SHS 280 Speech Production

Central Nervous System

Parts of nervous system encased in bone (brain, spinal cord)

Peripheral Nervous System

Parts not encased in bone (inner ear (hair cells), sensory neurons in hand, etc)

Spinal Cord

• sends motor signals to body

• receives sensory info from body

• responsible for some reflexes

Brainstem

• Necessary for basic survival functions (ex: automatic breathing)

• Controls almost all sensory info going in, motor signals going out

• regulates consciousness

• lesions can be fatal, cause comas, or cause sensory or motor problems

• Medulla Oblongata, Pons, Midbrain

Diencephalon

Contains thalamus and hypothalamus

Thalamus

• Relays sensorimotor info

• Routes projections for different sensory info to specific cortical areas

• Integrates sensorimotor info before sent to primary motor and premotor cortices

• Regulates cortically mediated cognitive functions

Hypothalamus

• Regulates body temp, blood volume, hunger and thirst, “set point”, reproduction, circadian rhythms

• Uses neural and hormonal signals

• Blood-brain barrier prevents items carried into bloodstream from entering the brain

• Blood-brain barrier is not intact

Cerebellum

• Modifies cortically generated motor plan

• Corrects on-going movements

• important for speech production

• balance

• timing

• coordination of fine motor skills

Frontal Lobe

• inhibition/self control

• last part of brain to develop

• large consumer of oxygenated blood

• disproportionately affected by intoxicants in blood

Occipital Lobe

• vision

Temporal Lobe

• Audition

• Memory

• Speech Perception

• Olfaction

Parietal Lobe

• spatial orientation

• cross-modal integration

• somatic sensation

Grey Matter

• cell bodies

• dendrites

• portions of axons

White Matter

• myelinated axons

• myelin comes from glial support cells

• wraps around axon and speeds up transmission of signals down axon

Bilateral Anatomic Symmetry

Both halves of brain look the same

Unilateral Functional Differences

Both halves of brain serve a different function

Contralateral Sensorimotor Control

Left brain controls right body, vice versa

Topographical Organization

Parts of world next to each other represented by neurons next to each other

Wilder Penfield

Neurosurgeon- mapped out topographical organization of motor cortex

Plasticity

• brain’s ability to reorganize

• greater at a young age

Ataxia

• poor muscle coordination

• balance issues

• unsteady gait

• caused by damage to cerebellum

Procedural Memory Deficits

• trouble with procedural tasks

• results from damage to basal ganglia, cerebellum, premotor cortex

Anterograde (episodic) Amnesia

• inability to form new memories of events

• results from damage to hippocampus

• patients can learn new skills

• patients can remember things before damage

Congenital Insensitivity to Pain

• individuals do not feel pain

• can still feel touch

• very dangerous

• no pain warnings

Broca’s Aphasia

• difficulty producing words

• not a motor problem

• speech is halting

• words are well formed

• very few grammatical words used

• some patients who cannot speak can sing

Medulla Oblongata

Controls automatic functions (breathing, heart rate, digestion)

Pons

Conveys movement info from cerebral hemispheres to cerebellum

Midbrain

• Controls eye movement, coordinates visual and auditory reflexes

• Contains substantia nigra, major population of dopaminergic neurons

• Degeneration of region key to Parkinson’s

Pineal Gland

• Produces melatonin

• Regulates Circadian Rhythms

Hypothalamus/Pituitary Gland Link

• Hormones play key role in regulatory role of hypothalamus

• Hormones generated in hypothalamus and sent to pituitary gland to control it

• Pituitary gland releases its own set of hormones into body

Lucy Fielding

• Discovered vascular link between hypothalamus and pituitary gland

Corpus Callosum

• thick band of fibers connecting left and right hemispheres

Hippocampus

• Involved in learning new memory

• Critical for formation of new memories, but not retention of old

• Older memories moved to cortical regions

Amygdala

• Reciprocal connections with hippocampus

• involved in memory and emotional reactions

Optic Chiasm

• helps send some info from both eyes to both brains

Suprachiasmatic Nucleus

• Sits above optic chiasm

• Controls circadian rhythms

Visual Cortex

• visual info sent to occipital lobe, starting with primary visual cortex

Heschl’s Gyrus

• auditory cortex lies in superior region of temporal lobe

• primary auditory cortex

Motor Cortex

• primary motor cortex drives motor activity

• topographic map of body (homunculus)

Sensory Cortex

• topographic

• processes incoming sensory info

• contains a homunculus

Language

Arbitrary, Systematic, Generative, Displacement

Language Modalities

Spoken, Written, Sign Language, Tactile Signing

Ursula Bellugi

Founder of neurobiology of ASL

Broca’s Area

• closely aligned with premotor cortex

• grammar processing

Wernicke’s Area

• near auditory cortex

• speech perception

Arcuate Fasciculus

• connects Broca’s and Wernicke’s areas

• damage causes trouble correcting self-made errors

• trouble repeating what someone else says

Somatosensation

5 types of senses:;

• touch pressure

• temperature

• pain

• proprioception

• kinesthesis

Braille

requires touch/pressure perception

Tactile Signing

• for individuals both hearing and vision impaired

• requires proprioception kinesthesis

Vision

Spoken language & ASL both rely on it

Memory

• language has temporal component

• learning to produce speech relies on procedural and semantic

Premotor Cortex

• planning of actions

• stimulations can cause complex movements

• sends most connections to primary motor cortex

• sends some connections directly to spinal cord

Primary Motor Cortex

• generates actions

• stimulation can cause simple movements

• receives input from somatosensory cortex

• area that controls muscles in one area often receives proprioceptive input from same area

