heredity in all living things. Genes are chemical instructions, inherited from your parents, that determine proteins. Each gene is a segment of DNA that is the code for the production of particular proteins (function: to make the proteins)
Why is gene regulation important in embryonic development?
The genes are important because they determine what proteins we have and the proteins determine who we are
How the genes develop during embryonic development will govern who we are, what we look like, all of our features
It is the “instruction manual” (and of course, there are also env. factors)
Give an example of each different type of hereditary pattern.
Autosomal recessive: only problematic is homozygous (this isn’t always true)
Autosomal dominant: huntington’s
X-linked disorder: fragile X syndrome, colour blindness
What are some examples of disorders linked to chromosomal mutations?
Down Syndrome, William’s Syndrome (deletion in a chromosome – a handful of genes are missing) – these are NOT inherited syndromes. They result from mutations
Discuss the impact of fragile X syndrome on a child.
Delayed speech and language development Mild-moderate intellectual disability Anxiety, ADHD 33% also have ASD Fragile X is the most common cause of ASD
Discuss the impact of Down’s syndrome on a child.
Extra 21st chromosome Delayed speech and language development Mild-moderate intellectual disability Attention problems, OCD Increased risk of gastroesophageal reflux, celiac disease, hypothyroidism, vision and hearing problems, cancer of blood-forming cells, Alzheimer disease Ramifications for family members: - Not typically inherited - Risks increase with the mother’s age at conception
