Neural Processes-- EXAM 3

vestibule

(utricle and saccule) which respond to changes in the position of the head with respect to gravity (linear acceleration).

brainstem nuclei connections and eyemovements

- Fibers project from the VN to form the medial longitudinal fasciculus that inputs into various nuclei in the brainstem that control eye movements. - These nuclei include the abducens nucleus in the pons, the trochlear nucleus in the midbrain, and the oculomotor nucleus in the midbrain. - From these nuclei, cranial nerves III, IV, and VI project to the extrinsic eye muscles that move the eyeballs. These connections allow you to keep your eyes fixed on a target while moving your head

central vestibular system

- vestibular portion of the cranial nerve travels through the internal auditory canal before inputting into the brainstem at the cerebellopontine angle -vestibular nucleus: 4 nuclei (superior, inferior, lateral, medial nuclei)

sensation: balance

-Spatial orientation: vestibular system provides information about where your head is located in space - - Direction and speed of how your body moves - Proprioception: the perception of the position and movement of the body

6 basic steps to how we hear

1. Sound transfers into the ear canal and causes the eardrum to move 2. The eardrum will vibrate which vibrates with the different sounds 3. These sound vibrations make their way through the ossicles to the cochlea 4. Sound vibrations make the fluid in the cochlea travel like ocean waves 5. Movement of fluid in turn makes the hair cells. The auditory nerve picks up any neural signals created by the hair cells. Hair cells at one end of the cochlea transfer low pitch sound information and hair cells at the opposite end transfer high pitch sound information. 6. The auditory nerve moves signals to the brain where they are then translated into recognizable and meaningful sounds. It is the brain that "hears".

two neurons from brinastem to muscle

1.Brainstem to spinal cord 2.Spinal cord to muscle

What is the outer ear made up of?

Auricle (Pinna), External Acoustic Meatus (External auditory canal), Eardrum

Auricle (Pinna)

Funnel-like structure

anterior (superior) canal

Head movement along the coronal plane touching your ear to your shoulder

Hearing

Hearing is the process by which the ear transforms sound vibrations in the external environment into nerve impulses that are conveyed to the brain, where they are interpreted as sounds.

What does the auricle do?

It helps collect sound waves traveling through the air and directs them into the external acoustic meatus, the pinna (auricle; ear lobe) locates, collects, and funnels acoustic energy into the inner ear, and acoustic energy is changed into mechanical energy in the middle ear

Sense of hearing

Made up of outer ear, middle ear, inner ear The ear also functions as a sense of equilibrium

External Acoustic Meatus (External auditory canal)

S-shaped tube that transports sound toward the eardrum

What are the auditory ossicles?

Tiny ligaments attach bones to wall of tympanic cavity, Are covered by mucous membrane, Bridge the ear drum and the inner ear, Transmit vibrations between eardrum and I.E., Malleus is attached to ear drum, Once eardrum vibrates so does malleus which causes Incus and then Stapes to vibrate in unison, Stapes is attached to oval window, Help increase(amplify) the force of vibrations from eardrum to oval window, Oval window vibrations move fluid in inner ear to stimulate hearing receptors, Mechanical energy vibrates the tympanic membrane (i.e., ear drum), Transmits this mechanical energy to the 3 smallest bones in the body

type I and type II vestibular hair cells

Type I is more like an IHC. Type II is more like an OHC Unlike cochlear hair cells, both Type I and Type II cells still have kinocilia.

stereo cilia in the utricle and saccule

Utricle ( hair up): linear acceleration in the horizontal axis ( move front and back, Head tilts, right and left) Saccule ( hair out): linear acceleration in the vertical axis( moving up and down In any head position, some hair cells will be depolarized and others hyperpolarized in both otolith organs (collective term used to refer to the utricle and the saccule).

brain stem organization

\•A last relay, before the cortex, occurs in the medial geniculate body (thalamus ); it's here that an important integration occurs. •Medial Geniculate Nucleus: auditory platform that relays auditory information to the auditory cortex •Leaving this relay, a third neuron carries the message up to the level of the lateral lemniscus, which is a tract of axons in the brainstem that carries information about sound from the cochlear nucleus to various brainstem nuclei and ultimately the contralateral inferior colliculus of the midbrain. •Inferior Colliculus - auditory center in the midbrain (tonographic) •Controls the auditory startle reflex, play an essential role in the localization of sound.•The Cochlear branch of the CNIII •The pathway carries messages from the cochlea, and each relay nucleus does a specific work of decoding and •The first relay of the primary auditory pathway occurs in the cochlear nuclei in the brain stem, which receive Type I spiral ganglion axons (auditory nerve); at this level an important decoding of the basic signal occurs: duration, intensity and frequency. •The second major relay in the brain stem is in the superior olivary complex: the majority of the auditory fibers synapse there having already crossed the midline. •From the CNC, the impulse travels up through to the pons to the Superior Olivary Complex • Function: integrating auditory information from both ears (i.e. binaural hearing) •Medial Superior Olivary Complex - low frequency hearing from both ears • Lateral Superior Olivary Complex - higher frequency hearing from both ears •A last relay, before the cortex, occurs in the medial geniculate body (thalamus ); it's here that an important integration occurs. •Medial Geniculate Nucleus: auditory platform that relays auditory information to the auditory cortex •The final neuron of the primary auditory pathway links the thalamus to the auditory cortex, where the message, already largely decoded during its passage through the previous neurons in the pathway, is recognized, memorized and perhaps integrated into a voluntary response.

