Week 6 Lesson 40: Principles of Sensory Processing

What are the three cranial nerves that control eye movements?

Oculomotor (CN III)

Trochlear (CN IV)

Abducens (CN VI)

What is the body’s control system that governs actions and reactions?

The nervous system

What neurons use detection of a stimulus via receptors and transmission to CNS via afferent/ascending pathways?

Sensory Neurons

What neurons used for central processing of information and decision making?

Integration centers

What neurons are used for the transmission of decisions (autonomic or voluntary) to effectors/efferent/descending pathways?

Motor neurons

What nerves make up the somatic nervous system?

Spinal and cranial nerves

What are the 4 parts of a neuron?

1. Dendrites (Receive signals)

2. Cell Body (Soma)

3. Axon (Transmits signals, myelinated)

4. Axion terminal synapses

What are the three types of functional neurons?

1. Sensory Neurons

2. Interneurons

3. Motor Neuron

What is the function of a sensory neuron?

Receive a stimulus and transmit it to the spine

What is the function of interneurons?

Distributes and propagates signals

What is the function of a motor neuron?

Receives stimulus and transmits it to muscles

The flow of electricity from due to the influx of what ions induce changes in the membrane potential creating an action potential?

Na, K, Cl, Ca

What are the two chemical synapsis?

Presynaptic membrane

Postsynaptic membrane

What chemical synapse is on the axon terminal of one neuron?

Presynaptic membrane

What is the chemical synapse that is on the dendritic zone of the next neuron?

Post synaptic membrane

Describe the synaptic transmission that leads to propagation of action potentials along the axon?

• Presynaptic action potentials arrive → AP causes Ca channels to open → Ca influx = exocytosis of neurotransmitters → NT bind to receptors on postsynaptic membrane, causing ion channels to open → Ionic influx = graded potential → Depolarization occurs, creating an AP → Propagation of APs along axon.

Neurotransmitters such as ACh are stored in the presynaptic vesicles. What does every neurotransmitter work on that is a sight for drug targets?

Specific receptors

The postsynaptic cell has multiple synapses, either excitatory or inhibitory. The effects are summarized as excitatory or inhibitory postsynaptic potentials. The sum of these potentials, if it reaches the threshold cause what at the trigger zone?

An Action potential

What electrical event is generated at a neuron trigger zone?

Action potentials

What are the four main divisions of the brain?

1. Forebrain

2. Brain stem

3. Cerebellum

4. ARAS

The Cerebrum is a part of the forebrain, what are the 4 lobes of the cortex of the cerebrum?

1. Frontal

2. Parietal

3. Occipital

4. Temporal

What is the function of the frontal lobe of the cerebrum?

Higher cognitive and motor functions (planning, problem solving, decision-making, social behavior)

What is the function of the Parietal, Occipital, and Temporal lobes?

Sensory processing (Make body aware of what type of stimuli was received)

Damage to the Frontal lobe can cause what problems?

Change behavior, motivation, and intelligence

Damage to the Parietal, Occipital, and Temporal lobes can cause what problems?

Loss of sensation or whatever function they have such as going blind

What is the subdivision of the cerebrum deals with motor control and voluntary movement?

Basal ganglia

Damage to the Basal ganglia can cause what problems?

Paresis or paralysis

What subdivision of the cerebrum deals with emotional precessing (amygdala), memory (hippocampus), Motivation/reward (nucleus accumbens).

Limbic system

What are the three subdivisions of the diencephalon?

1. Thalamus

2. Hypothalamus

3. Epithalamus (pineal gland)

Which subdivision of the diencephalon is a relay station and filter for sensory information with many projections to other functional areas?

The thalamus

Which subdivision of the diencephalon is the control center for the autonomic NS, body temperature regulation, sleep, hunger, and the hypothalamic-pituitary axis?

Hypothalamus

Which subdivision of the diencephalon deals with the circadian rythms?

Epithalamus (Pineal gland)

What are the three subdivisions of the brain stem?

1. Midbrain

2. Pons

3. Medulla

Which subdivision of the brains stem is used for passage of motor signals and sensory signals, EPS, and CN III and IV?

Midbrain

Which subdivision of the brainstem is used for passage for motor and sensory signals, Respiratory control centers, and CN V?

Pons

Which subdivision of the brainstem is used for passage for motor and sensory information, EPS, vital control center such as HR, BP, Resp, GIT, and CN VI to XII?

Medulla

What division of the brain has the function of fine-tuning movements and coordinating posture, balance, and gait?

Cerebellum

What part of the cerebellum mostly inhibits the deep cerebellar structures and vestibular nuclei?

The cerebellar cortex

How do the deeper structures of the cerebellar cortex effect the motor system?

Excite the motor system

Describe how the cerebellum receives and interprets information.

Receives info from motor cortex about intended movements → Receives info from body about the actual movement happening → Compares intended movement with the actual movement and sends corrective signals to motor cortex and brain stem for fine-tuning.

