PSYC317 Biopsychology Lecture 2: The Nervous System

A comprehensive set of practice flashcards covering key concepts from the lecture notes on the nervous system, brain evolution, neuron function, synaptic transmission, neurotransmitters, pharmacology, genetics, and classic case studies.

What is the Triune Brain Model and who proposed it?

Proposed by Paul MacLean in the 1960s; posits three brain levels: reptilian brain (brainstem and basal ganglia) for movement/basic functions, limbic system for emotions (paleo mammals), and outer cortex (neocortex) for higher cognition (neo-mammals).

What are the three evolutionary stages in the Triune Brain Model and their associated brain parts?

1) Lower animals (reptiles) with brainstem and basal ganglia; 2) Early mammals (paleo) with limbic system; 3) Humans/non-human primates (neo-mammals) with outer cortex.

What is a major flaw of the Triune Brain Model?

Evolution did not occur in a simple sequence; cortex is present in rodents; brain regions evolved in tandem and are interconnected; the model oversimplifies brain evolution.

What does PNS stand for and what are its two major divisions?

Peripheral Nervous System; divisions are the somatic nervous system and the autonomic nervous system.

What does CNS stand for and what are its two primary components?

Central Nervous System; consists of the brain and spinal cord.

Define afferent and efferent nerves.

Afferent nerves carry sensory information toward the CNS; efferent nerves carry motor commands away from the CNS.

What are the two subdivisions of the autonomic nervous system and their general roles?

Sympathetic (fight/flight) and parasympathetic (rest/digest) systems.

What are the main glial cell types that provide myelination in the CNS and PNS?

Oligodendrocytes in the CNS; Schwann cells in the PNS.

What is the Neuron Doctrine?

The idea that neurons are discrete, individual cells that communicate via synapses, forming the basis of information flow in the nervous system.

Who contributed key evidence for the Neuron Doctrine and what did they show?

Ramon y Cajal; demonstrated discrete neurons and directional signaling across synapses, supporting the neuron theory.

What did Sherrington contribute to our understanding of neural transmission?

Proposed the existence of synapses between neurons and introduced the concept of synaptic transmission, fueling the chemical vs electrical transmission debate.

What was Otto Loewi's classic experiment and its significance?

Demonstrated chemical synaptic transmission using two frog hearts connected by shared fluid; stimulation of the vagus slowed heart 1; chemical (acetylcholine) transferred to heart 2 slowed it as well.

What is acetylcholine and its effect on the heart via parasympathetic signaling?

ACH is a neurotransmitter released by parasympathetic nerves; binding to ACH receptors opens potassium channels, causing hyperpolarization and slowed heartbeat.

How does noradrenaline affect heart rate and through which mechanism?

Noradrenaline released by the sympathetic system raises heart rate by acting on adrenergic receptors and promoting calcium influx (depolarization).

Can acetylcholine bind to adrenergic receptors?

No; acetylcholine binds only to acetylcholine receptors (nicotinic/muscarinic), not adrenergic receptors.

What is the difference between receptor agonists and antagonists?

Agonists activate post-synaptic receptors; antagonists block receptors and do not activate them.

How can psychoactive drugs influence synaptic transmission?

By acting as receptor agonists or antagonists and by altering neurotransmitter availability in the synaptic cleft (e.g., SSRIs affect reuptake).

What does SSRI stand for and what is its mechanism?

Selective Serotonin Reuptake Inhibitor; blocks the serotonin transporter, increasing serotonin duration in the synapse without increasing release or receptor sensitivity.

Name the main excitatory and inhibitory neurotransmitters and their typical receptors mentioned.

Glutamate (excitatory; NMDA and metabotropic receptors) and GABA (inhibitory; GABA receptors).

What is the role of ATP and its breakdown products in neurotransmission?

ATP is a neurotransmitter; its breakdown products ADP, AMP, and adenosine also act on purinergic receptors, contributing to signaling.

What are MAO-A and MAO-B and why are they important in behavior research?

Monoamine oxidases (MAO-A and MAO-B) that break down monoamines (e.g., dopamine, serotonin); gene variations can affect transmitter levels and have been studied in relation to aggression and crime, with methodological limitations.

What is the so-called 'warrior gene' and what caveats accompany it?

MAO-A gene variant linked to aggression under adverse childhood experiences; findings are controversial and not universally applicable across ethnic groups; environment matters.

Explain gene-environment interaction in the context of MAO-A.

Behavior results from both genetic variation and life experiences; epigenetic regulation may modulate MAO-A/B expression in response to environment.

What does epigenetics refer to in this context?

Changes in gene expression without altering DNA sequence; environmental factors can turn genes on or off or alter expression levels.

What do HM and Phineas Gage illustrate about brain function?

HM (hippocampus surgery) and Phineas Gage (prefrontal cortex damage) illustrate how specific brain regions relate to memory and personality, supporting a holistic view of brain function.

How do rodent brains compare to human brains in terms of structure and evolution?

Rodents have smoother brains with fewer gyri/sulci but share similar cellular architecture; humans have more developed cortex; cross-species mapping helps explain human behavior.

Why should lower vs higher brain regions not be viewed as 'more or less advanced'?

Different regions have distinct roles and work together; evolution favors networked, interconnected systems rather than strict hierarchical progression.

What is the basic flow of information in the nervous system as described?

Sensory information enters via afferent pathways to the CNS; motor commands exit via efferent pathways to effectors; spinal cord damage can disrupt these flows, causing paralysis.

What is a typical description of the sensory/motor pathway in the notes?

Sensory nerves (afferent) sense the external world (e.g., touch) and send signals to the CNS; motor nerves (efferent) trigger actions in muscles and organs.

What anatomical differences are noted between rodent and human brains?

Rodents lack pronounced gyri and sulci; brains are smoother; humans have highly developed cortex with more folds, enabling complex cognition.