The Biology of Mind and Behavior: The Brain in Action

The Biology of Mind and Behavior:The Brain in Action

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“Copyright © Allyn & Bacon 2007

The Neuron��

�The basic unit of the nervous system� Receives signals from neurons or sense

organs� Processes signals� Sends signals to other neurons, muscles, or

organs

�The brain contains 100 billion neurons


Categories of neurons� Sensory neurons ��

� transmit impulses received by receptors�� to the central nervous system

� Motor neurons � � �� carry outgoing signals from the brain or spinal cord

to muscles and glands� Interneurons � � � � / � ��

� receive the signals from the sensory neurons and send impulses to other interneurons or to motorneurons. Found only in the brain, eyes and spinal cord

Brain circuit: A set of neurons that affect one another


The Neuron: Structure� �

� � �

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Structure of the NeuronBiological Biological CCondondiitionstions


Synaptic Transmission

TheSynapse

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Neural Impulses��

� Resting potential��

� More positively charged ions outside than inside��

� Action potential: “Firing” � � � �

Threshold exceeded � � / �

� Flow of ions through channels in membrane��

� All-or-none law( � � � � � �


Demo: How Fast Are Neurons?


Complexity of the Brain

� Is the brain the single most complex object in the universe?� 100,000,000,000 (100 billion) neurons� Average of 10,000 connections for each neuron� 10,000,000,000,000 (10 trillion) neural

connections!


Neurotransmitters:��

Dopamine��

Release of dopamine in certain areas of the brain produces intense feelings of pleasure. Too much dopamine in some areas of the brain may cause schizophrenia ( � � � � � ), while too little in other areas may lead to Parkinson’s disease ( � � � ).

Serotonin ( � � ��

� Role in mood regulation, role in depression (low levels)

� Important in the regulation of sleep and appetite


� The central nervous system � � � � �

� all the neurons in the brain and spinal cord

� The peripheral nervous system � � � � � �

� all the nerves connecting the brain and spinal cord to other parts of the body

� Somatic system � � / � � � � � �

� subdivision of the peripheral nervous system that carries messages to and from the sense receptors, muscles and the surface of the body

� Autonomic system � � /� � � � � �

� subdivision of the peripheral nervous system that connects with the internal organs and glands

The Organization of the Nervous SystemThe Organization of the Nervous System


Figure 2.7 The organization of the Nervous System


The Nervous System

Central Nervous System

P eri p h eral Nervous System

Sensory-Somati cNervous System

A utonomi cNervous System

P arasymp ath eti cNervous System

Symp ath eti cNervous System

Motor Output

Sensory I np utMo

tor O

utput


The Peripheral Nervous System��

� Autonomic Nervous System � � / � � � � � �� Sympathetic��

� Emergency preparedness� Fight-or-flight� Increased arousal

� Parasympathetic� ��

� Decreased arousal

� The Sensory-Somatic Nervous System�� Input-output connections� Cranial nerves� � � ��

� Skeletal system � �


The autonomic nervous systemThe autonomic nervous system


The CNS

� Brain� Spinal cord

� Reflex


The Brain: Structures

� Meninges � �

� Cerebral hemisphere� � �

� Lobes�

� Corpus collosum� �

� Cerebral cortex� � � �


The Brain: Lobes��

� Occipital lobes �

� Temporal lobes �

� Parietal lobes �

� Frontal lobes�


The Occipital Lobes � ��

� At the back of the head

� Functions include� Visual processing

� Seeing stars?


The Temporal Lobes � ��

� In front of the ears� Functions include

� Language comprehension� Sound processing� "Entering new information

in memory"� "Storing visual memories"


The Parietal Lobes � ��

� Top, rear of the brain� Functions include

� Attention� Spatial location� Somatosensory

processing


The Frontal Lobes � ��

� Front of the brain � Functions include

� Planning� Memory search� Motor processing� Reasoning

� Phineas Gage


Asymmetries of the BrainAsymmetries of the Brain

LeftLeftHemisphereHemisphere

RightRightHemisphereHemisphere

SplitSplit--Brain SurgeryBrain Surgery

Corpus Corpus CallosumCallosum


Hemispheric Specialization� Left hemisphere

� expressive language� logical activities� mathematical computation

� Right hemisphere� spatial and pattern recognition� facial identity and expressions of emotion� line slopes and dot locations


Split-Brain Surgery

Severed CorpusCallosum

��Asymmetries of the BrainAsymmetries of the Brain


After Split-Brain Surgery

Asymmetries of the BrainAsymmetries of the Brain


Split-Brain Research and the Hemispheric Interpreter


Subcortical Brain Areas


Subcortical Brain Areas

� Thalamus: Crossroads� Hypothalamus: Thermostat� Hippocampus: Remember� Amygdala: Inner feelings� Basal ganglia� � � : More

than habit-forming � � � � �

� � � �

� Brainstem: Wakeup call� Cerebellum: Walking tall


The Endocrine System ��

It acts more slowly, indirectly affecting the activities of cell groups throughout the body. It does so by means of hormones.

� Glands�� :organs located throughout the body that secrete special substances such as sweat, milk or particular hormones

� Hormones�� :chemicals secreted by the endocrine glands into the bloodstream and transported to other parts of the body

� Pituitary Gland ( � � � � � � � � / � �� :the “master gland”, controls the secretion activity of other endocrine glands. One of the pituitary hormones has the crucial job of controlling of the body’s growth.

� The adrenal glands�� :It plays an important role in determining mood, energy level, and ability to cope with stress.


Probing the Brain � � �� Detecting electrical activity

� Electroencephalograph (EEG) � �

� Magnetoencephalography (MEG)� Single-cell recording

� Visualizing structure� Computer-assisted tomography (CT scan)��

� � �

� Magnetic resonance imaging (MRI) � � �

� Visualizing function� Positron emission tomography (PET) � � � �

� � �

� Functional magnetic resonance imaging (fMRI)


Pictures of the Living BrainPictures of the Living Brain

CAT ScanCAT Scan

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MRI ScanMRI Scan



PET ScanPET Scan



Pictures of the Pictures of the Living BrainLiving Brain

PET ScanRed areas

indicate maximum brain

activity; blue areas show

minimum activity..


Observing the Brain

� Brain damage� Lesion� Stroke

� Stimulating the brain� Transcranial magnetic stimulation (TMS)


Genetic Studies and Behavior

� Selective breeding� animals that are high or low in a certain behavior or

physical trait are mated with each other� Twin studies

� monozygotic (identical), dizygotic (fraternal) twins� Molecular genetics��

� influence of specific genes on personality, and other specific behavioral traits

� Environmental influences on gene action� role of environment and interaction in manifestation of

a behavior or particular disorder


Evolution and the Brain

� Evolution� Natural selection� Adaptation� Reproduction of the fittest

The Biology of Mind and Behavior: The Brain in Action

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