Physiological Psych Part 1

Gall

Theory of organology- proposed brain was made up of different organs that drives particular traits, led to phrenology and localization of function that’s not true

Phineas Gage

Major changes to personality and behavior after damage to frontal lobe, first documented case relating brain with personality leading to localization of function, example of learning from loss

Moniz

Developed way to visualize artery structure in brain, earliest example of brain imagery, believed mental illness was due to malfunctioning synapses in frontal cortex which led to severing connections to frontal lobe which is leucotomy and then lobotomy which resulted in issues in patients but was still widely used

Hebb

Wrote about neural basis of learning which is the internal part of the brain, this year emphasized Skinner’s findings

Golgi

Led to advancements in knowledge about brain tissue, promoted concept of syncytium (fused axons) and reticular theory

Reticular theory

Neurons share direct connection, continuous network with no gaps/synapse

Cajal

Created detailed drawings and found that neurons were individual entities with signal transmission, neuron doctrine (nervous system made up of individual cells) which goes against syncytium, Cajal was right

Neuron doctrine

Neurons are individual cells with small gaps between (synapse), connections not random but specific pathways, dynamic polarization (parts of neurons take in information and some parts send information)

Henry Head

Charted sensory progress during regeneration of severed sensory nerves, introduced concept of different types of sensory fibers regenerating at different speeds

Loewi’s experiment

Tested if direct connection is needed for neurons, stimulated heart in container that shared fluid with another heart with no direct connection

Neurons

• Communicate by electrochemical signals (neurotransmitters)

• Around 100 billion neurons in the brain with each neuron making around 1000 connections

• Every connection collects input, process/decide, and produce output

• Can transmit information over distance

• Critical parts for communication are dendrites and axons

Glia cells

• Critical non-neural cells playing supportive function

• Supports neurons in structure, waste removal, creation of myelin sheath, promote neuron growth and guidance

Dendrite

Receive information

Axon

Send information

Dendritic Spines

Points of contact with other neurons, spines change as they grow and retract

Plasma membrane

• Lipid bilayer (2 layers of fats)

• Semi-permeable (only some compounds get through, so electric charges can’t get through)

• Limit of what can pass through is critical for action potential

Motor neurons

• Connects to muscle or organ

• System output component

• Many dendrites, only one axon, axon hillock, myelin sheath, terminal bouton

• Efferent

Sensory neurons

• Brings sensory information to brain

• System input component

• No true axons or dendrites

• Each end combination of myelinated and fast conduction with cell body located off to side

• Afferent

Interneuron

Communicates within nervous system, occurs in between input and output

Multipolar

Common, more complex processing, one axon and many dendrites, spinal motor neurons

Afferent neuron

• Approach and coming toward

• Sensory neurons bring sensory information to brain

Efferent neuron

• Exit and going away from

• Motor neurons connect to muscle or organ

Astrocytes

• Type of glia

• Surround neuron

• Removes waste

• Store and release glucose and potassium regulating ion concentrations

• Contact with vasculature at end feet which helps form blood brain barrier

Microglia

• Type of glia

• Assist in repair and proliferate (multiply) in damaged region

• Phagocytic function which removes waste and releases nitric oxide to kill damaged neurons

Oliogodendrocytes

• Type of glia

• Produce myelin and wrap sheath concentrically

• In CNS, oliogodendrocytes myelinate up to 50 axons at once, inhibit regrowth, and axons don’t regenerate

• In PNS, Schwann cell wrapping and myelinating only single axon, promote regrowth, and axons regenerate

• Interruption at nodes of Ranvier needed for saltatory conduction

Gliosis

Glia fill space left by dead neurons, seen after injury, may be combination of astrocytes and microglia, white here is glial cells not white matter

Dorsal (superior)

Top part of brain

Ventral (inferior)

Bottom part of brain

Lateral

Outer side of brain

Medial

Middle part of brain

Rostral (anterior)

Front part of brain

Caudal (posterior)

