PSYCH 230 - F.Central Nervous System

spinal cord

1. Receiving sensory information from the periphery and sending it to the brain (input, afferent)

2. Sending outgoing motor commands from the brain to the muscles (output, efferent)

nerve root

where we receive and send out neural information

grey matter

neurons

white matter

nerves/neural pathways

bell-magendie law: dorsal (back) nerves and horns

sensory (information comes in)

bell-magendie law: ventral (front) nerves and horns

motor (information goes out)

patellar tendon (knee-jerk) reflex

mallet hits, quad flexes, picked up by sensory/afferent neuron, comes into dorsal nerve root, goes to interneuron which reverses the signal, triggers motor efferent neuron out through ventral nerve root, results in opposing command to have hamstrings relax so our leg can move - does not rely on brain at all

chickens with chopped off head running around

the motor outputs do not necessarily rely on the brain

christopher reeve - case study

crushed spine (very high, near neck) and became paralyzed for the rest of his life; where injury happens determines the extent of the injury (near neck, mostly all down - near waist, waist down, etc - COULD affect communication with internal organs); had to use artificial ventilation and processes/equipment to survive

foramina (foramen magna)

hole in skull (for spinal cord)

meninges

membranes that enclose the brain and spinal cord

dura mater

uppermost layer of the meninges; thickest layer, almost like leather

arachnoid mater

middle layer of meninges; looks like a spiderweb

pia mater

lowest layer of meninges; thinnest layer, directly overlaps the brain

meningitis

inflammation of the meninges

brainstem (structure)

medulla, pons, midbrain

brainstem (functions)

survival functions

1. Ascending and descending sensory and motor information (spinal cord)

2. Control of blood pressure, gut, pupils, breathing (unique brain nuclei control this - lesions here can endanger life)

3. Attention and arousal

4. Mediates sensation and motor control of head, neck, and face via cranial nerves

cranial nerves

nerves that emerge directly from the brain, in contrast to spinal nerves - most come out of brainstem (through foramina); receive sensory information from the face because the spinal cord is not high enough; 12 in humans; sensory and motor cranial nerves (people can survive with damage to these nerves, but there will likely be consequences on sensation and motor)

trigeminal nerve (CN 5)

splits into 3 branches - sensory

1. Touch and movement to skin and face (tongue muscles, chin, cheek)

trigeminal neuralgia

inflammation of the trigeminal nerve, causing facial pain

olfactory nerve (CN 1)

does NOT go to the brainstem, goes into the olfactory bulb, and then the cortex

1. Allows us to smell

What is the result of why it isn’t in the brainstem?

1. This may be why odors have stronger memories, etc. because it goes straight into the areas that are associated with it

locus coeruleus

in brainstem; stress, attention, arousal, noradrenaline/norepinephrine; fight or flight

superior colliculus

in brainstem; vision

inferior colliculus

in brainstem; hearing

ventral tegmental area (VTA)

in brainstem; dopamine, motivation, arousal

substantia nigra

in brainstem; movement

parkinson’s disease

death of dopaminergic neurons in the substantia nigra

cerebellum

important for coordinating and learning fine motor movements and for maintaining posture

cerebellar ataxia

when the cerebellum is lesioned; impaired coordination due to cerebellar pathology

lower forebrain/diencephalon

thalamus, hypothalamus

thalamus

relays sensory signals to the cortex

medial geniculate nucleus

audio

lateral geniculate nucleus

vision

hypothalamus

under the thalamus

1. Motivation (drive - attention and aversion), reward, aversion, sex, aggression

   1. Mediated by substructures in hypothalamus

2. Body homeostasis (temperature, thirst, hunger) - nuclei within hypothalamus regulate this by comparing the body’s state with set points

3. Sends signals to pituitary gland to control hormone secretion (hormonal - slower, back up system to blood  - brain releeases hormones into bloodstream that is sent throughout the body) 

homeostasis

the process of maintaining the system at a stable state (temperature, thirst, hunger, etc)

limbic system

memory and emotion

1. hippocampus

2. amygdala

3. more? (debate)

hippocampus

learning and memory (episodic/events)

amygdala

fear and emotion (fear/learning to fear - may affect hippocampus as well)

basal ganglia

group of nuclei at the base of the forebrain and top of brainstem (includes substantia nigra)

1. Action and movement

cerebral cortex

outermost layer of our brain

1. High-level brain function and cognition

   1. Language, imagination, perception, planning, decision-making, memory, information integration, etc

cognition

the mental process of acquiring knowledge and understanding through thought, experience, and the senses

sulcus/sulci

groove in cerebral cortex (valley)

gyrus/gyri

bulge (mountain)

corpus callosum

bundle of axons that connects to hemispheres of the brain

frontal lobe

motor control, planning

parietal lobe

somatosensation, processing sensory information

occipital lobe

vision

temporal lobe

hearing

ventricles

4 spaces filled with cerebrospinal fluid (CSF)

1. Constant movement of fluid between ventricles

2. CSF bathes and cushions the brain, buoyancy

3. Flow of nutrients

blood-brain barrier

Semi-permeable separation between blood and brain that adds a layer of protection since the brain tissue is very sensitive (limits and restricts entry)

1. Protects the brain from circulating pathogens

2. Passes: Water, gases, hydrophobic molecules, glucose, and amino acids (prevents viral infections in the brain)

3. Blocks: Large hydrophilic molecules, bacteria

Challenge for drug delivery

astrocytes

1. provide structural support

2. anchors everything together

3. balance chemical concentrations outside of neuron

4. injury repair

microglia

1. provide immune defense by consuming and destroying foreign bodies in the brain

oligodendrocytes

1. wraps neurons with myelin that increases electrical signalling