ACC Lesions
•anterior cingulate cortex (ACC) error detection and monitoring
- lesions of ACC causes a complete cessation of motivated behavior - akinetic mutism, milder form called abulia
- caused by vascular pathology of ACA
PCC Dysfunction
•posterior cingulate cortex (PCC) spatial memory, configural learning, discriminative avoidance learning, emotional salience and autobiographical memories - more inward directed attention
-functional abnormalities are associated with Alzheimer’s, ADHD, autism, major depression and schizophrenia
Insula
pain, gustatory, vestibular
•empathy
•sense of humour
•lust and disgust, guilt, moral intuition
•damage can lead to apathy, loss of sexual desire, loss of disgust for unpalatable food, loss of craving for food, cigarettes, drugs and autonomic disorders such as neurogenic arrythmia and sudden cardia death
Amygdala
- collection of nuclei
- emotional center, attributes positive, neutral or negative values to all the stimulus and events encountered
- anxiety disorders, social phobias
•basolateral
-cortex
•central
brainstem, olfactory system
-damage causes pronounced autonomic responses- PTSD
•corticomedial
-hypothalamus
Forebrain Center for Sleep/Wakefulness
Damage around walls of 3rd ventricle and mid to caudal hypothalamus—-> drowsiness and lethargy
Damage to vicinity of lamina terminalis —-> wakefulness
Momoamergic neurons in the tuberomammillary nucleus project to widespread CNS areas, releasing histamine.
Histamine depolarises both thalamic and cortical neurons, and turning these histaminergic neurons off causes drowsiness or sleep.
Lateral mid -hypothalamus has a set of neurons with excitatory connections that use orexin (hypocretin) and communicate with ARAS and the histamine neurons.
Cholinergic neurons of the basal nucleus increase the excitability of cortical neurons.
GABAergic neurons of the preoptic region and anterior hypothalamus periodically inhibit the orexin and histamine neurons —-> sleep. These neurons receive input from the suprachiasmatic nucleus
Brainstem Centers for Sleep/Wakefulness
Ascending Reticular Activating System (ARAS) system is responsible for maintaining consciousness. (Midbrain RF, cholinergic cells and monoaminergic fibers that pass through it.)
- affects thalamus by shifting relay and association nuclei into tonic mode, and also to some midline and intralaminar nuclei which project to cortical areas, “activating” them.
- also through MFB directly to cortex
Reticular structures in the rostral medulla and caudal pons periodically participate in turning ARAS on and off, producing wakefulness and sleep. Lesions to the mid-pontine area can disconnect these structures —-> ARAS being left on.
Blood Supply Frontal Lobe
- Lateral surface - MCA
- Medial surface - ACA
- Inferior surface - ACA (VMPFC) and MCA (orbital frontal cortex)
Blood Supply Parietal Lobe
- Lateral surface - MCA
* Medial surface - ACA
Blood Supply Occipital Lobe
- Lateral surface - MCA
* Medial and interior surface - PCA
Blood Supply Temporal Lobe
- Lateral surface - MCA
- Medial inferior surface - PCA (fusiform gyrus, hippocampus)
- Anterior Temporal Pole - ICA and MCA (piriform cortex)
Blood Supply Limbic Lobe
- Cingulate Gyrus - ACA
* Parahippocampal Gyrus - PCA
Insula - MCA
•MCA
Blood Supply to Caudate Nucleus (head)
•perforating branches from MCA - lenticularstriate arteries (lacunar infarcts)
Blood Supply to Putamen
•perforating branches from MCA - lenticularstriate arteries (lacunar infarcts)
Blood Supply to Globus Pallidus
•Anterior Choroidal artery and perforating branches from the MCA
Blood Supply to Nucleus Accumbens
•perforating branches from ACA - medial striate artery (will also supply smal parts of the caudate and putamen)
Blood Supply to Amygdala
•Anterior Choroidal Artery (originates from ICA)
Blood Supply to Hippocampus
•PCA
Blood Supply to Thalamus
•perforating branches from the PCA, Posterior Communicating
Blood Supply to Internal Hypothalamus
•Posterior and Anterior Communicating, perforating branches of ICA (Anterior Choroidal)
Blood Supply to Internal Capsule
- Anterior Limb - perforating branches from ACA
- Posterior Limb - branches from MCA - Lenticulostriate and Anterior Choroidal
- Sub and Retro - lenticular - perforating branches from PCA
Blood SUply to Corpus Callosum
- genu and body - ACA
* selenium - PCA
Blood Supply to Cerebellum
- Superior surface - SCA
* Inferior surface, Anterior surface - PICA and AICA
Blood Supply to Brainstem
•Midbrain lateral - SCA
medial - PCA and BA
•Pons lateral - AICA
medial - BA
•Medulla lateral - PICA medial - VA and Anterior SPinal Arteries