Back part of brain

Coronal

Slices front to back

Sagittal

Slides from side to other side

Transverse

Slices from top to bottom

Nuclei

• Neuron cell bodies located in central nervous system

• Make up gray matter

• Process and initiate signals and serves as origin point for cranial nerves

Nerve

• Bundles of axons located in peripheral nervous system

• Composed of bundles of axons which make up white matter

• Transmits electric signals rapidly over long distances to and from target

Nervous system

Composed of CNS and PNS that can be divided into sections

Central nervous system

• Splits into brain and spinal cord

• Drives behavior

Peripheral nervous system

• Splits into somatic and autonomic

• Series of nerves that connect CNS to rest of body

• 31 pairs of spinal nerves with each nerve, which are axons of many neurons grouped together, each containing sensory and motor axons

• 12 pairs of cranial nerves with some sensory and some motor with some that are both

Autonomic

• Automatic

• Communicates internal body state information to and from CNS

• Splits into sympathetic and parasympathetic

• Innervates internal organs, most organs dually innervated where sympathetic and parasympathetic are both present

Sympathetic

Stimulates fight or flight, kicks in when there’s immediate physical threat for most animals

Parapsympathetic

Calms down from sympathetic activity and stress, conservation of energy and maintains homeostasis

Somatic

• Communicates external stimuli information to and from the central nervous system

• Splits into afferent (sensory information arriving in CNS) and efferent (motor information exiting CNS)

• Comprised of nerves (many neurons and axons)

Gray matter

Grey matter in spinal cord surrounded by white matter while opposite for brain, lots of cell bodies and dendrites processing information

White matter

Tissue that appears white because of bundle of myelinated fatty axons, acts as communication network as information flows from gray matter to white matter

Bell Magendie Law

Motor nerves faces and attaches to ventral of spinal cord while sensory nerve faces and attaches to dorsal for everyone

Cranial nerves

• Not all combination of both motor and sensory nerves, 12 cranial nerves

• If there’s damage to olfactory (smell) nerve it’ll produce inability to smell

• Bell’s palsy is damage to facial nerve which creates paralysis of one half of face

• Novocain given by dentist directed at trigeminal nerve which has both sensory and motor components to stop action potential of neurons so there’s loss of sensation and motor control

• Vagus nerve is the wandering nerve going throughout body and major part of the parasympathetic nervous system

Norepinephrine

Neurotransmitter for sympathetic system, brain messenger for attention, stress hormone

Acetylcholine

Neurotransmitter for parasympathetic, comes out of cranial nerves and sacral spinal cord

Protection of the CNS

Blood brain barrier, bone, membranes, cerebrospinal fluid

Blood brain barrier

• Prevents harmful substances from getting to neurons in brain and spinal cord

• Located where blood vessels contact brain tissues

• Endothelial cells (flat) tightly packed with no gaps

• Small uncharged molecules and fat soluble molecules including many drugs can go through

• Active transport required for glucose and amino acids (some hormones and vitamins)

Bones

Skull and vertebrae

Meninges

• 3 membranes surround brain and spinal cord, provide cushioning

• Pia mater: innermost

• Arachnoid mater: web like and spongy

• Dura mater: outermost tough and thick

Cerebrospinal fluid

• 4 Ventricles: fluid filled cavities in brain

• Continuously produced and absorbed by choroid plexus

• Allows brain to float reducing effective weight

• Found in central canal of spinal cord

Gyri and Sulci

Bumps and ridges folded to fit a lot into small space and to be closer to axonal connections

3 subdivisions of brain

Hindbrain, midbrain, forebrain

Brainstem

Midbrain, pons, medulla, doesn’t include cerebellum

Medulla (hindbrain)

Controls life sustaining functions like circulation of blood, respiration, reflexes, maintains muscle tone

Pons (hindbrain)

• Controls sleep and arousal

• Locus coeruleus: area in pons that produce norepinephrine for brain, can be activated by other higher regions

• Dysfunction: lack of paralysis in REM state

Cerebellum (hindbrain)

Little brain, coordination of movement and sense of balance, involved in abstract pattern learning and procedural memories

Mesencephalon (midbrain)

• Tectum (roof): superior colliculus (visual reflexes) and inferior colliculus (auditory reflexes)

• Tegmentum (floor): includes important neurotransmitter connections to other areas, substantia nigra (dopamine), ventral tegmental area

Thalamus (forebrain)

• Sensory relay center, all sensory information except for smell goes to thalamus

• Pathway connections very important, there’s direct connection to amygdala and to higher sensory processing centers

Hypothalamus (forebrain)

• Below thalamus and important part of endocrine system

• Associated with fighting, fleeing, feeding, and reproduction

Limbic system

• Areas involved in learning and memory, emotions, and motivation

• Doesn’t operate in isolation!

