PSYCH 377- Wong - Midterm #1

groups od neurons in CNS

nuclei

groups of axons within CNS

tracts

Rostral- caudal

nose to tail axis of the body

• roughly synonymous with anterior-posterior

dorsal-ventral

back to front axis of the body

• roughly synonymous with superior -inferior

medial-lateral

toward the middle or toward the side (aka the extremeties)

ipsilateral

structures that are on the same side of the body

• ex. spinal reflexes processd this way so they are able to react more quickly

contralateral

structures on opposite sides of the body

proximal

structures that are clsoe together

distal

structures that are far apart

afferent

movement toward the CNS

• things outside affects the body

• ex. sensory processing

efferent

movement away from the CNS

• body has an effect on the outside

• ex. motor actions

how is the nervous system divided

either based on its tructure or its function

central nervous system (CNS)

• includes the spinal cord and brain

• both protected by bone

peripheral nervous system (PNS)

• projects out to the body

• somatic nervous system provides interaction with the external world

  • autonomic nervous system→ sympahtetic and parasympathetic

sympathetic nervous system

part of the PNS

• influences fight or flight response

  • the 4fs→ fight, flight, freeze, and fawn

parasympathetic nervous system

art of the PNS

• exerts calming influence on the body

• rest and digest

how is the CNS protected

• bone surrounding tissue→ skull, vertebral column

• meninges→ holds CNS in place

• cerobrospinal fluid → fills the space in and around meninges to absorb shocks and carry out waste

• blood-brain barrier → chemical protection

layers of the meninges

• dura mater- tough outer covering

• arachnoid mater- weblike strucute connecting inner and outer layers

• pia mater- tough inner layer that adheres to the surface of the brain

the blood braon barrier

provides chemical protection

• fromed by astroglia holding the cells of blood vessels tightly together

• regulates what molecules can exit the blood supply to enter the brain

what happens if u cant remove the waste in CNS

produces high toxicity in the brain

arteries

supply blood to the brain

• branch to form samller versiions, delivering blood to specific parts of the brain

stroke

interuption of blood supply, through a blockage or a burst artery

process of forming neuorns and glia

stem cells divide which give rise to neuroblast cells, which develp into neuron and glioblasts, which differentiate into glia with more specific funtions

sensory neurons

• afferent

• transduce info from the environment'

• can be bipolar (one dendrite, one axon), psudounipolar (one axon that splits), or unipolar

• somatosensory neuron has only one projection from the soma

interneuron

• connect sensory and motor neurons within the CNS

  • often have extensive branching of the dendrites to gather information

motor neurons

• efferent

• found in ht brainstem and spinal cord

• project to muscles to carry out movment

ependymal cell

small, ovoid

• secretetes CSF

astrocyte

star-shaped, symmetrical; nutritive and support funciton

• forms mesh that wraps around blood vessicles

• helps transport nutrients into neurons

• form blood brain barrier

microglial cell

small, mesodermally derived; defensive function

• part of the immune system

oligodendroglia cell

asymmetrical: forms insulating myelin around axons in brain and spinal cord

• branches spread out and wrap around neurons to myelinate them

• makes myelin in CNS

schwann cell

asymmetrical; wraps around peripheral nerves to form insulaitng myelin

• wraps around whole cell to myelinate whole cell

• makes myelin within PNS

gray matter

contains the cell bodies and capillaries that supply them with blood

• the outer part of the cortex

white matter

the myelinated axons that connect with other parts of the brain

• myelin→where the axons are located

• typivally inderneath the cortex

reticular matter

netlike appearance that is a mix of grey and white matter

• found in subcortical areas

• tend to be found in the brainstem

development of the CNS

develops from 3 enlargements of the embryonic spinal cord (front to back)

• prosencephalon, mesencephalon, rhombencephalon

prosencephalon

in mammalsmm this divides to form the telencephalon (cortex and the brain) and the diencephalon (thalamus and hypothalamus)

mesencephalon

ramains and becomes the midbrain (in all vertebrates)

rhombencephalon

divides to form the metencephalon (pons and cerebellum) and the myelencephalon (medulla oblongata)

ventricles

hollow parts of the tube develop into the ventricles , which are filled with CSF

• lateral ___ → are contained in the relencephaon

• third ___ → at the midline of the brain

• fourth __ → between cerebelum and brianstem

• tube continues down the center of the spinal cord

spinal cord

grey matter surrounde by white matter

• nerve roots branch from the cord to carry motor commands to the body (anterior root) and conduct sensory information into the CNS (posterior root)

