Source: Barron’s AP Psychology

Neuroanatomy

Neuroanatomy

• The study of the parts and function of neurons

Neurons

• Individual nerve cells

Dendrites

• Root-like parts of the cell that stretch out from the cell body.

• Grow to make synaptic connections with other neurons

Cell Body (Soma)

• Contains the nucleus and other parts of the cell needed to sustain its life

Axon

• Wirelike structure ending in the terminal buttons that extends from the cell body

Myelin Sheath

• A fatty covering around the axon of some neurons that speeds neural impulses

Terminal Buttons

• The branched end of the axon that also contain neurotransmitters

Neurotransmitters

• Chemicals contained in terminal buttons that enable neurons to communicate

• Fit into receptor sites on the dendrites of neurons like a key into a lock

Synapse

• Space between the terminal buttons of one neuron and the dendrites of the next neuron

How a Neuron “Fires”

Background info: neuron membranes are selectively permeable; neurons start by having a slightly negative charge while + ions surround it

• Begins when the terminal buttons of neuron A are stimulated and release neurotransmitters into the synapse

• The neurotransmitters fit into neuron B’s receptor sites on the dendrites

• If enough neurotransmitters are received (level is called absolute threshold), neuron B’s membrane becomes permeable and positive ions rush through the cell (action potential)

• When the charge reaches the terminal buttons of neuron B, the buttons release their neurotransmitters into the synapse

• Process begins again if enough neurotransmitters are received by the next cell to pass on the threshold

All-or-none principle

• A neuron either fires completely or it does not fire.

Excitatory Neurotransmitters

• Excite the next cell into firing

Inhibitory Neurotransmitters

• Inhibit the next cell from firing

The Nervous System

Afferent Neurons (Sensory)

• Take information from senses to brain

Interneurons

• Once info reaches the brain or spinal cord, interneurons take the messages and send them elsewhere in the brain or onto efferent neurons

Efferent Neurons (Motor)

• Take information from the brain to the rest of the body

Central Nervous System

• Consists of brain + spinal cord (all nerves encased in bones)

Peripheral Nervous System

All nerves not encased in bone

• Somatic Nervous System

  • Controls voluntary muscle movements

• Autonomic Nervous System

  • Controls automatic functions of our body

  • Also control response to stress

  • Parasympathetic and sympathetic nervous systems

    • Sympathetic Nervous System

      • Mobilizes body to respond to stress

      • Alert system - accelerates some functions (e.g. heartbeat) but conserves resources needed for a quick response by slowing down other functions (e.g. digestion)

    • Parasympathetic Nervous System

      • Causes body to slow down AFTER a stress response (break pedal)

Reflexes → Reactions that occur the moment sensory impulses reach the spinal cord

The Brain

Ways of Studying the Brain

Accidents

• By observing the brain damage and behaviour after an accident, researchers can determine the functions the damaged part played in behaviour.

Lesions

• The removal or destruction of part of the brain

• Observe behaviour afterwards to determine function of that part of the brain

• Frontal Lobotomy (In the past, lesioning of frontal lobe was used to make the patients calm and relieve symptoms)

Electroencephalogram (EEG)

• Detects brain waves

• Examine what type of waves the brain produces during different stages of consciousness and use this information to generalize about brain function.

Computerized Axial Tomography Scan (CAT or CT)

• Several X-ray cameras that rotate around the brain and combine all the pictures into a detailed 3D picture

• Only show structure, not the functions or activity

Magnetic Resonance Imaging (MRI)

• Uses magnetic fields to measure the density and location of brain material.

• Only show structure, not functions or activity

Positron Emission Tomography Scan (PET)

• Shows what areas of the brain are most active during certain tasks

• Measures how much of a certain chemical parts of the brain are using

Functional MRI (fMRI)

• Combines elements of MRI and PET scans

• Show details of brain structures with information about blood flow in the brain

Brain Structure and Function

3 categories/sections: Hindbrain, Midbrain, Forebrain

Hindbrain

• Controls basic biological functions that keep us alive

• Medulla

  • Control of blood pressure, heart rate, and breathing

• Pons

  • Controls facial expressions

• Cerebellum

  • Coordinates habitual muscle movements

Midbrain

• Coordinates simple movements with sensory information

• reticular formation

  • A netlike connection of cells throughout the midbrain that controls general body arousal and the ability to focus our attention