Hippocampus (limbic system)

Learning and memory including spatial memory

Amygdala (limbic system)

• Emotions especially fear and anxiety

• Some stimuli carry innate fear and don’t require much conditioning to learn while some stimuli must be learned to generate fear

• Central region involved in innate fear while basolateral region more complex and can learn fear

• Gets input from thalamus, pain from PAG in midbrain, frontal cortex connections

• Has direct outward connection to motor cortex, hippocampus, and locus coerulues in pons that controls alertness

Basal ganglia

Plans movement control

Cerebral cortex

• Doesn’t work in isolation

• 4 major lobes: frontal, parietal, temporal, occipital

• Layered structure

• Gyri and sulci increase surface area and reduce axonal distance with multiple layers having more dendrites than axons, more gyri and sulci allows more neurons being able to process complex information

Central sulcus

Divides frontal and parietal with motor and sensory sulci

Lateral sylvian fissure

Divides temporal from frontal and parietal

Corpus callosum

Information bridge of axons between the left and right hemispheres

Occipital lobe

• Very back of brain

• Important for vision, visual information relayed from thalamus and sent to occipital lobe

Temporal lobe

• Primary auditory cortex

• There’s association areas related to memory

• Visual processing with multiple regions with specificity for identifying visual stimuli, prosopagnosia result from damage to temporal lobe

Parietal lobe

• Touch, pain, temperature, limb proprioception

• 2 main paths are pain and temperature then touch, proprioception, and movement

• Primary somatoesory area

• Also involved in visual perception, particularly awareness of where objects are in space, damage can lead to sensory neglect

Somatosensory cortex

• Postcentral gyrus in parietal lobe

• Sensory information coming from skin

• Size of cortical representation not proportional to size of body part, it’s proportional to acuity of touch

Sensory homunculus

Little human representation in head

Motor cortex

Precentral gyrus in frontal lobe, movement of skeletal muscles where size of cortical area is proprotional to precision of movement

Frontal lobe

• Area involved in highest and most complex cognitive functions

• Planning, morality, decisions, working memory

• Prefrontal cortex is most complex among the many sub regions of frontal lobe

Dorsolateral prefrontal cortex

• Associated with following rules and making decisions

• Decision making center

• Most evolutionary recent area

Ventromedial prefrontal cortex

• Has tight connections with amygdala

• Emotional component of executive function

• Being logical and not having emotions impact decision making

• Vmpc damage individuals have poor decision making in many respects

Electrical gradients

Distribution based on electrical charge

Chemical gradients

Distribution based on molecular composition

Electrochemical gradients

Both of electrical and chemical gradients happening simultaneously

Major concepts to understand neural conduction

Resting potential, Action potential, Graded potentials

Resting potential

• Inside of neuron there’s -70 millivolts compared to outside neuron

• Not passive process and necessary to have an action potential since electrochemical gradient is needed to start action potential

• Na+/K+ pump: necessary for resting potential, helps to restore balance of Na+ and K+ by moving 3 Na+ ions out and K+ ions in and requires ATP

Action potential

• Axons send information from cell body to axon terminal

• Begins at axon hillock

• If add positive current to inside cell there’s depolarization (polarity moves toward zero and more positive)

• If add negative current to inside cell there’s hyperpolarization (polarity moves away from resting potential and more negative)

• Threshold of excitation: around 55mv when voltage gated Na+ channels open and there’s enough positive current to reach -55mv triggering action potential, when cell reaches positive the gated Na+ channels close and gated K+ channels open as inside of cell becomes more negative, lastly there’s hyperpolarization of K+ channels slow to close, all or none action potential