Middle Ear (Tympanic Cavity)

air filled space in the temporal bone, contains 3 bones called auditory ossicles, oval window, auditory tube

neural pathways

cerebellum and balance- movements for balance brainstem and eye movements- forms the medial longitudinal fascicles to communicate with various brainstem nuclei (control eye movements) abducens (pons), trochlear and oculomotor (midbrain)-- allowing you to fixate eyes on an object while moving your head (aka vestibulo-ocular- reflex) reticular formation- implicated in motion sickness, coordinates the autonomic visceral function

3 main parts of the inner ear

cochlea, semicircular canals, vestibule

semicircular canals

combination head movements will include the combination of multiple canals upward, left movements sagittal, horizontal

Eardrum (tympanic membrane)

cone shaped, sometimes considered a part of the middle ear

auditory tube (eustachian tube)

connects middle ear to back of nasopharynx, conducts air between tympanic cavity and the outside of body by way of nose and mouth, helps maintain equal pressure of both sides of eardrum, function is noticeable during rapid altitude changes, popping sound is heard when hearing is restored back to normal

what is the auditory tube (Eustachian tube)

connects middle ear to nasal cavity

cochlea

dedicated to hearing; converting sound pressure patterns from the outer ear into electrochemical impulses which are passed on to the brain via the auditory nerve •The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth •In humans making 2.75 turns around its axis ( modiolus; The cochlear nerve, as well as spiral ganglion is situated inside it) •A core component of the cochlea is the Organ of Corti, the sensory organ of hearing

organ of corti

distributed along the partition separating the fluid chambers in the coiled tapered tube of the cochlea.

saggiato (posterior) canal

head movement along the sagittal plane nodding your head yes

horizontal. (lateral canal)

head movement on the horizontal plane looking both ways when crossing the street, your head moves to the left and to the right

bending of the stereo cilia towards the kinocilium causes hyper polarization

hyperpolarization

(Auditory) Sensory Transduction

is the process of converting acoustic or sound energy into a neural impulse

anastomosis of OORT

joining together of superior and inferior portions of vestibular nerve with auditory and facial nerves

what are the three bones called auditory ossicles?

malleus, incus, stapes

what is the oval window

opening of tympanic cavity that leads to inner ear

head position: gravity

saccule

head motion:angular acceleration

semicircular canals

peripheral vestibular system 2

semicircular canals: main organs of the vestibular system three semicircular canals filled with endolymph, breaching off of the labyrinth each represent a dimension of the world, with the canals sitting at right angles lateral: movement on the traverse or horizontal plane superior( anterior): movement on the coronal plane posterior: movement on the saggital plane

Eardrum

semitransparent membrane covered by a thin layer of skin on its outer surface and a mucosa membrane in the inside, has an oval margin and cone-shape with the cone apex pointing inward

Sensation (Audition)

sensing the environment through sound

endolymph

slide 29

paralymph

slide 29

Middle ear muscles

the middle ear muscles (MEM) alter the mechanical properties of the middle ear and thus modulate the way sound vibrations are transmitted to the cochlea. Two muscles are involved in this reflex (protection): •the stapedius, which attaches to the neck of the stapes, and the tensor tympani, which attaches to the neck of the malleus. -Regulate the movement of these bones

Perception (Audition)

the process of interpreting the sound

head motion: linear acceleration

utricle

Ventral Stream

what is it (auditory attention)

Dorsal Stream

where is it (location)

aphasia

• • Global: most severe aphasia, affects verbal formulation, comprehension, reading, and writing • •Wernicke's: comprehension difficulty and cannot repeat words spoken to them, but fluent verbal output — but affected by word salad • •Transcortical: can repeat words, but produce paraphasias like echolalia

disorders of the cortical auditory system

• Cortical deafness: sound is heard, but poorly understood • •Auditory Processing Disorder: difficulty interpreting the sound symbols (similar to dyslexia) • • Pure Word Deafness: inability to encode phonemes, but can hear other sounds (bilateral damage to the superior temporal lobes) • Aphasia: multimodal language disorder, high-level difficulty comprehending language

disorder of the inner ear

• Meniere's disease: build up of fluid (inner ear)

there are eight main characteristics of all languages

•1. Language is a code; it is a system of symbols used for transmitting messages •2. Language is used to represent ideas about the world. •3. Language is conventional, meaning that it is shared by a speaking community. •4. Language is systematic. Languages have rules and regulations for how the code is arranged •5. Languages use mostly arbitrary symbols to communicate with others. •6. Languages are generative in that speakers are continually creating novel utterances •7. Languages are dynamic in that they change over time. •8. Languages have universal characteristics (i.e. nouns, verbs, adjectives)

the three cochlear structures include

•1. Scala vestibuli or vestibular duct (containing perilymph), which lies superior to the cochlear duct and abuts the oval window •2. Scala tympani or tympanic duct (containing perilymph), which lies inferior to the cochlear duct and terminates at the round window •3. Scala media or cochlear duct (containing endolymph) a region of high potassium ion concentration that the stereocilia of the hair cells project into

the supplementary motor area

•After semantic assembly has been performed in the anterior ventral Left Inferior Frontal Cortex, From here, the language product is most likely sent to the supplementary motor area (SMA). •The product may be sent directly to the SMA or first relayed through cerebral motor regions, such as the basal ganglia and thalamus, before arriving at the SMA •The SMA then initiates the motor planning

writing problems

•Agraphia - an acquired disorder of writing • •Peripheral agraphia: writing difficulty due to visuospatial and attentional issues • •Central agraphia: writing system damaged

reading problems

•Alexia - an acquired disorder of reading • •Peripheral alexia: reading difficulty due to visuospatial and attentional issues • •Central alexia: reading system damaged

