chapter 1-Behavioral Neuroscience

Chapter 1 notes

neurons

receives and transmit info. to other cells

glia

serve many different functions

components of all neurons

• dendrites

• soma/cell body

• axon

• presynaptic terminals

motor neuron

• has its soma in the spinal cord

• receives excitation from other neurons

• conducts impulses along its axon to a muscle

sensory neuron

• specialized at one end to be highly sensitive to a particular type of stimulation (touch, light, sound, etc)

• sends neurons towards the brain and the spinal cord

dendrites

• contain receptors on the surface that bring information into the neuron

• some contain dendritic spines that further branch out and increase the surface area of the dendrite

  • greater surface area of the dendrite, the more info. it can receive

Axons

• responsible for transmitting nerve impulses towards other neurons, organs, or muscles

myelin sheath

fatty insulation that helps increase the speed of the nerve impulse across the axon.

• Interrupted by nodes of Ranvier that help the impulse skip parts of the axon

presynaptic terminals

end points of an axon release chemicals to communicate with other neurons

interneurons/intrinsic neurons

those whose dendrites and axons are completely contained WITHIN a single structure

• intrinsic neuron in thalamus might have all its components within the thalamus

types of Glia/Glial cells

• astrocytes

• microglia

• oligodendrocytes

• schwann cells

• radial glia

Astrocytes “The Caretakers”

• wraps around the synaptic terminal to synchronize closely related neurons.

• responsible for dilating blood vessels to bring more nutrients into brain areas with heightened activity

Microglia “The Cleaners”

• act as part of the immune system; removing viruses & fungi from the brain

• proliferate after brain damage, removing dead/damaged neurons

• contribute to learning by removing the weakest synapses

oligodendrocytes//schwann cells “CNS coaters”//“PNS coaters”

• build the myelin sheaths that surround and insulate certain vertebrate axons

• supply an axon with nutrients

• Oligodendrocytes act in the spinal cord & brain

• Schwann cells act in the peripheral nervous system

radial glia “The Escort”

• guide the migration of neurons and their axons and dendrites during embryonic development

• when embryonic development finishes, most radial glia differentiate into neurons

• smaller number differentiate into astrocytes and oligodendrocytes

Blood-brain barrier

• mechanism surrounding the brain and blocking most chemicals from entering

• small, uncharged molecules like oxygen & carbon dioxide cross barrier easily

  • essential to health, but can pose a difficulty in allowing certain chemicals to pass like chemotherapy for brain cancer

Active Transport

• protein-mediated process that EXPANDS energy to pump chemicals from the blood into the brain.

  • vitamins brought vis AT; Glucose, certain hormones, & amino acids

nerve impulse

ELECTRICAL message that’s transmitted down the axon of a neuron

• speed of a nerve impulse ranges from less than 1 meter/second to 100 meters/second

• ex. a touch on the shoulder reaches the brain quicker than a touch on the foot.

polarization

a difference in the electrical charge inside and outside of the cell

resting potential: electrical gradient

state of the neuron before the sending of a nerve impulse

• inside of the membrane is slightly negative with respect to outside

Sodium-Potassium pump (protein complex)

• continuously pumps 3 sodium ions out of cells while drawing 2 potassium ions into the cell

• helps maintain the electrical gradient

• uses active transport (requires ATP/energy)

concentration gradient (CG)

difference in the distribution of ions between the inside and outside of the membrane

-Sodium (Na+) CG wants to pull sodium INTO cell, b/c there is MORE sodium OUTSIDE

-Potassium (K+) CG wants to pull potassium OUT of cell, b/c there is MORE potassium INSIDE

Action Potential

a rapid depolarization of the neuron

voltage-gated channels

Proteins on the membrane that allow sodium and potassium to CROSS in and out of the cells.

major divisions of the nervous system

• somatic nervous system; communication between CNS and the body

• autonomic nervous system; sends/receives messages from diff. organs

• sympathetic nervous system; increased activity (“Flight or Fight”)

• parasympathetic nervous system; non-emergency responses (“Rest and Digest”)

major brain lobes and important structures

occipital lobe- primary visual/ striate cortex

parietal lobe- primary somatosensory cortex. Receives sensations from touch, muscle stretch, and joint receptors.

temporal lobe- primary auditory cortex. left lobe; understanding spoken language. right lobe; understanding non-verbal info.

frontal lobe- primary motor cortex; specialized for CONTROL. and prefrontal cortex; working memory and delayed-response task

organization of spinal cord and brainstem

Spinal cord; communicates with all sensory organs & muscles except those in the head. includes gray and white matter. Each segment sends sensory info ti the brain & receives motor commands from the brain.

brainstem; brain is split into 3 divisions: Hindbrain, Midbrain, and the Forebrain

what do the sections of the brainstem do?

1. Hindbrain- consists of the medulla, pons, and cerebellum

2. Midbrain- consists of tectum, superior & inferior colliculus (important for sensory processing), tegmentum, and substansia nigra (dopamine and pathway for facilitating movement)

3. Forebrain- consists of the cerebral cortex, thalamus//basal ganglia, and limbic system

explain the functions of the Forebrain parts

cerebral cortex; controls sensory-motor information primarily contralaterally

thalamus; most sensory info goes here first to be processed and send output to cerebral cortex (“switchboard”)

basal ganglia; integrate motivational & emotional behavior to increase the vigor of selected actions. critical in movements, skills, habits, & other learning

limbic system; motivation, emotions, drinking, sexual activity, anxiety, and aggression, etc. basic driving emotions to make life fun. “lizard brain”

explain the functions of the Midbrain parts

explain the functions of the Hindbrain parts

medulla- controls vital reflexes (breathing, HR, vomiting, sneezing, etc.)

pons- information rely, cranial nerves, facial movements like chewing, blinking, & hearing. also regulates unconscious control, breathing patterns and the sleeping mind

cerebellum- motor coordination, as well as attention shifting & between auditory/visual stimuli and rhythm recognition.