Functional Neuroanatomy. IBRO ISN African Neuroscience School 4-13 th Dec 2014 Nairobi, Kenya

Size: px

Start display at page:

Download "Functional Neuroanatomy. IBRO ISN African Neuroscience School 4-13 th Dec 2014 Nairobi, Kenya"

Candace Powers
5 years ago
Views:

1 Functional Neuroanatomy IBRO ISN African Neuroscience School 4-13 th Dec 2014 Nairobi, Kenya

2 What is/are the function(s) of the nervous system? Sensation Perception Visceral activities (Homeostasis) Behavior Cognitive function Learning Thinking Problem solving Motivation Emotions Arousal

3 billion nerve cells 10,000 different types of neurons Similar nerve cells form clusters (nuclei) involved in specific function. How many synapses?

4 Nerve Cells Very diverse morphology and phenotype

5 (D) Schwann Cells Glia Cells

8 Neuroscience 4 th Edition Divisions of the Nervous System Central Nervous System Peripheral Nervous System Autonomic Nervous System Enteric Nervous System

9 What is/are the function(s) of the nervous system? Sensation Perception Visceral activities (Homeostasis) Behavior Cognitive function Learning Thinking Problem solving Motivation Emotions Arousal

10 Localized or not?

11 Are Brain Functions Localized? Fritsch and Hitzig (1870) Penfield (1950 s) Lashley (1950 s) PET studies Some functions are localized Others are diffusely distributed

12 Phrenology anticipated localization of cerebral functions

13 Nervous System Input External and internal stimuli Nervous System Processing Retrieval Storage Routing to different regions Output Motor behavior

14 Inputs Somatic Nervous System

18 Spinothalamic pathway (Anterolateral Pathway) 2 Pain Transmission Pathways for Location, Intensity & Quality Trigeminal pathway Neuroscience Purves et al.

PAG sends signals to the parabrachial nucleus, medullary reticular formation, locus coeruleus, and Raphe

19 Endogenous Pain Modulation Nerve signals are sent form the somatic sensory cortex and hypothalamus to the periaqueductal gray matter (PAG). PAG sends signals to the parabrachial nucleus, medullary reticular formation, locus coeruleus, and Raphe nucleus. These in turn can control the in the transmission of nociceptive signals from the spinal cord to the brain. This involves different neurotransmitters, e.g., noradrenaline, serotonin.

20 Inputs - Visceral

21 Inputs from the special senses

22 Motor Output

23 Output - motor

24 Autonomic Endocrine

26 Nervous System Input External and internal stimuli Nervous System Processing Retrieval Storage Routing to different regions Output Motor behavior

27 Stretch Reflex

29 Pattern Generators

31 Organization of motor system Indirect Activation Pathways Direct Activation Pathways Control circuits Final common pathway

33 Behavior and brain functions have neuronal circuits which communicate with other circuits.

34 Emotions

35 Limbic Circuit - Emotions

36 What happens when that circuit is activated?

37 Language Function understanding language spoken language Broca s area Inferior frontal lobule Wernike s area Supramarginal gyrus. Brain functions are determined by: 1) how information is routed to a particular brain region and 2) the local circuits & properties of a region

38 Memory and Learning Memory -Storage of information, facts, and skills. Learning change in behavior or thought patterns. Journal club on this Hippocampus

39 Addictive Behavior

40 Areas of the Prefrontal Cortex

41 5% of the cortical area Frontal cortex Parietal cortex Temporal cortex

42 Cortical Functions

43 Lesions of the Parietal Association Cortex: Deficits of attention In 1941, British neurologist, W. R. Brain, reported three patients with unilateral parietal lobe lesions in whom the primary problem was varying degrees of perceptual difficulty. Contralateral neglect syndrome

44 Though not suffering from a loss of topographical memory or an inability to describe familiar routes, they nonetheless got lost in going from one room to another in their own homes, always making the same error of choosing a right turn instead of a left, or a door on the right instead of one on the left. In each case there was a massive lesion in the right parieto-occipital region, and it is suggested that this resulted in an inattention to or a neglect of the left external space. The patient who is thus cut off from the sensations which are necessary for the construction of a body scheme may react to the situation in several different ways. He may remember that the limbs on his left side are still there, or he may periodically forget them until reminded of their presence. He may have an illusion of their absence, i.e. they may feel absent although he knows that they are there; he may believe that they are absent but allows himself to be convinced by evidence to the contrary; or, finally, his belief in their absence may be unamenable to reason and evidence to the contrary and so constitute a delusion. W.R. Brain, 1941 (Brain 64:pp. 257 and 264) Generally considered the first account of the link between parietal lobe lesions and deficits in attention or perceptual awareness.

45 Contralateral neglect syndrome Inability to perceive and attend to objects, or even one s own body, in a part of space, despite the fact that visual acuity, somatic sensation, and motor ability remain intact. Affected individuals fail to report, respond to, or even orient to stimuli presented to the side of the body or visual space opposite the lesion. Difficulty in performing complex motor tasks on the neglected side, including dressing themselves, reaching for objects, writing, drawing, and, to a less extent, orienting to sounds. Signs of neglect can be temporary or permanent denial of the existence of the side body or extrapersonal space opposite the lesion.

46 The location of the underlying lesions in eight patients diagnosed with contralateral neglect syndrome Heilman & Valenstein, 1985

47 Characteristic performance on visuospatial tasks by individuals suffering from contralateral neglect syndrome Self portraits by artist Anton Raederscheidt A, B from Prosner & Raichle, 1994 C from Jung, 1974

48 Function is subserved by neuronal circuits. Neuronal circuits talk to each other. An motor or mental output is produced. reflection will either result in the output being carried out or suppressed. Some outputs are out of consciousness control % is sub-consciousness processing.

49 Reference Purves et al Neuroscience. PubMed Bookshelf

Modules 4 & 6. The Biology of Mind

Modules 4 & 6. The Biology of Mind Modules 4 & 6 The Biology of Mind 1 Neuron - 100 Billion - Communication System Glial cells Cell body (nucleus) Dendrites Axon Axon Terminals (terminal buttons) Synaptic cleft 3 4 Communication Within