KNES 351

brain; spinal cord

sensory receptors, nerves; motor nerves

the most complex organ in the human body

Neurons!

86 billion

150 trillion synapses

1.3-1.5kg in adults

20-25%

**It uses primarily glucose!

transmits electrical impulses to and from the brain

Afferent and Efferent tracks (also we have sensorimotor integration)

transmit electrical impulses from the body to the brain

(inward)

transmit electrical impulses from the brain to the body

(outward)

Transform sensory into basic motor activity (e.g. tendon tap reflex)

-incorporating sensation about one's body and the external environment to shape movement

- link between nerves and muscle

redraw reflex

send electrical impulses to and from the spinal cord

send sensory information from active sensory receptors to the spinal cord

send motor commands from the spinal cord to activate skeletal muscle

modified ending of sensory nerves. First step in processing that leads to our sense of touch and proprioception (sense of body position, motion and force in the absence of vision)

Merkle, Meissner, Ruffini, Pacinian

- Muscle spindles

- Golgi tendon organ = force through muscle

- The autonomic division: controls self-regulated action of internal organs and glands

- Somatic division: controls voluntary movement of skeletal muscles

the state of the body and environment.

**The CNS processes this information and generates appropriate responses

towards the nose

towards the coccyx (tail bone)

(anterior) towards the belly

(posterior) towards the back or top of head

(frontal plane slice)

Towards the midline

away from the midline

Look at the picture

1. Cerebrum (thoughts)

2. Diencephalon (relay center)

3. Brainstem (life functions, e.g. breathing, swallowing)

4. Cerebellum (posture & balance, corrects error)

1. 2 hemispheres (left - R hand and right - L hand)

2. Cerebral cortex (gray matter - upper level processing)

3. White matter (including corpus callosum)

communication between the hemispheres

1. Basal ganglia

2. Amygdala

3. Hippocampus

movement (vigor, amplitude) and motor learning

Expression of emotion

memory formation

Cool fact: there are place cells in the hippocampus to remember familiar environments and when you are reminded of a place (smell, vision, etc) these cells fire

Cerebral hemispheres

perceptual, motor (mostly planning) and cognitive function.

NO. All of these structures are in both hemispheres of the brain, with slightbilateral differences (e.g., handedness, especially in cortex). Each structureis subdivided into several anatomically and functionally distinct areas.

- Hand dominance = motor cortex has more connection and larger SA for specific digits

1. Frontal lobe

2. Parietal lobe

3. Occipital lobe

4. Temporal lobe

overlying cranial bones that form the skull

motor planning, organizing behavior, decision making, working memory.

*lots of higher functions

sensory guidance of motor actions, multisensory integration, spatial awareness.

*lots of vestibular cues (balance and spatial orientation for the purpose of coordinating movement with balance)

early visual processing (direction, orientation, colour, motion)

vision, hearing, memory, language

NO. Each lobe of cerebral cortex is further subdivided into several anatomically and functionally distinct regions.

The corpus callosum (also known as callosal commissure) is a wide, flatbundle of axons that connects and allows communication betweenstructures in the two cerebral hemispheres.

* allows for a balance of forces and integrated movement (e.g. belly rub and head pat)

1. Thalamus

2. Hypothalamus

• Essential link in sensory pathways(aside from olfactory receptors) from periphery to brain. (temp., cutaneous, pain, etc.)

• Interconnects cerebellum and basal ganglia with regions of cerebral cortex involved in cognition and movement. (info both in and out)

**Relay center

• Somatic growth, eating, drinking.

• Essential component of neuro-endocrine system (pituitary gland). (GH, FSH, etc.)

• Motivation (release dopamine, norepi., epi., etc.) and arousal

1. Midbrain

2. Pons

3. Medulla

rostral to pons

• Linkages between cerebellum, basalganglia, and cerebral cortex.

• Involved in hearing and control of eye movements (oculomotor control).

(Vestibular function = VOR reflex)

rostral to medulla, protrudes from ventral surface of spinal cord.

• Pontine nucleus: Relay info about sensation and movement from cerebral cortex to cerebellum.

• Sleep, respiration, taste.

Crossing over of controls

caudal part of brainstem and direct extension of spinal cord.

• Regulates blood pressure and respiration.

• Early pathways of taste, hearing, balance, and control of head, neck and limb muscles.

