PSYC 101 Ch. 4

Fixed species-specific behaviours

Behaviours that are consistent within a species.

Brain's role

Critical for generating behaviour.

Phineas Gage (before injury)

Well-balanced mind, smart businessman, persistent.

Phineas Gage (after injury)

Fitful, irreverent, profane; 'no longer Gage.'

Significance of Phineas Gage case

Brain damage impacts personality and behaviour.

Neuron Doctrine

Neurons are discrete but function as a network.

Reticular Theory

Neurons form a continuous network.

Dendrites

Receive information.

Axon

Carries signals; covered by myelin sheath (formed by glial cells).

Nodes of Ranvier

Gaps in myelin that speed up signal transmission.

Soma (cell body)

Coordinates processes, contains the nucleus.

Grey Matter

Unmyelinated axons, cell bodies.

White Matter

Myelinated axons; signal 'jumps' for faster transmission.

Multiple Sclerosis (MS)

Myelin degradation → loss of neural signal → numbness, weakness, motor issues.

Sensory Neurons

Convert external stimuli to nervous signals (bipolar).

Motor Neurons

Control muscles; typically multipolar.

Interneurons

Modulate local activity (CNS, multipolar).

Purkinje Cells

Carry information from the cerebellum to brain/spinal cord.

Pyramidal Cells

Triangular cell body, found in the cerebral cortex.

Bipolar Cells

Sensory neurons in the retina.

Neurons

Transmit signals, action potentials, and neurotransmitters.

Glia

Support neurons, provide nutrients, and influence transmission.

Astrocytes

Manage blood-brain barrier, modulate activity.

Oligodendrocytes

Myelinate CNS neurons (up to 50 neurons).

Schwann Cells

Myelinate PNS neurons (1mm = 1000 cells).

Microglia

Brain's guardians; destroy pathogens, clean debris.

Resting Potential

-70mV; inside is negative relative to outside.

Action Potential

Electric spike (+40mV); follows 'all or none' principle.

Saltatory Conduction

Signal jumps between Nodes of Ranvier (faster).

Synapse

Gap where neurotransmitters transfer signals.

Acetylcholine (ACh)

Voluntary motor control, attention, memory.

Dopamine

Motor behaviour, pleasure; linked to schizophrenia (high) and Parkinson's (low).

Glutamate

Major excitatory transmitter.

GABA

Inhibitory; low GABA = seizures.

Serotonin

Mood, sleep, eating; low levels → depression.

Norepinephrine

Vigilance, awareness.

Endorphins

Pain relief, mood elevation.

Agonists

Increase neurotransmitter action (e.g., Amphetamine, Cocaine).

Antagonists

Decrease neurotransmitter function (e.g., Beta-blockers).

Key Mechanism of Drugs

Drugs alter receptor function but not action potential magnitude.

Epigenetics

Changes in gene expression without altering DNA methylation.

Influence of Epigenetics

Environment and experiences can turn genes 'on' or 'off.'

Genes

Units of heredity, made of DNA, organized in chromosomes.

Mutations

Cause diversity; subject to evolutionary pressures.

Heritability

Measure of how much variability in traits is due to genetics (0 to 1 scale).

Universal human behaviours

Behaviours like aversion to pain, socializing needs, and the drive to eat, reproduce, and seek understanding.

Human nervous system

An interacting network of neurons conveying electrochemical information throughout the body.

Central nervous system (CNS)

Consists of the brain and spinal cord.

Peripheral nervous system (PNS)

Comprises the somatic and autonomic nervous systems.

Sympathetic nervous system

Prepares the body for action in challenging situations.

Parasympathetic nervous system

Returns the body to a resting state.

Endocrine system

A network of glands producing and secreting hormones regulating functions like metabolism.

Pituitary gland

Known as the 'master gland' of the endocrine system.

Hypothalamus Role

Sends hormonal signals to the pituitary gland to regulate bodily functions.

Major divisions of the brain

Hindbrain, midbrain, and forebrain.

Function of hindbrain

Coordinates basic functions such as respiration, alertness, and motor skills.

Structure regulating heart rate

Medulla.

Function of cerebellum

Controls fine motor skills, balance, and coordination.

Function of midbrain

Orients organisms to sensory stimuli and is involved in movement and arousal.

Role of forebrain

Controls complex cognitive, emotional, sensory, and motor functions.

Subcortical structures

Thalamus, hypothalamus, hippocampus, amygdala, and basal ganglia.

Brain plasticity

The brain's ability to adapt to changes in sensory input and reassign functions.

Corpus callosum

A bundle of axons connecting the two hemispheres of the brain.

Structural vs. functional imaging

Structural imaging reveals brain anatomy; functional imaging shows brain activity.

MRI drawbacks

Slow, expensive, unsuitable for patients with metal implants.

fMRI

Detects blood flow changes in the brain, reflecting areas of neural activity.

Mirror neurons

Active when performing or observing an action, found in the frontal and parietal lobes.

Lateralization of language

Predominantly controlled by the left hemisphere, discovered by Broca and Wernicke.

Phineas Gage's case

Showed the frontal lobe's role in emotion regulation, planning, and decision-making.

PET scans drawbacks

Expose patients to radiation and are costly.

Hippocampus role

Creates new memories and integrates them into long-term storage.

Amygdala damage effect

Impairment in emotional processing, particularly fear.

Reflex arc

Neural pathway that controls reflex actions, often involving sensory, motor, and interneurons.

Transcranial magnetic stimulation (TMS)

Uses strong magnetic pulses to temporarily induce or block neuronal activity.

Somatosensory cortex

Located in the parietal lobe, it processes touch information from the body.