Biological Psychology

Biological Psychology

• Study of the physiological, evolutionary, and developmental mechanisms of behavior and experience.
• Relates biology to issues of psychology.
• Neuroscience includes much that is relevant to behavior, including anatomy and chemistry.
• Perception occurs in the brain.
• Mental activity and certain types of brain activity are inseparable.
• Should be cautious about what is an explanation and what is not.
• Physiological Psychology studies the neural mechanisms of behavior through direct brain manipulation and recording.
• Psychopharmacology focuses on manipulating neural activity and behavior with drugs.
• Neuropsychology studies the psychological effects of brain dysfunction in human patients.
• Psychophysiology studies the relation between physiological activity and psychological processes in humans using noninvasive methods.
• Cognitive Neuroscience studies the neural bases of cognition, like thought, memory, attention, and complex perceptual processes.
• Comparative Psychology compares the behavior of different species to understand evolution, genetics, and adaptiveness of behavior.

Biological Explanations to Behavior

• Physiological Explanation relates behavior to the activity of the brain and other organs, dealing with the body's machinery.
• Ontogenetic Explanation describes how a structure or behavior develops, including genetic, nutritional, and experiential influences.
• Evolutionary Explanation notes that animal features are modifications of ancestral species' features.
• Functional Explanation describes why a structure or behavior evolved, such as dominant males spreading genes.

Animal Use in Research

• Studies nonhumans because behavior mechanisms are similar across species and easier to study.
• Interested in animals and want to learn about human evolution.
• Legal or ethical restrictions prevent certain human research.

The Nervous System: Neurons

• Neurons receive and transmit information to other cells.

Structures of an Animal Cell

• Membrane separates the inside of the cell from the outside environment.
• Protein Channel permits a controlled flow of chemicals.
• Nucleus is the central processing body of the cell, containing the chromosomes.
• Mitochondrion performs metabolic activities, providing energy for the cell.
• Ribosomes synthesize new protein molecules.
• Endoplasmic Reticulum transports newly synthesized proteins.

Structures of a Neuron

• Motor Neuron's soma is in the spinal cord, receives excitation through dendrites, and conducts impulses along its axon to a muscle.
• Sensory Neuron is specialized to be highly sensitive to stimulation, such as light, sound, or touch.
• Dendrites receive information from other neurons via synaptic receptors.
• Cell Body / Soma contains the nucleus, ribosomes, and mitochondria.
• Axon conveys impulses toward other neurons, an organ, or a muscle.
• Myelin Sheath covers the axons, speeding up transmission, with interruptions at nodes of Ranvier.
• Presynaptic Terminal releases chemicals that cross the junction between neurons.
• Synapses are junctions between the axon of a neuron and the dendrite of another.
• Efferent Neuron carries information away from a structure.
• Afferent Neuron brings information into a structure.
• Interneuron's dendrites and axon are entirely within a single structure.
• Glia are other components of the nervous system that perform many functions.
• Glia outnumber neurons in the cerebral cortex; neurons outnumber glia in other areas.

Types of Glia

• Astrocytes synchronize closely related neurons, important for generating rhythms.
• Microglia remove viruses, fungi, and dead neurons, acting as part of the immune system.
• Oligodendrocytes, in the brain and spinal cord, build myelin sheaths around certain vertebrate axons.
• Schwann Cells, in the periphery of the body, build myelin sheaths around certain vertebrate axons.
• Radial Glia guide the migration of neurons and their axons/dendrites during embryonic development.

Blood-Brain Barrier

• Minimizes the risk of irreparable brain damage, the body lines the brain's blood vessels with tightly packed cells.
• Capillary walls block viruses, bacteria, and harmful chemicals.
• Active transport, a protein-mediated process, expends energy to pump chemicals from the blood into the brain.

Nourishment of Vertebrate Neurons

• Vertebrate neurons depend almost entirely on glucose, a sugar.
• The liver makes glucose from carbohydrates, amino acids, and glycerol.
• Body needs vitamin B1, thiamine, to use glucose.

The Nerve Impulse

• Nerve Impulse is the electrical message transmitted down the axon of a neuron.
• The impulse is regenerated at points along the axon.
• Resting Potential refers to the state of the neuron prior to sending a nerve impulse.

Polarization

• The membrane of a neuron has an electrical gradient, polarization, with a difference in the electrical charge inside and outside of the cell.
• Electrical potential inside the membrane is slightly negative with respect to the outside, known as the resting potential.
• Selective Permeability: The membrane is selectively permeable, allowing some chemicals to pass more freely than others.

Sodium-Potassium Pump

• The Sodium-Potassium Pump transports three sodium ions out of the cell while drawing two potassium ions into it.
• Helps maintain the electrical gradient, using active transport that requires energy.

Action Potential

• The resting potential remains stable until the neuron is stimulated.
• Stimulation triggers messages called Action Potentials.
• Action potential is a rapid depolarization of the neuron.
• Stimulation past the threshold of excitation triggers a nerve impulse.

Propagation of Action Potential

• Action Potential transmission described as propagation down the axon.
• The action potential is not directly traveling down the axon.

Neurotransmitters

• Chemical messengers that transmit signals across synapses between neurons

Sequence of Chemical Events at a Synapse

• Neuron synthesizes neurotransmitters in axon terminals and the cell body.
• Action potentials enable calcium to enter the cell and release neurotransmitters into the synaptic cleft.
• Molecules diffuse across the cleft, attach to receptors, and alter postsynaptic neuron activity.
• Neurotransmitter molecules separate from receptors.
• Molecules may be taken back or diffuse away.
• Some postsynaptic cells send reverse messages to control neurotransmitter release.