1. Maintaining posture and balance.

2. Coordinating head, eye and arm movements.

3. Error-based motor learning.

4. Receives somatosensory information from the spinal cord.

5. Receives copies of motor commands from cerebral cortex.

Despite accounting for less than 10% of brain volume, the cerebellumcontains more than 50% of the brain’s neurons. It has more neurons thanany other brain structure, including cerebral cortex!

muscle spindles, golgi tendon organ, eyes and cutaneous receptors

1. Receives sensory information from skin, muscles, and joints. (free nerve endings, thermoreceptors, etc.)

2. Contains motor neurons responsible for voluntary movements. (ventral horn)

3. Performs basic integration of somatosensory feedback and motor responses (reflexes).

- reflex is also integrated and higher centers can override

1. dorsal horn

2. ventral horn

3. intermediate zones

Sensory neurons (cell bodies in the dorsal route ganglia) from muscles and skin terminate in the dorsal horn of the spinal cord. (input)

Cell bodies and axons of motor neurons that influence muscle firing patterns. (output)

Interneurons that influence firing patterns of sensory (dorsal horn) neurons and motor neurons (ventral horn)

- aid in the decussation of pain and temp. receptors when entering the spine

- aid in polysynaptic reflexes such as the tendon tap (interneuron splits so that alpha motor neuron will cause contraction and inhibitory interneuron will allow other muscle to relax.

prevent reflex through anticipation

the spinal cord

31 pairs of sensory and motor nerves

somatosensory, touch, pain, temp., and information from visceral sensory organs

the 'final common pathway' through which all higher brain areas controlling movement must act

Yes! it varies along its length

Large number of sensory and motor fibers entering and leaving the spinal cord to innervate the upper limbs

Large number of sensory and motor fibers entering and leaving the spinal cord to innervate the lower limbs

An increasing proportion of ascending and descending axons (i.e. emphasis on cortical processing)

- based on level of spine

- more and more information as it also must carry lower portion

- more white matter to carry all the nerves

increasing proportion of gray matter (i.e. emphasis on spinal processing)

So that we consciously know what the motor plan was so that we may fix mistakes by comparing it to our somatosensory information being received from the spinal cord.

e.g. reflex: one muscle contracts, the opposing one relaxes

- The interneuron turns the excitatory impulse into an inhibitory through GABA neurotransmitter

a non-invasive tool that can be used to monitor and perturb movements to examine sensory and motor functions.

can be used to apply independent loads at the shoulder and/or elbow

linkages and troughs

to monitor and perturb the participant's arm while they make movements in the horizontal plane

*ONLY reaching in 2D (forward/backwards, left/right)

• Monitor and record arm movements

• Quantify how the nervous system responds to unexpected perturbations

• Quantify sensory and motor deficits in clinical populations

Hand motion profiles and hand speed profiles

*record arm motion while participants perform sensory and motor tasks with their arm

- Reaching to the door knob is much more precise as it is a small target

- The push bar is a much larger target therefore, when it is perturbed participants won't go to the middle of the bar, they will simple go somewhere along the length

*Subjects increase their response to counter load and correct back to circular target

• Subjects instructed to reach the spatial goal.

• no perturbations (loads) applied on most trials.

• perturbations on 20% of trials

• visual-feedback removed at perturbation onset (sensory feedback comes from muscles).

We assess the motor cortex and cerebellum by using position sense (no vision)

*match position that the robot moves their arm to

Only controls endpoint/hands

devices being used to assist in movement rehabilitation

1. Easy to use and non-invasive.

2. Useful for quantifying and perturbing body motion.

3. Easy to integrate with other tools such as EMG.

1. Expensive

2. Can require long setup times. (have to calibrate based on different people)

3. Can't replicate many features of how humans move freely in space (unnatural?)

an invasive technique used to record the activity of peripheral neurons

- Tungsten electrode is driven into peripheral nerve tract. (single cell recordings)

- Guided by sound and signal properties.

- Time consuming process – experimental sessions often last > 3hrs.

- Pioneered by Swedish scientists KE Hagbarth and A Vallbo in 1965-66.

the axon of a sensory neuron and its myelin sheath (if present)

a bundle of individual nerve fibers

connective tissue surrounding nerve fibers, fascicles, and nerves, respectively.

is the collection of all structures including connective tissue and blood vessels.

An electrode is inserted into the nerve beside a nerve fiber to record its activity during simple behavioural tasks

Large diameter:

- large group of muscles controlled

- higher recruitment group (more F produced)

- less precise muscle control

- fast twitch

Small diameter:

- smaller group of muscles controlled

- smaller recruitment group (less F produced)

- more fine movement

- slow twitch

- probably won't hit a node because they are so small

- produce a "double-hat" AP because you are reading the peaks @ both nodes of Ranvier (signals are sent in both directions)

1. Search (find the nerve)

2. Characterize (motor/sensory, what type of receptor, where on skin/muscle)

3. Position

4. Stimulate

Tungsten electrode is driven into peripheral sensory neuron.

Guided by sound and signal properties.

There is a lot of electrical stimuli in the human body, so it takes the average to filter out noise