indirect motor system

•Also known as extrapyramidal system •Whereas the pyramidal system controls voluntary motor movement, the extrapyramidal system controls involuntary movements involved in posture, muscle tone, and reflexes, as well as the coordination or modulation of movements. •There are several tracts involved in the extrapyramidal system: Two that originate in the cortex are the corticoreticular and corticorubral tracts. •The corticoreticular tract begins at the premotor (BA 6), motor (BA 4), and sensory cortices (Bas 1, 2, 3) and inputs into the reticular formation of the brainstem, which projects to various other structures like the cerebellum and cranial nerve nuclei •The corticorubral tract also arises from the cortex but inputs into the midbrain's red nucleus •The other four extrapyramidal tracts, which originate in the brainstem, are the rubrospinal (red nucleus -cervical spinal cord, flexor tone in the limbs), vestibulospinal (vestibular nucleus- motor nucleus of spinal cord regulates muscle tone to maintain balance and posture), reticulospinal (reticular formation- motor neurons in the spinal cord, play role in reflexes), and tectospinal tracts (tectum of the midbrain- cervical spinal cord, head posture with eye movements) •Basal ganglia and cerebellar circuits could be subsumed under this system •Includes the medial motor systems: •Anterior corticospinal •Vestibulospinal •Reticulospinal •Tectospinal

direct motor pathway

•Also known as pyramidal system •Involves lateral motor system - lateral corticobulbar (controls the movement of the speech muscles) and corticospinal tracts •Function of pathway - voluntary motor movement of contralateral limbs/speech muscles •This pathway makes few stops •Crosses over (decussates) at medulla/spinal cord juncture •The pyramidal system is a voluntary motor system that controls gross motor movement. In other words, it controls those actions we consciously make but in unrefined way. The refinement comes through the basal ganglia and cerebellar control circuits. •The tracts that make up this system are very direct, begin in the primary motor cortex (BA 4), The pyramidal tracts travel to the brainstem where they decussate (i.e., cross over) to the other side at the medulla and spinal cord juncture. This decussation is responsible for what is called contralateral innervation (right side of the brain controls the left side of the body) •lateral corticobulbar tract, once it has decussated at the medulla, it leaves the brainstem as a cranial nerve that then innervates various muscles in the head and neck. •The cranial nerves that are important to speech include V, VII, IX, X, and XII. •Neuroscientists have made a useful distinction in the pyramidal system •Calling the part that courses from the cortex to the brainstem the upper tract, or upper motor neurons (UMNs) •and calling the part that leaves the brainstem as a cranial nerve the lower tract, or lower motor neurons (LMNs). •Damage to the UMNs results in spastic muscles due to overactive muscle tone (hypertonia) and reflexes (hyperreflexia), whereas damage to the LMNs results in the opposite-flaccid muscles

aphasia 2

•Aphasia •An acquired multimodality language disorder •Acquired = caused by stroke, brain injury, etc. •Multimodality = problem in multiple language modalities (listening, speaking, reading, writing) •Language = the symbolic code we use to communicate •Disorder = language system does not function as it should

sensory pathways important for speech

•Ascending Sensory Pathways (motor) •Three major ascending sensory pathways relay sensory information like touch, pressure, temperature, and proprioception to various brain structures

disorder of the outer and middle ear

•Aural atresia: failure of the ear canal to open •Microtia: called small ear •Otosclerosis ( middle ear): abnormal bone growth inside the ear

frontal lobe processing

•Broca's area (BAs 44, 45) shows activation during complex syntactic activities

the left interior frontal cortex

•Consists of Broca's area (BAs 44, 45) as well as the pars orbitalis. •It is associated with syntactic comprehension, It is also involved in language production by working with other regions (e.g., insular cortex, fusiform gyrus). •Broca's area can be described as necessary for properly formed oral language, but it works with other regions such as pars orbitalis, frontal operculum, insular cortex, and fusiform gyrus

multisystem damage

•Damage to one system leads to one or two types of dysarthria •What happens when multiple systems are damaged, such as in the case of amyotrophic lateral sclerosis (ALS)? •People with conditions like ALS will have mixed dysarthria, which is a mixture of two or more of the pure dysarthrias

speech issues

•Damage to the direct motor pathway can lead to: • •Spastic dysarthria (bilateral UMN damage) • •Unilateral UMN dysarthria (unilateral UMN damage) • •Flaccid dysarthria (LMN damage)

speech issues 2

•Damage to the extrapyramidal system can lead to: • •Hyperkinetic dysarthria (Huntington disease) •Hypokinetic dysarthria (Parkinson disease)

indirect motor system damage

•Dyskinesias (involuntary, face, arms, legs or trunk movements) •Tremors (rhythmic in its movement) •Rest tremors •Action tremors •Chorea (movement disorder that causes involuntary, irregular, unpredictable muscle movements) •Athetosis (abnormal muscle contractions cause involuntary writhing movements) •Dystonia (involuntary muscle contractions that cause slow repetitive movements) •Myoclonus (quick, involuntary muscle jerk)

symptoms of aphasia

•Expressive language problems: •Agrammatism •Anomia •Jargon •Neologism •Paraphasia •Literal •Verbal •Verbal stereotypes •Agraphia •Receptive language problems: •Auditory comprehension loss •Alexia

responses in the vestibular nerve

•Firing of vestibular nerve is more closely related to head velocity than head acceleration. •Nerves from the SCC detect velocity of head rotation •Nerves from Utricle and Saccule detect acceleration but respond slowly—The response does not begin immediately and fades slowly

