NEU 4

How many senses are there?

8, depending on how you count, Vision, Audition, Olfaction (Smelling), Gustation (Tasting), Somatosensation (Touching), Proprioception (Body Position), Vestibular (Head Position), Interoception (Internal Feelings)

What does the vestibular sense for?

It is for balance and head movement, the semicircular canals are responsible for this

What are the semicircular canals?

In the inner ear and are arranged in 90-degree angels from each other (x,y,z), are full of a fluid called endolymph

What is the ampulla?

A bump at the bottom of the each of the semicircular canals

What is the cupula?

A gelatinous mass, that holds vestibular hair cells. The cupula is in the ampulla

What happens when you are still and then rotate your head?

When you are still, the fluid in the semicircular canals is also still, when you move your head, the endolymph lags behind and pushes the jello-like cupula in the opposite direction

What is proprioception?

Awareness of the body’s position, get signals from skeletal muscles, tendons, and joints

What are muscle spindle afferents?

Sensory nerve fibers wrapped around muscles fibers, detecting stretch and contraction

What are Golgi tendon organs?

Sensory nerve fibers embedded in the intersections of the muscle and tendon, sense the force being applied to the muscle

What are joint receptors?

Receptors embedded in capsules surrounding joint sensing the angle of the joint

What is kinesthesis?

Sense of movement, combination of proprioception, vision, and vestibular sense

What are the layers of skin?

Outer layer is epidermis, next is dermis, and then the subcutaneous tissue

What are adaptation rates?

Fast, burst of action potentials stimulus applied and removed, fires to “on” and “off”, slow, remain active when in contact with stimulus, responding to continuous pressure

What are receptive fields?

The area of the skin/body to which a certain receptor will respond, the smaller the receptive field, the higher the acuity

What are Merkel disks?

They are slow adapting, with small receptive fields, close to the surface of skin, detect fine-grain textures and detail, shaped like stars, a lot in the fingertips and lips

What are Meissner’s corpuscles?

They are fast adapting, with small receptive fields close the surface of skin, like a string weaving through disks, good at detecting movement across the skin, maintain grip

What are Pacinian corpuscles?

They are fast adapting with large receptive fields, deeper in the skin, endings are like a concentric series of water ballons, good at detecting vibration and pressure

What are Ruffini endings?

They are slow adapting, with large receptive fields, deeper in the skin, endings are spread out in a horizontal bulb, detect stretching of skin (pressure), some joint receptors are actually Ruffini endings

What are free nerve endings?

Some nerve endings are wrapped around the base of hairs

What are thermoreceptors?

Receptors that respond to temperature, warm receptors respond to capsaicin, cool receptors respond to menthol

What are nociceptors?

Sense pain, respond to temperature, chemicals, pressure, and inflammation

What is going on with interoception and the autonomic nervous system?

Contains huge diverse set of sense about internal body, many never reach the cortex, important for homeostasis

Is interoception diverse?

Yes, includes thermoreceptors (liver and skeletal muscles), chemoreceptors (nerves surrounding blood vessels sense presence carbon dioxide in plasma), mechanoreceptors (sense stretching of smooth muscles like stomach and bladder).

What is the physical-social pain overlap hypothesis?

Similar brain areas are active while experiencing social and physical pain

What are brains for?

Moving!

What are the different types of muscle

Skeletal muscles (connects to tendons which pull on bones moves body around), Smooth muscle (walls of hollow organs, stomach, airways, blood vessels) move matter around, Cardiac muscle (heart, pumps blood)

What is the somatic motor system

Skeletal muscles and associated parts of nervous system

What are flexors and extensors

Flexors, move bone toward the body (bicep), extensors, move bone away from body (triceps), they are antagonistic pairs, if flexors contract, extensors relax and if extensors contract, flexors relax, multiple muscles working together to flex or extend are synergists pairs

What makes up the muscle composition?

B to S - Muscle, fascicle, single muscle fiber, and myofibril

What are myofibrils?

Tiny threads within muscle fibers which are muscle cells, which bundle into fascicles which combine into a muscle

What are lower motor neurons?