Cortical Representation

• motor functions organized topographically

• size of cortical area for body part related to precision of motor control

• training and injury can affect size and representation of body part

• plastic and experience based

Motor Equivalence

Ability to use multiple body parts or muscle groups to achieve the same goal

Basal Ganglia

Involved in refinement of motor activity

• suppresses competing motor activity

• regulates desired motor activity

• contributes to learned complex movements

Ann Graybiel

Conducted research on role of basal ganglia on forming habits

Nucleus Accumbens

• central structure for reward

• involved in addiction

Substantia Nigra

Major source of dopaminergic nerves

Dopamine

• critical for reward/addiction

  • degeneration of these neurons can lead to Parkinson’s

Inhibition

Tells motor cortex not to do something (-1)

Excitation

Tells motor cortex to yes do this thing (1)

Direct Pathway

• Even number of inhibitors

• Substantia nigra excites it

Indirect Pathway

• Odd number of inhibitors

• Substantia nigra inhibits it

Parkinson’s Disease

• Reduction of dopaminergic neurons in substantia nigra

• Characterized by:

  • resting tremors

  • slow movements (bradykinesia)

  • shuffling gait

  • difficulty initiating movements

Treatments for Parkinson’s Disease

• L-dopa (precursor to dopamine)

• direct deep brain stimulation

Huda Zoghbi

Work on the genetics of neurological disorders including spinocerebellar ataxia

Longitudinal Cerebellar Divisions

• Median (vermis)

• Paramedian

• Lateral Hemisphere

Median (vermis)

• posture

• locomotion

• gaze

Paramedian

controls distal muscles of limbs and digits

Lateral Hemisphere

• only receives input from cerebral cortex

• involved in planning and mental rehearsal of complex actions

• involved in conscious monitoring of movement errors

• output goes to motor cortex but is mediated by dentate nucleus

Lobular Cerebellar Divisions

• Anterior

• Posterior

• Flocculonodular

Anterior Lobe

controls motor tone & walking position

Posterior Lobe

controls cortically directed skilled movements

Flocculonodular Lobe

Equilibrium & eye movements

Cerebellar Peduncles

Connections between cerebellum and brainstem

Proprioception

Knowing where your body is in space

Afferent Pathways

• “arriving” info

• motor and sensory info come into cerebellum

• maintaining upright posture

• conscious & unconscious proprioception

• info from motor cortex, visual & auditory info

Efferent Pathways

• “exiting” info

• projects to brainstem, thalamus, and motor cortex (but mostly motor cortex)

• allows cerebellum to mediate motor activity

Corticospinal Tract

• controls voluntary movements of skeletal muscles

• projections originate from primary motor cortex, premotor cortex, & sensory cortex

Corticobulbar Tract

• aka corticonuclear tract

• controls head & facial muscles via cranial nerves

Spinal Divisions

31

• Cervical (8)

• Thoracic (12)

• Lumbar (5)

• Sacral (5)

• Coccygeal (1)

Dorsal Horn

Part of spinal cord containing sensory fibers

Ventral Horn

Part of spinal cord containing motor fibers

Dorsal Ramus

Part of spinal nerve handling sensorimotor function in posterior part of body

Ventral Ramus

Part of spinal nerve handling sensorimotor function in anterior part of body

3 groups of fiber tracts

• dorsal fasciculus (sensory fibers)

• lateral fasciculus (motor & sensory fibers)

• ventral fasciculus (motor & sensory fibers)

Dermatome Map

(Sensory) Map of where fibers enter the spinal cord and what part of body they innervate

Myotome Map

(Motor) Map of where fibers leave the spinal cord and what muscles they innervate

Alpha Motor Neurons

• major spinal neurons

• each innervates around 200 muscle fibers

• rapid impulse conduction

• involved in voluntary and reflexive movements of head, trunk, and extremities

Ascending Fibers

• sensory

• up through spinal cord

• afferent

Descending Fibers

• motor

• down through spinal cord

• efferent

Gamma Motor Neurons

• smaller diameter

• slow impulse control

• modulate muscles responses

Neuromuscular Junction

• motor neurons synapse onto muscles

• release a neurotransmitter (chemical signal) acetylcholine

• cause action potential in muscle fiber

• action potential leads to release of calcium

• effect of calcium differs across muscle types

• muscle fiber contracts

Lily Jan

Investigates ion channel functioning including muscular function

Antagonist Muscles

• only contract in response to acetylcholine

• make muscles move in opposite direction

Joint Capsule Receptors

• located in joints

• detects joint position

• helps with proprioception and kinesthesis

Muscle Spindle Receptors

• embedded in muscles

• spindle shaped

• detect muscle stretch

• cause reflex where stretched muscle contracts

• prevents antagonist muscle from contracting

• helps with proprioception and kinesthesis

Golgi Tendon Organs

• located near where muscle and tendon meet

• senses tension at junction

• too much tension inhibits contracting muscle & activated antagonist muscle

• helps with proprioception and kinesthesis

Interneurons

• integrates sensory & motor functions

• facilitates & sharpens motor neuron activity