CHAPTER 3 NEUROSCIENCE AND BEHAVIOR

THE NEURON Basic info Structure

THE ELECTROCHEMICAL PROCESS The neuron is adapted for sending and receiving signals. This is done within and between neurons. HOW?

WITHIN THE CELL, THE NATURE OF THE NEURAL IMPULSE IS ELECTRICAL. All-or-nothing Principle Impulse along the axon is called axonal transmission

STEPS OF ACTION POTENTIAL Dendrites receive neurotransmitter from another neuron across the synapse. Reached its threshold- then fires based on the all-or-none response. Opens up a portal in axon, and lets in positive ions (Sodium) which mix with negative ions (Potassium) that is already inside the axon (thus Neurons at rest have a slightly negative charge). The mixing of + and – ions causes an electrical charge that opens up the next portal (letting in more K) while closing the original portal. Process continues down axon to the axon terminal. Terminal buttons turns electrical charge into chemical (neurotransmitter) and shoots message to next neuron across the synapse.

Action Potential

How a Neuron fires

THE CHEMICAL PROCESS IS VIA NEUROTRANSMITTERS Dozens of chemicals have been identified that perform different functions in the brain.

BASIC NEUROTRANSMITTERS Acetylcholine (ACh) Controls skeletal muscles Contributes to the regulation of attention, arousal and memory Some ACh receptors are stimulated by nicotine

Dopamine (DA) Contributes to control of voluntary movement, pleasurable emotions Decreased levels associated with Parkinson’s Disease Overactive at DA synapses associated with schizophrenia Cocaine and amphetamines elevate activity at DA synapses

Norepinephrine (NE) Contributes to modulation of mood and arousal Cocaine and amphetamines elevate the activity at NE synapses

Serotonin Involved in regulation of sleep and wakefulness, eating and aggression Abnormal levels may contribute to depression and OCD Prozac and similar antidepressant drugs affect serotonin circuits

Gamma-aminobutyic acid (GABA) Serves as widely distributed inhibitory transmitter Valium and similar antianxiety drugs work at GABA synapses

Endorphins Resemble opiate drugs in structure and effect Contribute to pain relief and perhaps to some pleasurable emotions

THE REFLEX ARC Types of sensory receptors (get information from the environment). There are four types... The simplest form of a behavior is called a reflex. We need to know the basic types of neurons.

GENERAL DIVISIONS OF THE NERVOUS SYSTEM Peripheral Nervous System (PNS) Somatic Nervous System Autonomic Nervous System Sympathetic Nervous System Parasympathetic Nervous System

Central Nervous System (CNS) Spinal Cord The Brain

THE BRAIN

DIVISIONS OF THE BRAIN Hindbrain, located at the rear base of the skull Contains the cerebellum, the medulla, the pons

THE MIDBRAIN Located just above the pons Function: relays sensory information Brain stem and reticular activating system

THE FOREBRAIN The hindbrain and forebrain compose the brain’s central core Thalamus (information relay) Hypothalamus (motivation, emotion) Higher-thinking processes

HIGHER-THINKING PROCESSES Cerebral cortex Cerebrum

PINKY AND THE BRAIN

HOW DO THE TWO HEMISPHERES OF THE BRAIN COMMUNICATE?

LATERALIZATION OF FUNCTION OF THE HUMAN BRAIN Split Brain- although similarly located both cerebral hemispheres generally have similar functions, but... There are some differences or lateralization of functions shown to exist How did scientist figure this out???

LEFT AND RIGHT BRAIN SPECIALIZATION

LEFT HEMISPHERE SPECIALIZATION Speech and Language Functions Wernicke’s Area Broca’s Area

RIGHT HEMISPHERE SPECIALIZATION Spatial Functions (patterns (gestalten), visual configurations, color discrimination) Musical Functions

PHINEAS GAGE A railroad construction worker in Vermont in Dynamite blew a tamper rod through his eye and out his skull. Remarkably, he survived, but was never the same. Once considerate and friendly, he was now overbearing and indecisive. Theory: executive control system in prefrontal cortex was damaged.

LESIONS Cutting of brain tissue Ablation – destroy brain tissue (Essentially these are the same thing) Do we do this today?

BRAIN IMAGING TECHNIQUES The are now many, highly specific methods to see into your brain. Assignment to follow will help you discover the techniques used today. Modern forms of imaging: EEG CAT MRI and fMRI PET MEG SPECT DTI

EEG Transmit electrical activity (brain waves)

CAT OR CT SCAN Computerized axial tomography- computerized image of x-rays

MRI Magnetic resonance imaging (MRI) – magnetic field to develop image of the brain Functional MRI (fMRI) – detect the use of oxygen in the brain

PET Positron emission tomography- slightly radioactive solution injected to see metabolic activity in imaged part of the brain

THE ENDOCRINE SYSTEM A system of glands that secrete hormones. Similar to nervous system, except hormones work a lot slower than neurotransmitters. Neurotransmitters Hormones

The Major Endocrine Glands