They control muscles, specifically alpha motor neurons actually trigger the contraction of muscles, their cell bodies exist in the spinal cord, their axons exit the ventral horn of the spinal cord, and are bundled together into the ventral root

What are motor units?

one alpha motor neuron and all the muscle fibers it innervates, the smaller the # of muscle fibers in a motor unit, the more precise the control

What is a motor pool?

All the alpha motor neurons that innervate a muscle

What neuromuscular junctions?

Synapses between motor neurons and muscle fibers, motor neurons release ACh into synapse, muscles cells have end plates folds to fit around terminal buttons, nicotinic ACh receptors

What are action potentials in muscles?

ACh causes EPSPs in muscle fibers, when threshold is reached, voltage gated sodium ion channels open, depolarizing the muscle fiber

What happens with muscle fibers with action potentials

Myofibrils are divided into shorter segments called sarcomeres, which are then separated by Z lines. In the sarcomeres there is thin filaments called actin, and thick filaments called myosin, they slide along each other to contract muscles

How does the sliding of myosin and actin occur?

Myosin binds to Actin using ATP to row itself along, re-binding as it goes. At rest, myosin can’t bind because Action is blocked by tropomyosin and troponin

What happens when the muscle fiber is depolarized?

It opens voltage-gated calcium ion channels then calcium binds to troponin and changes the shape of tropomyosin exposing binding sites for myosin

What nerves are involved with skin and muscle?

Skin, afferent nerves, info goes to the brain, then info comes from the brain via efferent nerves and to the muscle

What are reflexes?

They are involuntary movements that respond to stimuli, they do not require the brain, it is all spinal cord

What is the stretch reflex?

Proprioceptors in muscles detect passive stretch of muscle, these axons synapse onto a motor neuron in the spinal cord which sends contraction to the same muscle

What is monosynaptic?

Only two neurons and one synapse

What are interneurons?

Relay neurons, integrate sensory and motor signals, responsible for many spinal reflexes

What is reciprocal innervation?

Sensory neuron stimulates motor neuron and interneuron, motor neuron of extensor is excited, and interneuron sends inhibition to motor neuron of antagonistic flexor muscle

What is the pain withdrawal reflex

Flexors are excited (pull limbs closer to body), extensors are inhibited (reciprocal innervation)

What is the Golgi tendon reflex

Excessive force on tendons is sense by Golgi tendon organs, signals stimulate interneurons, interneurons send inhibition to the same muscle, and excitation to antagonistic muscle

What is the scratch reflex?

Oscillator circuit, rate relatively fixes and mediated by spinal cord, human raspberry, similar oscillator circuits are produced by central pattern generators in spinal cord, cerebellum, and brainstem.

What are infant reflexes

Grasping, stimulation of palm causes infant to close fingers in grasp, rooting, infants turn their heads and suckle in response to their cheek being touched, reflex can reappear in very drunk adults

What is the big picture with lower motor neurons?

They have cell bodies in spinal cord and axons which actually cause contraction of muscle

What are upper motor neurons?

Have cell bodies in the brain (cortex or brainstem) and axons which travel down the spinal cord and influence interneurons and lower motor neurons

What are lateral pathways?

Cell bodies in cortex, axons cross over to contralateral side in the medulla at the pyramidal decussation, controls contralateral skeletal muscles for voluntary movement

What are ventro-medial tracts?

Cell bodies in sub-cortical structures with axons that synapse in various points of spinal cord, mainly for involuntary motor control (both sides of body, coordinated limb movements, posture of neck, shoulders, trunk)

What is the M1

Primary motor cortex, main place in brain that sends signals to lower motor neurons to control muscles, generally control voluntary movement of skeletal muscles, cell bodies of upper motor neurons

Where are the cell bodies of upper motor neurons?

In the cortex, and axons project down to lower motor neurons

How is M1 topological organized?

Adjacent body parts are controlled by adjacent areas of M1

How does M1 also show cortical magnification?

Important parts take up more space, regardless of size

Do species have equivalent M1 and S1?

No, different species have different parts magnified in M and S1

What are the pre-motor and supplementary motor areas?

