Psych 118 - Lecture 9 (full)
Lecture Announcement
Medical appointment affects lecture schedule:
No in-person meeting on Thursday.
Virtual lecture will be pre-recorded and posted after class today for asynchronous viewing.
No attendance quiz for this session.
Next live meeting scheduled for the following Tuesday.
Exam Two Information
Date: November 13 (next week).
Coverage:
Units covered: Four, Five, Six for Exam Two.
Future material for Exam Two: Units Seven and Eight.
Unit breakdown:
Unit Four: 2 lectures
Unit Five: 2 lectures
Unit Six: 3 lectures
Total so far: 7 lectures
Unit Seven: 3 lectures
Unit Eight: 2 lectures
Total lectures including both units: 5
Adjustment made to ensure balanced content for the exam:
Will include only two-thirds of Unit Six material in the exam.
Evolution of the Vertebrate Brain
Continued from previous discussion on evolution related to brain size and complexity.
Encephalization Quotient (EQ):
Definition: A measure of brain size relative to body size, often associated with intelligence.
Question posed: Why are larger brains often associated with greater intelligence?
Associated with flexibility in behavior.
Examined through functional neural connectivity (neural connectivity).
Functional Neural Connectivity
Importance of neuron connections as brain size increases.
Examined through two models:
Model A: Increase in connection numbers to maintain proportional connectivity.
Example:
Hypothetical ancestral animal with 4 neurons has 12 total connections (4 neurons × 3 each).
Ancestral with 8 neurons has 56 connections (
8 neurons × 7 each = 56 total connections).
Model B: Maintained absolute number of connections.
Example:
Ancestral animal (4 neurons) still only connects each neuron to 3 others, yielding the same 12 connections.
Comparative analysis shows evidence for maintenance of absolute number of connections over proportional.
Brain Structure Evolution
Two mechanisms for evolution of new brain structures:
Phylogenetic Conversion:
From ancestral type to a new type.
Example: Conversion of brain Area Three in model A compared to model B (visual illustration).
Phylogenetic Proliferation:
Contains two types.
Segregation: Original structure replaced by multiple new forms.
Addition: New structures added while retaining old structures.
Examples of Evolutionary Mechanisms
Phylogenetic Conversion in Mammalian Neocortex
Shift from nuclear pattern to laminar pattern in mammals.
Implications: Increased complexity and functionality.
Phylogenetic Proliferation Example
Illustrates changes across amniotes vs anamniotes.
Changes in dorsal thalamus (size and number) across species.
Neural Scaling Across Species
Investigated how number and size of neurons scale with brain size.
Found distinct scaling rules for primates versus non-primates.
Non-primates: Increase in neuron size leads to lower density.
Primates: Increase in neuron number without increase in neuron size leads to stable density.
Implications on brain processing power and cognitive functions.
Adaptive Specialization in Sensory Systems
General overview of sensory systems:
Role in transducing environmental energy into neural energy.
Vision & Audition Examples:
Comparative studies in birds (e.g., owls vs. robins) demonstrate adaptation in eye placement and function.
Color discrimination: Humans (trichromatic) vs. pigeons (pentachromatic).
Auditory range: Evolution of sound perception in Elephants and Ultrasonics in bats.
Conclusion of Unit Five
Reminder to watch the virtual lecture on Thursday, as there will be no in-person meeting.
Next lecture will continue exploration into Unit Six.