Forebrain

• Controls thought and reason (what makes us human)

• Thalamus

  • Receives the sensory signals coming up the spinal cord and sends them to the appropriate areas in the rest of the forebrain

• Hypothalamus

  • Metabolic functions

  • e.g. body temperature, sexual arousal (libido), hunger, thirst, and the endocrine system

• Amygdala

  • Vital to experiences of emotion

• Hippocampus

  • Processes memory to be permanently stored in other areas of the cerebral cortex

Cerebral Cortex

• Grey wrinkled surface of the brain (layer of densely packed neurons)

• Overtime, the dendrites of the neurons grow and connect with other neurons to form the complex neural web

• Fissures

  • Wrinkled surface of the cerebral cortex to increase surface area

Hemispheres

Theories: Left = logic and sequential tasks, Right = spatial and creative tasks

• Contralateral control

  • Left hemisphere

    • Sensory and motor functions of RIGHT half of body

  • Right hemisphere

    • Sensory and motor functions of LEFT half of body

• Brain Lateralization

  • Specialization of function in each hemisphere

  • Research is done by examining split-brain patients

    • Corpus callosum (nerve bundle that connects the two hemispheres) is cut to treat severe epilepsy

    • Operation pioneered by Roger Sperry and Michael Gazzaniga

    • Cannot orally report info only in the right hemisphere since spoken language is in the left hemisphere

The cerebral cortex has eight (8) lobes (4 on each hemisphere - )

• Association area

  • Any area of the cerebral cortex that is not associated with receiving sensory information or controlling muscle movements

• Frontal Lobes

  • Large areas of the cerebral cortex located at the top front part of the brain behind the eyes

  • Anterior of frontal lobe is the prefrontal cortex

    • Critical role in thought directing process

  • Two special areas for language processing

    • Broca’s area (Paul Broca)

      • Frontal lobe; responsible for controlling muscles involved in producing speech

    • Wernicke’s Area (Carl Wernicke)

      • Temporal lobe; responsible for understanding of spoken and written language

  • Motor Cortex

    • Thin, vertical strip at the back of the frontal lobe

    • Sends signals to our muscles, controlling our voluntary movements

    • Top of the body is controlled my neurons at the bottom of this cortex, progressing down the body as you go up the cortex

• Parietal Lobes

  • Located behind the frontal lobe but still on the top of the brain

  • Contain sensory cortex (somato-sensory cortex)

    • Thin vertical strip that receives incoming touch sensations from the rest of our body

    • Top of sensory cortex receives sensations from the bottom of the body and vice versa

• Occipital Lobes

  • At the very back of our brain, farthest from our eyes

  • Interpret messages from our eyes in our visual cortex

  • Impulses from right half of each retina are processed in the visual cortex in the right occipital lobe

  • Impulses from left half of each retina are processed in the visual cortex in the left occipital lobe

• Temporal Lobes

  • Process sound sensed by our ears (auditory cortex)

  • Sound received by either ear is processed in both auditory cortices

  • Damage to this area affects ability to interpret spoken language (Wernicke’s area)

Brain Plasticity

• The ability of the nervous system to change its activity in response to intrinsic or extrinsic stimuli by reorganizing its structure, functions, or connections.

The Endocrine System

Endocrine System

• A system of glands that secrete hormones that affect many different biological processes in our bodies

• Controlled by hypothalamus

Adrenal Glands

• Produce adrenaline

• Signals body to prepare for fight or flight (autonomic nervous system - involuntary responses)

Ovaries and Testes

• Produce sex hormones

• Levels of estrogen and testosterone may explain gender differences (Developmental Psychology)

Genetics

Most traits are the results of nature and nurture

Monozygotic Twins

• Identical twins - same genetic material

• Thomas Bouchard studied twins raised in different families to see if traits were nature or nurture

  • Criticized because twins share the same physical characteristics, thus causing others to treat them in similar ways (effective psychological environment).

Chromosomal Abnormalities occur when chromosomes from the father (XY) and the mother (XX) fail to properly combine

• Turner’s syndrome

  • Single X chromosome instead of a 23rd pair

• Klinefelter’s syndrome

  • Extra X chromosome, thus XXY pattern

• Down syndrome

  • Extra chromosome on 21st pair