Ch. 1: Biology and Behavior

A brief history of neuropsychology

• Franz Gall

  • Had the earliest theories saying that behavior, intellect, and personality can be linked to brain anatomy

  • Believed that psychological attributes reflect in the skull’s structure

• Pierre Flourens

  • Pioneered extirpation, also known as ablation

  • Surgical removal of brain structures to see how behavior is affected

  • Asserted that specific parts of the brain had specific functions

• William James

  • Founded functionalism, which studies how the mind adapts to the environment

• John Dewey

  • Contributed to functionalism

  • Criticized the reflex arc, which broke the process of reacting to a stimulus into discrete parts

• Paul Broca

  • Broca’s area - damage causes an inability to speak

  • Found that specific brain lesions caused specific impairments

• Hermann von Helmholtz

  • Measured speed of nerve impulses

  • The earliest “link” between psychology and the natural sciences

• Sir Charles Sherrington

  • Inferred the existences of synapses

  • Incorrectly thought that synapses were primarily electrical

Organization of the human nervous system

• Sensory / afferent neurons

• Motor / efferent neurons

• Interneurons

  • Most common type

  • Found between other neurons

• Reflex arcs

  • Control reflexive behavior

  • Relay information to the source of the stimuli while simultaneously throwing routing it towards the brain

• Central nervous system (CNS)

• Peripheral nervous system (PNS)

  • 31 pairs of spinal nerves

  • 12 pairs of cranial nerves

  • Somatic nervous system

  • Autonomic nervous system

    • Parasympathetic nervous system

    • Sympathetic nervous system

Organization of the brain

• The meninges

  • Dura mater

  • Arachnoid mater

  • Pia mater

  • Help reabsorb CSF

    • CSF is produced in the ventricles

• The brainstem

  • Comprised of the hindbrain and midbrain

  • Evolutionarily developed earlier

• The cerebral cortex

  • Evolutionarily developed most recently

• Development

  • Prenatally develops from the neural tube

  • The hindbrain splits into the myelencephalon and metencephalon

  • The forebrain splits into the telencephalon and diencephalon

• The hindbrain

  • AKA rhombencephalon

  • Balance, motor coordination

  • Arousal processes, i.e. sleeping and waking

  • Holds the reticular formation

  • Myelencephalon

    • Medulla oblongata

    • Regulates vital life functions (ex. breathing, heartbeat)

  • Metencephalon

    • Pons and cerebellum

    • Posture, speech, balance, movement

    • Impaired by alcohol

• The midbrain

  • AKA mesencephalon

  • Receives sensorimotor information

  • Involved with involuntary reflexes

  • Superior colliculi

    • Visual input

  • Inferior colliculi

    • Auditory input

• The forebrain

  • AKA prosencephalon

  • Includes the limbic system

  • Emotion, memory, and complex cognition

  • Telencephalon

    • Cerebral cortex

    • Basal ganglia

    • Limbic system

  • Diencephalon

    • Thalamus

    • Hypothalamus

    • Posterior pituitary gland

    • Pineal gland

• Methods of mapping the brain

  • Extirpation / ablation

  • Cortical maps

    • Stimulation of a specific cortex with an electrode during operation

  • Electroencephalogram (EEG)

    • Uses ultrasensitive microelectrodes

  • Regional cerebral blood flow (rCBF)

    • Assumes that increased blood flow to certain structures correlates with cognitive function

    • A radioactive gas is inhaled and absorbed into the bloodstream; radioactivity is then detected to determine blood flow

  • Computed axial tomography (CAT / CT)

    • Uses multiple angled X-rays to produce cross-sectional images

  • Positron emission tomography (PET)

    • Ingestion of radioactive sugar

    • Dispersion and uptake through the target tissue is imaged

  • Magnetic resonance imaging (MRI)

    • Magnetic field interacts with hydrogen atoms to determine hydrogen-dense regions

  • Functional magnetic resonance imaging (fMRI)

