Conceptual exploration of the Kandel, E. R. (2000) and Swason (2008) articles Takashi Yamauchi Texas A&M University.

Conceptual exploration of the Kandel, E. R. (2000) and Swason

(2008) articles

Takashi Yamauchi

Texas A&M University

Kandel 2000

• Main messages– Localization of mental functions

• P. 15 “Mental processes are represented in the brain by their elementary processing operations.”

• Elementary operations of cognitive functions are localized in the brain.

• P.15 • “We now appreciate that all cognitive abilities

result from the interaction of many simple processing mechanisms distributed in many different regions of the brain.”

Metaphor: railroad system

• These elementary operations are localized but they are interconnected.

• They often work in parallel. – “The better, more realistic metaphor is to think

of mental processes as several railroad lines that all feed into the same terminal.” P.16

– The damage to one pathway does not necessary interfere with the system as a whole.

Evidence:

• Historical findings– Ramon y Cajal– Frantz Joseph Gall– Pierre Paul Broca– Karl Wernickie– Affective traits and personality are localized.

Questions

• How much can I buy his idea of localization?

• Doesn’t this idea resonate with the “structuralist” approach?

• If so, can’t I apply the criticism that Gestalt psychologists raised for structuralism?

• How do you find “elementary cognitive operations”? What criteria do we use?

Swason (2009)

• Basic characteristic– Interconnection between structure and

function

• Evolutionary perspective– Simple organisms that do not have a nervous

system– Organisms with a simple nervous system

(sensory neurons, motor neurons, interneurons)

– Vertebrate nervous systems

• First multicellular animals (akin to modern-day sponges)– No nervous system– can’t move, but have smooth muscle cells. – These cells (independent effectors) react

directly to environmental chemicals. • 3min

– http://www.youtube.com/watch?v=BW05vMziy2o&feature=fvsr

– http://www.youtube.com/watch?v=Q3AdWGElTFw

• The first animal with a nervous system. – Jellyfish, corals, anemones, hydra– they can move (the first accomplishment of the

nervous system appears to be locomotion). • 1min• http://www.youtube.com/watch?v=GTXinF8ZVCo

Sensory neurons & Motor neurons

• the cells facing the external environment became specialized to detect stimuli. – Increased stimulus sensitivity– Faster responses– Some localization (sensory neurons

responding to different stimulus modalities can be distributed in different body regions.

Fig. 2.3

A: no nervous system. React directly to environmental stimuli (e.g., sponges)

B: sensory neurons detect stimuli and send signals directly to effector cells (e.g., muscle). They are sensorimotor neurons.

C: sensory neurons send signals to motor neurons, which send signals to effector cells.

interneurons

• E.g., flatworm http://en.wikipedia.org/wiki/Flatworm

• Bilateral symmetry• centralization

– the division of the nervous system such as the central nervous system and the peripheral nervous system

• cephalization– the concentration of nervous tissues –

head

Fig. 2.5

interneurons

• Create convergence and divergence of information processing• Excitatory and inhibitory signals.• The vase majority of vertebrate brain neurons are

interneurons (p. 20)

vertebrates• Animals that have backbones• Originated 520 million years ago during the Cambrian explosion

(Wikipedia)• The early stage of embryogenesis is basically the same in all

vertebrates. – Differentiation of the CNS and heart appear first– Prenatal brain development– 2:19 min; http://www.youtube.com/watch?v=UgT5rUQ9EmQ– 5:29 min http://www.youtube.com/watch?v=mMDPP-Wy3sI&feature=related

Basic plan of nervous system connectivity

• A model of basic wiring

S: sensory; I: intrinsic input; C: cognitive input

M: motor responseB: behavior

•There are basic connectivity divisions in cognitive, intrinsic, and sensory input.

•Cognitive, intrinsic, and sensory segments are interconnected.

•Cognitive, intrinsic, and sensory segments receive feedback from the motor system.

Motor systems•Motor systems are organized hierarchically.

•MN: motoneurons directly linked to muscle fibers. •MPG: motor pattern generator

•MPI: motor patter initiator (recognize and initiate MPG)

•Cognitive, intrinsic, and sensory segments all intervene the three levels directly.

Sensory systems

• There are several receptor types (e.g., visual, auditory, tactile, etc.)

• They work in parallel

Cognitive system

• The cerebral cortex and cerebral nuclei (basal ganglia) are most important part of the cognitive system

• Sensory responses reflexive

• Cognitive responses anticipatory

• (planning, prioritizing, initiating, evaluating)

Intrinsic systems

• Sleep-wake, arousal, motivational state

• Pleasure-pain,

• Feeling / affect

How pharmacological and genetic networks relate to

functional systems

• Pharmacological networks– Types of neurotransmitters, their dominant

release sites – Neurotransmitter systems are not by and

large functional systems

Summary p. 31

• “there is no simple relationship between the CNS’s topographic or regional differentiation and its functional organization.”

• “The CNS is more like a network rather than hierarchical organization.”

Overview of the adult mammalian

nervous system p. 31• CNS and PNS