Neural Signaling

Sensory/Afferent Neurons

Receive stimuli from the environment

Interneurones

Neurons that process information

Motor neurons/Efferent

Neurons that allow muscles or effectors to move

Neuroglia in the CNS

1. Oligodendrocytes

2. Astrocytes

3. Microgial

4. Ependymal

Oligodendrocytes

Myelination in the CNS only- several projections wrap themselves around the axon of a neuron

Astrocytes

1. Modify the chemistry of the brain

2. Support spatial and physical structures

3. Interact with capillaries

4. Affect the synapse

Ways Astrocytes modify the chemistry of the brain

1. Take up excess K+ from the ECF

2. Clear metabolic waste “glymphatic system”

3. Chemicals signals to neurons and other cells

Ways Astrocytes modify the physical/spatial aspects of the brain

1. “Glue of the CNS”

2. Scaffold for traveling neurons during development

3. Neural scars to repair injuries

Ways Astrocytes interact with capillaries

1. Induce blood-brain barrier

2. Transfer nutrients from blood to neurons

Ways Astrocytes affect the synapse

1. Enhance and modify synaptic transmission

2. Take up/ degrade local neurotransmitters

Microgial cells

Immune defense cells of the CNS (closely related to monocytes)

Ependymal cells

Produce cerebrospinal fluid and help CSF flow through the ventricles of the brain using cilia

________, ________, _______, and _________ allow for structural protection of the CNS

1. Cranium and vertebral column

2. Meninges

3. CSF

4. Blood-brain barrier

Cerebrospinal fluid

Allows for buoyancy of the brain, nutrient and waste exchange

Blood-brain barrier physiological aspects

Highly selective transporters

Blood-brain barrier anatomical aspects

Endothelial tight junctions

_______ & _________ have free exchange in the BBB

CSF and ISF

BBB helps prevent against

Chemical fluctuations of the plasma

Oxygen supply to the CNS is hard because

The brain cannot resort to anabolic metabolism

Glucose supply to the brain is crucial because

It can only use glucose (when starving it can use ketone)

Cerebral Cortex is responsible for

1. Conscious thought & behavior

2. Sensory perception

3. Intellectual functions & learning

4. Memory

5. Complex function

Hemispheric lateralization

The cerebral cortex is split into the left brain and right brain

Left brain

Categorical hemisphere & right side of the body

Examples of left brain processes

Logic, math, reasoning, language

Right brain

Special/visual (creative) hemisphere and left side of the body

Examples of right brain processes

Spatial, visual, facial recognition

Corpus callosum

Allows communication across the sides of the brain

What happens if the corpus callosum is severed?

Functions of the brain hemispheres are isolated

Lobes of the brain

1. Occipital

2. Temporal

3. Frontal

4. Parietal

Occipital lobes

Visual perception and interpretation

Temporal lobe

Auditory processing

Frontal lobe

Voluntary motor activity, motor speech, elaboration of thought, personality

Parietal lobe

Somatosensory sensory and proprioception

Primary Sensory Corticles

Perception and decoding of action potentials in context

Primary sensory corticles decode depending on

Frequency of the stimulus and what wire it comes through

homonculus

“Little man” mappable size of the field of perception in the brain leads to finer resolution

Cortical Association areas

Compare to memory and experience and assign meaning to the signals coming in

Higher order association areas

The integration of all of the sensory input (ex. Hearing, vision, head orientation)

Prefrontal Association cortex

Where brainstorming occurs and where the working memory plans voluntary activity, decision-making, and creativity

Working memory

Temporarily stores and manipulates memory and sensory information for planning and reasoning

Limbic association cortex

Motivation, emotion, and memory are connected here

Higher Motor area

Prepares motor program by coordinating movements relying on sensory input, fine tuning of the cerebellum

Primary Motor cortex

Splits program into each muscle involved

Lower brain and spinal cord

In charge of unconscious skeletal muscle activity and generates patterns of movement

2 cortexes controlling language

1. Wernickes Area

2. Broca’s area

Wernickes area

Interpreting and understanding language- naming things and word association

Broca’s area

Programs sounds of speaking

Where is Broca’s area located?

In the higher motor area of the brain

Plasticity

The ability to change or be functionally remodeled for demand

Brain plasticity is due to

New connections, not new neurons

Subcortical regions of the brain

1. White matter

2. Gray matter

3. Nuclei

4. Basal nuclei

5. Limbic system

6. Diencephalon

White matter

Wires of the brain- axons

Gray matter

Plugs of the brain- cell bodies

Basal nuclei

Areas of gray matter in cortex

What do basal nuclei do?

Inhibitory motor tone to balance excitement of muscles and maintain purposeful motor activity

Limbic system

Processing emotion

2 portions of the brain crucial to the Limbic system

Hippocampus and amygdala

Hippocampus

Memory and retreival

Amygdala

Assigns emotion to memory

Diencephalon

Contains the thalamus and hypothalamus

Thalamus

Relay stations of the brain- all signals go through the thalamus and helps to direct attention

What one sense does NOT go through the thalamus?

The Olfactory sense- goes right to the amygdala

Hypothalamus

Homeostatic control center- makes judgement call about the set point and decides to activate parts of the body/brain

Cerebellum

The “comparator” balances and controls eye movement & fine-tunes motor control

Brain stem components

1. Midbrain

2. Pons

3. Medulla oblongata

Brainstem function

A vital bridge because info always comes through the brainstem- the start of cranial nerves and carries out homeostatic decisions

The brainstem contains the RAS

Reticular activating system

Reticular activating system

Network throughout brain controls degree of cortex, alertness, and attention