    • Same technique as MRI

    • Additionally measures changes in blood flow

    • Useful for monitoring neural activity

Parts of the forebrain

• Thalamus

  • Relay station

• Hypothalamus

  • Homeostatic function

  • Primary regulator of the autonomic nervous system

  • Lateral hypothalamus

    • Signals hunger

    • Removal of Lateral Hypothalamus = Lacks Hunger

  • Ventromedial (VMH) hypothalamus

    • Satiety center

    • Removal of VMH = Very Much Hungry

  • Anterior hypothalamus

    • Primarily stimulates sexual behavior

    • Sleep and body temp.

• Other parts of the diencephalon

  • Posterior pituitary

    • Releases ADH / vasopressin and oxytocin

  • Pineal gland

• Basal ganglia

  • Coordinates muscle movement and posture

  • Extrapyramidal system

    • Gathers positional information to send it to the CNS

    • Does not directly use motor neurons

  • Parkinson’s disease

    • Results from the destruction of the basal ganglia

    • Characterized by jerky movements and resting tremors

• Limbic system

  • Emotion and memory

  • Septal nuclei

    • A primary pleasure center

    • Possibly related to addictive behavior

  • Amygdala

    • Defensive and aggressive behavior

  • Hippocampus

    • Learning and memory

    • Fornix: for communication with other parts of the limbic system

    • Anterograde amnesia: inability to form new memories

    • Retrograde amnesia: inability to remember old memories

  • Anterior cingulate cortex

    • Higher order cognition

      • Impulse control

      • Decision making

• Cerebral cortex

  • AKA neocortex

  • Association areas integrate information from various brain regions

  • Projection areas perform rudimentary perceptual and motor tasks

  • The central sulcus divides the frontal and parietal lobes

  • Frontal lobe

    • Prefrontal cortex

      • Association area

      • Directs operations of other brain regions

      • Stimulates alertness with the RAS

      • Supervises emotion, memory, impulse control, etc.

    • Primary motor cortex

      • Projection area

      • Located on the precentral gyrus

      • Initiates voluntary motor movements

      • The motor homunculus is a visual representation of how parts of the primary motor cortex correlate to their associated body parts

    • Broca’s area

      • Speech production

      • Usually found in the “dominant” hemisphere - the left hemisphere (for both left- and right-handed individuals)

  • Parietal lobe

    • Somatosensory cortex

      • Located on the postcentral gyrus

      • Somatosensory information processing

      • Destination for signals regarding touch, temperature, pressure, and pain

      • Sometimes bundled with the motor cortex and called the sensorimotor cortex

  • Occipital lobe

    • Visual cortex

      • AKA striate cortex

      • Visual processing

  • Temporal lobe

    • Auditory cortex

      • Site of sound processing

    • Wernicke’s area

      • Language comprehension

    • Speech shadowing is a process which researches both stuttering and perception, where participants recite alongside auditory input

  • Cerebral hemispheres and laterality

    • Contralateral - a side of the brain usually communicates with the opposite side of the body

    • Ipsilateral - in rare cases, hemisphere-to-body communication occurs on the same side

    • Dominant hemisphere

      • Usually the left

      • Functions analytically, i.e. language, logic, math, etc.

    • Nondominant hemisphere

      • Usually the right

      • Intuition, creativity, music cognition, spatial processing, etc.

    • Connected via the corpus callosum

• Influences on behavior

  • Neurotransmitters

    • Agonists: drugs that mimic neurotransmitter activity

    • Antagonists: drugs that block neurotransmitter activity

    • Acetylcholine

      • Acts mostly as an excitatory neurotransmitter

      • In the cardiovascular system, acts as an inhibitory neurotransmitter

      • Awareness and attention

      • Loss of cholinergic neurons in the brain is linked to Alzheimer’s

    • Catecholamines

      • Epinephrine (adrenaline)

        • From the adrenal medulla

        • Acts more like a hormone

      • Norepinephrine (noradrenaline)

