University Studies 15A: Consciousness I Brains
Jan 05, 2016
University Studies 15A:
Consciousness I
Brains
Brains: More than we can hope to learn
Brain Details: What and Why?
“Why” will lead us to ‘What”
We want to know about consciousness as the quality of first-person experience of the world.
We want to know about the “I think,” “I see,” “I feel.”
“What” we want to know about in the brain is what is important for the creation of this first-person quality.
Some aspects of the brain will not matter that much:
The actual biochemistry of neuronal firing
The actual biology of “long-term potentiation”
We will need to know some of the basics of brain structure (i.e. neuroanatomy)
We will need to know some of the basics of functional organization (covered in greater detail in later lectures)
Today we start with the basics of brain structure
A Final Point about Actual Neurons:
Note the myelin sheath surrounding the axon.
These glial cells are basically fat. They serve to insulate the axon and make its electrical transmission more efficient.
Neurons that have acquired the myelin sheath form the “white matter” of the brain.
Although as “species-ists,” we are most interested in the human brain, some perspective is useful.
Brain Stem:
Much nervous system housekeeping (breathing, heart beat)Connects the spinal cord to the brain
Cerebellum:Muscle control
Olfactory bulb & Optic Lobe:Brain hardware devoted to handling smell and sight
Brain Parts: the Early Version
For Humans, same basics + expanded cortex:
Let’s follow Baar’s and Gage’s approach and build from the brainstem up.
The Brainstem, Pons, and Thalami:
thalamusPons
The Brainstem, Pons, Thalami, Hippocampi, and Amygdalas:
hippocampusamygdala
Brainstem, Pons, Thalami, Hippocampi, Amygdalas,and Everything Else:
Basal ganglia
Cerebellum
The basic human brain
Cortex
White Matter
Another Drawing of the Same Structures + Reticular Formation
In humans, the cortex grows somewhat slowly:
More crucial for us are two other aspects of maturation: Dendritic Arborization: the creation of new dendrites Myelination: the covering of the axons with myelin
The Neocortex is a made of six layers of cells which grows in an “inside-out” pattern.
The Neocortex is a made of six layers of cells which grows in an “inside-out” pattern starting with Layer 6.
Layer 1: Not many actual cells Mainly dendrites from cells in other layers to allow dense horizontal connectionsLayers 2 - 3: Horizontal connections (like Layer 1) Axons leading to cells in Layers 4-6Layer 4: Most input (axons from White Matter) end here Mainly dendrites from cells in other layersLayers 5-6: Output neurons to other areas of brain
Terms you might as well learn:Dorsal: UpVentral: Down
The Cortex
The Four Lobes:Occipital LobeParietal LobeTemporal LobeFrontal Lobe
Two Major Lines:Central SulcusSylvian (Lateral) Fissure
Sylvian (Lateral) Fissure
Central Sulcus
Lateral: On the side Medial: In the middle
Functional Organization of the Cortex
Primary Visual Cortex
Visual Association Areas
Auditory Cortex
Primary Somatosensory Cortex
Somatosensory Association Areas
Motor Cortex
Premotor Cortex
Prefrontal Cortex
On the Two Sides of the Central Sulcus
In front of the central sulcus, the motor cortex
Behind the central sulcus, the primary somatosensory cortex
“White Matter” Fiber Pathways(Back of the Brain to the Left)
One Last Neuroanatomical Slide: The Medial Temporal Lobe Structures
Limbic Cortex (Paleocortex) goes with Limbic System
One Last Neuroanatomical Slide (Really): The Medial Temporal Lobe Structures
Anterior Cingulate cortex
Parahippocampal cortex