LMN damage

•Flaccid muscles •Hypotonia •Hyporeflexia (- reflexes) •No clonus •No Babinski sign •Marked atrophy •Fasciculations

the inner ear

•Footplate of the stapes perturbs (rocking in/out) the oval window (entrance of the cochlea) • Another energy change occurs, in which mechanical energy turns into hydraulic energy (fluid) •Mechanical energy turns into electrical energy as it bends the haircuts of the Organ of Corti •The innermost part of the vertebrate ear • Mainly responsible for sound detection and balance •Consists of the bony labyrinth (The bony labyrinth is a series of bony cavities within the petrous part of the temporal bone. It consists of three parts - the cochlea, vestibule and the three semi-circular canals, contain a fluid called perilymph) •Inside the bony labyrinth (membranous labyrinth; lies within the bony labyrinth. It consists of the cochlear duct, semi-circular ducts, utricle and the saccule. The membranous labyrinth is filled with fluid called endolymph) •The inner ear has two openings into the middle ear, both covered by membranes. The oval window lies between the middle ear and the vestibule, whilst the round window separates the middle ear from the scala tympani (part of the cochlear duct)

the neural basis of language

•Important language regions of the cortex include the inferior frontal gyrus (Brodmann areas [BAs] 44, 45), the superior temporal gyrus (BAs 41, 42, 22), some of the middle temporal gyrus (BAs 20, 21, 37, 38), and the inferior parietal lobe (BAs 39, 40). •They are known as the perisylvian region because they all border the sylvian fissure, also known as the lateral fissure

temporla lobe processing

•In regard to the cerebral cortex, primary analysis of the auditory information (i.e., phonological analysis) begins at the Heschl gyrus (primary Auditory cortex) •Left PAC sensitive to speech sound characteristics •Right PAC sensitive to pitch. •Then information is sent in two directions: •1. Planum temporale (PT) via a short-range rostral fiber pathway •2. Auditory information is sent to the planum polare (Heschl gyrus), via a short-range caudal fiber pathway •Superior temporal gyrus involved in the processing of syntactic structure •Posterior temporal lobe activated in processing a verb and its arguments

connections between the frontal and temporal lobes

•In terms of connectivity within the perisylvian region, There are different pathways; two dorsal pathways and two ventral pathways •The first Dorsal pathway connects Wernicke's area (BA 22) to the premotor cortex (BA 6) •The second Dorsal pathway connects Wernicke's area to of Broca's area (BA 44) •The first Ventral pathway connects the superior temporal gyrus (i.e., BA 41, BA 42) to Broca's area (BA 45) •The second ventral pathway connects the anterior superior temporal gyrus to the frontal operculum •Ventral Facilitate the attachment of meaning to sounds and sound combinations, whereas the dorsal pathways support auditory- motor integration

vestibulospinal reflex

•Info from utricle and saccule received by lateral vestibular nucleus (LVN) •LVN sends signal to body muscles via lateral vestibular tracts to help stabilize the body • •If head is rapidly inclined towards one side, muscles tense on opposite side. • •Clinical correlate: Computerized Platform Posturography

vestibulo-collic reflex

•Info from utricle, saccule, and SCC received by medial vestibular nucleus (MVN) •MVN sends signal to neck and upper back muscles via medial vestibular tracts to help stabilize the head • •Keeps head still in space, or on a level plane when you walk (allows for the rotation of one's head when the body stays in place) •Clinical correlate: Videonystagmography (VNG), Positionals

red nucleus: motor coordination and gait

•Input from contralateral motor cortex and ipsilateral cerebellum. •Output •To inferior colliculus, which then connects to the cerebellum. •To reticular formation and spinal cord.

conceptual level

•Involves our thoughts, feelings, and ideas •When we want to express ideas orally through speech, and so forth, through speech, language encoding must take place in upcoming levels •Prefrontal cortex and limbic system probably have primary role at this level

linguistic planning level

•Involves two parts: •Linguistic planning: which includes language content, form, and use (or semantics, grammar, and pragmatics) •Content: meaning of our language •Form: the structure or grammar of language •language use: involves all the pragmatic rules we use as we express language through speech. •Motor planning: plans and arrangements of phonemes •Linguistic planning engages the dominant language hemisphere, which is the left hemisphere in most people •Premotor cortex (BA 6) important area for planning

final common pathway

•It is called the final common pathway because it is the last leg of the journey for all motor signals. Part of the lower motor neurons (LMNs) •Involves: •Cranial nerves in the case of speech •Alpha motor neurons: innervate extrafusal muscle fibers involved in muscle contraction •Gamma motor neurons: innervate intrafusal muscle fibers involved in proprioception •The FCP for speech includes the cranial and spinal nerves involved in phonation, resonance, and articulation as well as spinal nerves involved in respiration. •Respiration provides the power for speech. •Phonation provides the raw sound for speech. •Resonance provides the tonal qualities for speech. •Articulation provides the speech soundsfor speech

labyrinthitis

•Labyrinthitis is an infection of the inner ear that affects the vestibular nerve. It is usually caused by a virus but can also be bacterial in origin •Labyrinthitis is usually triggered by an infection, such as a cold or flu. Hearing loss, dizziness, and a spinning sensation (vertigo) are common symptoms.

the components of language

•Language consists of three basic components: • •1. Content: refers to word meaning • •2. Form: grammar refers to the shape or structure of language. This involves the language's sound structure (phonology), word structure (morphology), and phrase/sentence structure (syntax). •3. Use: known as pragmatics, which refers to how we practically use language with other human beings.

definition of language

•Language is a generative and dynamic code containing universal characteristics whereby ideas about the world are expressed through a conventional system of arbitrary symbols for communication.