  • 4 segments - name based on the vertebrae the nerve roots to pass to exit the CNS

what are the 4 segments of the spinal cord

• cervical (top half above the shoulder)

• thoracic (body)

• lumbar (mid back)

• sacral

dermatomes

describe the region of the body surface innervated by each nerve

• slices of the body

Law of Bell Megendie

afferent/sensory information enters though the posterior parts of the spinal cord of the efferent/motor neurons exit through the anterior parts of the spinal cord

spinal reflexes

generated in the spinal cord based on posteriorsensory input making a direct connection onto the anterior motor output pathways

refelxes

basic behaviors that occur without cognitive input (no cortical input or cerebrum needed)

• more complex ones can integrate information across multiple spinal cord segment s

cranial nerves

12 pairs of nerves branch from the brain and brainstem to provide sensory and motor innervation to the head, similar to what the spinal nerves do for the body

• some are afferent (sensory), some are efferent (motor), and some are mixed

sympathetic branch of ANS

• gets body ready for action

• sympathetic ganglia are close to the spinal cord → for the immediate action

parasympathetic branch of ANS

• calms the body down

• near the target organs → being relaxed not as urgent as getting ready to move

brainstem

extends from where the spinal cord enters the skull to the forebrain

• hindbrain

cerebellum

important for motor control and sensory integration

pons

connects cerebellum with the rest of the brain

medulla

regulates functions such as breathing and heart rate

reticular formation

spans the pons and medulla, and sends projects to the cortex to maintain alertness and arousal

midbrain

• tectum

• tegmentum

• pariaqueductal gray matter

tectum

• posterior aspects of the midbrain

• superior colliculi relay visual information

• inferior colliculi relay auditory information

tegmentum

• anterior aspect of the midbrain

• nuclei here are involved in motor control, inlcuding the substantia nigra and the red nucleus

diencephalon

connects the brainstem to the brain

• hypothalamus, thalamus, and epithalamus

hypothalamus

• many nuclei influence a wide range of behaviours

• produces and releases many hormones that influence the entire body

• HPA axis→ contorls basic functions

thalamus

• almost all information destined for the cortex passes through the thalamus

• relay station- central hub

• some nuclei relay esnsory info to the cortex

• other nuclei relay information between cortical regions

• other nuclei relay information from the cortex to the brainstem

epithalamus

nuclei found posterior to the thalamus

Telencephalon

main structures include the neocortex, the basal ganglia, and the limbic system

• basal ganglia are important for motor control and motor learning

• limbic system is important for spatial and emotional functions

basal ganglia

includes the putamen, caudate nucleus, and globus palladus

• integrate sensory and motor information to produce fluid, skilled movements and is important for motor learning

• assocaitive learning (stimulus-response pairing) takes place here

what does damage to basal ganglia result in

motor issues, either hyperkinetic or hypokinetic

• ex. huntington’s disease (excessive movement) and parkinsons (loss of movement)

limbic system

wraps around the thalamus and basal ganglia

• represents an older part of the brain from evolutionary history

  • includes amygdala, hippocampus, and cingulate cortex

amygdala

small nuclei in medial temporal lobes

• important in emotion and understanding emotions in others

hippocampus

seahorse shaped structure in medial temporal lobes

• important in persoanl memories and navigation

cingulate cortex

arc over the lateral ventricles

• involved in decision making and executive functions

neocortex

wraps around the limbic system

• outer layer of the forebrain

• very thin and includes 6 layers of cells

• divided into 2 hemispheres by the longitudinal fissure

• 4 lobes have different funitons

primary areas

receive projections directly frm sensory systems or project directly to muscles

secondary areas

located near primary areas and do more elaborate processing of the information

• more elaborate processing

tertiary areas

integrate information across senses to coordinate cognitive fucntions and behaviours

• combining other areas of the brain for processing

outer layers of cortex (I, II, III)

receives input from other cortical areas

• intehrate information

layer IV of cortex

primarily receives input from sensory systems

• afferent

Layers V and VI of cortex

sends output to other brain areas or to the spinal cord for motor control

• efferent

cortical connections

long-range connections between cortical areas enable the coordination of high-level brrhaviours

• connections between different lobes

• connections from one part of a lobe to another

• connections between the 2 hemispheres

• connections through thalamus

what are single-cell recordings good for…

action potentials

difference between action potential and graded potentials

Graded potentials are variable, short-distance signals that decay with distance, while action potentials are all-or-nothing signals that propagate over long distances without losing strength.

