The Biology of Behavior Chapter 3- Part 1 Ettinger’s Psychology- The Science of Behavior 4e

The Nervous System Nervous System -2 subdivisions CNS, Central Nervous System consists of the brain and spinal cord Peripheral Nervous System, PNS transmits messages to and from the brain Somatic NS Autonomic NS

FIGURE 3.1 Divisions of the Nervous System

Neurons-basic units Neurons are the specialized cells of the nervous system Billions in the brain alone 3 classes Sensory (afferent) neurons Motor (efferent) neurons Interneurons Communication between afferent and efferent neurons as with ither interneurons

FIGURE 3.2 Neuron Structure Psychology: The Science of Behavior, 3/e, CHAPTER 3© 2009 BVT Publishing

Neural Transmission Chemical transmission of substances called neurotransmitters Bundles of neuron fibers = nerves Bundles fibers allow continuous travel of message from CNS PNS (neurotransmission animation)

FIGURE 3.3 Neuron Electrical Activity

Neural Electric Activity Resting potential Net negative charge Graded potentials Voltage change in dendrites to prepare to receive impulse Action potentials Electrical progression along axis to release neurotransmitters All-or-none law: strength of action potential doesn’t depend on strength of stimulation Animation to demonstrate electrical activity: s/actionpotential.swf

All or none… Glia cells inslulate, remove waste, provide nutrients and increase conductivity Myelin sheath covers some axons, made of glial cells Node of Ranvier- gap in myelin sheath Synapse- membranes on pre and post membranes and gap (chasm) between

FIGURE 3.4 Synapse How neurotransmitters get from one neuron to another:

Neurotransmitters

Neurotransmitters and Behavior Schizophrenia, a severe psychological disorder, seems to be related to excessive dopamine neutotransmitter and dopamine neurons in several brain areas. Antipsychotic drugs inhibit the effects of dopamine in the brain, reducing the over- reaction to it. Depression, probably the most common psychological disturbance, appears to be related to 2 neurotransmitters: norepinephrine and serotonin. Tricyclic drugs are helpful in relieving depression and seem to increase the availability in specific brain area

FIGURE 3.5 Functions of the Sympathetic and Parasympathetic Nervous System FIGHT OR FLIGHT

FIGURE 3.6 Bisected View of the Human Brain, Showing the Locations of Major Structures and Areas Psychology: The Science of Behavior, 3/e, CHAPTER 3© 2009 BVT Publishing

FIGURE 3.7 Neural Control of Simple Reflexes Psychology: The Science of Behavior, 3/e, CHAPTER 3© 2009 BVT Publishing

FIGURE 3.8 The Limbic System Psychology: The Science of Behavior, 3/e, CHAPTER 3© 2009 BVT Publishing

The Limbic System Structures in the central core of the brain. Emotional memory Memory, motivation, and learning 1.Amygdala Small structure near Hippocampus Important in aggression, anger, rage, fear- motivated behaviors (social cognition and decision-making)

Limbic System 2) Hippocampus Important for learning and memory Damage may inhibit new learning May be impacted by early life stress 3) Septal Area associated with experience of pleasure Pleasure and reward areas called mesolimbic- cortical system

Limbic system 4) Hypothalamus Below the thalamus Contains control mechanisms for some body systems to maintain homeostasis Hub of the neuroendochrine system influences the pituitary gland Integrates emotional expressions through interaction with endocrine system

Limbic System 5) Thalamus Pair of structures above the hypothalamus, in each hemisphere Routes sensory info to cerebral cortex All sensory info except smell goes thru thalamus before being sent to appropriate cortical area Works w/ reticular formation to regulate sleep and alertness ADHD appears to be caused by interruptions in brain circuits btw thalamus and frontal cortex

FIGURE 3.9 Localization of Cortical Functions in the Four Lobes of the Left Cerebral Cortex Psychology: The Science of Behavior, 3/e, CHAPTER 3© 2009 BVT Publishing

The Basal Ganglia Made up of caudate nucleus, putamen and substantia nigra Receive messages from cortex and thalamus Function: initiate and control motion Common disorder is Parkinson’s from destruction of dopamine- containing neurons

Cerebral Cortex Thin outer covering of the brain, a.k.a. the neo-cortex Contours are to make the most efficient use of space Motor and Sensory Cortices Areas of the body that require the most motor control and sensory information get the most representation on the cortex. Attiribution of space on the cortices is upside down

FIGURE 3.10 Primary Areas of the Motor Cortex and the Somatosensory Cortex Motor Cortex Somatosensory Cortex

Cerebral cortex… Called gray matter because of lack of myelination which appears white Memories are stored in the cortex Analyzes and translates incoming messages into responses Motor and Sensory cortex =25% Association cortex-the rest

Lobes and sulci Frontal lobe- largest and foremost Higher order functioning Motor cortex is just posterior Followed by Central Sulcus Function: Motor nerves from left motor cortex control right side of the body Broca’s area very important in speech production Until 1960s, pre-frontal lobotomy was surgery that intended to minimize dysfunction and calm moods of mental patients

Lobes… Occipital Location of visual cortex Temporal Lobes Primary function: hearing Location of auditory cortex, and Wernicke’s area- for understanding speech Damage or injury can cause agnosias

Lobes.. Parietal- behind central fissure Front of the lobe made up of the somatosensory cortex- receiver for all sensory info Relates visual and spatial information Mental rotation Injury to parietal lobe can cause contralateral neglect

FIGURE 3.11 Passage of Visual Information in Brains with an Intact and a Severed Corpus Callosum

Lateralization of the Brain For most people: – Speech production and understanding are primarily L hemi function – Spatial orientation, recognition and naming of objects and perception of relationships among them are primarily R hemi Hemispheres are – Asymmetrical – Differ in anatomy, electrical activity and chemistry – Separate specialized functions don’t mean separate systems – Communication occurs through corpus collosum nerve fibers

Neuroplasticity and Split Brain function Because of injury or severe medical conditions, researchers have been able to study what happens when one side of the brain is removed- more significant than severing the Corpus Collosum but with similar effects – What would you expect to happen? – Here’s what might: –

FIGURE 3.12 The Major Glands of the Endocrine System

Sex Differences in the Brain Quantities and distribution of sex hormones Thickness of cerebral cortex : > on Left in females ◦ Language, arithmetic calculation, landmark memory > on right in males ◦ Some spatial tasks, math reasoning, orientation skills All cortical structures and hypothalamus are small in females- due to different amounts of estradiol (hormone) during development Potential differences between males and females in aptitude and performance are more likely due to environment than documented neurological differences