neurological control of resonance and articulation

•Neurological control of articulation and resonance is a complicated process controlled by at least five cranial nerves: the trigeminal (V), facial (VII), glossopharyngeal (IX), vagus (X), and hypoglossal (XII). •The pathway for motor control arises in the primary motor cortex (BA 4), projects as the lateral corticobulbar tract to various brainstem nuclei, and then continues as cranial nerves V, VII, IX, X, and XII to the various articulatory muscles. •The trigeminal nerve V controls the opening and closing of the mandible. •The facial nerve VII controls the muscles of the face, including muscles that purse, open, raise, lower, and retract the lips •Glossopharyngeal nerve IX innervated the stylopharyngeus muscle. This muscle plays a role in elevating and opening the pharynx. •The vagus nerve X role in phonation innervates muscles of the soft palate •The vagus nerve functions with the assistance of the spinal accessory nerve (cranial nerve XI). •There are two sets of tongue muscles, the intrinsic tongue muscles that control fine motor movement and the extrinsic tongue muscles that control gross motor function •The hypoglossal nerve controls all of these muscles with the exception of one extrinsic tongue muscle (which has vagal innervation (CN X)), the palatoglossus muscle, damage to these nerve have some paresis to the tongue.

apraxia of speech (AOS)

•Neurological damage leading to AOS can occur in the following: •Broca's area (BA 44, 45) •Supplementary motor area (BA 6) •Insula (insular cortex) •Basal ganglia

is there a vestibular cortex?

•No. There is no primary vestibular cortex. •There are multiple areas of cortex that receive projections (direct or indirect) from the vestibular nuclei and that project back to the vestibular nuclei •Tip of intraparietal sulcus (2v) •Neck and trunk region of central sulcus (3a) •Temporoparietal junction •Precentral gyrus •Parieto-insular vestibular cortex at the posterior end of the insula •Other parts of limbic system

the oral production of language

•Our decision to speak to another human most likely originates in the prefrontal cortex, In addition, the prefrontal cortex receives information from the limbic system, our emotional center, via the thalamus.

cochlear nucleus

•Primarily made up of multipolar neurons and can be devided into •Posterior Cochlear Nucleus (pyramidal cells) we don't really know what they do •Anterior Cochlear Nucleus (aka Ventral CN), containing three localized cell types, preserves the topographic arrangement of the basilar membrane • Spherical bushy cells - anterior ,sound localization •Globular bushy cells (middle) - sensitive to specific frequency information • Octopus cells - wider range of frequency

cerebral cortex organization

•Primary Auditory Cortex (BA 41 & 42) •Tonographic organization of the cochlea • Heschl's Gyrus: superior part of the temporal lobe on the superior temporal gyrus (gyri of Heschl) •1-3 gyri, differ depending on person and lobe • Function: perceive and discriminate sound information •Wernicke's Area (Auditory Association Cortex; BA 22) •Posterior two thirds to the superior temporal gyrus (planum temporale) — most typically left lateralized for language input •Arcuate Fasciculus: connects BA 22 to BA 44, 45 (Broca's area)

cerebellum

•Projections from the vestibular nerve and vestibular nuclei contact the vestibulocerebellum (flocconodular lobe) those cells then contact the deep cerebellar nuclei Projections of the deep nuclei Thalamus Superior colliculus Red nucleus Reticular formation Vestibular nuclei

vestibule-ocular reflex

•Purpose: To maintain stable vision while the head is moving by generating eye movements equal and opposite to head movement • •Two types (most head movement involves both): •Rotational from angular movement (SCCs) •Translational from horizontal (utricle) or vertical (saccule) linear movement • •Clinical correlate: videonystagmography (VNG), rotary chair, bedside tests

the cochlear structures include

•Reissner's membrane, which separates the vestibular duct from the cochlear duct •The basilar membrane, a main structural element that separates the cochlear duct from the tympanic duct and determines the mechanical wave propagation properties of the cochlear partition •The Organ of Corti, the sensory epithelium, a cellular layer on the basilar membrane, in which sensory hair cells are powered by the potential difference between the perilymph and the endolymph •The spiral ligament is a fibrous cushion located between the stria vascularis and the bony otic capsule ( support the membranous COCHLEAR DUCT) •Hair cells, sensory cells in the Organ of Corti, topped with hair-like structures called stereocilia •The helicotrema, the location where the tympanic duct and the vestibular duct merge, at the apex of the cochlea •The cochlear nerve that carries auditory sensory information from the cochlea of the inner ear directly to the brain.

sensory tracts and speech

•Sense receptors in the skin and muscles send sensory signals to the dorsal root ganglion of the spinal nerve or ganglia in brainstem, then carry the signal through the thalamus to the postcentral gyrus of the parietal lobe. •The sensory functions of this pathway include fine touch (as is found in the hands and mouth), vibratory sense, and proprioception. This sensory feedback is important to the speech process •Proprioception is the body's eyes for itself or the body's knowledge of where its parts are in space •Made up of two things: •Kinesthesia: brain's awareness of position and movement of structures (e.g., tongue) •Joint position sense

neurological control of respiration

•Several neurons in the pons and medulla regulate respiration, which is ultimately controlled by the autonomic nervous system •The pontomedullary respiratory center is the CNS area responsible for automatic breathing, and damage to it can lead to respiratory arrest, asphyxiation, and death •This control center has three groups •1. The dorsal respiratory group (DRG). (medulla, responsible for respiratory rhythm and inspiration (i.e., breathing in)) •2. The ventral respiratory group (VRG) (medulla and is responsible for inspiration and expiration during forced breathing (e.g., breathing during exercise)) •3. pontine respiratory group (PRG) (upper pons, acts as an "off" switch controlling the point at which inspiration is terminated and therefore determining the depth and frequency of breathing

neurology of balance

•Sixth sense (balance) - Audition, Olfaction, Tactile, Gustation, Vision •Involves coordination of the head and eyes for spatial orientation •Integration of vision and proprioception (perception of the relative position of one's body) •Vestibular System: same location as the cochlea (inner ear) Human ability to maintain balance depends on the ability of the central nervous system to coordinate sensory input from three systems... •Vestibular •Visual •Somatosensory And to control motor output through... •Vestibulospinal tracts •Reticulospinal tracts •Vestibulo-oculomotor tracts •Voluntary motor (pyramidal/corticospinal) tracts •The vestibular system can be divided into two main systems: the central system (the brain and brainstem) and the peripheral system (the inner ear and the pathways to the brainstem). The inner ear, known as the labyrinth, contains 2 primary structures: the cochlea, responsible for hearing, and the vestibular apparatus, responsible for maintaining balance, stability and spatial orientation.

