Brain Facts Chapter 1: Brain Basics

Cerebrum

largest part of the brain

corpus callosum

bridge between the hemispheres

cerebral cortex

deeply folded surface of the cerebrum; concious thought

(folded to create more surface area)

frontal lobe

coordinates movement, speech, memory, emotion, and higher cognitive skills

occipital lobes

process visual information and recognize colors and shapes

temporal lobe

some visual processing and interpret auditory info

Hippocampus

curved substances below cerebral cortex; region of temporal lobe for memories

Amygdala

within temporal lobe; integrates memory and emotion

limbic system

includes thalamus, hypothalamus, hippocampus, and amygdala

regulate emotion and motivaton

Thalamus

integrates sensory info and relays it to other parts of the brain

Hypothalamus

sends hormonal signals to the rest of the body through the pituatary gland

Forebrain

cerebral cortex and limbic system

Midbrain

beneath the thalamus; coordinates eye movements and reflexes to sounds; inhibits unwanted body movements; coordinates sensory input and motor output

Basal ganglia

some midbrain and some forebrain that regulates complex body movements

Hindbrain

plays roles in glucose regulation and sleep and includes regions that control movement

Cerebellum

second largest part of the brain, divided into two hemispheres

coordinates voluntary functions, helps new motor skills, roles in spatial and temporal functions

Pons

under cerebellum and influences breathing and posture

Medulla

connects brain to spinal cord and controls basic functions such as heart rate and breathing

Brainstem

made of midbrain, pons, and medulla

nerve tracts

nerve fibers form bundles

smaller anterior commisure

transmits signals between the left and right temporal lobes

neural network

group of nerve tracts connecting regions in the brain

thalamocortical loop

connects thalamus with parts of the cortex and back

what is an example of a thalamocortical loop?

visual cortex sending signals to the thalamus to be integrated with the other senses

brain waves

signals produced by the thalamocortical loop that can be detected by an electroencephalograph

which waves does your awake brain usually produce?

alpha and beta waves

alpha waves

usually orginiate in the parietal and occipital loves when your brain is relaxed and your eyes are close (8-13 hz frequency)

beta waves

produced by frontal and parietal regions of brainwhen processing input or focusing on a task (14-30)

which waves are typical in sleep

delta and theta waves

theta waves

(4-7 hz)

delta waves

occur during deep sleep (<3.5)

Which waves are stronger out of delta, theta, alpha, and beta?

Alpha and delta are strong, beta and theta are weaker

- all still microvolts though

spinal tracts

chains of neurons that pass signals through the brainstem and spinal cord

basal ganglia

takes info from cortical that allow movement and produce signals to the cortexto enable or inhibit movement

What do loops that connect the brainstem and the cerebellum do?

influence timing and strength of motor signals

some include cerebral cortex that enables environment and emotional context to influence movement

What do the networks that loop the hippocampus into the sensory cortex do?

determine if environmental signals are familiar or new

What do the networks that link the hippocampus to the thalamus and hypothalamus?

allow memory to influence concious behavior as well as unconcious physiological responses

What are reflex loops?

circuits allowing action before thoughts- the action is controlled by info that goes in and out the spinal cord and never to the cortex

neural circuts

interconnected neurons that turn entering signals into output patterns that can be sent to other parts of the brain

Where can one find a lot of neural circuits and how are they arranged?

The cerebral cortex; in a stack of distinct layers

What are excitatory neurons?

they excite the next cell into firing; most common

What is the most common type of excitatory neuron in the cerebral cortex?

pyramidal cells; cone shapes cell body - each has two sets of dendrites and a multibranched axon

inhibitory neurons

prevent other neurons from firing and regulate acitivity of a circuit

feed-foward inhibitory circuit

inhibitory interneurons connect neighboring neural circuits in a way that the excitatory cells in one column send inhibitory signals to adjacent columns, reducing activity

feedback inhibiton

send signals to downstream excitatory neighbors and to interneurons that reach back and inhibit layers of the same circuit

glia

support cells of neurons

what are the four types of glial cells

astrocytes, ependymal cells, microglia, oligodendrocytes

What do astrocytes do?

form a network in the brain that regulates ion concentrations, provide them with nutrients, mop up extra neurotransmitter, and regulate formation of new connections between neurons

What do microglia do?

function mainly as phagocytes, but can also regulate formation of new neuronal connections

What do ependymal cells do?

make the cerebrospinal fluid

What do oligodendrocytes do?

form myelin sheaths

Kinesins

work the protein down the axon through microtubules

What are the two types of receptors?

ionotropic and metabotropic

ionotropic receptors

neurotransmitter binds to an ion channel that changes shape and widens for ions

metabotropic receptors

receptors connected by a cascade triggered by neurotransmitter on receptor

Reuptake

process by which neurotransmitters are broken down or reabsorbed by the axon terminal

glutamate

most common excitatory neurotransmitter that can bind to AMPA (fast and brief) and NMDA (slow) receptors

AMPA and NMDA are important for learning and memory

GABA (gamma-aminobutyric acid)

most common inhibitory neurotransmitter; ionotropic GABA lets chloride enter the cell and metabotropic releases potassium ions

Neuromodulators

suppress neurotransmitter release

Prostaglandins

lipids that change the brain's response to pain and inflammation