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Behavioral Neuroscience

Chapter 2

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Biology and Behavior

• The term behavioral neuroscience describes the work of scientists from several disciplines who work to understand how the nervous system is related to behavior.

• Concerned with:

SensingProcessingResponding

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The Evolutionary Perspective

• The evolutionary perspective > role of physiological structures & behaviors; adaptation to the environment

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Natural Selection

• Natural selection = the most fit organisms survive; they adapt best to the environment; pass on genes

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The Nervous System

• We use the processes of sensing, processing, and responding to interact with the environment.

• The nervous system is divided into two parts: – central nervous system (CNS-brain and spinal

cord)– peripheral nervous system (PNS-all parts of

the nervous system outside the CNS)

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The CNS

• The spinal cord is composed of sensory (afferent or ascending) and motor (efferent or descending) nerves.

• Interneurons may connect sensory and motor neurons.

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CNS Nerves

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CNS Nerves

• A reflex arc occurs in less than 1/1000 of a second• A typical “fast” response that uses brain pathways takes

about 1/10th of a second

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CNS NervesThe Cranial Nerves

•Olfactory•Optic•Oculomotor•Trochlear•Trigeminal•Abducens•Facial•Auditory-vestibular•Glossopharyngeal•Vagus•Spinal Accessory•Hypoglossal

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The PNS

• PNS > the somatic division and the autonomic division.

• Somatic division > sensory nerves run from receptors to the brain; motor nerves run to the glands and muscles.

• Autonomic division > sympathetic division, which mobilizes body's resources, and the parasympathetic division which returns body to homeostasis.

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Divisions of the Nervous SystemCentral Nervous

System– Brain– Spinal cord

Peripheral Nervous System–Somatic –Autonomic

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Neurons: The Basic Cells

• The cells that make up the nervous system are called neurons.

• Neurons are composed of:– dendrites > receive signals from adjacent neurons – cell body or soma – axon > transmits signals – terminal buttons > contain

neurotransmitters.

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Structure of a Neuron

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Structure of a Neuron

Bipolar > interneurons or association neurons

Unipolar > usually sensory neurons

Multipolar > tend to be motor neurons

All neurons carry impulses in only one direction

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The Synapse

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Key Neurotransmitters

• Acetylcholine (ACh)

• Dopamine

• Serotonin

• Endorphins

• Norepinephrine

• Gamma amino butryic acid (GABA)

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Refractory Period

• Neurotransmitters must be removed from the synapse before another signal can be transmitted.

Removal is accomplished either by breakdown or by reuptake.

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Agonists and Antagonists

• Agonists > drugs that promote the action of a neurotransmitter.

• Antagonists > drugs that inhibit the action of a neurotransmitter.

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Neuromodulators

• Neuromodulators have more widespread and indirect effects than neurotransmitters.

• Neuromodulators also influence transmission between cells.

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The Action Potential

The reversal in electrical charge is known as the action potential.

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The Brain: A Closer Look

• Phrenology is not a science. Popularized in the 1800s by Franz Joseph Gall

• Gall > skills and characteristics determined by id’ing bumps on the skull.

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The Brain: A Closer Look

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The Brain: A Closer Look

Early studies stimulated or

removed portions of the cortex.

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The Brain

• The brain is divided into the hindbrain, the midbrain, and the forebrain.

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The Hindbrain

• The most primitive of the three main divisions.

• Major structures > medulla, pons, and cerebellum.

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The Brain

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Balance and

movement

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The Midbrain

The midbrain, pons, and medulla lie on top of the spinal cord. Together they make up the brain stem.

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The Forebrain

The forebrain consists of subcortical structures and the two hemispheres of the cerebral cortex

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The Corpus Callosum

• Millions of myelinated axons connecting the brain’s hemispheres

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Subcortical Structures Thalamus

Like a relay station to areas of the cortex

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Subcortical Structures Thalamus

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Subcortical Structures Hypothalamus

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The Cortex

• The cerebral cortex covers the forebrain and is divided into four lobes: – frontal– parietal– temporal– and occipital

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Occipital lobe

Visual center

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Parietal lobe

Includes somatosensory cortex (input from environment)

Helps process perceptions

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Temporal lobe

•Hearing•Understanding language•Memory

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Frontal lobe

You are who you are because of this lobe. •Personality•Emotions•Controlling judgment•Impulses •Sexual behavior•Using Language •Movement

Motor Cortex

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Somatosensory and Motor Cortexes

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More About the Brain

• Aphasia

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More About the Brain

AphasiaCAT Scan

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More About the Brain

Apraxia of lid opening

(blepharospasm)

ApraxiaLoss or impairment of the ability to execute complex, coordinated movements without impairment of the muscles or senses.

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Split-Brain and Lateralization

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Split-Brain Experiment

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The Endocrine System

• Endocrine system:– Ductless glands that

regulate growth, reproduction, metabolism, mood, and some behavior

• Hormones: – Chemical messengers

secreted into the bloodstream

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The Endocrine System

• Cortisol:

• CortiSlim?

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The Endocrine System• “Cortisol is the body's main

stress hormone, and is required for many vital purposes -- proper glucose metabolism, blood pressure, immune function and inflammatory response are a few. In times of stress, either mental or physical, the body can produce an excessive amount of cortisol. At these high levels, cortisol is a nasty little number indeed. It can negatively affect cognitive performance, suppress thyroid function, foster blood sugar imbalances and the subsequent deposition of body fat, decrease bone density, as well as other things. Athletes don't like cortisol, as it is catabolic -- i.e., muscle-wasting, rather than anabolic -- i.e., muscle building.”