Biological Bases of Behavior

Laurel McKayPeriod 1

EEG- measures changes in brain electrical activity, can allow for localization of functions in the brain

CAT Scans-make cross-sectional images of the brain

MRI- similar to a CAT scan but generates more detailed pictures of the brain

Functional MRI’s and PET Scans allow scientists to view the brain as it is working, uses a diffusion of radioactive glucose in the brain to highlight the point of interest

PET Scan

Physiological Techniques

Central Nervous System: brain & spinal cord Peripheral Nervous System: all other nerves Brain= central processing center for thoughts, motivations &

emotions (made up of neurons) In the spinal cord neurons are bundled together into nerves Afferents=nerves sending info to the brain Efferents=nerves conveying info from the brain Most movements are controlled by the brain but some are

controlled by transmission from afferent to efferent cells

Functional Organization of the Nervous System

The Peripheral Nervous System can be divided into: - Somatic Nervous System-Autonomic Nervous System

Somatic: responsible for voluntary movement of large skeletal muscles

Autonomic: controls the nonskeletal or smooth muscles (ex: in the heart and digestive tract)

Functional Organization of the Nervous System (cont.)

Functional Organization of the Nervous System (cont.)

Autonomic Nervous System divides into:◦ Sympathetic Nervous System◦ Parasympathetic Nervous System

Sympathetic: associated with processes that burn energy, fight or flight reaction

Parasympathetic: associated with conserving energy

Brain’s 3 regions: Forebrain, Midbrain, Hindbrain Forebrain= limbic system, hypothalamus, thalamus &

cerebral cortex Limbic System: area of the brain involved in learning,

emotion, and memory, includes the hippocampus (learning and memory formation), the amygdala (used when angry) , and the septum (used when fearful)

Hypothalamus: controls the temperature and water balance of the body & the ANS & the endocrine system

Thalamus: gateway for sensory input to the brain Cerebral Cortex: outer layer of the brain, used in higher

cognitive functions (thinking, language use, etc.)

Neuroanatomy

Neuroanatomy (cont.) Midbrain=reticular

activating system (consciousness, attention, wakefulness), processes sensory input

The midbrain, hindbrain, thalamus & hypothalamus form the brain stem (junction between the brain & spinal cord)

Hindbrain=cerebellum, medulla oblongata & pons Cerebellum: controls muscle tone and balance Medulla Oblongata: controls heart rate, swallowing,

breathing, and digestion Pons: passes info from one brain to another Cerebral Cortex: covers the outer surface of the brain Corpus Callosum: a band of nerves that joins together

the two halves of the brain

Neuroanatomy (cont.)

Frontal Lobe: higher level thought and reasoning, contains the primary motor cortex

Parietal Lobe: somatosensory info, contains the primary somatosensory cortex (temp., pressure, texture and pain)

Temporal Lobe: auditory input Occipital Lobe: visual input Apraxia: inability to organize movement Agnosia: inability to process sensory input Alexia: the inability to read

Neuroanatomy (cont.)

Neural Transmission Nerves=bundles of neurons Soma= cell body Dendrites=branch out from the

soma Axon=a long, tube-like

structure that responds to input from dendrites and soma

Myelin Sheath=fatty coating around the axon

Terminal buttons=knobs on the branched end of the axon

Resting potential: the electrical charge of a neuron at rest Once the electrical charge reaches minus 50 millivolts the

neuron will be ready to fire which leads to… Action Potential: the nerve impulse/ sending the message During action potential the axon membrane is pierced by ion

channels, then sodium ions rush into the axon After the impulse there is a negative after-potential (a drop in

electrical charge below the resting potential) Neurotransmitters: chemical messengers that cross the

synapse (ex: acetylcholine, serotonin, dopamine)

Neural Transmission (cont.)

Neural Transmission (cont.)

Relays info from one part of the body to another using glands that release hormones

Pituitary Gland: master gland, releases hormones to other glands, controlled by the hypothalamus

Adrenal gland secretes epinephrine (adrenaline) and norepinephrine (noradrenaline)

Thyroid Gland: at the front of the neck, regulates metabolism

Endocrine System

The application of principles of evolutionary theory to the study of behavior

Traits: distinctive characteristics or behavior patterns that are determined by genetics

A dominant trait is more likely to be expressed in offspring than a recessive trait

The environment influences us too Nature vs. Nurture debate Genetic Abnormalities cause disorders such as Down’s

Syndrome (a break in the 21st chromosome)

Genetics