UMN damage

•Spastic muscles •Hypertonia •Hyperreflexia (+ reflexes) •Clonus •(+) Babinski sign •No atrophy •No fasciculations

the motor speech system

•Speech production is the process by which thoughts are translated into speech. This includes the selection of words, the organization of relevant grammatical forms, and then the articulation of the resulting sounds by the motor system using the vocal apparatus. •Speech production is not the same as language production since language can also be produced manually by gestures, such as those used in American Sign Language (ASL). •Speech is a dynamic motor process involving the coordination of respiration, phonation, resonance, and articulation in order to produce strings of speech sounds grouped together in words. •Normally speech is created with pulmonary pressure provided by the lungs that generates sound by phonation through the glottis in the larynx that then is modified by the vocal tract into different vowels and consonants. •The development of speech production throughout an individual's life starts from an infant's first babble and is transformed into fully developed speech by the age of five •In general, The motor system is a complex system involving a number ofpathways and structures that make movement of both voluntary and involuntary muscles possible. •The motor speech system is a subunit of the motor system. •Understanding of the motor system gives us an understanding of the motor speech system as well as motor speech disorders •The production of spoken language involves major levels of processing: •Conceptual level •Linguistic planning level •Motor planning/ programming level •Motor control circuits •Direct motor pathway •Indirect motor pathway •Final common pathway •Sensory system

lateral vestibulospinal tract

•Starts in the lateral vestibular nucleus of the pons •Axons descend through the brainstem and then travel within the ventral/anterior column of the spinal cord •Projection is uncrossed •Innervates neurons along the entire length of the cord •Helps restore and maintain upright posture—primarily using muscles located away from the head.

medial vestibulospinal tract

•Starts in the medial vestibular nucleus of the medulla oblongata •Axons descend through the brainstem and then travel within the ventral/anterior column of the spinal cord •Innervates neurons primarily in the cervical and upper thoracic areas of the spinal cord

divisions of the vestibular nerve

•Superior division: utricle, anterior part of saccule, and horizontal and anterior canals •Inferior division: posterior part of saccule and posterior canal

peripheral vestibular system

•Talking about the Vestibule, we have: •Outer bony labyrinth (Perilymph , ↑Na+ ↓ K+) • •Inside the bony labyrinth, membranous labyrinth ( Saccule + utricle) filled with endolymph, ↑ K+ ↓ Na+ •Inside the membranous labyrinth there is a special detector called Maculae ( in both Saccule + utricle)

Peripheral Vestibular System

•Talking about the Vestibule, we have: •Outer bony labyrinth (Perilymph , ↑Na+ ↓ K+) • •Inside the bony labyrinth, membranous labyrinth ( Semicircular duct) filled with endolymph, ↑ K+ ↓ Na+ •Inside the membranous labyrinth there is a special detector called Cristae Ampullaris ( in Semicircular duct) •Semicircular duct exist within the bony Semicircular canals •Rotational (angular) acceleration to maintain dynamic equilibrium.

the primary motor cortex

•The SMA sends the motor information for the intended language production to the primary motor cortex (BA 4).

topographic representation

•The basilar membrane is a pseudo-resonant structure •Like the strings on an instrument varies in width and stiffness. •Unlike the parallel strings of a guitar, the basilar membrane is a single structure with different width, stiffness, mass, damping. •The motion of the basilar membrane is generally described as a traveling wave •The properties of the membrane at a given point along its length determine its characteristic frequency (CF), the frequency at which it is most sensitive to sound vibrations. •The base is narrow thick and stiff and has a high frequency resonance and the apex is wide, thin and flaccid with a low frequency resonance. •Basis on the basilar membrane. The location of peak vibration on the basilar membrane encodes the frequency •Auditory nerve fibers are tonotopically organized based on which IHC they innervate (i.e., base vs. apex of cochlea); each fiber is "tuned" (i.e., has the highest firing rate, or most sensitivity) to a preferred, or characteristic, frequency •Each auditory nerve fiber responds best to a particular frequency called the characteristic frequency

Organ of Corti

•The organ of Corti is a specialized sensory epithelium that allows for the transduction of sound vibrations into neural signals. •Located on the basilar membrane. •Contains two types of hair cells: inner hair cells and outer hair cells.

maculae

•The otoconia allow you to sense that movement as long as there is a change in linear motion. •When the hair bundles are deflected—e.g., because of a tilt of the head—the hair cells are stimulated to alter the rate of the nerve impulses that they are constantly sending via the vestibular nerve fibers to the brainstem •Tip-link open the mech-gated channels •K+ & Ca+ rush into the hair cells as results Bending of cilia towards the kinocilium (depolarize the inside positive) •No ion flux the interior negative and hyperpolarization happen •Ca+ help in neurotransmitters release (i.e., glutamate and aspartate) •Neural pulses to the vestibular ganglion to the central nervous system

auditory comprehension of language

•The peripheral auditory system (outer, middle, inner) •Energy transfer from acoustic to mechanical to hydraulic to chemical-electrical. •The cochlear branch of the cochleovestibular nerve (cranial nerve VIII) picks up the chemical-electrical signal produced in the organ of Corti and transmits it to the cochlear nucleus of the brainstem. •The cochlear nucleus routes this information through various brainstem structures to the thalamus, which, in turn, routes the signal to the primary auditory cortex (PAC).