Chemical Events at a Synapse

• Synthesis: The neuron synthesizes neurotransmitters, small are in the axon terminals and neuropeptides are in the cell body.
• Release*: Action potentials trigger calcium influx and neurotransmitter release into synaptic cleft.
• Binding: Neurotransmitters diffuse across and bind to receptors, altering its activity.
• Separation: neurotransmitter molecules detach from the receptors.
• Reuptake/Breakdown: Some neurotransmitters are reabsorbed, others diffuse or are broken
• Regulation: Postsynaptic neurons send signals to regulate NT release.

Types of Neurotransmitters & Their Functions

• Amino Acids: Glutamate – Promotes Neural Excitation
• GABA (Gamma-Aminobutyric Acid): Inhibitory NT, reduces excitability, promotes relaxation, and prevents overstimulation
• Glycine: Works with GABA to inhibit excessive neural activity.
• Monoamines: Ex. Acetylcholine, Serotonin, Dopamine, Epinephrine, Norepinephrine
• Neuropeptides (Neuromodulators): Ex, Endorphins, Substance P, Oxytocin
• Purines: Adenosine - Inhibits neural activity ATP - Acts as excitatory neurotransmitter that transfers energy and synaptic signaling.

Biological Implications of Neurotransmitters

• Serotonin plays a major role in mood disorders.
• Permissive Hypothesis: Low serotonin leads to more fluctuation
• Monoamine Hypothesis: Imbalances in serotonin, dopamine, and norepinephrine

Function / Excess / Deficiency Chart

Hormones & Endocrine System Definition & Function

• Shift away from NTs to the endocrine system and "stress hypothesis" of depression
• Hormones are chemicals, NTs are a telephone signal
• The stress hypothesis focuses on the HPA Axis which can lead to excessive stress which causes immune suppression, digestive issues, heart and mental health disorders.
• dysregulation- leads to persistent stress and maladaptive responses to stress.
• Stress activated the sympathetic nervous system
• Secondary Reaction (HPA Activation): Hypothalamus releases Corticotropin-Releasing Hormone (CRH)
• pituitary gland releases Adrenocorticotropic Hormone and high cortisol levels trigger a negative feedback loop

HPA Axis Dysfunction & Chronic Stress

Prolonged stress keeps the HPA axis overactivated, causing:Elevated cortisol levels and Weakened cortisol response to to acute stress

Key Takeaways

Imbalances in neurotransmitters contribute to mental health disorders Chronic stress disrupts the HPA axis, causing prolonged high levels and associated health problems

Structure of the Nervous System

CNS - Composed of the brain and spinal cord. PNS - Connects the CNS to the rest of the body. SNS - Controls voluntary movements and sensory input. ANS - Regulates involuntary functions. includes the Sympathetic NS

Components of the Spinal chord

Communicates with the body via sensory and motor nerves. Dorsal Root Ganglia - Clusters of sensory neuron cell bodies Gray Matter - "H-shaped" region with neuron cell bodies & dendrites. White Matter - Myelinated axons

Autonomic Nervous System

Sympathetic Nervous System A network of nerves that prepare the organs for a burst of vigorous activity. Releases norepinephrine

Parasympathetic Nervous System

• The "rest and digest" system.
• Releases acetylcholine.

Major Brain Divisions

Consists of. Hindbrain (Medulla, Pons, Cerebellum). Midbrain (Tectum, Tegmentum, Colliculi, Substantia Nigra). Forebrain (Cerebral Cortex, Thalamus, Basal Ganglia, Limbic System).

The Hindbrain and its functions

Medulla- Controls involuntary functions Communicates with the body via 12 pairs of cranial nerves and Pons Bridges the two brain hemispheres and allows cross-body control Cerebellum-Coordinates movement, balance, and timing

Midbrain

Tectum - The "roof" of the midbrain. Superior Colliculus - Vision processing. Inferior Colliculus - Auditory processing. Substantia Nigra - Produces dopamine (essential for movement)

Forebrain

Cerebral Cortex which Is Outer layer of the brain Thalamus-Sensory relay station. Basal Ganglia-Controls movement, motivation, habits. Limbic System -Processes fear and emotional responses Hypothalamus-Regulates hunger, thirst, temperature, hormones. Pituitary Gland-Produces hormones affecting stress, growth, metabolism. Hippocampus-Essential for memory formation and spatial navigation.

The Ventricles & Cerebrospinal Fluid (CSF)

CSF- Cushions and supports the brain. Hydrocephalus-Condition where excessive CSF leads to brain swelling.

The nervous system is divided into the CNS and PNS The hindbrain controls basic survival functions The midbrain is responsible for sensory processing and movement The forebrain handles higher cognitive functions, emotions, and voluntary actions The limbic system plays a role in emotions, memory, and motivation CSF protects and nourishes the brain,

The Parts of the Cerebral Cortex

• The cerebral cortex is the outermost layer of the brain, responsible for higher mental functions such as perception, thinking, and decision-making
• The folds and wrinkles (gyri and sulci) increase its surface area, allowing more neurons to process vast amounts of information
• The cortex consists of gray matter, composed mainly of neurons, lacking the myelin insulation found in white matter

The Four Lobes of the Cerebral Cortex

• Occipital Lobe(Vision)- Processes visual information
• Parietal Lobe (Touch & Spatial Processing): Processes sensory input
• Temporal Lobe (Hearing, Language, & Memory): Processes sound information.
• Frontal Lobe (Thinking, Planning, & Movement): Behavioral control & impulse inhibition.

The Prefrontal Cortex (Decision-Making & Personality)

Prefrontal Cortex develops last and is responsible for complex cognition such as planning, personality, decision making

Prefrontal Lobotomy (Historical Medical Practice)

A surgical procedure that damaged connections in the prefrontal cortex to alter behavior to treat mental illnesses Performed surgery damage on brain