100% satisfaction guarantee Immediately available after payment Both online and in PDF No strings attached
logo-home
Summary NHB (Neurobiology and Human Behaviour) Neurophysiology Practical Notes £2.99
Add to cart

Summary

Summary NHB (Neurobiology and Human Behaviour) Neurophysiology Practical Notes

 0 purchase

University of Cambridge (Medicine 1st class): Summary of key points of NHB (Neurobiology and Human Behaviour) Neurophysiology practicals for 2nd year.

Preview 2 out of 5  pages

  • June 29, 2023
  • 5
  • 2022/2023
  • Summary
All documents for this subject (32)
avatar-seller
rokesharumugam
NHB (Neurobiology and Human Behaviour)
Neurophysiology Practical Notes
Structure and function of eye
Mapping visual field and blind spot
Using perimeter
Meridians (i.e. angles from the vertical)
Nasal and temporal parts of eye field swapped on retina
Hunting animals have forward-facing eyes so larger binocular than monocular
field, prey have inverse
Fovea is central 5˚ (1-1.5mm, macula is ~6mm) but 30-50% of V1
Peripheral vision is needed for posture and walking
Range of accommodation is difference in power at near and far
Refractive error = (1/F - 2)
● 2 is for a lens
● F is furthest distance (m) that is in focus

Mapping blind spot
Paper is 28.5cm away from eye so 1 cm along the paper is ~2˚
● TOA: O is 1, A is 28.5, so angle is tan^-1(1/28.5) ~= 2˚
● Since 1 radian = 57˚, 28.5cm along the paper would be ~57˚, 1/28.5 of
that would be ~2˚
Blind spot is centred at 16-18˚ temporally (on visual field) from centre
Blind spot is 5-10˚ in diameter so 1.5 to 3mm on retina

Measuring visual acuity
An object 1.0 cm in size, viewed from a distance of 57.0 cm subtends an angle
of 1.0 degree.
300 µm on the retina is about 1 degree.
The slenderest foveal cone has a diameter of about 2.3 µm (30 seconds)
Retina is 17mm from the optics of the eye
Eye is ~20mm in diameter
Opticians charts are based on ‘normal’ acuity being 1 minute but its actually
40-30 seconds
you are nearly ten times better at detecting a vernier offset than the gap
between the prongs of a letter E
Thickness of retina
● Parafovea (where GC layer is thickest): ~418µm
○ Near optic disk is also thick because of GC axons not cell bodies
● Peripherally: ~200µm
Thickness of innermost layer of axons (GC axons)
● Parafovea: ~30µm
● Near optic disk: ~200µm

Histology of retina
The slender, lightly-stained outer segments of the receptors contain the
photopigments. The more substantial inner segments contain the densely-

, staining (pink) ellipsoids (bigger in cones than in rods).
The layer of GC axons is separated from the vitreous humour by the inner
limiting membrane, which is made of the dilated ends of Müller's cells
Viewing the retina
● (Scanning laser) ophthalmoscope for retina
○ Light does not go through lens
● Slit lamp (with Volk lens) for cornea
● Optical Coherence Tomography

Cutaneous sensation and ischaemic nerve block
Detection, localisation (is second stimulus in same place as former) and
resolution (are two close stimuli perceived as one) threshold
Detection
● Use Von Frey hair on non-hairy skin (otherwise indentation will also be
caused by disturbing hairs)
● compression is related to the length and thickness of the bristle

Ischaemia
Can cut off blood supply by inflating cuff to 160mmHg
All function is usually lost aft ~20mins, not safe to keep going past 30mins
Motor function
● Pincer grip plastic, record force to pull from grasp

Order of loss (theoretically)
● Large fibres (touch, vibration (Pacinian corpuscles have some of the
largest myelinated fibres), body position sense (proprioception),
muscle strength (Aa))
○ But grip strength can survive after light touch which goes against

muscles being all Aa (bigger) and touch being Ab
● small myelinated fibres (pin-prick pain, cool/cold)
● unmyelinated C fibres (warmth (pleasant sensation), itch, unpleasant
burning pain).

Observations
● 2-7mins: mild pins and needles that can be relieved by rubbing
● 10-15mins: paralysis of small hand muscles
○ Touch, deep pressure and position sense are lost before warmth,

cold and pain
○ But all are lost distal to proximal
○ Slow pain is lost later and becomes more unpleasant
● 12-15mins: numbness in fingertips
● 20-25mins: arm below cuff is mostly paralysed and anaesthetised
(except for slow pain)
● Last stages, only C fibres left
○ stimuli feel painful which had previously felt innocuous or (at least)

The benefits of buying summaries with Stuvia:

Guaranteed quality through customer reviews

Guaranteed quality through customer reviews

Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.

Quick and easy check-out

Quick and easy check-out

You can quickly pay through credit card for the summaries. There is no membership needed.

Focus on what matters

Focus on what matters

Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!

Frequently asked questions

What do I get when I buy this document?

You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.

Satisfaction guarantee: how does it work?

Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.

Who am I buying these notes from?

Stuvia is a marketplace, so you are not buying this document from us, but from seller rokesharumugam. Stuvia facilitates payment to the seller.

Will I be stuck with a subscription?

No, you only buy these notes for £2.99. You're not tied to anything after your purchase.

Can Stuvia be trusted?

4.6 stars on Google & Trustpilot (+1000 reviews)

64670 documents were sold in the last 30 days

Founded in 2010, the go-to place to buy revision notes and other study material for 15 years now

Start selling
£2.99
  • (0)
Add to cart
Added