ya, 2008)
Lesions of the:
A) rostral head of caudate impairment of working memory, strategy, formation, flexibility, neglect if right caudate or aphasia if left caudate
B) ventral striatum Behavioural disorders (e.g. disinhibition, irritability, obsessive compulsive disorder)
Forebrain - Thalamus (in Diencephalo) 1
The thalamus has a key role in transforming information to and from the cortex.
It is a large two-lobed structure.
The m***a intermedia is a sort of bridge that connects the two lobes.
The internal medullary lamina divides the medial from the lateral group of nuclei.
External medullary lamina forms the lateral boundary of the thalamus medial to the internal capsule, which contains afferent and efferent nerve fibres p***ing to and from the thalamus to the cerebral cortex
Thalamic nuclei are divided into:
Medial, Lateral and Anterior nuclei
plus the intralaminar nuclei
Each specific nucleus receives connection from the region of the cerebral cortex upon which it projects (usually primary motor and sensory areas)
Receive input from several areas and each nucleus projects to one of the three ***ociation cortex (P-T-O ***. c.; PreF c.; Limbic c.)
Widespread connections also towards other thalamic nuclei and some of these are inhibitory (e.g. reticular formation)
Forebrain - Thalamus 2
Thalamo-cortical projections run through the internal capsule. In the internal capsule there are also the fibers from cortex to
medulla and spinal cord.
The internal capsule continues more laterally and superiorly with the corona radiata, which contains descending axons of the corticospinal tract.
Forebrain - Hypothalamus
The Hypothalamus is a complex structure containing many nuclei and tracts.
It controls the autonomic nervous system and the endocrine system with direct link to the pituitary gland.
- Much of the endocrine system is controlled by hormones produced by cells in the hypothalamus. These hormones (realising – e.g. gonadotropin- releasing hormone) “instruct” the pituitary gland to secrete the specific hormone (e.g. gonadotropic hormone)
- Descending tracts to brain stem to regulate autonomic centres related to cardiovascular and breathing functions
- Integrating emotions and autonomic responses
- Link to centre for “set points” relating to appetite, body temperature -
Biological clock and circadian rhythms
- Link to limbic system
Forebrain - Limbic System (in Telencephalo)
subcallosal gyrus (anterior and inferior continuation of the cingulate gyrus)
Hippocampal formation (hippocampus, dentate gyrus and subiculum)
Amygdala has two important projections to hypothalamus and dorso-medial thalamic nuclei and it receives an important afferent input from the olfactory tract
Emotional processing (e.g. fear) and social behaviour
Bilateral damage of amygdala results in Klüver-Bucy syndrome
CT and MRI neuroimaging
How the brain looks like?
Computed tomography (CT).
Various attenuation intensity of x-rays according to type of tissue. This is computerised into numbers.
Positive numbers (+1,000) are represented white (e.g. bone), negative numbers (-1,000) are represented black (e.g. air)
The brain and related structures in CT
Structure/fluid/space - grey scale
Bone/acute blood - very white
Grey matter - light grey
White matter - medium grey
Cerebrospinal fluid - dark grey to black
Subacute blood - light grey
CT and MRI: MRI
Structure/fluid/space T1 T2
Bone - very black - very black
Air - very black - very black
Grey matter - dark grey - light grey
White matter - light grey - dark grey
Cerebrospinal fluid - very black - very white
Edema - Dark grey - light grey to white
CT and MRI: Advantages
Advantages of CT scan:
- Clearly shows acute and subacute hemorrhages into the meningeal spaces and brain
-Better in showing bone and bone fractures
-Rapid (important for emergency) and cheap
-Advantages of MRI scan:
-Excellent spatial resolution. It better differentiates white and grey matter than CT Scan.
-It clearly shows acute or subacute infarcts or ischemia or brain edema
-No radiation exposition and, at the present, not known harmful effects