        • Acts more like a neurotransmitter

        • Low levels linked with depression

        • High levels linked with anxiety

      • Dopamine

        • Movement and posture

        • Imbalances are linked to schizophrenia

        • The dopamine hypothesis of schizophrenia links the condition to an excess of or oversensitivity to dopamine in the brain

        • Loss of dopaminergic receptors is linked to Parkinson’s disease

    • Serotonin

      • Classified as a monoamine / biogenic amine, like the epinephrine, norepinephrine, and dopamine

      • Mood, eating, sleeping, and dreaming

      • Oversupply is linked to mania

      • Undersupply linked to depression

    • GABA

      • Produces inhibitory postsynaptic potentials (IPSPs), i.e. stabilizes neural activity

      • Causes hyperpolarization (in the postsynaptic membrane)

    • Glycine

      • Inhibitory

      • Causes a chloride influx, leading to hyperpolarization

    • Glutamate

      • Excitatory

    • Peptides that act as neurotransmitters

      • AKA neuromodulators, neuropeptides

      • Slower to act, and effects last longer

      • Important examples include endorphins and enkephalins

        • Painkiller properties, like opioids

  • Endocrine system

    • Hypophyseal portal system

      • Connects hypothalamus and pituitary glands

    • Anterior pituitary gland

      • “Master” gland

      • Controlled by the hypothalamus

    • Adrenal gland

      • Adrenal medulla

        • Epinephrine and norepinephrine

      • Adrenal cortex

        • Cortisol and other corticosteroids

        • Helps produce sex hormones

    • Gonads

      • Produce sex hormones

      • Increases libido

  • Genetics and behavior

    • Innate behavior

      • Genetically programmed by evolution, regardless of situation or environment

    • Learned behavior

    • Adaptive value

      • The extent to which something positively affects the fitness of a species

    • Family studies

      • Conducted because related individuals are more genotypically similar than unrelated individuals

    • Concordance rate

      • Likelihood that twins exhibit the same trait

    • Twin studies

      • Studies that compare the concordance rate of a trait between monozygotic (identical) and dizygotic (fraternal) twins

    • Adoption studies

      • Compares similarities between the biological relatives and the child versus the adoptive relatives and the child

Development

• Critical periods: periods of development where children are particularly susceptible to environmental factors

• Prenatal

  • Neurulation occurs when the ectoderm above the notochord begins to furrow

    • Forms a neural groove, with neural folds at the side

  • The neural crest is positioned at the leading edge of each neural fold, and will migrate throughout the body to form other tissues

  • The furrow closes to form the neural tube

    • The neural tube forms the CNS

    • Has an alar plate which becomes sensory neurons

    • Has a basal plate which becomes motor neurons

  • The umbilical cord attaches the fetus to the uterine wall and placenta

  • The placenta transmits resources between mother and fetus

• Motor

  • Reflexes are behaviors that occur in response to stimuli without higher cognitive input

  • Primitive reflexes are reflexes that disappear with age

    • The Moro reflex describes how babies, when their head is moved abruptly, fling out their arms, then retract their arms and begin crying

    • The Babinski reflex describes how toes flare apart when the bottom of the sole of the foot is stimulated

    • The grasping reflex occurs when infants curl their fingers around objects placed in the hand

  • Gross motor skills incorporate large muscle groups and whole body motion (i.e. sitting, walking, etc.)

  • Fine motor skills use smaller muscles in the fingers, toes, eyes, etc.

• Social

  • Stranger anxiety: fear and apprehension towards unknown individuals

  • Separation anxiety: fear of being separated from parental figures

  • Parallel play: a type of play where children will play alongside one another without influencing each other’s behaviors

  • Developmental milestones: abilities and behaviors that emerge as a person develops

    • Motor skills progress head to toe, and from the core to periphery

    • Social skills shift from parent-oriented to self-oriented to other-oriented

    • Language skills become increasingly complex