Development

EXAM 1

Neurogenesis

Mitosis (cell division)

• produces new neurons and glia (ventricular zone)

• neurons DONT divide once they are formed

Development Order

1. Neurogenesis

2. Migration

3. Differentiation

4. Apoptosis

Neuron Migration

cells move away from the ventricular layer

• they establish distinct populations

• Radial glial cells act as guides for cells to migrate along.

Gonadotropin Releasing Hormone (GnRH)

• master regulator of estrogen, progesterone, menstrual cycles, fertility, testosterone, sperm production, etc.

Kallmann’s Syndrome

• anosmic (inability to smell)

• they lack an olfactory bulb

  • smell and infertility

Cell Differentiation

once cells reach their destinations they begin to express their genes to make the proteins they need.

• allows a cell to acquire its specific appearance and function

cell-autonomous

• intrinsic

  • independent of other cells, driven by internal genes

neural environment

• extrinsic

  • affected by neighboring cells

sonic hedgehog

a gene regulating cell differentiation

• concentration influences differentiation

• produced in the base of the embryo

SHH concentrations

high: becomes MN (Motor Neurons)

low: becomes V1/2 (Interneurons)

Apoptosis

Clean, "gene-driven" suicide. The cell is recycled by the immune system.

• the neuron turns on a set of genes that results in the production of caspases that destroy the cell

  • cell recycled by immune system

Necrosis

"Messy" death from injury (stroke/toxin). The cell leaks and causes inflammation.

• stroke, or toxin, it swells and leaks

• teh dead cells build up and cause inflammation

growth factors

• neurons that do not receive enough growth factors begin apoptosis

• they keep neurons alive, need a specific threshold

ephrin-A receptor

when inactivated in mice, overgrowth of forebrain and folding of cerebral cortex

cortical development

• Researchers took scans of children with an MRI every 2 years for 8-10 years

• Tracked brain development changes in individuals

Synaptic Pruning

studies showed less synapses in teens than children

• The loss or development of synapses to fine-tune the circuit (pruning).

increased synapse density

mice with increased synapse density show less social motivation and recognition

Fragile X

• most common inherited cause of intellectual disability

• more severe impact in males

• mutation in (FMR-1)

FMR-1

• inhibits protein synthesis

• regulated by neural activity

  • without this, over-synthesis occurs

Phosphorylation

Adding a phosphate group to FMR1 blocks its activity, allowing protein synthesis to increase.

autism spectrum

harder times empathizing with neurotypical people

• LOWER activation of a frontal cortex area containing a type of cell referred to as mirror neurons

mirror neurons

• discovered in rhesus monkeys

• set of neurons active both while grabbing something AND watching someone grab something

transcranial magnetic stimulation (TMS)

stimulates regions containing motor neurons

• measures motor evoked potential

Autism cause

• NO CONSENSUS FOR A SINGLE CAUSE OF AUTISM

• numerous genes and environmental factors interact to produce autistic symptoms

• NO connection between vaccines

cognitive decline

• Often starts with spatial memory (e.g., forgetting where the car is parked).

• learning/memory declines with age

memory and aging

• older subjects show less cortical activation during memory retrieval

• may be explained by loss of neurons/ neuronal connections

Use it or Lose it" Principle

Risk of decline is reduced by:

• Complex, low-routine occupations.

• Intellectually stimulating activities (travel, reading).

• Having a spouse with "high cognitive status."