What division of the brain is not an actual division but a functional unit. It is a network of connected nuclei throughout the proximal spinal cord, the brainstem and diencephalon.

ARAS

What are the three functions of the ARAS?

1. Consciousness

2. Attention

3. Arousal

What does the function of consciousness mean in relation to ARAS function?

Sensory information is projected to the cortex for awareness

What does the function of Attention mean in relation to ARAS function?

It filters sensory input, suppressing distractive stimuli and forwarding prioritized signals to the cerebrum for focused attention.

What does the function of arousal mean in relation to ARAS function?

It acts as an on-off switch for sensory signals, controlling sleep-wake cycles

What part of the ARAS is considered the main relay station for the sensory input?

Thalamus

What type of matter in the spinal cord has dorsal, lateral, ventral funiculus; containing mostly axons?

White matter

What type of matter in the spinal cord has dorsal, ventral, lateral horns, and central gray (containing mostly nuclei and interneurons)?

Grey matter

Which neurons travel via the dorsal root ganglion, dorsal roots into dorsal gray horns?

Sensory neurons

What neurons travel via the ventral gray horns and ventral roots into peripheral nerves (LMN)?

Motor neurons

The spinal cord segment is equal to the origin of how many spinal nerves?

1

In every spinal cord segment releases what that contains motor, sensory, and autonomic fibers?

Mixed spinal nerve

Every plexus nerve carries what to and from several spinal cord segments?

Sensory and motor fibers

Describe the 1st orfer in the 3-order neuron chain?

Runs from a sensory receptor in a peripheral nerve into the spinal cord, sometimes to the medulla

Describe the 2nd order in the 3-Order Neuron chain?

Runs from the spinal cord or medulla to the ARAS

Describe the 3rd order in the 3-Order Neuron chain

From the ARAS to the cortex for conscious perception

What are the two neuron chains of the descending motor system?

Upper motor neurons

Lower Motor neuron

What neuron chain have nuclei in the brain (cortex and brainstem) and axons cursing from the brain down the spinal cord, synapsing in the ventral gray horns?

Upper motor neurons

What neuron chain have axons leaving the spinal cord via the spinal nerves and innervates skeletal muscles at neuromuscular junctions causing muscle contraction/relaxation?

Lower motor neurons

What is the conscious or subconscious awareness of external or internal stimuli?

Sensation

What are the 5 somatic senses?

1. Pain

2. Touch

3. Temperature

4. Itch

5. Proprioception

What are the 5 special senses?

1. Vision

2. Hearing

3. Balance

4. Taste

5. Smell

What is a specialized ionic channel in a sensory nerve ending or cell that detects a specific stimulus and converts it into electrical signals for the nervous system?

Sensory receptor

Most receptors are what type of channel?

Ion channel

Most receptors are embedded where?

In free nerve endings

What are the three types of receptors for propriception?

1. Muscle spindles

2. Tendon golgi organ

3. Joint receptors

What are the 4 types of energies that a receptor could respond to?

1. Mechanical

2. Chemical

3. Thermal

4. Electromagnetic

What type of receptor is a mechanically gated ion channel embedded in sensory nerve endings, causing a membrane deviation, opening channels, and changing ion flow, causing an impulse?

Mechanoreceptors

What receptor is a ligand-gated ion channels which open after binding a specific chemical (ligand) creating an impulse?

Chemoreceptors

In what instances are chemoreceptors are used?

Pain, Itch, Taste, Smell

What type of receptors are temperature sensitive ion channels that open or close in response to temperature changes?

Thermoreceptors

What type of receptor absorb electromagnetic energy inducing metabolic changes, which change ion channels?

Photoreceptors

Where are photoreceptors used?

Retina

What is the common mechanism of all sensory receptors?

Irrespective of the type of sensory receptor, its stimulation changes ionic flow, leading to the generation of impulses (action potentials) in the sensory neuron

For the face the 1st order neurons run in cranial nerve to the brain stem mostly in which nerve?

CN V trigeminal

The 2nd order neurons run from the brain stem to the thalamus. Their cell bodies form what that is equivalent to the dorsal gray horms for spinal nerves?

Distinct Nuclei in the brainstem

Is it true that most sensory receptors are ion channels and that their stimulation causes action potentials in the sensory neurons, which are propagated to the brain via a 3-order neuron chain?

Yes its true

What is the forebrain’s cerebral cortex responsibility for the concious awareness and localization of the incoming stimuli called?

Perception

How does the brain know that the arriving action potentials via the 3rd order neurons represent a specific modality?

1. Cortex is divided into functional areas

2. Signals from one modality always terminate in their dedicated cortex

3. Mapping enables the correct interpretation of the type of stimulating energy

How does the brain know which body part was stimulated?

Point to point projection

What is point to point projection?

Each dedicated cortex contains an image of the body allowing signals from a specific body part always projects to the same location within its dedicated sensory cortex

What is an overrepresented body parts reflect higher densities of sensory receptors, mores sensitive areas reflect animals lifestyle.?

Homunculus