1b - Brain Anatomy and Localisation of Behaviour Flashcards
Outline the Basic Structure of the Nervous System
The Nervous System is split into the CENTRAL (CNS) and the Peripheral (PNS)
CNS
–> Brain and Spinal Cord
Brain:
- Brain Stem
- Cerebral Hemispheres
Cerebral Hemispheres:
- Cortex
- Subcortical Structures
- White-matter tracts
PNS
–> Somatic and Autonomic Nervous System
Autonomic Nervous System
- Sympathetic Nervous System
- Parasympathetic Nervous System
Outline Basic Brain Anatomy Development
The nervous system begins to develop at about 2 weeks
- it starts as a little group of cells that slowly thickens
- It then differentiates into a fore/mid/hind brain
- It then folds overitslef
–> During this: the forebrain develops into the CORTEX, the midbrain develops into structures like the THALAMUS (close to the brainstem), and the HINDBRAIN develops into the cerebellum
Basics: What is the corpus collosum
White matter tracts (numerous axons) connecting the two hemispheres
What is grey matter? What is white matter? What is a gyrus? What is a sulcus?
Grey Matter
–> Body/soma of a neuron
–> Is on the outer part of the brain
White Matter
–> Situated under the grey matter
–> Made of the long elongated part of the nerve cells (axon) - the white appearance of white matter comes from the light colour of myelin
Gyrus –> a plateau on cortical surfaces
Sulcus –> a fold/ditch in cortical surface (major sulci are often referred to as fissures)
Name some of the major gyruses
Precentral gyrus and postcentral gyrus
Frontal Gyrus (frontal lobe)
from top to bottom, superior, middle, inferior
Temporal Gyrus (temporal lobe)
again superior, middle, inferior
Name some of the major sulci
The major sulci have been used to divide the brain into four parts
LEFT: parieto-occipital sulcus
CENTRAL: Central sulcus/fissure
RIGHT-BOTTOM: Sylvian fissure
Basics: How is the cerebral hemisphere divided into lobes?
The cerebral hemispheres are divided into four lobes separated by the three major sulci:
- central sulcus, lateral sulcus, parietal-occipital sulcus
INTO
Frontal lobe
Temporal Lobe (bottom)
Parietal lobe
Occipital lobe (back - small)
Coordinates and Orientations: Outline the meanings of…
- Superior/Dorsal
- Anterior/Rostral
- Posterior/Caudal
- Inferior/Ventral
- Lateral
- Medial
Superior/Dorsal: means UP
Anterior/Rosteal: means FRONT
Posterior/Caudal: means BACK
Inferior/Ventral: means BELOW
Lateral - means ‘outside’
Medial - means ‘inside’
Orientation of ‘Slices’
-What is an AXIAL slice
- What is a CORONAL slice
- What is a SAGITTAL slice?
Axial: Horizontally (through the MIDDLE)
Coronal: Top to bottom
Sagittal: Front to back
What is Cytoarchitecture
How the brain is divided into regions from an anatomical perspective - what areas have the same CELL TYPE
Brodmann found that cortical regions vary in the detailed cellular structure (types of neurons) and cellular arrangement (layers and density)
–> These are known as Brodmann areas and have a loose relation to function
Localisation of Function: What is the brain stem
Brain Stem: Lies in the middle of our brain
- Involved in managing vital functions
- Basic physiological and metabolic processes are controlled by groups of neurons in the brainstem –> including the THALAMUS and HYPOTHALAMUS
–> These functions such as respiration, digestion, glucose metabolism etc.
(Well protected area = it is VITAL)
Eg. cells in the core of the brainstem involved in the control of arousal and sleep (communicates with hypothalamus)
Perception: How is perception hierarchically organised
The cortical areas where the sensory information arrives are referred to as PRIMARY VISUAL/AUDITORY/SENSORY-MOTOR AREAS
–> This perceptual information then gets passed to the secondary sensory areas, where more sophisticated processing takes place
–> From the secondary sensory areas, the processing moves to the ASSOCIATION AREAS, where information from different modalities is integrated
Thalamic Nuclei are relays for sensory information
Visual Perception: Hierarchical Organisation
Visual processing is segregated into…
- what pathway: specialised in the analysis of the stimulus features
- where pathway: specialised in rapid detection of stimulus location and motion
Motor Functions: How are they organised hierarchically
The control of movement has a similar structure
1. Primary motor cortex - exerts direct control over movement
2. Premotor and supplementary motor areas - involved in the planning of movements and integration of motor behaviour with other behaviour
3. Some subcortical structures (Basal Ganglia and brainstem structures - are also involved in the fine-grained coordination and timing of movements
Brodmanns areas 4,6,8
What are the challenges for localising function in these key examples:
–> Dorso-lateral prefrontal cortex
–> Broca’s area
Dorso-lateral prefrontal cortex is extremely pronounced in humans
–> YET: patients with lesions to this region rarely show specific deficits - seem normal
Lateral frontal cortex - home of internally driven action (movement, speaking, working memory)
Broca’s Area
–> left of the brain
–> damage = acute language problem (Broca’s aphasia)
–> organisation of vocal expression
BUT
–> Studies that use language tasks don’t find activity in the Broca’s area, and studies that don’t use language tasks DO find Broca’s activation
–> Area is active in various tasks