PMA and SMA are anterior of M1, PMA is more ventro-lateral and SMA are more dorso-medial, both do motor planning, PMA current environment, SMA memories and both sides of body

What is the posterior parental cortex?

Integrate sensory and motor information, send signals back and forth with frontal motor areas

What is the cerebellum?

For rapid, well-coordinated movements that require precise timing, muscle memory, communicated to brain and neurons not muscles, only 10% of brain mass but 50% of neurons, around 50 billion

What are cerebellum purkinje cells

Have flat dendritic branching trees

What are cerebellar circuits?

Code time as distance as a signal travels, purkinje cells respond to different muscle groups, activity along parallel fibers represents timing of different moves

How does the basal ganglia play a role?

Keeps track of motor sub-goals, selecting the appropriate signal at the appropriate time, automates complex sequential tasks, involved in skill/procedural learning and memory

What does the striatum do?

Receives sensor motor input from thalamus, regiments, and cortex

What does the globus pallidus do?

Sends output to motor cortex via thalamus and parts of the brainstem

How is the basal ganglia process a re entrant system

Looping signals to and from the cortex and subcortical structures

What are some issues with the basal ganglia?

OCD, ADD, Tourette’s, and Parkinson’s

What are mirror neurons?

Mirror cells respond when a subject sees/feels self performing familiar act and when seeing another individual perform the same action

Do genetic and experiential factors combine?

No, they do not combine in an additive fashion

Is natural selection stagnant?

No it is not stagnant, it can change

What were Darwin’s evidence of evolution?

Fossil evidence, impact of selective breeding, and structural similarities among living species

What are chromosomes?

Genes are found on chromosomes, humans have 23

What is DNA?

Pairing of nucleotides,

What is a gene?

Segment of DNA that contains the molecular instructions for making a protein

What is an allele?

Gene variant

What did Mendel do?

Crossed a line bred true for brown seeds with one bred true for white, first generation had all brown seeds, when this generation was bred it was then 3 brown and 1 white

What is gene expression?

The output of genetic code and if the output is observable it’s a phenotype

What is transcription?

DNA to RNA, happens in nucleus

What is translation?

Process of converting RNA into proteins, happens on ribosomes

What is DNA transcribed by?

RNA polymerase

Where are our genes?

All in cells!

What are transcription factors?

Proteins that bind to DNA and influence which genes get expressed

Is XY or XX individuals more likely to express genetic traits that are sex linked?

XY, there are genes on the X chromosome that do not have a matching pair on the Y

What is X inactivation?

Process that causes most of the genes on an X chromosome in individuals with XX to be silenced

What are three types of epigenetic modifications?

Histone remodeling, DNA methylation, Gene silencing (RNAi)

What is DNA methylation?

Attachment of methyl group directly to DNA, unresolved trauma is correlated with DNA methylation

What is histone modification?

Modification of histone protein (around which DNA is coiled)

What are phantom limbs?

People feeling pain in limbs that are missing

What is experience depend plasticity?

Neurons adapt based on a persons activity and environment

How does plasticity change over the lifespan?

Metaphorically “lower” brain areas are plastic in finance become less plastic over time (V, M, S, and A1), “higher” brain areas are plastic for our entire lives, (hippocampus, frontal lobe, higher visual areas)

What is memory?

The process of encoding, storing, and retrieving information

What is hebbian learning?

Learning at the synaptic level

What is LTP?

Synapses with frequency activity become more reliable, cells that are co-active for neural circuits that are co activated

Why are the post-synaptic changes in plasticity?

Dendrites grow more branches, grow more dendritic spines, more space for new synapse to form, dendrites grow more and more receptors

What are pre-synaptic changes?

Axon terminal buttons split and branch more, metabolic changes in the presynaptic changes cell trigger more and longer neurotransmitter release

What are the areas of long term memory?

There is explicit and implicit

What is explicit memory?

Episodic (hippocampus) and declarative (semantic)

What is implicit memory?

Procedural (basal ganglia) and priming!

What is amnesia?

Memory deficit due to brain damage

What is amnesia?

Memory deficit due to brain damage