neuro-lecture 2
Post on 26-Jan-2017
229 Views
Preview:
TRANSCRIPT
Neuroscience & Psychology
ObjectivesGain a general understanding of the nervous systemGain knowledge of the structure and function of the
neuronNavigate your way around the major brain areas and
understand their function
Nervous System Hierarchy
Central nervous systemBrain
~2% of body weight, uses ~20% of resourcesComposed of bunches of neurons, which form nerves
Spinal cordComplex tangle of nerves that stretch from brain to
tailboneCollects & transmits info between brain and peripheral
nervous systemAlso initiates reflexes: automatic responses to an
event
Peripheral Nervous System
PNS links the CNS to the organs, muscles, and glands of the body
PNS has two partsSomatic (SNS): nerves controlling voluntary muscle
movementsAutonomic (ANS): controls glands, organs, blood
vesselsANS has two parts
Sympathetic: arouses body to prepare for action (fight or flight)
Parasympathetic: slows down body to reserve energy
Sympathetic and Parasympathetic
The NeuronAll brain activity originates with the neuronThe messengers of the brain-world
These cells receive signals from neurons or sense organs, process the signals, and send them to other neurons, muscles, or organs
Three typesSensory: respond to sensory organ inputMotor: send signals to muscles to control movement Interneurons: the go-between of sensory and motor neurons
We have about 100 billion neuronsMost, but not all, can be re-grown (severe spinal cord injury
vs. cutting your finger)
The Neuron
The Neuron: StructureCell body: houses nucleusCell Membrane: skin of the cellAxon: cable extending from the cell body
Impulse from cell body travels along axon to its end, where terminal buttons release neurotransmitters (chemical messengers), received by other neurons
Axon is covered by myelin sheath, which is composed of a fatty substance that helps impulses travel the length of the axon
DendriteBranches extending from cell membrane that receive
neurotransmitters from other neurons
The DendriteIncreases receptive surface of the neuronContacts occur along surface of dendrite
The AxonAxon hillockMyelin sheathNodes of Ranvier
The points just between the myelin sheaths
The Neuron in ActionWhen a neuron receives impulses from other
neurons, the cell membrane allows open exchange of positively and negatively charged ionsAction potential (change in electrical charge) runs down
axon to terminal buttonsThis all starts with the axon hillock – the gatekeeper of
the neuronTerminal buttons release neurotransmittersNeurotransmitters cross the synaptic cleft to the
dendrite of the receiving neuron
The Neuron in action
Communication in the Neuron
All-or-nothingThe action potential either happens or it doesn’t
Non-decrementalAction potentials don’t change in amount (voltage) as they
travelRefractory period
Neurons need 2ms to recover before they can transmit again
ThresholdThe minimum level of stimulation required to trigger a
neural impulseOnce you reach the threshold, the action potential doesn’t
get bigger
Important Neurotransmitters
Acetylcholine (Ach) Slows down the body, memory, and attention (involved in
Alzheimer’s disease)Dopamine (DA)
Voluntary movement, attention, and learning; high levels are associated w/schizophrenia
Endorphin Reduce sensitivity to pain; linked with pleasure (opiate-like)
Serotonin Arousal, sleep; Prozac increases levels of serotonin
Norepinephrine Helps control alertness and arousal; low levels can depress mood
History of Studying the Brain
Franz Joseph Gall (1758 – 1828)Phrenology
The study of the structure of the skull to determine a person’s character and mental capacity
26 ‘organs’ on the surfaceof the brain
History of Studying the Brain
Phrenological Map of the Skull
History of Studying the Brain
Flourens (1794 – 1867)Emphasized the importance of experimental research
of the brainCarefully controlled experiments on animals to
determine localities of brain and their functionsMoved the field of brain research into a more scientific
arena
Areas of the Brain
Five Major Brain Areas CEREBRAL CORTEX is involved in your higher mental functions
of perceptual awareness, recognition and interpretation of sensory stimuli (mostly based on memories).
PREFRONTAL CORTEX is involved in your conscious thinking processes, especially making choices by using your brainpower
LIMBIC SYSTEM is involved in the expression of your instincts and feeling processes, including your moods, since it includes your hypothalamus and amygdala parts;
CEREBELLUM is involved in your posture and many coordinated movements;
BRAINSTEM controls your body's most basic unconscious life-sustaining functions, including your breathing and heartbeat.
Cerebral CortexTwo halves, four lobes
Frontal lobe (seat of intelligence)Motor cortex (walking, chewing)
Parietal lobeSensory cortex
Prosopagnosia (face blindness) Unilateral neglect (only realize half)
Temporal lobeAuditory areas (opposite ear)
Occipital lobeVisual areas (opposite eye)
Prefrontal CortexThe prefrontal cortex (PFC) is the very front of the
brain, located right beneath the forehead. It is in the anterior (front) region of the frontal lobes.
It is responsible for the executive functions, which include mediating conflicting thoughts, making choices between right and wrong or good and bad, predicting future events, and governing social control — such as suppressing emotional or sexual urges.
The prefrontal cortex is the brain center most strongly implicated in qualities like sentience, human general intelligence, and personality.
Limbic SystemHormonal system*Hypothalamus
FeedingReproductive behaviorTemperature
HippocampusMemory
AmygdalaFeedingMemoryEmotion
CerebellumThe cerebellum (Latin for little brain) is a region
of the brain that plays an important role in motor control. It is also involved in some cognitive functions such as attention and language, and probably in some emotional functions such as regulating fear and pleasure responses.
Brain MappingHow your brain is laid out. Actually, how any
animals brain is laid out.Two parts, linked together, but functioning as
one unit/different units.Distinct differences between hemispheres. Left
handed-ness or right handed-ness.
Left & Right Functions
Two Cerebral HemispheresContralateral arrangementCorpus callosum
Thick band of nerve fibers connecting the hemispheres
It’s how the 2 hemispheres communicateRight-brained vs. left-brained? Bicamerialism??
OR
Brain StemRegion of the brain where the spinal cord enters the
skull and swellsMedulla
Regulates heart-rate, breathing, blood pressure, and motor movements
CerebellumControls skilled motor movements
Brain StemPons
Connects the two hemispheres of the cerebellumReticular formation
SleepAttention
ThalamusRelay center
Filters & organizes information from senses
Preserve Your Brain
This is a “normal”brain firing
This is a brainthat has just doneecstasy
top related