the otolith organs sense linear accleration

•The saccule senses acceleration in the sagittal vertical plane: up and down (so it senses gravity) and forward and backward. Mnemonic: Saccule - Sagittal •The utricle senses acceleration in the horizontal plane

motor planning/programming level

•The second part of planning is motor planning •Motor planning: plans and arrangements of phonemes (the movement goals with respect to the articulators) •Motor plans can be thought of as blueprints for actualizing phonemes. •Neuroanatomically, the frontal lobe is important for motor planning, specifically Broca's area (Brodmann areas [BAs] 44, 45), parts of the premotor cortex (BA 6), and the supplementary motor area. •Motor Programming: specifies which muscles will be used in moving the relevant articulators specified in the motor plan, involve discrete movements of tongue, lips, etc. •Proper speech sound production requires that the speech organs move accurately and precisely in terms of articulatory target, timing, muscle tone, and force. •Sensory information is also incorporated into the process to give feedback ( allow correction) •The neurological structures involved in programming include the cerebellum, basal ganglia, and supplementary motor area as well as other cortical areas, like Broca's area.

semicircular canals 2

•The semicircular ducts provide sensory input for experiences of rotary movements. They are oriented along the X, Y, and Z axes. •Each canal is filled with a fluid called endolymph and contains motion sensors (crista ampullaris) within the fluids •Within the ampulla is a mound of hair cells and supporting cells called crista ampullaris •These hair cells have many cytoplasmic projections on the apical surface called stereocilia •Stereocilia which are embedded in a gelatinous structure called the cupula •The bending of these stereocilia alters an electric signal that is transmitted to the brain

speech issues associated with the motor planning and programming levels

•The umbrella term motor speech disorders (MSDs) includes two disorders, dysarthria and apraxia of speech (AOS) •Dysarthria collectively make up 92% of MSD cases •While apraxia of speech accounts for the remaining 8% •When lesions occur to the structures vital to the motor planning and programming levels, AOS may result. •Dysarthria is a motor speech disorder in which the muscles that are used to produce speech are damaged, paralyzed, weakened, or any difficulty controlling them, causes slurred or slow speech that can be difficult to understand. •Dysarthria occurs when a patient's muscles do not coordinate together to produce speech •Dysarthria can be the result of stroke or a degenerative condition, but it is also frequently seen in people with cerebral palsy, Parkinson's disease, or multiple sclerosis. •Apraxia of speech (AOS) is a neurological disorder that affects the brain pathways involved in producing speech, Patients with apraxia are unable to perform vocal movements even though they comprehend the task. Apraxia usually follows a brain injury, neurodegenerative disease, brain tumor, stroke, or head trauma. People who live with apraxia have difficulty putting words together in the correct order or 'reaching' for the correct word while speaking

neurological control of phonation

•The vagus nerve (cranial nerve X) is a crucial nerve for proper phonatory function. •Lateral corticobulbar fibers arise from the primary motor cortex (BA 4) and input into the nucleus ambiguous (NA) in the brainstem. •The vagus nerve projects from the NA and splits into two branches, the superior laryngeal nerve (SLN) and the recurrent laryngeal nerve (RLN). •The RLN innervates all the intrinsic laryngeal muscles with the exception of the cricothyroid muscle, which is innervated by the SLN •Unilateral UMN damage to the vagus nerve has little effect on the voice other than possible vocal harshness. Bilateral UMN lesions can paralyze both vocal cords

outer hair cells

•There are approximately 12,000 outer hair cells. •They have appearance of flask (test tube) •Mostly receive efferent information from the brain •Not only do they react to the information received from the Brain but they also receive "chemical messages" from inside the cochlea which tell them to either elongate or shrink ( like pistons) •The net effect of their mechanical actions is to change the mechanical properties of the basilar membrane at specific spot. •Outer hair cells amplify basilar membrane motion. The amount of amplification is greatest at low input levels and at frequencies close to the characteristic frequency of the place on the basilar membrane where the hair cell is located. •Outer hair cells improve hearing sensitivity and lead to a compressive basilar membrane growth function, which is reflected in neural activity in the auditory nerve •Without outer hair cells, we would have approximately 40-60 db of sensorineural hearing loss. •In summery, outer hair cells have 2 functions: •1. They amplify soft sounds( below 40-60 decibels) •2. They ' fine-tune' the frequency resolution of the basilar membrane (frequency selectivity)

inner hair cells

•There are approximately 3,000 inner hair cells •They have a flask shape •They mostly send afferent information to the brain via the eighth cranial nerve •Most specifically, these 3000 hair cells stimulate 30,000 eighth cranial nerve fibers from each cochlea •The inner hair cells are the actual sensory receptors, and 95% of the fibers of the auditory nerve that project to the brain arise from this subpopulation •Hair cell stereocilia are at the core of electro-mechanical transduction. •They do transformation of sound vibration into a neural signal that can be interpreted by the brain. •Both types of hair cell have a similar transduction mechanism, but different functions •The deflection (toward the tallest) of the stereocilia causes stretch-sensitive ion channels to open. •Stereocilia bathe in endolymph, which is rich in potassium and characterized by an endocochlear potential of +80 mV •As a result, the electric potential between the endolymph and the hair cell body (between 135 and 150 mV) causes a massive influx of potassium ions from the endolymph to the hair cell when the mechanically-sensitive ion channels open. •This cation influx depolarises the hair cell. • At the same time, another cation, calcium (Ca2+), also enters the cell. •K+ channels close before the stereocilia return back to the modiolus. This is an adaptation method which allows rapid, successive, stimulation cycles to occur. •Releasing the neurotransmitter glutamate (excitation) •Glutamate (neurotransmitter) excites the auditory nerve Neuron takes over a chemical-electrical nerve impulse sent from Organ of Corti to the Central Auditory System (via CN VIII to the brain) •Neural Impulse ( last stage) •Starting from the cochlear branch of CN VIII, neural impulses transmit to the auditory centers of the brain •Diseases •Acoustic Neuroma: benign tumor grows on the nerve - removal usually damages the nerve