how are graded potentials recorded

using electroencephalography (EEG), event- related potential recordings (ERP), or magnetoencephalography (MEG)

single-cell recording

electrodes inserted into or adjacent to an individual neuron

• activity of the neuron is then related to the behaviors of the organism

• more common in the PNS

firing patterns of neurons vary…

depending on what information they encode

• context of the activity seems important in neuornal firing patterns

brain waves during sleep

1. alpha/beta waves from wakefulness transition to theta waves when u have fallen asleep (hypnic/myoclonic jerks)

2. brain waves decelerate, heart rate slows, body temp decreases, muscles relax, eye movement cease (sleep spindles, and k-complexes)

3. appearance of delta waves (sycnhronous firing)

4. REM sleep (last between 20mins-1hr)

EEG

used in real time to observe the brain as the subject performs cognitive tasks

• coherence theory

coherence theory

suggests that there is a relation between the EEG activity and behaviour

• high → low-frequency, high-amplitude waves, coordinated activity of neurons = low cognitive load

• low → high frequency, low amplitude waves, associated wifth asynchronous firing, actively processing information

grand average

removesnoise, and clarifies signal

• increases signal to noise ratio

magnetoencephalography (MEG)

electrical charges moving along a neuron generate magnetic field. these can be mapped using squid

• maps can estimate lcoation sof the neurons generating those magnetic fields

brain stimulation

stimulating part of the brain and observing the resulting behaviour helps neuroscientists understand the function of that brain region

• DBS

deep brain stimulation (DBS

implant elctrodes into the brain region of interest (highly invasive)

• stimulates the region at different frequencies to treat clinical conditions (ex. depression, OCD, epilepsy, parkinsons)

transcranial magnetic stimulation (TMS)

applies a strong magnetic field at the surface of the skull to change the elctrical activity og the adjacent neurons

• can stimulate or inactivate the neurons, allowing researchers to infer the function of the area from behavioural changes

• can treat pain, movment disorders, and depression

traditional x-rays

provide an image of the brain, an image of the structure that did not show activity an d mostly showed the bone

pneumoencephalography

replaces some of the CSF in spinal cord with air and collects images as the air moves to the ventricles, increasing contrast

angiography

injects tracer into the blood supply htat will absorb x-rays and result in a high reoslution image of the circualtory system

• can be used to look for clots and hemorrhages

computed tomography (CT)

narrow beams of xrays are recorded passing through the brain at different angles (combines multiple xrays)

• computer software reconstructs the 3D brain

dynamic brain imaging

reveals task-related activity

• providing indirect measures of brain activity, looking the lood flow changes and blood oxygenation leevl changes that correlate with neural activity

PET imaging

radiotracer ingested (active neurons take in more of the tracer), annhilation photons produed as a result of the tracer that travel in the opposite direction

• opposing radition detectors record the event when struck simultaneously, multiple rings of radiation detectos arranged in subject’s head → 63 images recorded in parallel horizontal slices

subtractioin brain imaging

isolating the brain activity related to the task by subtracting out the noise

• average out task-related activity across subjects to find areas common across subjects

Magnetic Resonance Imaging (MRI)

radiofrequency energy used to force protons to a 90 degree angle to the magnetic field, and they give off energy as they reorient to the magentic field

• T1 → measure time it takes for proton to reorient to the strng magentic field

• T2 → measure how long it takes for protons to become desynchronized once radiofrequency turns off

• T1 and T2 constants vary in dfferent tissues, which canbe used to map diff types of tissue in the brain

Diffusion Tensor Imaging (DTI)

maps movement of water molecules, direction of movement is random in the ventricles or the cell body, but is constrained along the length of the axon

• highlights axonal connnectios between diff parts of the brain

functional fMRI (fMRI)

measures blood oxygne level-dependent contrast (BOLD) signal in brain

• active neurons require more reources than neurons at rest , increased blood flow overcompensates for neural activity, so there is an increase in oxygentation around active neurons

• infer brain/neural usage

resting-state fMRI (rs-fMRI)

looks at activity of the brain when it is not engaged in any particular task → different brain regions show correlated levels of activity

• motifs are patterns of activity spreading from one cortical area to another → can characterize cognitive processes

optical tomography (fNIRS)

shines near-infrated light through the skill and detects light reflected from the blood

• difference in light absorption provides a measure of blood oxygenation and computer reconstructs the image of the brain activity and hoe that changes as the task chages