(Exam 2) Evolution, Development, & Brain Organization

Neurogenesis

process by which new, functional neurons are generated

Proliferation

• production of new cells

• 28 wks gestation

Megalencephaly

(bigger brain) results from over-proliferation

Microencephaly

(smaller brain) Results from reduced proliferation

Chemicals guide neuron ____ until adulthood

migration

Deficit in chemicals lead to….

decreased brain size and decreased axon growth

Differentiation

Cell changes into a specialized type of neuron

• axon and dendrites form

What grows first: axons or dendrites?

axons

dendrites start forming after ____

migration, when neurons reach destination

Myelination….

continues gradually through adolescence and adulthood

synaptogenesis

• process where neurons form new synapses & discard old ones

• (slows down in older ppl)

Synaptic Pruning

process where the brain eliminates weak, unused, or redundant neural connections (synapses)

too much synaptic pruning can lead to

memory loss (alzheimer’s)

too little synaptic pruning can lead to

overstimulations (Autism, schizophrenia)

Fine tuning by experience

brain's ability to reorganize and form new neural connections in response to learning, experience, or targeted practice

A _______ enhances sprouting of axons and dendrites in many species

stimulating enviornment

BDNF

Brain derived neurotrophic factor (protein; supports the survival, growth, and maintenance of neurons)

The spinal cord communicates with

sense organs and muscles

Each segment of the spinal cord sends ____ information to the brain

sensory

Each segment of the spinal cord receives ____ ____ from the brain

motor commands

Strategies after spinal cord injury

stem cells& glial cells promote regeneration, neurotrophic factos, electrical stimulation

Hindbrain

Postural support:

• medulla

• pons

• cerebellum

medulla

contains nuclei that regulate vital functions (i.e. breathing, heart rate)

pons

acts as bridge

cerebellum

“little brain” crucial for motor coordination

Disconnection of hindbrain from the rest of the brain

vegetative state

Midbrain

Spontaneous behavior

• sensory and motor components

• important for operant behaviors

Diencephalon

• Thalamus

• Hypothalamus

• pituitary gland

Thalamus

• “switch box”

• directs incoming sensory info to the appropriate regions of cortex

• receives instructions from cortex regarding which sensory info is to be transmitted

Hypothalamus

Important for motivated behaviors (i.e. sleep, eating, fight/flight), thermo regulation

Pituitary gland

Hormones

• communicates with hypothalamus

Telencephalon

• limbic system

• basil ganglia

• cortex

Limbic System

important for emotion, learning, and memory

Including hippocampus, cingulate gyrus, olfactory bulb, & amygdala

Basil ganglia

muscle/procedural memory

Includes: caudate nucleus, putamen, globus pallidus, and SN

Basil ganglia is reciprocally connected with the ____ forming and _____

• cerebral cortext

• looping neural system

Cortex

intention; skilled movements and sequences, problem solving

How is the cortex split?

Output: frontal

Input: temporal, parietal, occipital (sensory)

Cortical organization

Layers: input and output

Columns: Interaction (function)

Neurons within a column are

functionally similar

Most interactions between neurons take place ____

vertically

Different columns pertain to

different body parts

column modules are more apparent in

sensory regions

Middle layers (IV)

input zone of sensory analysis; sensory areas have a larger layer

Layers V and VI

output zone; send axons to other cortical and brain areas

Motor areas have a large layer ___ and a small layer ___

V, IV

Superficial Layers (i.e. II & III)

Receive inputs from other cortical areas and integrate them with inputs from layer IV.