cortical reading areas

•There are three reading systems in the left hemisphere, one in the anterior portion and two in the posterior portion. The term systems is used rather than areas because these systems encompass more than one Brodmann area. •The first posterior called parietotemporal reading system (word analysis, meaning the decoding of words at the phonemic level, comprehension of written and spoken language) •The second posterior reading system is the occipitotemporal reading system (concerned with visual word recognition rapid, access to whole word) •Anterior reading system, involves Broca's area as well as the ventral and dorsal premotor areas (play role in word analysis in terms of spoken language syntax and articulation, but it may also play a role in silent reading)

motor control circuits

•There are two control circuits important to speech, the basal ganglia and the cerebellum. •These circuits are important in motor programming of speech by coordinating, integrating, and refining the movements of the direct and indirect pathways •These circuits can be thought of as fine tuners, just as tuning up a car makes it run smoother and more efficiently •The basal ganglia are a collection of nuclei including the caudate nucleus, putamen, globus pallidus, substantia nigra, and subthalamic nucleus •This system is central to the indirect motor system •The basal ganglia nuclei form various afferent and efferent loops connecting the cerebral cortex, premotor cortex, supplementary motor area, thalamus, and substantia nigra •Use several neurotransmitters to regulate motor functioning, including acetylcholine (ACh), dopamine, and gamma-aminobutyric acid (GABA). •They function to Regulate muscle tone and posture and to smooth or refine muscle contraction •Damage to the basal ganglia system results in dyskinesias and conditions like Parkinson disease and Huntington disease •The Cerebellar Circuit (Indirect motor pathway) •The cerebellum can be divided into two hemispheres, the right cerebellar and left cerebellar hemisphere. Each hemisphere has three lobes: the flocculonodular, anterior, and posterior •The posterior lobe plays the most important role in speech production, it automatically incorporates feedback, for coordinating skilled, sequential voluntary muscle activity, (crucial in speech production) •The cerebellum plays a role in a motor feedback loop between the cerebellum and the premotor cortex (BA 6) •When the primary motor strip (BA 4) sends a motor signal through the direct motor system (unrefined) •A copy travel to The cerebellum compares information with the proprioception and kinesthetic information it receives from muscles and joints and coordinates muscle activity so that it is smooth and precise ( refine) •The cerebellum makes an important contribution to the diadochokinesia (i.e., precise, rapid, alternating movements) necessary for speech •Disruptions in this ability lead to ataxia, a lack of order and coordination between muscles

Alexia and Aphasia•

•Typically, people with peripheral alexia (pure, neglect, attentional, or visual) do not have a co-occurring aphasia. • •On the other hand, people with central alexia (surface, deep, or phonological) typically have a co-occurring aphasia.

vestibular schwannoma

•Vestibular Schwannoma An acoustic neuroma (vestibular schwannoma) is a benign tumor that develops on the balance (vestibular) and hearing, or auditory (cochlear) nerves leading from your inner ear to the brain, The pressure on the nerve from the tumor may cause hearing loss and imbalance.

projections of the vestibular nuclei

•Vestibulospinal pathways •Lateral: Throughout spinal cord (vestibulo-spinal reflex) •Medial: Cervical and thoracic spine (vestibulo-colic reflex) •Reticulospinal pathways •Lateral (medullary): Movement & coordination •Medial (pontine): Posture

projections of the vestibular nuclei 2

•Vestibulospinal pathways •Lateral: Throughout spinal cord (vestibulo-spinal reflex) •Medial: Cervical and thoracic spine (vestibulo-colic reflex) •Reticulospinal pathways •Lateral (medullary): Movement & coordination •Medial (pontine): Posture •Vestibulo-oculomotor pathways: Eye movements needed to keep looking at what you want to see even when you are moving. •Cerebellum: Coordination of voluntary (not reflexive) movement, motor learning

visual comprehension of language

•We can also visually comprehend language through reading •Our eyes gather visual information and pass it through the visual pathways to cortical areas for processing •We have two visual fields, a left visual field and a right visual field, both eyes participate in each visual field. •Retinal ganglion cell axons project from the eyes to the optic chiasm. •Crossing over (nasal only)of optic nerve fibres at the optic chiasm allows the visual cortex to receive the same hemispheric visual field from both eyes. (temporal retinas do not cross) •The optic tracts begin at the optic chiasm and conduct retinal ganglion cell axons to the lateral geniculate nucleus of the thalamus. From the lateral geniculate nucleus, thegeniculocalcarinetract projects to the occipital lobe, visual arear(BA17, BA18, BA19

the written expression of language

•Writing, like reading, is a uniquely human function that relies upon our language abilities. •Writing is a powerful skill in conveying ideas not only to large groups of people but also to people living in different eras. •There are three key processes involved in our ability to write •First, there is the language involved in our written communication. •Second, there is the motor control necessary to manipulate pen in hand in relation to paper (premotor cortex (BA 6)) •Third, there is significant visuospatial involvement because writing involves the use of vision guiding motor movements in the three-dimensional writing space (Left Superior Parietal Lobe) •Somatosensory association cortex (also involve), active during writing activities.

recap of brain stem organization

•lobe -> middle ear -> cochlea Organ of Corti (cochlea) - > CN VIII -> CNC (brainstem) -> SOC (pons) -> Inferior Colliculus (midbrain) -> Medial Geniculate Nucleus (Thalamus) -> Auditory Cortex

semicircular canals

•which respond to rotational movements (angular acceleration)